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android-kvm / linux / cd7fa3e1b0bc9c210eba23edbe8d6884f0368281 / . / arch / s390 / mm / gmap.c
blob: 329682655af26f581712f99a02afde3631d24fc2 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* KVM guest address space mapping code
*
* Copyright IBM Corp. 2007, 2020
* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
* David Hildenbrand <david@redhat.com>
* Janosch Frank <frankja@linux.vnet.ibm.com>
*/
#include <linux/kernel.h>
#include <linux/pagewalk.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/swapops.h>
#include <linux/ksm.h>
#include <linux/mman.h>
#include <linux/pgtable.h>
#include <asm/page-states.h>
#include <asm/pgalloc.h>
#include <asm/gmap.h>
#include <asm/page.h>
#include <asm/tlb.h>
#define GMAP_SHADOW_FAKE_TABLE 1ULL
static struct page *gmap_alloc_crst(void)
{
struct page *page;
page = alloc_pages(GFP_KERNEL_ACCOUNT, CRST_ALLOC_ORDER);
if (!page)
return NULL;
__arch_set_page_dat(page_to_virt(page), 1UL << CRST_ALLOC_ORDER);
return page;
}
/**
* gmap_alloc - allocate and initialize a guest address space
* @limit: maximum address of the gmap address space
*
* Returns a guest address space structure.
*/
static struct gmap *gmap_alloc(unsigned long limit)
{
struct gmap *gmap;
struct page *page;
unsigned long *table;
unsigned long etype, atype;
if (limit < _REGION3_SIZE) {
limit = _REGION3_SIZE - 1;
atype = _ASCE_TYPE_SEGMENT;
etype = _SEGMENT_ENTRY_EMPTY;
} else if (limit < _REGION2_SIZE) {
limit = _REGION2_SIZE - 1;
atype = _ASCE_TYPE_REGION3;
etype = _REGION3_ENTRY_EMPTY;
} else if (limit < _REGION1_SIZE) {
limit = _REGION1_SIZE - 1;
atype = _ASCE_TYPE_REGION2;
etype = _REGION2_ENTRY_EMPTY;
} else {
limit = -1UL;
atype = _ASCE_TYPE_REGION1;
etype = _REGION1_ENTRY_EMPTY;
}
gmap = kzalloc(sizeof(struct gmap), GFP_KERNEL_ACCOUNT);
if (!gmap)
goto out;
INIT_LIST_HEAD(&gmap->crst_list);
INIT_LIST_HEAD(&gmap->children);
INIT_LIST_HEAD(&gmap->pt_list);
INIT_RADIX_TREE(&gmap->guest_to_host, GFP_KERNEL_ACCOUNT);
INIT_RADIX_TREE(&gmap->host_to_guest, GFP_ATOMIC | __GFP_ACCOUNT);
INIT_RADIX_TREE(&gmap->host_to_rmap, GFP_ATOMIC | __GFP_ACCOUNT);
spin_lock_init(&gmap->guest_table_lock);
spin_lock_init(&gmap->shadow_lock);
refcount_set(&gmap->ref_count, 1);
page = gmap_alloc_crst();
if (!page)
goto out_free;
page->index = 0;
list_add(&page->lru, &gmap->crst_list);
table = page_to_virt(page);
crst_table_init(table, etype);
gmap->table = table;
gmap->asce = atype | _ASCE_TABLE_LENGTH |
_ASCE_USER_BITS | __pa(table);
gmap->asce_end = limit;
return gmap;
out_free:
kfree(gmap);
out:
return NULL;
}
/**
* gmap_create - create a guest address space
* @mm: pointer to the parent mm_struct
* @limit: maximum size of the gmap address space
*
* Returns a guest address space structure.
*/
struct gmap *gmap_create(struct mm_struct *mm, unsigned long limit)
{
struct gmap *gmap;
unsigned long gmap_asce;
gmap = gmap_alloc(limit);
if (!gmap)
return NULL;
gmap->mm = mm;
spin_lock(&mm->context.lock);
list_add_rcu(&gmap->list, &mm->context.gmap_list);
if (list_is_singular(&mm->context.gmap_list))
gmap_asce = gmap->asce;
else
gmap_asce = -1UL;
WRITE_ONCE(mm->context.gmap_asce, gmap_asce);
spin_unlock(&mm->context.lock);
return gmap;
}
EXPORT_SYMBOL_GPL(gmap_create);
static void gmap_flush_tlb(struct gmap *gmap)
{
if (MACHINE_HAS_IDTE)
__tlb_flush_idte(gmap->asce);
else
__tlb_flush_global();
}
static void gmap_radix_tree_free(struct radix_tree_root *root)
{
struct radix_tree_iter iter;
unsigned long indices[16];
unsigned long index;
void __rcu **slot;
int i, nr;
/* A radix tree is freed by deleting all of its entries */
index = 0;
do {
nr = 0;
radix_tree_for_each_slot(slot, root, &iter, index) {
indices[nr] = iter.index;
if (++nr == 16)
break;
}
for (i = 0; i < nr; i++) {
index = indices[i];
radix_tree_delete(root, index);
}
} while (nr > 0);
}
static void gmap_rmap_radix_tree_free(struct radix_tree_root *root)
{
struct gmap_rmap *rmap, *rnext, *head;
struct radix_tree_iter iter;
unsigned long indices[16];
unsigned long index;
void __rcu **slot;
int i, nr;
/* A radix tree is freed by deleting all of its entries */
index = 0;
do {
nr = 0;
radix_tree_for_each_slot(slot, root, &iter, index) {
indices[nr] = iter.index;
if (++nr == 16)
break;
}
for (i = 0; i < nr; i++) {
index = indices[i];
head = radix_tree_delete(root, index);
gmap_for_each_rmap_safe(rmap, rnext, head)
kfree(rmap);
}
} while (nr > 0);
}
/**
* gmap_free - free a guest address space
* @gmap: pointer to the guest address space structure
*
* No locks required. There are no references to this gmap anymore.
*/
static void gmap_free(struct gmap *gmap)
{
struct page *page, *next;
/* Flush tlb of all gmaps (if not already done for shadows) */
if (!(gmap_is_shadow(gmap) && gmap->removed))
gmap_flush_tlb(gmap);
/* Free all segment & region tables. */
list_for_each_entry_safe(page, next, &gmap->crst_list, lru)
__free_pages(page, CRST_ALLOC_ORDER);
gmap_radix_tree_free(&gmap->guest_to_host);
gmap_radix_tree_free(&gmap->host_to_guest);
/* Free additional data for a shadow gmap */
if (gmap_is_shadow(gmap)) {
struct ptdesc *ptdesc, *n;
/* Free all page tables. */
list_for_each_entry_safe(ptdesc, n, &gmap->pt_list, pt_list)
page_table_free_pgste(ptdesc);
gmap_rmap_radix_tree_free(&gmap->host_to_rmap);
/* Release reference to the parent */
gmap_put(gmap->parent);
}
kfree(gmap);
}
/**
* gmap_get - increase reference counter for guest address space
* @gmap: pointer to the guest address space structure
*
* Returns the gmap pointer
*/
struct gmap *gmap_get(struct gmap *gmap)
{
refcount_inc(&gmap->ref_count);
return gmap;
}
EXPORT_SYMBOL_GPL(gmap_get);
/**
* gmap_put - decrease reference counter for guest address space
* @gmap: pointer to the guest address space structure
*
* If the reference counter reaches zero the guest address space is freed.
*/
void gmap_put(struct gmap *gmap)
{
if (refcount_dec_and_test(&gmap->ref_count))
gmap_free(gmap);
}
EXPORT_SYMBOL_GPL(gmap_put);
/**
* gmap_remove - remove a guest address space but do not free it yet
* @gmap: pointer to the guest address space structure
*/
void gmap_remove(struct gmap *gmap)
{
struct gmap *sg, *next;
unsigned long gmap_asce;
/* Remove all shadow gmaps linked to this gmap */
if (!list_empty(&gmap->children)) {
spin_lock(&gmap->shadow_lock);
list_for_each_entry_safe(sg, next, &gmap->children, list) {
list_del(&sg->list);
gmap_put(sg);
}
spin_unlock(&gmap->shadow_lock);
}
/* Remove gmap from the pre-mm list */
spin_lock(&gmap->mm->context.lock);
list_del_rcu(&gmap->list);
if (list_empty(&gmap->mm->context.gmap_list))
gmap_asce = 0;
else if (list_is_singular(&gmap->mm->context.gmap_list))
gmap_asce = list_first_entry(&gmap->mm->context.gmap_list,
struct gmap, list)->asce;
else
gmap_asce = -1UL;
WRITE_ONCE(gmap->mm->context.gmap_asce, gmap_asce);
spin_unlock(&gmap->mm->context.lock);
synchronize_rcu();
/* Put reference */
gmap_put(gmap);
}
EXPORT_SYMBOL_GPL(gmap_remove);
/*
* gmap_alloc_table is assumed to be called with mmap_lock held
*/
static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
unsigned long init, unsigned long gaddr)
{
struct page *page;
unsigned long *new;
/* since we dont free the gmap table until gmap_free we can unlock */
page = gmap_alloc_crst();
if (!page)
return -ENOMEM;
new = page_to_virt(page);
crst_table_init(new, init);
spin_lock(&gmap->guest_table_lock);
if (*table & _REGION_ENTRY_INVALID) {
list_add(&page->lru, &gmap->crst_list);
*table = __pa(new) | _REGION_ENTRY_LENGTH |
(*table & _REGION_ENTRY_TYPE_MASK);
page->index = gaddr;
page = NULL;
}
spin_unlock(&gmap->guest_table_lock);
if (page)
__free_pages(page, CRST_ALLOC_ORDER);
return 0;
}
/**
* __gmap_segment_gaddr - find virtual address from segment pointer
* @entry: pointer to a segment table entry in the guest address space
*
* Returns the virtual address in the guest address space for the segment
*/
static unsigned long __gmap_segment_gaddr(unsigned long *entry)
{
struct page *page;
unsigned long offset;
offset = (unsigned long) entry / sizeof(unsigned long);
offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
page = pmd_pgtable_page((pmd_t *) entry);
return page->index + offset;
}
/**
* __gmap_unlink_by_vmaddr - unlink a single segment via a host address
* @gmap: pointer to the guest address space structure
* @vmaddr: address in the host process address space
*
* Returns 1 if a TLB flush is required
*/
static int __gmap_unlink_by_vmaddr(struct gmap *gmap, unsigned long vmaddr)
{
unsigned long *entry;
int flush = 0;
BUG_ON(gmap_is_shadow(gmap));
spin_lock(&gmap->guest_table_lock);
entry = radix_tree_delete(&gmap->host_to_guest, vmaddr >> PMD_SHIFT);
if (entry) {
flush = (*entry != _SEGMENT_ENTRY_EMPTY);
*entry = _SEGMENT_ENTRY_EMPTY;
}
spin_unlock(&gmap->guest_table_lock);
return flush;
}
/**
* __gmap_unmap_by_gaddr - unmap a single segment via a guest address
* @gmap: pointer to the guest address space structure
* @gaddr: address in the guest address space
*
* Returns 1 if a TLB flush is required
*/
static int __gmap_unmap_by_gaddr(struct gmap *gmap, unsigned long gaddr)
{
unsigned long vmaddr;
vmaddr = (unsigned long) radix_tree_delete(&gmap->guest_to_host,
gaddr >> PMD_SHIFT);
return vmaddr ? __gmap_unlink_by_vmaddr(gmap, vmaddr) : 0;
}
/**
* gmap_unmap_segment - unmap segment from the guest address space
* @gmap: pointer to the guest address space structure
* @to: address in the guest address space
* @len: length of the memory area to unmap
*
* Returns 0 if the unmap succeeded, -EINVAL if not.
*/
int gmap_unmap_segment(struct gmap *gmap, unsigned long to, unsigned long len)
{
unsigned long off;
int flush;
BUG_ON(gmap_is_shadow(gmap));
if ((to | len) & (PMD_SIZE - 1))
return -EINVAL;
if (len == 0 || to + len < to)
return -EINVAL;
flush = 0;
mmap_write_lock(gmap->mm);
for (off = 0; off < len; off += PMD_SIZE)
flush |= __gmap_unmap_by_gaddr(gmap, to + off);
mmap_write_unlock(gmap->mm);
if (flush)
gmap_flush_tlb(gmap);
return 0;
}
EXPORT_SYMBOL_GPL(gmap_unmap_segment);
/**
* gmap_map_segment - map a segment to the guest address space
* @gmap: pointer to the guest address space structure
* @from: source address in the parent address space
* @to: target address in the guest address space
* @len: length of the memory area to map
*
* Returns 0 if the mmap succeeded, -EINVAL or -ENOMEM if not.
*/
int gmap_map_segment(struct gmap *gmap, unsigned long from,
unsigned long to, unsigned long len)
{
unsigned long off;
int flush;
BUG_ON(gmap_is_shadow(gmap));
if ((from | to | len) & (PMD_SIZE - 1))
return -EINVAL;
if (len == 0 || from + len < from || to + len < to ||
from + len - 1 > TASK_SIZE_MAX || to + len - 1 > gmap->asce_end)
return -EINVAL;
flush = 0;
mmap_write_lock(gmap->mm);
for (off = 0; off < len; off += PMD_SIZE) {
/* Remove old translation */
flush |= __gmap_unmap_by_gaddr(gmap, to + off);
/* Store new translation */
if (radix_tree_insert(&gmap->guest_to_host,
(to + off) >> PMD_SHIFT,
(void *) from + off))
break;
}
mmap_write_unlock(gmap->mm);
if (flush)
gmap_flush_tlb(gmap);
if (off >= len)
return 0;
gmap_unmap_segment(gmap, to, len);
return -ENOMEM;
}
EXPORT_SYMBOL_GPL(gmap_map_segment);
/**
* __gmap_translate - translate a guest address to a user space address
* @gmap: pointer to guest mapping meta data structure
* @gaddr: guest address
*
* Returns user space address which corresponds to the guest address or
* -EFAULT if no such mapping exists.
* This function does not establish potentially missing page table entries.
* The mmap_lock of the mm that belongs to the address space must be held
* when this function gets called.
*
* Note: Can also be called for shadow gmaps.
*/
unsigned long __gmap_translate(struct gmap *gmap, unsigned long gaddr)
{
unsigned long vmaddr;
vmaddr = (unsigned long)
radix_tree_lookup(&gmap->guest_to_host, gaddr >> PMD_SHIFT);
/* Note: guest_to_host is empty for a shadow gmap */
return vmaddr ? (vmaddr | (gaddr & ~PMD_MASK)) : -EFAULT;
}
EXPORT_SYMBOL_GPL(__gmap_translate);
/**
* gmap_translate - translate a guest address to a user space address
* @gmap: pointer to guest mapping meta data structure
* @gaddr: guest address
*
* Returns user space address which corresponds to the guest address or
* -EFAULT if no such mapping exists.
* This function does not establish potentially missing page table entries.
*/
unsigned long gmap_translate(struct gmap *gmap, unsigned long gaddr)
{
unsigned long rc;
mmap_read_lock(gmap->mm);
rc = __gmap_translate(gmap, gaddr);
mmap_read_unlock(gmap->mm);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_translate);
/**
* gmap_unlink - disconnect a page table from the gmap shadow tables
* @mm: pointer to the parent mm_struct
* @table: pointer to the host page table
* @vmaddr: vm address associated with the host page table
*/
void gmap_unlink(struct mm_struct *mm, unsigned long *table,
unsigned long vmaddr)
{
struct gmap *gmap;
int flush;
rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
flush = __gmap_unlink_by_vmaddr(gmap, vmaddr);
if (flush)
gmap_flush_tlb(gmap);
}
rcu_read_unlock();
}
static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *old, pmd_t new,
unsigned long gaddr);
/**
* __gmap_link - set up shadow page tables to connect a host to a guest address
* @gmap: pointer to guest mapping meta data structure
* @gaddr: guest address
* @vmaddr: vm address
*
* Returns 0 on success, -ENOMEM for out of memory conditions, and -EFAULT
* if the vm address is already mapped to a different guest segment.
* The mmap_lock of the mm that belongs to the address space must be held
* when this function gets called.
*/
int __gmap_link(struct gmap *gmap, unsigned long gaddr, unsigned long vmaddr)
{
struct mm_struct *mm;
unsigned long *table;
spinlock_t *ptl;
pgd_t *pgd;
p4d_t *p4d;
pud_t *pud;
pmd_t *pmd;
u64 unprot;
int rc;
BUG_ON(gmap_is_shadow(gmap));
/* Create higher level tables in the gmap page table */
table = gmap->table;
if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION1) {
table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
if ((*table & _REGION_ENTRY_INVALID) &&
gmap_alloc_table(gmap, table, _REGION2_ENTRY_EMPTY,
gaddr & _REGION1_MASK))
return -ENOMEM;
table = __va(*table & _REGION_ENTRY_ORIGIN);
}
if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION2) {
table += (gaddr & _REGION2_INDEX) >> _REGION2_SHIFT;
if ((*table & _REGION_ENTRY_INVALID) &&
gmap_alloc_table(gmap, table, _REGION3_ENTRY_EMPTY,
gaddr & _REGION2_MASK))
return -ENOMEM;
table = __va(*table & _REGION_ENTRY_ORIGIN);
}
if ((gmap->asce & _ASCE_TYPE_MASK) >= _ASCE_TYPE_REGION3) {
table += (gaddr & _REGION3_INDEX) >> _REGION3_SHIFT;
if ((*table & _REGION_ENTRY_INVALID) &&
gmap_alloc_table(gmap, table, _SEGMENT_ENTRY_EMPTY,
gaddr & _REGION3_MASK))
return -ENOMEM;
table = __va(*table & _REGION_ENTRY_ORIGIN);
}
table += (gaddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
/* Walk the parent mm page table */
mm = gmap->mm;
pgd = pgd_offset(mm, vmaddr);
VM_BUG_ON(pgd_none(*pgd));
p4d = p4d_offset(pgd, vmaddr);
VM_BUG_ON(p4d_none(*p4d));
pud = pud_offset(p4d, vmaddr);
VM_BUG_ON(pud_none(*pud));
/* large puds cannot yet be handled */
if (pud_leaf(*pud))
return -EFAULT;
pmd = pmd_offset(pud, vmaddr);
VM_BUG_ON(pmd_none(*pmd));
/* Are we allowed to use huge pages? */
if (pmd_leaf(*pmd) && !gmap->mm->context.allow_gmap_hpage_1m)
return -EFAULT;
/* Link gmap segment table entry location to page table. */
rc = radix_tree_preload(GFP_KERNEL_ACCOUNT);
if (rc)
return rc;
ptl = pmd_lock(mm, pmd);
spin_lock(&gmap->guest_table_lock);
if (*table == _SEGMENT_ENTRY_EMPTY) {
rc = radix_tree_insert(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT, table);
if (!rc) {
if (pmd_leaf(*pmd)) {
*table = (pmd_val(*pmd) &
_SEGMENT_ENTRY_HARDWARE_BITS_LARGE)
| _SEGMENT_ENTRY_GMAP_UC;
} else
*table = pmd_val(*pmd) &
_SEGMENT_ENTRY_HARDWARE_BITS;
}
} else if (*table & _SEGMENT_ENTRY_PROTECT &&
!(pmd_val(*pmd) & _SEGMENT_ENTRY_PROTECT)) {
unprot = (u64)*table;
unprot &= ~_SEGMENT_ENTRY_PROTECT;
unprot |= _SEGMENT_ENTRY_GMAP_UC;
gmap_pmdp_xchg(gmap, (pmd_t *)table, __pmd(unprot), gaddr);
}
spin_unlock(&gmap->guest_table_lock);
spin_unlock(ptl);
radix_tree_preload_end();
return rc;
}
/**
* fixup_user_fault_nowait - manually resolve a user page fault without waiting
* @mm: mm_struct of target mm
* @address: user address
* @fault_flags:flags to pass down to handle_mm_fault()
* @unlocked: did we unlock the mmap_lock while retrying
*
* This function behaves similarly to fixup_user_fault(), but it guarantees
* that the fault will be resolved without waiting. The function might drop
* and re-acquire the mm lock, in which case @unlocked will be set to true.
*
* The guarantee is that the fault is handled without waiting, but the
* function itself might sleep, due to the lock.
*
* Context: Needs to be called with mm->mmap_lock held in read mode, and will
* return with the lock held in read mode; @unlocked will indicate whether
* the lock has been dropped and re-acquired. This is the same behaviour as
* fixup_user_fault().
*
* Return: 0 on success, -EAGAIN if the fault cannot be resolved without
* waiting, -EFAULT if the fault cannot be resolved, -ENOMEM if out of
* memory.
*/
static int fixup_user_fault_nowait(struct mm_struct *mm, unsigned long address,
unsigned int fault_flags, bool *unlocked)
{
struct vm_area_struct *vma;
unsigned int test_flags;
vm_fault_t fault;
int rc;
fault_flags |= FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT;
test_flags = fault_flags & FAULT_FLAG_WRITE ? VM_WRITE : VM_READ;
vma = find_vma(mm, address);
if (unlikely(!vma || address < vma->vm_start))
return -EFAULT;
if (unlikely(!(vma->vm_flags & test_flags)))
return -EFAULT;
fault = handle_mm_fault(vma, address, fault_flags, NULL);
/* the mm lock has been dropped, take it again */
if (fault & VM_FAULT_COMPLETED) {
*unlocked = true;
mmap_read_lock(mm);
return 0;
}
/* the mm lock has not been dropped */
if (fault & VM_FAULT_ERROR) {
rc = vm_fault_to_errno(fault, 0);
BUG_ON(!rc);
return rc;
}
/* the mm lock has not been dropped because of FAULT_FLAG_RETRY_NOWAIT */
if (fault & VM_FAULT_RETRY)
return -EAGAIN;
/* nothing needed to be done and the mm lock has not been dropped */
return 0;
}
/**
* __gmap_fault - resolve a fault on a guest address
* @gmap: pointer to guest mapping meta data structure
* @gaddr: guest address
* @fault_flags: flags to pass down to handle_mm_fault()
*
* Context: Needs to be called with mm->mmap_lock held in read mode. Might
* drop and re-acquire the lock. Will always return with the lock held.
*/
static int __gmap_fault(struct gmap *gmap, unsigned long gaddr, unsigned int fault_flags)
{
unsigned long vmaddr;
bool unlocked;
int rc = 0;
retry:
unlocked = false;
vmaddr = __gmap_translate(gmap, gaddr);
if (IS_ERR_VALUE(vmaddr))
return vmaddr;
if (fault_flags & FAULT_FLAG_RETRY_NOWAIT)
rc = fixup_user_fault_nowait(gmap->mm, vmaddr, fault_flags, &unlocked);
else
rc = fixup_user_fault(gmap->mm, vmaddr, fault_flags, &unlocked);
if (rc)
return rc;
/*
* In the case that fixup_user_fault unlocked the mmap_lock during
* fault-in, redo __gmap_translate() to avoid racing with a
* map/unmap_segment.
* In particular, __gmap_translate(), fixup_user_fault{,_nowait}(),
* and __gmap_link() must all be called atomically in one go; if the
* lock had been dropped in between, a retry is needed.
*/
if (unlocked)
goto retry;
return __gmap_link(gmap, gaddr, vmaddr);
}
/**
* gmap_fault - resolve a fault on a guest address
* @gmap: pointer to guest mapping meta data structure
* @gaddr: guest address
* @fault_flags: flags to pass down to handle_mm_fault()
*
* Returns 0 on success, -ENOMEM for out of memory conditions, -EFAULT if the
* vm address is already mapped to a different guest segment, and -EAGAIN if
* FAULT_FLAG_RETRY_NOWAIT was specified and the fault could not be processed
* immediately.
*/
int gmap_fault(struct gmap *gmap, unsigned long gaddr, unsigned int fault_flags)
{
int rc;
mmap_read_lock(gmap->mm);
rc = __gmap_fault(gmap, gaddr, fault_flags);
mmap_read_unlock(gmap->mm);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_fault);
/*
* this function is assumed to be called with mmap_lock held
*/
void __gmap_zap(struct gmap *gmap, unsigned long gaddr)
{
struct vm_area_struct *vma;
unsigned long vmaddr;
spinlock_t *ptl;
pte_t *ptep;
/* Find the vm address for the guest address */
vmaddr = (unsigned long) radix_tree_lookup(&gmap->guest_to_host,
gaddr >> PMD_SHIFT);
if (vmaddr) {
vmaddr |= gaddr & ~PMD_MASK;
vma = vma_lookup(gmap->mm, vmaddr);
if (!vma || is_vm_hugetlb_page(vma))
return;
/* Get pointer to the page table entry */
ptep = get_locked_pte(gmap->mm, vmaddr, &ptl);
if (likely(ptep)) {
ptep_zap_unused(gmap->mm, vmaddr, ptep, 0);
pte_unmap_unlock(ptep, ptl);
}
}
}
EXPORT_SYMBOL_GPL(__gmap_zap);
void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
{
unsigned long gaddr, vmaddr, size;
struct vm_area_struct *vma;
mmap_read_lock(gmap->mm);
for (gaddr = from; gaddr < to;
gaddr = (gaddr + PMD_SIZE) & PMD_MASK) {
/* Find the vm address for the guest address */
vmaddr = (unsigned long)
radix_tree_lookup(&gmap->guest_to_host,
gaddr >> PMD_SHIFT);
if (!vmaddr)
continue;
vmaddr |= gaddr & ~PMD_MASK;
/* Find vma in the parent mm */
vma = find_vma(gmap->mm, vmaddr);
if (!vma)
continue;
/*
* We do not discard pages that are backed by
* hugetlbfs, so we don't have to refault them.
*/
if (is_vm_hugetlb_page(vma))
continue;
size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
zap_page_range_single(vma, vmaddr, size, NULL);
}
mmap_read_unlock(gmap->mm);
}
EXPORT_SYMBOL_GPL(gmap_discard);
static LIST_HEAD(gmap_notifier_list);
static DEFINE_SPINLOCK(gmap_notifier_lock);
/**
* gmap_register_pte_notifier - register a pte invalidation callback
* @nb: pointer to the gmap notifier block
*/
void gmap_register_pte_notifier(struct gmap_notifier *nb)
{
spin_lock(&gmap_notifier_lock);
list_add_rcu(&nb->list, &gmap_notifier_list);
spin_unlock(&gmap_notifier_lock);
}
EXPORT_SYMBOL_GPL(gmap_register_pte_notifier);
/**
* gmap_unregister_pte_notifier - remove a pte invalidation callback
* @nb: pointer to the gmap notifier block
*/
void gmap_unregister_pte_notifier(struct gmap_notifier *nb)
{
spin_lock(&gmap_notifier_lock);
list_del_rcu(&nb->list);
spin_unlock(&gmap_notifier_lock);
synchronize_rcu();
}
EXPORT_SYMBOL_GPL(gmap_unregister_pte_notifier);
/**
* gmap_call_notifier - call all registered invalidation callbacks
* @gmap: pointer to guest mapping meta data structure
* @start: start virtual address in the guest address space
* @end: end virtual address in the guest address space
*/
static void gmap_call_notifier(struct gmap *gmap, unsigned long start,
unsigned long end)
{
struct gmap_notifier *nb;
list_for_each_entry(nb, &gmap_notifier_list, list)
nb->notifier_call(gmap, start, end);
}
/**
* gmap_table_walk - walk the gmap page tables
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @level: page table level to stop at
*
* Returns a table entry pointer for the given guest address and @level
* @level=0 : returns a pointer to a page table table entry (or NULL)
* @level=1 : returns a pointer to a segment table entry (or NULL)
* @level=2 : returns a pointer to a region-3 table entry (or NULL)
* @level=3 : returns a pointer to a region-2 table entry (or NULL)
* @level=4 : returns a pointer to a region-1 table entry (or NULL)
*
* Returns NULL if the gmap page tables could not be walked to the
* requested level.
*
* Note: Can also be called for shadow gmaps.
*/
static inline unsigned long *gmap_table_walk(struct gmap *gmap,
unsigned long gaddr, int level)
{
const int asce_type = gmap->asce & _ASCE_TYPE_MASK;
unsigned long *table = gmap->table;
if (gmap_is_shadow(gmap) && gmap->removed)
return NULL;
if (WARN_ON_ONCE(level > (asce_type >> 2) + 1))
return NULL;
if (asce_type != _ASCE_TYPE_REGION1 &&
gaddr & (-1UL << (31 + (asce_type >> 2) * 11)))
return NULL;
switch (asce_type) {
case _ASCE_TYPE_REGION1:
table += (gaddr & _REGION1_INDEX) >> _REGION1_SHIFT;
if (level == 4)
break;
if (*table & _REGION_ENTRY_INVALID)
return NULL;
table = __va(*table & _REGION_ENTRY_ORIGIN);
fallthrough;
case _ASCE_TYPE_REGION2:
table += (gaddr & _REGION2_INDEX) >> _REGION2_SHIFT;
if (level == 3)
break;
if (*table & _REGION_ENTRY_INVALID)
return NULL;
table = __va(*table & _REGION_ENTRY_ORIGIN);
fallthrough;
case _ASCE_TYPE_REGION3:
table += (gaddr & _REGION3_INDEX) >> _REGION3_SHIFT;
if (level == 2)
break;
if (*table & _REGION_ENTRY_INVALID)
return NULL;
table = __va(*table & _REGION_ENTRY_ORIGIN);
fallthrough;
case _ASCE_TYPE_SEGMENT:
table += (gaddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
if (level == 1)
break;
if (*table & _REGION_ENTRY_INVALID)
return NULL;
table = __va(*table & _SEGMENT_ENTRY_ORIGIN);
table += (gaddr & _PAGE_INDEX) >> _PAGE_SHIFT;
}
return table;
}
/**
* gmap_pte_op_walk - walk the gmap page table, get the page table lock
* and return the pte pointer
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @ptl: pointer to the spinlock pointer
*
* Returns a pointer to the locked pte for a guest address, or NULL
*/
static pte_t *gmap_pte_op_walk(struct gmap *gmap, unsigned long gaddr,
spinlock_t **ptl)
{
unsigned long *table;
BUG_ON(gmap_is_shadow(gmap));
/* Walk the gmap page table, lock and get pte pointer */
table = gmap_table_walk(gmap, gaddr, 1); /* get segment pointer */
if (!table || *table & _SEGMENT_ENTRY_INVALID)
return NULL;
return pte_alloc_map_lock(gmap->mm, (pmd_t *) table, gaddr, ptl);
}
/**
* gmap_pte_op_fixup - force a page in and connect the gmap page table
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @vmaddr: address in the host process address space
* @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
*
* Returns 0 if the caller can retry __gmap_translate (might fail again),
* -ENOMEM if out of memory and -EFAULT if anything goes wrong while fixing
* up or connecting the gmap page table.
*/
static int gmap_pte_op_fixup(struct gmap *gmap, unsigned long gaddr,
unsigned long vmaddr, int prot)
{
struct mm_struct *mm = gmap->mm;
unsigned int fault_flags;
bool unlocked = false;
BUG_ON(gmap_is_shadow(gmap));
fault_flags = (prot == PROT_WRITE) ? FAULT_FLAG_WRITE : 0;
if (fixup_user_fault(mm, vmaddr, fault_flags, &unlocked))
return -EFAULT;
if (unlocked)
/* lost mmap_lock, caller has to retry __gmap_translate */
return 0;
/* Connect the page tables */
return __gmap_link(gmap, gaddr, vmaddr);
}
/**
* gmap_pte_op_end - release the page table lock
* @ptep: pointer to the locked pte
* @ptl: pointer to the page table spinlock
*/
static void gmap_pte_op_end(pte_t *ptep, spinlock_t *ptl)
{
pte_unmap_unlock(ptep, ptl);
}
/**
* gmap_pmd_op_walk - walk the gmap tables, get the guest table lock
* and return the pmd pointer
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
*
* Returns a pointer to the pmd for a guest address, or NULL
*/
static inline pmd_t *gmap_pmd_op_walk(struct gmap *gmap, unsigned long gaddr)
{
pmd_t *pmdp;
BUG_ON(gmap_is_shadow(gmap));
pmdp = (pmd_t *) gmap_table_walk(gmap, gaddr, 1);
if (!pmdp)
return NULL;
/* without huge pages, there is no need to take the table lock */
if (!gmap->mm->context.allow_gmap_hpage_1m)
return pmd_none(*pmdp) ? NULL : pmdp;
spin_lock(&gmap->guest_table_lock);
if (pmd_none(*pmdp)) {
spin_unlock(&gmap->guest_table_lock);
return NULL;
}
/* 4k page table entries are locked via the pte (pte_alloc_map_lock). */
if (!pmd_leaf(*pmdp))
spin_unlock(&gmap->guest_table_lock);
return pmdp;
}
/**
* gmap_pmd_op_end - release the guest_table_lock if needed
* @gmap: pointer to the guest mapping meta data structure
* @pmdp: pointer to the pmd
*/
static inline void gmap_pmd_op_end(struct gmap *gmap, pmd_t *pmdp)
{
if (pmd_leaf(*pmdp))
spin_unlock(&gmap->guest_table_lock);
}
/*
* gmap_protect_pmd - remove access rights to memory and set pmd notification bits
* @pmdp: pointer to the pmd to be protected
* @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
* @bits: notification bits to set
*
* Returns:
* 0 if successfully protected
* -EAGAIN if a fixup is needed
* -EINVAL if unsupported notifier bits have been specified
*
* Expected to be called with sg->mm->mmap_lock in read and
* guest_table_lock held.
*/
static int gmap_protect_pmd(struct gmap *gmap, unsigned long gaddr,
pmd_t *pmdp, int prot, unsigned long bits)
{
int pmd_i = pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID;
int pmd_p = pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT;
pmd_t new = *pmdp;
/* Fixup needed */
if ((pmd_i && (prot != PROT_NONE)) || (pmd_p && (prot == PROT_WRITE)))
return -EAGAIN;
if (prot == PROT_NONE && !pmd_i) {
new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
}
if (prot == PROT_READ && !pmd_p) {
new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_INVALID));
new = set_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_PROTECT));
gmap_pmdp_xchg(gmap, pmdp, new, gaddr);
}
if (bits & GMAP_NOTIFY_MPROT)
set_pmd(pmdp, set_pmd_bit(*pmdp, __pgprot(_SEGMENT_ENTRY_GMAP_IN)));
/* Shadow GMAP protection needs split PMDs */
if (bits & GMAP_NOTIFY_SHADOW)
return -EINVAL;
return 0;
}
/*
* gmap_protect_pte - remove access rights to memory and set pgste bits
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @pmdp: pointer to the pmd associated with the pte
* @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
* @bits: notification bits to set
*
* Returns 0 if successfully protected, -ENOMEM if out of memory and
* -EAGAIN if a fixup is needed.
*
* Expected to be called with sg->mm->mmap_lock in read
*/
static int gmap_protect_pte(struct gmap *gmap, unsigned long gaddr,
pmd_t *pmdp, int prot, unsigned long bits)
{
int rc;
pte_t *ptep;
spinlock_t *ptl;
unsigned long pbits = 0;
if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
return -EAGAIN;
ptep = pte_alloc_map_lock(gmap->mm, pmdp, gaddr, &ptl);
if (!ptep)
return -ENOMEM;
pbits |= (bits & GMAP_NOTIFY_MPROT) ? PGSTE_IN_BIT : 0;
pbits |= (bits & GMAP_NOTIFY_SHADOW) ? PGSTE_VSIE_BIT : 0;
/* Protect and unlock. */
rc = ptep_force_prot(gmap->mm, gaddr, ptep, prot, pbits);
gmap_pte_op_end(ptep, ptl);
return rc;
}
/*
* gmap_protect_range - remove access rights to memory and set pgste bits
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @len: size of area
* @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
* @bits: pgste notification bits to set
*
* Returns 0 if successfully protected, -ENOMEM if out of memory and
* -EFAULT if gaddr is invalid (or mapping for shadows is missing).
*
* Called with sg->mm->mmap_lock in read.
*/
static int gmap_protect_range(struct gmap *gmap, unsigned long gaddr,
unsigned long len, int prot, unsigned long bits)
{
unsigned long vmaddr, dist;
pmd_t *pmdp;
int rc;
BUG_ON(gmap_is_shadow(gmap));
while (len) {
rc = -EAGAIN;
pmdp = gmap_pmd_op_walk(gmap, gaddr);
if (pmdp) {
if (!pmd_leaf(*pmdp)) {
rc = gmap_protect_pte(gmap, gaddr, pmdp, prot,
bits);
if (!rc) {
len -= PAGE_SIZE;
gaddr += PAGE_SIZE;
}
} else {
rc = gmap_protect_pmd(gmap, gaddr, pmdp, prot,
bits);
if (!rc) {
dist = HPAGE_SIZE - (gaddr & ~HPAGE_MASK);
len = len < dist ? 0 : len - dist;
gaddr = (gaddr & HPAGE_MASK) + HPAGE_SIZE;
}
}
gmap_pmd_op_end(gmap, pmdp);
}
if (rc) {
if (rc == -EINVAL)
return rc;
/* -EAGAIN, fixup of userspace mm and gmap */
vmaddr = __gmap_translate(gmap, gaddr);
if (IS_ERR_VALUE(vmaddr))
return vmaddr;
rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, prot);
if (rc)
return rc;
}
}
return 0;
}
/**
* gmap_mprotect_notify - change access rights for a range of ptes and
* call the notifier if any pte changes again
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @len: size of area
* @prot: indicates access rights: PROT_NONE, PROT_READ or PROT_WRITE
*
* Returns 0 if for each page in the given range a gmap mapping exists,
* the new access rights could be set and the notifier could be armed.
* If the gmap mapping is missing for one or more pages -EFAULT is
* returned. If no memory could be allocated -ENOMEM is returned.
* This function establishes missing page table entries.
*/
int gmap_mprotect_notify(struct gmap *gmap, unsigned long gaddr,
unsigned long len, int prot)
{
int rc;
if ((gaddr & ~PAGE_MASK) || (len & ~PAGE_MASK) || gmap_is_shadow(gmap))
return -EINVAL;
if (!MACHINE_HAS_ESOP && prot == PROT_READ)
return -EINVAL;
mmap_read_lock(gmap->mm);
rc = gmap_protect_range(gmap, gaddr, len, prot, GMAP_NOTIFY_MPROT);
mmap_read_unlock(gmap->mm);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_mprotect_notify);
/**
* gmap_read_table - get an unsigned long value from a guest page table using
* absolute addressing, without marking the page referenced.
* @gmap: pointer to guest mapping meta data structure
* @gaddr: virtual address in the guest address space
* @val: pointer to the unsigned long value to return
*
* Returns 0 if the value was read, -ENOMEM if out of memory and -EFAULT
* if reading using the virtual address failed. -EINVAL if called on a gmap
* shadow.
*
* Called with gmap->mm->mmap_lock in read.
*/
int gmap_read_table(struct gmap *gmap, unsigned long gaddr, unsigned long *val)
{
unsigned long address, vmaddr;
spinlock_t *ptl;
pte_t *ptep, pte;
int rc;
if (gmap_is_shadow(gmap))
return -EINVAL;
while (1) {
rc = -EAGAIN;
ptep = gmap_pte_op_walk(gmap, gaddr, &ptl);
if (ptep) {
pte = *ptep;
if (pte_present(pte) && (pte_val(pte) & _PAGE_READ)) {
address = pte_val(pte) & PAGE_MASK;
address += gaddr & ~PAGE_MASK;
*val = *(unsigned long *)__va(address);
set_pte(ptep, set_pte_bit(*ptep, __pgprot(_PAGE_YOUNG)));
/* Do *NOT* clear the _PAGE_INVALID bit! */
rc = 0;
}
gmap_pte_op_end(ptep, ptl);
}
if (!rc)
break;
vmaddr = __gmap_translate(gmap, gaddr);
if (IS_ERR_VALUE(vmaddr)) {
rc = vmaddr;
break;
}
rc = gmap_pte_op_fixup(gmap, gaddr, vmaddr, PROT_READ);
if (rc)
break;
}
return rc;
}
EXPORT_SYMBOL_GPL(gmap_read_table);
/**
* gmap_insert_rmap - add a rmap to the host_to_rmap radix tree
* @sg: pointer to the shadow guest address space structure
* @vmaddr: vm address associated with the rmap
* @rmap: pointer to the rmap structure
*
* Called with the sg->guest_table_lock
*/
static inline void gmap_insert_rmap(struct gmap *sg, unsigned long vmaddr,
struct gmap_rmap *rmap)
{
struct gmap_rmap *temp;
void __rcu **slot;
BUG_ON(!gmap_is_shadow(sg));
slot = radix_tree_lookup_slot(&sg->host_to_rmap, vmaddr >> PAGE_SHIFT);
if (slot) {
rmap->next = radix_tree_deref_slot_protected(slot,
&sg->guest_table_lock);
for (temp = rmap->next; temp; temp = temp->next) {
if (temp->raddr == rmap->raddr) {
kfree(rmap);
return;
}
}
radix_tree_replace_slot(&sg->host_to_rmap, slot, rmap);
} else {
rmap->next = NULL;
radix_tree_insert(&sg->host_to_rmap, vmaddr >> PAGE_SHIFT,
rmap);
}
}
/**
* gmap_protect_rmap - restrict access rights to memory (RO) and create an rmap
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow gmap
* @paddr: address in the parent guest address space
* @len: length of the memory area to protect
*
* Returns 0 if successfully protected and the rmap was created, -ENOMEM
* if out of memory and -EFAULT if paddr is invalid.
*/
static int gmap_protect_rmap(struct gmap *sg, unsigned long raddr,
unsigned long paddr, unsigned long len)
{
struct gmap *parent;
struct gmap_rmap *rmap;
unsigned long vmaddr;
spinlock_t *ptl;
pte_t *ptep;
int rc;
BUG_ON(!gmap_is_shadow(sg));
parent = sg->parent;
while (len) {
vmaddr = __gmap_translate(parent, paddr);
if (IS_ERR_VALUE(vmaddr))
return vmaddr;
rmap = kzalloc(sizeof(*rmap), GFP_KERNEL_ACCOUNT);
if (!rmap)
return -ENOMEM;
rmap->raddr = raddr;
rc = radix_tree_preload(GFP_KERNEL_ACCOUNT);
if (rc) {
kfree(rmap);
return rc;
}
rc = -EAGAIN;
ptep = gmap_pte_op_walk(parent, paddr, &ptl);
if (ptep) {
spin_lock(&sg->guest_table_lock);
rc = ptep_force_prot(parent->mm, paddr, ptep, PROT_READ,
PGSTE_VSIE_BIT);
if (!rc)
gmap_insert_rmap(sg, vmaddr, rmap);
spin_unlock(&sg->guest_table_lock);
gmap_pte_op_end(ptep, ptl);
}
radix_tree_preload_end();
if (rc) {
kfree(rmap);
rc = gmap_pte_op_fixup(parent, paddr, vmaddr, PROT_READ);
if (rc)
return rc;
continue;
}
paddr += PAGE_SIZE;
len -= PAGE_SIZE;
}
return 0;
}
#define _SHADOW_RMAP_MASK 0x7
#define _SHADOW_RMAP_REGION1 0x5
#define _SHADOW_RMAP_REGION2 0x4
#define _SHADOW_RMAP_REGION3 0x3
#define _SHADOW_RMAP_SEGMENT 0x2
#define _SHADOW_RMAP_PGTABLE 0x1
/**
* gmap_idte_one - invalidate a single region or segment table entry
* @asce: region or segment table *origin* + table-type bits
* @vaddr: virtual address to identify the table entry to flush
*
* The invalid bit of a single region or segment table entry is set
* and the associated TLB entries depending on the entry are flushed.
* The table-type of the @asce identifies the portion of the @vaddr
* that is used as the invalidation index.
*/
static inline void gmap_idte_one(unsigned long asce, unsigned long vaddr)
{
asm volatile(
" idte %0,0,%1"
: : "a" (asce), "a" (vaddr) : "cc", "memory");
}
/**
* gmap_unshadow_page - remove a page from a shadow page table
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
*
* Called with the sg->guest_table_lock
*/
static void gmap_unshadow_page(struct gmap *sg, unsigned long raddr)
{
unsigned long *table;
BUG_ON(!gmap_is_shadow(sg));
table = gmap_table_walk(sg, raddr, 0); /* get page table pointer */
if (!table || *table & _PAGE_INVALID)
return;
gmap_call_notifier(sg, raddr, raddr + _PAGE_SIZE - 1);
ptep_unshadow_pte(sg->mm, raddr, (pte_t *) table);
}
/**
* __gmap_unshadow_pgt - remove all entries from a shadow page table
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
* @pgt: pointer to the start of a shadow page table
*
* Called with the sg->guest_table_lock
*/
static void __gmap_unshadow_pgt(struct gmap *sg, unsigned long raddr,
unsigned long *pgt)
{
int i;
BUG_ON(!gmap_is_shadow(sg));
for (i = 0; i < _PAGE_ENTRIES; i++, raddr += _PAGE_SIZE)
pgt[i] = _PAGE_INVALID;
}
/**
* gmap_unshadow_pgt - remove a shadow page table from a segment entry
* @sg: pointer to the shadow guest address space structure
* @raddr: address in the shadow guest address space
*
* Called with the sg->guest_table_lock
*/
static void gmap_unshadow_pgt(struct gmap *sg, unsigned long raddr)
{
unsigned long *ste;
phys_addr_t sto, pgt;
struct ptdesc *ptdesc;
BUG_ON(!gmap_is_shadow(sg));
ste = gmap_table_walk(sg, raddr, 1); /* get segment pointer */
if (!ste || !(*ste & _SEGMENT_ENTRY_ORIGIN))
return;
gmap_call_notifier(sg, raddr, raddr + _SEGMENT_SIZE - 1);
sto = __pa(ste - ((raddr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT));
gmap_idte_one(sto | _ASCE_TYPE_SEGMENT, raddr);
pgt = *ste & _SEGMENT_ENTRY_ORIGIN;
*ste = _SEGMENT_ENTRY_EMPTY;
__gmap_unshadow_pgt(sg, raddr, __va(pgt));
/* Free page table */
ptdesc = page_ptdesc(phys_to_page(pgt));
list_del(&ptdesc->pt_list);
page_table_free_pgste(ptdesc);
}
/**
* __gmap_unshadow_sgt - remove all entries from a shadow segment table
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
* @sgt: pointer to the start of a shadow segment table
*
* Called with the sg->guest_table_lock
*/
static void __gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr,
unsigned long *sgt)
{
struct ptdesc *ptdesc;
phys_addr_t pgt;
int i;
BUG_ON(!gmap_is_shadow(sg));
for (i = 0; i < _CRST_ENTRIES; i++, raddr += _SEGMENT_SIZE) {
if (!(sgt[i] & _SEGMENT_ENTRY_ORIGIN))
continue;
pgt = sgt[i] & _REGION_ENTRY_ORIGIN;
sgt[i] = _SEGMENT_ENTRY_EMPTY;
__gmap_unshadow_pgt(sg, raddr, __va(pgt));
/* Free page table */
ptdesc = page_ptdesc(phys_to_page(pgt));
list_del(&ptdesc->pt_list);
page_table_free_pgste(ptdesc);
}
}
/**
* gmap_unshadow_sgt - remove a shadow segment table from a region-3 entry
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
*
* Called with the shadow->guest_table_lock
*/
static void gmap_unshadow_sgt(struct gmap *sg, unsigned long raddr)
{
unsigned long r3o, *r3e;
phys_addr_t sgt;
struct page *page;
BUG_ON(!gmap_is_shadow(sg));
r3e = gmap_table_walk(sg, raddr, 2); /* get region-3 pointer */
if (!r3e || !(*r3e & _REGION_ENTRY_ORIGIN))
return;
gmap_call_notifier(sg, raddr, raddr + _REGION3_SIZE - 1);
r3o = (unsigned long) (r3e - ((raddr & _REGION3_INDEX) >> _REGION3_SHIFT));
gmap_idte_one(__pa(r3o) | _ASCE_TYPE_REGION3, raddr);
sgt = *r3e & _REGION_ENTRY_ORIGIN;
*r3e = _REGION3_ENTRY_EMPTY;
__gmap_unshadow_sgt(sg, raddr, __va(sgt));
/* Free segment table */
page = phys_to_page(sgt);
list_del(&page->lru);
__free_pages(page, CRST_ALLOC_ORDER);
}
/**
* __gmap_unshadow_r3t - remove all entries from a shadow region-3 table
* @sg: pointer to the shadow guest address space structure
* @raddr: address in the shadow guest address space
* @r3t: pointer to the start of a shadow region-3 table
*
* Called with the sg->guest_table_lock
*/
static void __gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr,
unsigned long *r3t)
{
struct page *page;
phys_addr_t sgt;
int i;
BUG_ON(!gmap_is_shadow(sg));
for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION3_SIZE) {
if (!(r3t[i] & _REGION_ENTRY_ORIGIN))
continue;
sgt = r3t[i] & _REGION_ENTRY_ORIGIN;
r3t[i] = _REGION3_ENTRY_EMPTY;
__gmap_unshadow_sgt(sg, raddr, __va(sgt));
/* Free segment table */
page = phys_to_page(sgt);
list_del(&page->lru);
__free_pages(page, CRST_ALLOC_ORDER);
}
}
/**
* gmap_unshadow_r3t - remove a shadow region-3 table from a region-2 entry
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
*
* Called with the sg->guest_table_lock
*/
static void gmap_unshadow_r3t(struct gmap *sg, unsigned long raddr)
{
unsigned long r2o, *r2e;
phys_addr_t r3t;
struct page *page;
BUG_ON(!gmap_is_shadow(sg));
r2e = gmap_table_walk(sg, raddr, 3); /* get region-2 pointer */
if (!r2e || !(*r2e & _REGION_ENTRY_ORIGIN))
return;
gmap_call_notifier(sg, raddr, raddr + _REGION2_SIZE - 1);
r2o = (unsigned long) (r2e - ((raddr & _REGION2_INDEX) >> _REGION2_SHIFT));
gmap_idte_one(__pa(r2o) | _ASCE_TYPE_REGION2, raddr);
r3t = *r2e & _REGION_ENTRY_ORIGIN;
*r2e = _REGION2_ENTRY_EMPTY;
__gmap_unshadow_r3t(sg, raddr, __va(r3t));
/* Free region 3 table */
page = phys_to_page(r3t);
list_del(&page->lru);
__free_pages(page, CRST_ALLOC_ORDER);
}
/**
* __gmap_unshadow_r2t - remove all entries from a shadow region-2 table
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
* @r2t: pointer to the start of a shadow region-2 table
*
* Called with the sg->guest_table_lock
*/
static void __gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr,
unsigned long *r2t)
{
phys_addr_t r3t;
struct page *page;
int i;
BUG_ON(!gmap_is_shadow(sg));
for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION2_SIZE) {
if (!(r2t[i] & _REGION_ENTRY_ORIGIN))
continue;
r3t = r2t[i] & _REGION_ENTRY_ORIGIN;
r2t[i] = _REGION2_ENTRY_EMPTY;
__gmap_unshadow_r3t(sg, raddr, __va(r3t));
/* Free region 3 table */
page = phys_to_page(r3t);
list_del(&page->lru);
__free_pages(page, CRST_ALLOC_ORDER);
}
}
/**
* gmap_unshadow_r2t - remove a shadow region-2 table from a region-1 entry
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
*
* Called with the sg->guest_table_lock
*/
static void gmap_unshadow_r2t(struct gmap *sg, unsigned long raddr)
{
unsigned long r1o, *r1e;
struct page *page;
phys_addr_t r2t;
BUG_ON(!gmap_is_shadow(sg));
r1e = gmap_table_walk(sg, raddr, 4); /* get region-1 pointer */
if (!r1e || !(*r1e & _REGION_ENTRY_ORIGIN))
return;
gmap_call_notifier(sg, raddr, raddr + _REGION1_SIZE - 1);
r1o = (unsigned long) (r1e - ((raddr & _REGION1_INDEX) >> _REGION1_SHIFT));
gmap_idte_one(__pa(r1o) | _ASCE_TYPE_REGION1, raddr);
r2t = *r1e & _REGION_ENTRY_ORIGIN;
*r1e = _REGION1_ENTRY_EMPTY;
__gmap_unshadow_r2t(sg, raddr, __va(r2t));
/* Free region 2 table */
page = phys_to_page(r2t);
list_del(&page->lru);
__free_pages(page, CRST_ALLOC_ORDER);
}
/**
* __gmap_unshadow_r1t - remove all entries from a shadow region-1 table
* @sg: pointer to the shadow guest address space structure
* @raddr: rmap address in the shadow guest address space
* @r1t: pointer to the start of a shadow region-1 table
*
* Called with the shadow->guest_table_lock
*/
static void __gmap_unshadow_r1t(struct gmap *sg, unsigned long raddr,
unsigned long *r1t)
{
unsigned long asce;
struct page *page;
phys_addr_t r2t;
int i;
BUG_ON(!gmap_is_shadow(sg));
asce = __pa(r1t) | _ASCE_TYPE_REGION1;
for (i = 0; i < _CRST_ENTRIES; i++, raddr += _REGION1_SIZE) {
if (!(r1t[i] & _REGION_ENTRY_ORIGIN))
continue;
r2t = r1t[i] & _REGION_ENTRY_ORIGIN;
__gmap_unshadow_r2t(sg, raddr, __va(r2t));
/* Clear entry and flush translation r1t -> r2t */
gmap_idte_one(asce, raddr);
r1t[i] = _REGION1_ENTRY_EMPTY;
/* Free region 2 table */
page = phys_to_page(r2t);
list_del(&page->lru);
__free_pages(page, CRST_ALLOC_ORDER);
}
}
/**
* gmap_unshadow - remove a shadow page table completely
* @sg: pointer to the shadow guest address space structure
*
* Called with sg->guest_table_lock
*/
static void gmap_unshadow(struct gmap *sg)
{
unsigned long *table;
BUG_ON(!gmap_is_shadow(sg));
if (sg->removed)
return;
sg->removed = 1;
gmap_call_notifier(sg, 0, -1UL);
gmap_flush_tlb(sg);
table = __va(sg->asce & _ASCE_ORIGIN);
switch (sg->asce & _ASCE_TYPE_MASK) {
case _ASCE_TYPE_REGION1:
__gmap_unshadow_r1t(sg, 0, table);
break;
case _ASCE_TYPE_REGION2:
__gmap_unshadow_r2t(sg, 0, table);
break;
case _ASCE_TYPE_REGION3:
__gmap_unshadow_r3t(sg, 0, table);
break;
case _ASCE_TYPE_SEGMENT:
__gmap_unshadow_sgt(sg, 0, table);
break;
}
}
/**
* gmap_find_shadow - find a specific asce in the list of shadow tables
* @parent: pointer to the parent gmap
* @asce: ASCE for which the shadow table is created
* @edat_level: edat level to be used for the shadow translation
*
* Returns the pointer to a gmap if a shadow table with the given asce is
* already available, ERR_PTR(-EAGAIN) if another one is just being created,
* otherwise NULL
*/
static struct gmap *gmap_find_shadow(struct gmap *parent, unsigned long asce,
int edat_level)
{
struct gmap *sg;
list_for_each_entry(sg, &parent->children, list) {
if (sg->orig_asce != asce || sg->edat_level != edat_level ||
sg->removed)
continue;
if (!sg->initialized)
return ERR_PTR(-EAGAIN);
refcount_inc(&sg->ref_count);
return sg;
}
return NULL;
}
/**
* gmap_shadow_valid - check if a shadow guest address space matches the
* given properties and is still valid
* @sg: pointer to the shadow guest address space structure
* @asce: ASCE for which the shadow table is requested
* @edat_level: edat level to be used for the shadow translation
*
* Returns 1 if the gmap shadow is still valid and matches the given
* properties, the caller can continue using it. Returns 0 otherwise, the
* caller has to request a new shadow gmap in this case.
*
*/
int gmap_shadow_valid(struct gmap *sg, unsigned long asce, int edat_level)
{
if (sg->removed)
return 0;
return sg->orig_asce == asce && sg->edat_level == edat_level;
}
EXPORT_SYMBOL_GPL(gmap_shadow_valid);
/**
* gmap_shadow - create/find a shadow guest address space
* @parent: pointer to the parent gmap
* @asce: ASCE for which the shadow table is created
* @edat_level: edat level to be used for the shadow translation
*
* The pages of the top level page table referred by the asce parameter
* will be set to read-only and marked in the PGSTEs of the kvm process.
* The shadow table will be removed automatically on any change to the
* PTE mapping for the source table.
*
* Returns a guest address space structure, ERR_PTR(-ENOMEM) if out of memory,
* ERR_PTR(-EAGAIN) if the caller has to retry and ERR_PTR(-EFAULT) if the
* parent gmap table could not be protected.
*/
struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
int edat_level)
{
struct gmap *sg, *new;
unsigned long limit;
int rc;
BUG_ON(parent->mm->context.allow_gmap_hpage_1m);
BUG_ON(gmap_is_shadow(parent));
spin_lock(&parent->shadow_lock);
sg = gmap_find_shadow(parent, asce, edat_level);
spin_unlock(&parent->shadow_lock);
if (sg)
return sg;
/* Create a new shadow gmap */
limit = -1UL >> (33 - (((asce & _ASCE_TYPE_MASK) >> 2) * 11));
if (asce & _ASCE_REAL_SPACE)
limit = -1UL;
new = gmap_alloc(limit);
if (!new)
return ERR_PTR(-ENOMEM);
new->mm = parent->mm;
new->parent = gmap_get(parent);
new->private = parent->private;
new->orig_asce = asce;
new->edat_level = edat_level;
new->initialized = false;
spin_lock(&parent->shadow_lock);
/* Recheck if another CPU created the same shadow */
sg = gmap_find_shadow(parent, asce, edat_level);
if (sg) {
spin_unlock(&parent->shadow_lock);
gmap_free(new);
return sg;
}
if (asce & _ASCE_REAL_SPACE) {
/* only allow one real-space gmap shadow */
list_for_each_entry(sg, &parent->children, list) {
if (sg->orig_asce & _ASCE_REAL_SPACE) {
spin_lock(&sg->guest_table_lock);
gmap_unshadow(sg);
spin_unlock(&sg->guest_table_lock);
list_del(&sg->list);
gmap_put(sg);
break;
}
}
}
refcount_set(&new->ref_count, 2);
list_add(&new->list, &parent->children);
if (asce & _ASCE_REAL_SPACE) {
/* nothing to protect, return right away */
new->initialized = true;
spin_unlock(&parent->shadow_lock);
return new;
}
spin_unlock(&parent->shadow_lock);
/* protect after insertion, so it will get properly invalidated */
mmap_read_lock(parent->mm);
rc = gmap_protect_range(parent, asce & _ASCE_ORIGIN,
((asce & _ASCE_TABLE_LENGTH) + 1) * PAGE_SIZE,
PROT_READ, GMAP_NOTIFY_SHADOW);
mmap_read_unlock(parent->mm);
spin_lock(&parent->shadow_lock);
new->initialized = true;
if (rc) {
list_del(&new->list);
gmap_free(new);
new = ERR_PTR(rc);
}
spin_unlock(&parent->shadow_lock);
return new;
}
EXPORT_SYMBOL_GPL(gmap_shadow);
/**
* gmap_shadow_r2t - create an empty shadow region 2 table
* @sg: pointer to the shadow guest address space structure
* @saddr: faulting address in the shadow gmap
* @r2t: parent gmap address of the region 2 table to get shadowed
* @fake: r2t references contiguous guest memory block, not a r2t
*
* The r2t parameter specifies the address of the source table. The
* four pages of the source table are made read-only in the parent gmap
* address space. A write to the source table area @r2t will automatically
* remove the shadow r2 table and all of its descendants.
*
* Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
* shadow table structure is incomplete, -ENOMEM if out of memory and
* -EFAULT if an address in the parent gmap could not be resolved.
*
* Called with sg->mm->mmap_lock in read.
*/
int gmap_shadow_r2t(struct gmap *sg, unsigned long saddr, unsigned long r2t,
int fake)
{
unsigned long raddr, origin, offset, len;
unsigned long *table;
phys_addr_t s_r2t;
struct page *page;
int rc;
BUG_ON(!gmap_is_shadow(sg));
/* Allocate a shadow region second table */
page = gmap_alloc_crst();
if (!page)
return -ENOMEM;
page->index = r2t & _REGION_ENTRY_ORIGIN;
if (fake)
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_r2t = page_to_phys(page);
/* Install shadow region second table */
spin_lock(&sg->guest_table_lock);
table = gmap_table_walk(sg, saddr, 4); /* get region-1 pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
goto out_free;
}
if (!(*table & _REGION_ENTRY_INVALID)) {
rc = 0; /* Already established */
goto out_free;
} else if (*table & _REGION_ENTRY_ORIGIN) {
rc = -EAGAIN; /* Race with shadow */
goto out_free;
}
crst_table_init(__va(s_r2t), _REGION2_ENTRY_EMPTY);
/* mark as invalid as long as the parent table is not protected */
*table = s_r2t | _REGION_ENTRY_LENGTH |
_REGION_ENTRY_TYPE_R1 | _REGION_ENTRY_INVALID;
if (sg->edat_level >= 1)
*table |= (r2t & _REGION_ENTRY_PROTECT);
list_add(&page->lru, &sg->crst_list);
if (fake) {
/* nothing to protect for fake tables */
*table &= ~_REGION_ENTRY_INVALID;
spin_unlock(&sg->guest_table_lock);
return 0;
}
spin_unlock(&sg->guest_table_lock);
/* Make r2t read-only in parent gmap page table */
raddr = (saddr & _REGION1_MASK) | _SHADOW_RMAP_REGION1;
origin = r2t & _REGION_ENTRY_ORIGIN;
offset = ((r2t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
len = ((r2t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
spin_lock(&sg->guest_table_lock);
if (!rc) {
table = gmap_table_walk(sg, saddr, 4);
if (!table || (*table & _REGION_ENTRY_ORIGIN) != s_r2t)
rc = -EAGAIN; /* Race with unshadow */
else
*table &= ~_REGION_ENTRY_INVALID;
} else {
gmap_unshadow_r2t(sg, raddr);
}
spin_unlock(&sg->guest_table_lock);
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
__free_pages(page, CRST_ALLOC_ORDER);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_shadow_r2t);
/**
* gmap_shadow_r3t - create a shadow region 3 table
* @sg: pointer to the shadow guest address space structure
* @saddr: faulting address in the shadow gmap
* @r3t: parent gmap address of the region 3 table to get shadowed
* @fake: r3t references contiguous guest memory block, not a r3t
*
* Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
* shadow table structure is incomplete, -ENOMEM if out of memory and
* -EFAULT if an address in the parent gmap could not be resolved.
*
* Called with sg->mm->mmap_lock in read.
*/
int gmap_shadow_r3t(struct gmap *sg, unsigned long saddr, unsigned long r3t,
int fake)
{
unsigned long raddr, origin, offset, len;
unsigned long *table;
phys_addr_t s_r3t;
struct page *page;
int rc;
BUG_ON(!gmap_is_shadow(sg));
/* Allocate a shadow region second table */
page = gmap_alloc_crst();
if (!page)
return -ENOMEM;
page->index = r3t & _REGION_ENTRY_ORIGIN;
if (fake)
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_r3t = page_to_phys(page);
/* Install shadow region second table */
spin_lock(&sg->guest_table_lock);
table = gmap_table_walk(sg, saddr, 3); /* get region-2 pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
goto out_free;
}
if (!(*table & _REGION_ENTRY_INVALID)) {
rc = 0; /* Already established */
goto out_free;
} else if (*table & _REGION_ENTRY_ORIGIN) {
rc = -EAGAIN; /* Race with shadow */
goto out_free;
}
crst_table_init(__va(s_r3t), _REGION3_ENTRY_EMPTY);
/* mark as invalid as long as the parent table is not protected */
*table = s_r3t | _REGION_ENTRY_LENGTH |
_REGION_ENTRY_TYPE_R2 | _REGION_ENTRY_INVALID;
if (sg->edat_level >= 1)
*table |= (r3t & _REGION_ENTRY_PROTECT);
list_add(&page->lru, &sg->crst_list);
if (fake) {
/* nothing to protect for fake tables */
*table &= ~_REGION_ENTRY_INVALID;
spin_unlock(&sg->guest_table_lock);
return 0;
}
spin_unlock(&sg->guest_table_lock);
/* Make r3t read-only in parent gmap page table */
raddr = (saddr & _REGION2_MASK) | _SHADOW_RMAP_REGION2;
origin = r3t & _REGION_ENTRY_ORIGIN;
offset = ((r3t & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
len = ((r3t & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
spin_lock(&sg->guest_table_lock);
if (!rc) {
table = gmap_table_walk(sg, saddr, 3);
if (!table || (*table & _REGION_ENTRY_ORIGIN) != s_r3t)
rc = -EAGAIN; /* Race with unshadow */
else
*table &= ~_REGION_ENTRY_INVALID;
} else {
gmap_unshadow_r3t(sg, raddr);
}
spin_unlock(&sg->guest_table_lock);
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
__free_pages(page, CRST_ALLOC_ORDER);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_shadow_r3t);
/**
* gmap_shadow_sgt - create a shadow segment table
* @sg: pointer to the shadow guest address space structure
* @saddr: faulting address in the shadow gmap
* @sgt: parent gmap address of the segment table to get shadowed
* @fake: sgt references contiguous guest memory block, not a sgt
*
* Returns: 0 if successfully shadowed or already shadowed, -EAGAIN if the
* shadow table structure is incomplete, -ENOMEM if out of memory and
* -EFAULT if an address in the parent gmap could not be resolved.
*
* Called with sg->mm->mmap_lock in read.
*/
int gmap_shadow_sgt(struct gmap *sg, unsigned long saddr, unsigned long sgt,
int fake)
{
unsigned long raddr, origin, offset, len;
unsigned long *table;
phys_addr_t s_sgt;
struct page *page;
int rc;
BUG_ON(!gmap_is_shadow(sg) || (sgt & _REGION3_ENTRY_LARGE));
/* Allocate a shadow segment table */
page = gmap_alloc_crst();
if (!page)
return -ENOMEM;
page->index = sgt & _REGION_ENTRY_ORIGIN;
if (fake)
page->index |= GMAP_SHADOW_FAKE_TABLE;
s_sgt = page_to_phys(page);
/* Install shadow region second table */
spin_lock(&sg->guest_table_lock);
table = gmap_table_walk(sg, saddr, 2); /* get region-3 pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
goto out_free;
}
if (!(*table & _REGION_ENTRY_INVALID)) {
rc = 0; /* Already established */
goto out_free;
} else if (*table & _REGION_ENTRY_ORIGIN) {
rc = -EAGAIN; /* Race with shadow */
goto out_free;
}
crst_table_init(__va(s_sgt), _SEGMENT_ENTRY_EMPTY);
/* mark as invalid as long as the parent table is not protected */
*table = s_sgt | _REGION_ENTRY_LENGTH |
_REGION_ENTRY_TYPE_R3 | _REGION_ENTRY_INVALID;
if (sg->edat_level >= 1)
*table |= sgt & _REGION_ENTRY_PROTECT;
list_add(&page->lru, &sg->crst_list);
if (fake) {
/* nothing to protect for fake tables */
*table &= ~_REGION_ENTRY_INVALID;
spin_unlock(&sg->guest_table_lock);
return 0;
}
spin_unlock(&sg->guest_table_lock);
/* Make sgt read-only in parent gmap page table */
raddr = (saddr & _REGION3_MASK) | _SHADOW_RMAP_REGION3;
origin = sgt & _REGION_ENTRY_ORIGIN;
offset = ((sgt & _REGION_ENTRY_OFFSET) >> 6) * PAGE_SIZE;
len = ((sgt & _REGION_ENTRY_LENGTH) + 1) * PAGE_SIZE - offset;
rc = gmap_protect_rmap(sg, raddr, origin + offset, len);
spin_lock(&sg->guest_table_lock);
if (!rc) {
table = gmap_table_walk(sg, saddr, 2);
if (!table || (*table & _REGION_ENTRY_ORIGIN) != s_sgt)
rc = -EAGAIN; /* Race with unshadow */
else
*table &= ~_REGION_ENTRY_INVALID;
} else {
gmap_unshadow_sgt(sg, raddr);
}
spin_unlock(&sg->guest_table_lock);
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
__free_pages(page, CRST_ALLOC_ORDER);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_shadow_sgt);
/**
* gmap_shadow_pgt_lookup - find a shadow page table
* @sg: pointer to the shadow guest address space structure
* @saddr: the address in the shadow aguest address space
* @pgt: parent gmap address of the page table to get shadowed
* @dat_protection: if the pgtable is marked as protected by dat
* @fake: pgt references contiguous guest memory block, not a pgtable
*
* Returns 0 if the shadow page table was found and -EAGAIN if the page
* table was not found.
*
* Called with sg->mm->mmap_lock in read.
*/
int gmap_shadow_pgt_lookup(struct gmap *sg, unsigned long saddr,
unsigned long *pgt, int *dat_protection,
int *fake)
{
unsigned long *table;
struct page *page;
int rc;
BUG_ON(!gmap_is_shadow(sg));
spin_lock(&sg->guest_table_lock);
table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
if (table && !(*table & _SEGMENT_ENTRY_INVALID)) {
/* Shadow page tables are full pages (pte+pgste) */
page = pfn_to_page(*table >> PAGE_SHIFT);
*pgt = page->index & ~GMAP_SHADOW_FAKE_TABLE;
*dat_protection = !!(*table & _SEGMENT_ENTRY_PROTECT);
*fake = !!(page->index & GMAP_SHADOW_FAKE_TABLE);
rc = 0;
} else {
rc = -EAGAIN;
}
spin_unlock(&sg->guest_table_lock);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_shadow_pgt_lookup);
/**
* gmap_shadow_pgt - instantiate a shadow page table
* @sg: pointer to the shadow guest address space structure
* @saddr: faulting address in the shadow gmap
* @pgt: parent gmap address of the page table to get shadowed
* @fake: pgt references contiguous guest memory block, not a pgtable
*
* Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
* shadow table structure is incomplete, -ENOMEM if out of memory,
* -EFAULT if an address in the parent gmap could not be resolved and
*
* Called with gmap->mm->mmap_lock in read
*/
int gmap_shadow_pgt(struct gmap *sg, unsigned long saddr, unsigned long pgt,
int fake)
{
unsigned long raddr, origin;
unsigned long *table;
struct ptdesc *ptdesc;
phys_addr_t s_pgt;
int rc;
BUG_ON(!gmap_is_shadow(sg) || (pgt & _SEGMENT_ENTRY_LARGE));
/* Allocate a shadow page table */
ptdesc = page_table_alloc_pgste(sg->mm);
if (!ptdesc)
return -ENOMEM;
ptdesc->pt_index = pgt & _SEGMENT_ENTRY_ORIGIN;
if (fake)
ptdesc->pt_index |= GMAP_SHADOW_FAKE_TABLE;
s_pgt = page_to_phys(ptdesc_page(ptdesc));
/* Install shadow page table */
spin_lock(&sg->guest_table_lock);
table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
if (!table) {
rc = -EAGAIN; /* Race with unshadow */
goto out_free;
}
if (!(*table & _SEGMENT_ENTRY_INVALID)) {
rc = 0; /* Already established */
goto out_free;
} else if (*table & _SEGMENT_ENTRY_ORIGIN) {
rc = -EAGAIN; /* Race with shadow */
goto out_free;
}
/* mark as invalid as long as the parent table is not protected */
*table = (unsigned long) s_pgt | _SEGMENT_ENTRY |
(pgt & _SEGMENT_ENTRY_PROTECT) | _SEGMENT_ENTRY_INVALID;
list_add(&ptdesc->pt_list, &sg->pt_list);
if (fake) {
/* nothing to protect for fake tables */
*table &= ~_SEGMENT_ENTRY_INVALID;
spin_unlock(&sg->guest_table_lock);
return 0;
}
spin_unlock(&sg->guest_table_lock);
/* Make pgt read-only in parent gmap page table (not the pgste) */
raddr = (saddr & _SEGMENT_MASK) | _SHADOW_RMAP_SEGMENT;
origin = pgt & _SEGMENT_ENTRY_ORIGIN & PAGE_MASK;
rc = gmap_protect_rmap(sg, raddr, origin, PAGE_SIZE);
spin_lock(&sg->guest_table_lock);
if (!rc) {
table = gmap_table_walk(sg, saddr, 1);
if (!table || (*table & _SEGMENT_ENTRY_ORIGIN) != s_pgt)
rc = -EAGAIN; /* Race with unshadow */
else
*table &= ~_SEGMENT_ENTRY_INVALID;
} else {
gmap_unshadow_pgt(sg, raddr);
}
spin_unlock(&sg->guest_table_lock);
return rc;
out_free:
spin_unlock(&sg->guest_table_lock);
page_table_free_pgste(ptdesc);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_shadow_pgt);
/**
* gmap_shadow_page - create a shadow page mapping
* @sg: pointer to the shadow guest address space structure
* @saddr: faulting address in the shadow gmap
* @pte: pte in parent gmap address space to get shadowed
*
* Returns 0 if successfully shadowed or already shadowed, -EAGAIN if the
* shadow table structure is incomplete, -ENOMEM if out of memory and
* -EFAULT if an address in the parent gmap could not be resolved.
*
* Called with sg->mm->mmap_lock in read.
*/
int gmap_shadow_page(struct gmap *sg, unsigned long saddr, pte_t pte)
{
struct gmap *parent;
struct gmap_rmap *rmap;
unsigned long vmaddr, paddr;
spinlock_t *ptl;
pte_t *sptep, *tptep;
int prot;
int rc;
BUG_ON(!gmap_is_shadow(sg));
parent = sg->parent;
prot = (pte_val(pte) & _PAGE_PROTECT) ? PROT_READ : PROT_WRITE;
rmap = kzalloc(sizeof(*rmap), GFP_KERNEL_ACCOUNT);
if (!rmap)
return -ENOMEM;
rmap->raddr = (saddr & PAGE_MASK) | _SHADOW_RMAP_PGTABLE;
while (1) {
paddr = pte_val(pte) & PAGE_MASK;
vmaddr = __gmap_translate(parent, paddr);
if (IS_ERR_VALUE(vmaddr)) {
rc = vmaddr;
break;
}
rc = radix_tree_preload(GFP_KERNEL_ACCOUNT);
if (rc)
break;
rc = -EAGAIN;
sptep = gmap_pte_op_walk(parent, paddr, &ptl);
if (sptep) {
spin_lock(&sg->guest_table_lock);
/* Get page table pointer */
tptep = (pte_t *) gmap_table_walk(sg, saddr, 0);
if (!tptep) {
spin_unlock(&sg->guest_table_lock);
gmap_pte_op_end(sptep, ptl);
radix_tree_preload_end();
break;
}
rc = ptep_shadow_pte(sg->mm, saddr, sptep, tptep, pte);
if (rc > 0) {
/* Success and a new mapping */
gmap_insert_rmap(sg, vmaddr, rmap);
rmap = NULL;
rc = 0;
}
gmap_pte_op_end(sptep, ptl);
spin_unlock(&sg->guest_table_lock);
}
radix_tree_preload_end();
if (!rc)
break;
rc = gmap_pte_op_fixup(parent, paddr, vmaddr, prot);
if (rc)
break;
}
kfree(rmap);
return rc;
}
EXPORT_SYMBOL_GPL(gmap_shadow_page);
/*
* gmap_shadow_notify - handle notifications for shadow gmap
*
* Called with sg->parent->shadow_lock.
*/
static void gmap_shadow_notify(struct gmap *sg, unsigned long vmaddr,
unsigned long gaddr)
{
struct gmap_rmap *rmap, *rnext, *head;
unsigned long start, end, bits, raddr;
BUG_ON(!gmap_is_shadow(sg));
spin_lock(&sg->guest_table_lock);
if (sg->removed) {
spin_unlock(&sg->guest_table_lock);
return;
}
/* Check for top level table */
start = sg->orig_asce & _ASCE_ORIGIN;
end = start + ((sg->orig_asce & _ASCE_TABLE_LENGTH) + 1) * PAGE_SIZE;
if (!(sg->orig_asce & _ASCE_REAL_SPACE) && gaddr >= start &&
gaddr < end) {
/* The complete shadow table has to go */
gmap_unshadow(sg);
spin_unlock(&sg->guest_table_lock);
list_del(&sg->list);
gmap_put(sg);
return;
}
/* Remove the page table tree from on specific entry */
head = radix_tree_delete(&sg->host_to_rmap, vmaddr >> PAGE_SHIFT);
gmap_for_each_rmap_safe(rmap, rnext, head) {
bits = rmap->raddr & _SHADOW_RMAP_MASK;
raddr = rmap->raddr ^ bits;
switch (bits) {
case _SHADOW_RMAP_REGION1:
gmap_unshadow_r2t(sg, raddr);
break;
case _SHADOW_RMAP_REGION2:
gmap_unshadow_r3t(sg, raddr);
break;
case _SHADOW_RMAP_REGION3:
gmap_unshadow_sgt(sg, raddr);
break;
case _SHADOW_RMAP_SEGMENT:
gmap_unshadow_pgt(sg, raddr);
break;
case _SHADOW_RMAP_PGTABLE:
gmap_unshadow_page(sg, raddr);
break;
}
kfree(rmap);
}
spin_unlock(&sg->guest_table_lock);
}
/**
* ptep_notify - call all invalidation callbacks for a specific pte.
* @mm: pointer to the process mm_struct
* @vmaddr: virtual address in the process address space
* @pte: pointer to the page table entry
* @bits: bits from the pgste that caused the notify call
*
* This function is assumed to be called with the page table lock held
* for the pte to notify.
*/
void ptep_notify(struct mm_struct *mm, unsigned long vmaddr,
pte_t *pte, unsigned long bits)
{
unsigned long offset, gaddr = 0;
unsigned long *table;
struct gmap *gmap, *sg, *next;
offset = ((unsigned long) pte) & (255 * sizeof(pte_t));
offset = offset * (PAGE_SIZE / sizeof(pte_t));
rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
spin_lock(&gmap->guest_table_lock);
table = radix_tree_lookup(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (table)
gaddr = __gmap_segment_gaddr(table) + offset;
spin_unlock(&gmap->guest_table_lock);
if (!table)
continue;
if (!list_empty(&gmap->children) && (bits & PGSTE_VSIE_BIT)) {
spin_lock(&gmap->shadow_lock);
list_for_each_entry_safe(sg, next,
&gmap->children, list)
gmap_shadow_notify(sg, vmaddr, gaddr);
spin_unlock(&gmap->shadow_lock);
}
if (bits & PGSTE_IN_BIT)
gmap_call_notifier(gmap, gaddr, gaddr + PAGE_SIZE - 1);
}
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(ptep_notify);
static void pmdp_notify_gmap(struct gmap *gmap, pmd_t *pmdp,
unsigned long gaddr)
{
set_pmd(pmdp, clear_pmd_bit(*pmdp, __pgprot(_SEGMENT_ENTRY_GMAP_IN)));
gmap_call_notifier(gmap, gaddr, gaddr + HPAGE_SIZE - 1);
}
/**
* gmap_pmdp_xchg - exchange a gmap pmd with another
* @gmap: pointer to the guest address space structure
* @pmdp: pointer to the pmd entry
* @new: replacement entry
* @gaddr: the affected guest address
*
* This function is assumed to be called with the guest_table_lock
* held.
*/
static void gmap_pmdp_xchg(struct gmap *gmap, pmd_t *pmdp, pmd_t new,
unsigned long gaddr)
{
gaddr &= HPAGE_MASK;
pmdp_notify_gmap(gmap, pmdp, gaddr);
new = clear_pmd_bit(new, __pgprot(_SEGMENT_ENTRY_GMAP_IN));
if (MACHINE_HAS_TLB_GUEST)
__pmdp_idte(gaddr, (pmd_t *)pmdp, IDTE_GUEST_ASCE, gmap->asce,
IDTE_GLOBAL);
else if (MACHINE_HAS_IDTE)
__pmdp_idte(gaddr, (pmd_t *)pmdp, 0, 0, IDTE_GLOBAL);
else
__pmdp_csp(pmdp);
set_pmd(pmdp, new);
}
static void gmap_pmdp_clear(struct mm_struct *mm, unsigned long vmaddr,
int purge)
{
pmd_t *pmdp;
struct gmap *gmap;
unsigned long gaddr;
rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
spin_lock(&gmap->guest_table_lock);
pmdp = (pmd_t *)radix_tree_delete(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (pmdp) {
gaddr = __gmap_segment_gaddr((unsigned long *)pmdp);
pmdp_notify_gmap(gmap, pmdp, gaddr);
WARN_ON(pmd_val(*pmdp) & ~(_SEGMENT_ENTRY_HARDWARE_BITS_LARGE |
_SEGMENT_ENTRY_GMAP_UC));
if (purge)
__pmdp_csp(pmdp);
set_pmd(pmdp, __pmd(_SEGMENT_ENTRY_EMPTY));
}
spin_unlock(&gmap->guest_table_lock);
}
rcu_read_unlock();
}
/**
* gmap_pmdp_invalidate - invalidate all affected guest pmd entries without
* flushing
* @mm: pointer to the process mm_struct
* @vmaddr: virtual address in the process address space
*/
void gmap_pmdp_invalidate(struct mm_struct *mm, unsigned long vmaddr)
{
gmap_pmdp_clear(mm, vmaddr, 0);
}
EXPORT_SYMBOL_GPL(gmap_pmdp_invalidate);
/**
* gmap_pmdp_csp - csp all affected guest pmd entries
* @mm: pointer to the process mm_struct
* @vmaddr: virtual address in the process address space
*/
void gmap_pmdp_csp(struct mm_struct *mm, unsigned long vmaddr)
{
gmap_pmdp_clear(mm, vmaddr, 1);
}
EXPORT_SYMBOL_GPL(gmap_pmdp_csp);
/**
* gmap_pmdp_idte_local - invalidate and clear a guest pmd entry
* @mm: pointer to the process mm_struct
* @vmaddr: virtual address in the process address space
*/
void gmap_pmdp_idte_local(struct mm_struct *mm, unsigned long vmaddr)
{
unsigned long *entry, gaddr;
struct gmap *gmap;
pmd_t *pmdp;
rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
spin_lock(&gmap->guest_table_lock);
entry = radix_tree_delete(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (entry) {
pmdp = (pmd_t *)entry;
gaddr = __gmap_segment_gaddr(entry);
pmdp_notify_gmap(gmap, pmdp, gaddr);
WARN_ON(*entry & ~(_SEGMENT_ENTRY_HARDWARE_BITS_LARGE |
_SEGMENT_ENTRY_GMAP_UC));
if (MACHINE_HAS_TLB_GUEST)
__pmdp_idte(gaddr, pmdp, IDTE_GUEST_ASCE,
gmap->asce, IDTE_LOCAL);
else if (MACHINE_HAS_IDTE)
__pmdp_idte(gaddr, pmdp, 0, 0, IDTE_LOCAL);
*entry = _SEGMENT_ENTRY_EMPTY;
}
spin_unlock(&gmap->guest_table_lock);
}
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(gmap_pmdp_idte_local);
/**
* gmap_pmdp_idte_global - invalidate and clear a guest pmd entry
* @mm: pointer to the process mm_struct
* @vmaddr: virtual address in the process address space
*/
void gmap_pmdp_idte_global(struct mm_struct *mm, unsigned long vmaddr)
{
unsigned long *entry, gaddr;
struct gmap *gmap;
pmd_t *pmdp;
rcu_read_lock();
list_for_each_entry_rcu(gmap, &mm->context.gmap_list, list) {
spin_lock(&gmap->guest_table_lock);
entry = radix_tree_delete(&gmap->host_to_guest,
vmaddr >> PMD_SHIFT);
if (entry) {
pmdp = (pmd_t *)entry;
gaddr = __gmap_segment_gaddr(entry);
pmdp_notify_gmap(gmap, pmdp, gaddr);
WARN_ON(*entry & ~(_SEGMENT_ENTRY_HARDWARE_BITS_LARGE |
_SEGMENT_ENTRY_GMAP_UC));
if (MACHINE_HAS_TLB_GUEST)
__pmdp_idte(gaddr, pmdp, IDTE_GUEST_ASCE,
gmap->asce, IDTE_GLOBAL);
else if (MACHINE_HAS_IDTE)
__pmdp_idte(gaddr, pmdp, 0, 0, IDTE_GLOBAL);
else
__pmdp_csp(pmdp);
*entry = _SEGMENT_ENTRY_EMPTY;
}
spin_unlock(&gmap->guest_table_lock);
}
rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(gmap_pmdp_idte_global);
/**
* gmap_test_and_clear_dirty_pmd - test and reset segment dirty status
* @gmap: pointer to guest address space
* @pmdp: pointer to the pmd to be tested
* @gaddr: virtual address in the guest address space
*
* This function is assumed to be called with the guest_table_lock
* held.
*/
static bool gmap_test_and_clear_dirty_pmd(struct gmap *gmap, pmd_t *pmdp,
unsigned long gaddr)
{
if (pmd_val(*pmdp) & _SEGMENT_ENTRY_INVALID)
return false;
/* Already protected memory, which did not change is clean */
if (pmd_val(*pmdp) & _SEGMENT_ENTRY_PROTECT &&
!(pmd_val(*pmdp) & _SEGMENT_ENTRY_GMAP_UC))
return false;
/* Clear UC indication and reset protection */
set_pmd(pmdp, clear_pmd_bit(*pmdp, __pgprot(_SEGMENT_ENTRY_GMAP_UC)));
gmap_protect_pmd(gmap, gaddr, pmdp, PROT_READ, 0);
return true;
}
/**
* gmap_sync_dirty_log_pmd - set bitmap based on dirty status of segment
* @gmap: pointer to guest address space
* @bitmap: dirty bitmap for this pmd
* @gaddr: virtual address in the guest address space
* @vmaddr: virtual address in the host address space
*
* This function is assumed to be called with the guest_table_lock
* held.
*/
void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long bitmap[4],
unsigned long gaddr, unsigned long vmaddr)
{
int i;
pmd_t *pmdp;
pte_t *ptep;
spinlock_t *ptl;
pmdp = gmap_pmd_op_walk(gmap, gaddr);
if (!pmdp)
return;
if (pmd_leaf(*pmdp)) {
if (gmap_test_and_clear_dirty_pmd(gmap, pmdp, gaddr))
bitmap_fill(bitmap, _PAGE_ENTRIES);
} else {
for (i = 0; i < _PAGE_ENTRIES; i++, vmaddr += PAGE_SIZE) {
ptep = pte_alloc_map_lock(gmap->mm, pmdp, vmaddr, &ptl);
if (!ptep)
continue;
if (ptep_test_and_clear_uc(gmap->mm, vmaddr, ptep))
set_bit(i, bitmap);
pte_unmap_unlock(ptep, ptl);
}
}
gmap_pmd_op_end(gmap, pmdp);
}
EXPORT_SYMBOL_GPL(gmap_sync_dirty_log_pmd);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
static int thp_split_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
struct vm_area_struct *vma = walk->vma;
split_huge_pmd(vma, pmd, addr);
return 0;
}
static const struct mm_walk_ops thp_split_walk_ops = {
.pmd_entry = thp_split_walk_pmd_entry,
.walk_lock = PGWALK_WRLOCK_VERIFY,
};
static inline void thp_split_mm(struct mm_struct *mm)
{
struct vm_area_struct *vma;
VMA_ITERATOR(vmi, mm, 0);
for_each_vma(vmi, vma) {
vm_flags_mod(vma, VM_NOHUGEPAGE, VM_HUGEPAGE);
walk_page_vma(vma, &thp_split_walk_ops, NULL);
}
mm->def_flags |= VM_NOHUGEPAGE;
}
#else
static inline void thp_split_mm(struct mm_struct *mm)
{
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/*
* switch on pgstes for its userspace process (for kvm)
*/
int s390_enable_sie(void)
{
struct mm_struct *mm = current->mm;
/* Do we have pgstes? if yes, we are done */
if (mm_has_pgste(mm))
return 0;
/* Fail if the page tables are 2K */
if (!mm_alloc_pgste(mm))
return -EINVAL;
mmap_write_lock(mm);
mm->context.has_pgste = 1;
/* split thp mappings and disable thp for future mappings */
thp_split_mm(mm);
mmap_write_unlock(mm);
return 0;
}
EXPORT_SYMBOL_GPL(s390_enable_sie);
static int find_zeropage_pte_entry(pte_t *pte, unsigned long addr,
unsigned long end, struct mm_walk *walk)
{
unsigned long *found_addr = walk->private;
/* Return 1 of the page is a zeropage. */
if (is_zero_pfn(pte_pfn(*pte))) {
/*
* Shared zeropage in e.g., a FS DAX mapping? We cannot do the
* right thing and likely don't care: FAULT_FLAG_UNSHARE
* currently only works in COW mappings, which is also where
* mm_forbids_zeropage() is checked.
*/
if (!is_cow_mapping(walk->vma->vm_flags))
return -EFAULT;
*found_addr = addr;
return 1;
}
return 0;
}
static const struct mm_walk_ops find_zeropage_ops = {
.pte_entry = find_zeropage_pte_entry,
.walk_lock = PGWALK_WRLOCK,
};
/*
* Unshare all shared zeropages, replacing them by anonymous pages. Note that
* we cannot simply zap all shared zeropages, because this could later
* trigger unexpected userfaultfd missing events.
*
* This must be called after mm->context.allow_cow_sharing was
* set to 0, to avoid future mappings of shared zeropages.
*
* mm contracts with s390, that even if mm were to remove a page table,
* and racing with walk_page_range_vma() calling pte_offset_map_lock()
* would fail, it will never insert a page table containing empty zero
* pages once mm_forbids_zeropage(mm) i.e.
* mm->context.allow_cow_sharing is set to 0.
*/
static int __s390_unshare_zeropages(struct mm_struct *mm)
{
struct vm_area_struct *vma;
VMA_ITERATOR(vmi, mm, 0);
unsigned long addr;
vm_fault_t fault;
int rc;
for_each_vma(vmi, vma) {
/*
* We could only look at COW mappings, but it's more future
* proof to catch unexpected zeropages in other mappings and
* fail.
*/
if ((vma->vm_flags & VM_PFNMAP) || is_vm_hugetlb_page(vma))
continue;
addr = vma->vm_start;
retry:
rc = walk_page_range_vma(vma, addr, vma->vm_end,
&find_zeropage_ops, &addr);
if (rc < 0)
return rc;
else if (!rc)
continue;
/* addr was updated by find_zeropage_pte_entry() */
fault = handle_mm_fault(vma, addr,
FAULT_FLAG_UNSHARE | FAULT_FLAG_REMOTE,
NULL);
if (fault & VM_FAULT_OOM)
return -ENOMEM;
/*
* See break_ksm(): even after handle_mm_fault() returned 0, we
* must start the lookup from the current address, because
* handle_mm_fault() may back out if there's any difficulty.
*
* VM_FAULT_SIGBUS and VM_FAULT_SIGSEGV are unexpected but
* maybe they could trigger in the future on concurrent
* truncation. In that case, the shared zeropage would be gone
* and we can simply retry and make progress.
*/
cond_resched();
goto retry;
}
return 0;
}
static int __s390_disable_cow_sharing(struct mm_struct *mm)
{
int rc;
if (!mm->context.allow_cow_sharing)
return 0;
mm->context.allow_cow_sharing = 0;
/* Replace all shared zeropages by anonymous pages. */
rc = __s390_unshare_zeropages(mm);
/*
* Make sure to disable KSM (if enabled for the whole process or
* individual VMAs). Note that nothing currently hinders user space
* from re-enabling it.
*/
if (!rc)
rc = ksm_disable(mm);
if (rc)
mm->context.allow_cow_sharing = 1;
return rc;
}
/*
* Disable most COW-sharing of memory pages for the whole process:
* (1) Disable KSM and unmerge/unshare any KSM pages.
* (2) Disallow shared zeropages and unshare any zerpages that are mapped.
*
* Not that we currently don't bother with COW-shared pages that are shared
* with parent/child processes due to fork().
*/
int s390_disable_cow_sharing(void)
{
int rc;
mmap_write_lock(current->mm);
rc = __s390_disable_cow_sharing(current->mm);
mmap_write_unlock(current->mm);
return rc;
}
EXPORT_SYMBOL_GPL(s390_disable_cow_sharing);
/*
* Enable storage key handling from now on and initialize the storage
* keys with the default key.
*/
static int __s390_enable_skey_pte(pte_t *pte, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
/* Clear storage key */
ptep_zap_key(walk->mm, addr, pte);
return 0;
}
/*
* Give a chance to schedule after setting a key to 256 pages.
* We only hold the mm lock, which is a rwsem and the kvm srcu.
* Both can sleep.
*/
static int __s390_enable_skey_pmd(pmd_t *pmd, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
cond_resched();
return 0;
}
static int __s390_enable_skey_hugetlb(pte_t *pte, unsigned long addr,
unsigned long hmask, unsigned long next,
struct mm_walk *walk)
{
pmd_t *pmd = (pmd_t *)pte;
unsigned long start, end;
struct folio *folio = page_folio(pmd_page(*pmd));
/*
* The write check makes sure we do not set a key on shared
* memory. This is needed as the walker does not differentiate
* between actual guest memory and the process executable or
* shared libraries.
*/
if (pmd_val(*pmd) & _SEGMENT_ENTRY_INVALID ||
!(pmd_val(*pmd) & _SEGMENT_ENTRY_WRITE))
return 0;
start = pmd_val(*pmd) & HPAGE_MASK;
end = start + HPAGE_SIZE;
__storage_key_init_range(start, end);
set_bit(PG_arch_1, &folio->flags);
cond_resched();
return 0;
}
static const struct mm_walk_ops enable_skey_walk_ops = {
.hugetlb_entry = __s390_enable_skey_hugetlb,
.pte_entry = __s390_enable_skey_pte,
.pmd_entry = __s390_enable_skey_pmd,
.walk_lock = PGWALK_WRLOCK,
};
int s390_enable_skey(void)
{
struct mm_struct *mm = current->mm;
int rc = 0;
mmap_write_lock(mm);
if (mm_uses_skeys(mm))
goto out_up;
mm->context.uses_skeys = 1;
rc = __s390_disable_cow_sharing(mm);
if (rc) {
mm->context.uses_skeys = 0;
goto out_up;
}
walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
out_up:
mmap_write_unlock(mm);
return rc;
}
EXPORT_SYMBOL_GPL(s390_enable_skey);
/*
* Reset CMMA state, make all pages stable again.
*/
static int __s390_reset_cmma(pte_t *pte, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
ptep_zap_unused(walk->mm, addr, pte, 1);
return 0;
}
static const struct mm_walk_ops reset_cmma_walk_ops = {
.pte_entry = __s390_reset_cmma,
.walk_lock = PGWALK_WRLOCK,
};
void s390_reset_cmma(struct mm_struct *mm)
{
mmap_write_lock(mm);
walk_page_range(mm, 0, TASK_SIZE, &reset_cmma_walk_ops, NULL);
mmap_write_unlock(mm);
}
EXPORT_SYMBOL_GPL(s390_reset_cmma);
#define GATHER_GET_PAGES 32
struct reset_walk_state {
unsigned long next;
unsigned long count;
unsigned long pfns[GATHER_GET_PAGES];
};
static int s390_gather_pages(pte_t *ptep, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
struct reset_walk_state *p = walk->private;
pte_t pte = READ_ONCE(*ptep);
if (pte_present(pte)) {
/* we have a reference from the mapping, take an extra one */
get_page(phys_to_page(pte_val(pte)));
p->pfns[p->count] = phys_to_pfn(pte_val(pte));
p->next = next;
p->count++;
}
return p->count >= GATHER_GET_PAGES;
}
static const struct mm_walk_ops gather_pages_ops = {
.pte_entry = s390_gather_pages,
.walk_lock = PGWALK_RDLOCK,
};
/*
* Call the Destroy secure page UVC on each page in the given array of PFNs.
* Each page needs to have an extra reference, which will be released here.
*/
void s390_uv_destroy_pfns(unsigned long count, unsigned long *pfns)
{
struct folio *folio;
unsigned long i;
for (i = 0; i < count; i++) {
folio = pfn_folio(pfns[i]);
/* we always have an extra reference */
uv_destroy_folio(folio);
/* get rid of the extra reference */
folio_put(folio);
cond_resched();
}
}
EXPORT_SYMBOL_GPL(s390_uv_destroy_pfns);
/**
* __s390_uv_destroy_range - Call the destroy secure page UVC on each page
* in the given range of the given address space.
* @mm: the mm to operate on
* @start: the start of the range
* @end: the end of the range
* @interruptible: if not 0, stop when a fatal signal is received
*
* Walk the given range of the given address space and call the destroy
* secure page UVC on each page. Optionally exit early if a fatal signal is
* pending.
*
* Return: 0 on success, -EINTR if the function stopped before completing
*/
int __s390_uv_destroy_range(struct mm_struct *mm, unsigned long start,
unsigned long end, bool interruptible)
{
struct reset_walk_state state = { .next = start };
int r = 1;
while (r > 0) {
state.count = 0;
mmap_read_lock(mm);
r = walk_page_range(mm, state.next, end, &gather_pages_ops, &state);
mmap_read_unlock(mm);
cond_resched();
s390_uv_destroy_pfns(state.count, state.pfns);
if (interruptible && fatal_signal_pending(current))
return -EINTR;
}
return 0;
}
EXPORT_SYMBOL_GPL(__s390_uv_destroy_range);
/**
* s390_unlist_old_asce - Remove the topmost level of page tables from the
* list of page tables of the gmap.
* @gmap: the gmap whose table is to be removed
*
* On s390x, KVM keeps a list of all pages containing the page tables of the
* gmap (the CRST list). This list is used at tear down time to free all
* pages that are now not needed anymore.
*
* This function removes the topmost page of the tree (the one pointed to by
* the ASCE) from the CRST list.
*
* This means that it will not be freed when the VM is torn down, and needs
* to be handled separately by the caller, unless a leak is actually
* intended. Notice that this function will only remove the page from the
* list, the page will still be used as a top level page table (and ASCE).
*/
void s390_unlist_old_asce(struct gmap *gmap)
{
struct page *old;
old = virt_to_page(gmap->table);
spin_lock(&gmap->guest_table_lock);
list_del(&old->lru);
/*
* Sometimes the topmost page might need to be "removed" multiple
* times, for example if the VM is rebooted into secure mode several
* times concurrently, or if s390_replace_asce fails after calling
* s390_remove_old_asce and is attempted again later. In that case
* the old asce has been removed from the list, and therefore it
* will not be freed when the VM terminates, but the ASCE is still
* in use and still pointed to.
* A subsequent call to replace_asce will follow the pointer and try
* to remove the same page from the list again.
* Therefore it's necessary that the page of the ASCE has valid
* pointers, so list_del can work (and do nothing) without
* dereferencing stale or invalid pointers.
*/
INIT_LIST_HEAD(&old->lru);
spin_unlock(&gmap->guest_table_lock);
}
EXPORT_SYMBOL_GPL(s390_unlist_old_asce);
/**
* s390_replace_asce - Try to replace the current ASCE of a gmap with a copy
* @gmap: the gmap whose ASCE needs to be replaced
*
* If the ASCE is a SEGMENT type then this function will return -EINVAL,
* otherwise the pointers in the host_to_guest radix tree will keep pointing
* to the wrong pages, causing use-after-free and memory corruption.
* If the allocation of the new top level page table fails, the ASCE is not
* replaced.
* In any case, the old ASCE is always removed from the gmap CRST list.
* Therefore the caller has to make sure to save a pointer to it
* beforehand, unless a leak is actually intended.
*/
int s390_replace_asce(struct gmap *gmap)
{
unsigned long asce;
struct page *page;
void *table;
s390_unlist_old_asce(gmap);
/* Replacing segment type ASCEs would cause serious issues */
if ((gmap->asce & _ASCE_TYPE_MASK) == _ASCE_TYPE_SEGMENT)
return -EINVAL;
page = gmap_alloc_crst();
if (!page)
return -ENOMEM;
page->index = 0;
table = page_to_virt(page);
memcpy(table, gmap->table, 1UL << (CRST_ALLOC_ORDER + PAGE_SHIFT));
/*
* The caller has to deal with the old ASCE, but here we make sure
* the new one is properly added to the CRST list, so that
* it will be freed when the VM is torn down.
*/
spin_lock(&gmap->guest_table_lock);
list_add(&page->lru, &gmap->crst_list);
spin_unlock(&gmap->guest_table_lock);
/* Set new table origin while preserving existing ASCE control bits */
asce = (gmap->asce & ~_ASCE_ORIGIN) | __pa(table);
WRITE_ONCE(gmap->asce, asce);
WRITE_ONCE(gmap->mm->context.gmap_asce, asce);
WRITE_ONCE(gmap->table, table);
return 0;
}
EXPORT_SYMBOL_GPL(s390_replace_asce);