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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Virtio-mem device driver.
*
* Copyright Red Hat, Inc. 2020
*
* Author(s): David Hildenbrand <david@redhat.com>
*/
#include <linux/virtio.h>
#include <linux/virtio_mem.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/memory_hotplug.h>
#include <linux/memory.h>
#include <linux/hrtimer.h>
#include <linux/crash_dump.h>
#include <linux/mutex.h>
#include <linux/bitmap.h>
#include <linux/lockdep.h>
#include <acpi/acpi_numa.h>
static bool unplug_online = true;
module_param(unplug_online, bool, 0644);
MODULE_PARM_DESC(unplug_online, "Try to unplug online memory");
static bool force_bbm;
module_param(force_bbm, bool, 0444);
MODULE_PARM_DESC(force_bbm,
"Force Big Block Mode. Default is 0 (auto-selection)");
static unsigned long bbm_block_size;
module_param(bbm_block_size, ulong, 0444);
MODULE_PARM_DESC(bbm_block_size,
"Big Block size in bytes. Default is 0 (auto-detection).");
static bool bbm_safe_unplug = true;
module_param(bbm_safe_unplug, bool, 0444);
MODULE_PARM_DESC(bbm_safe_unplug,
"Use a safe unplug mechanism in BBM, avoiding long/endless loops");
/*
* virtio-mem currently supports the following modes of operation:
*
* * Sub Block Mode (SBM): A Linux memory block spans 2..X subblocks (SB). The
* size of a Sub Block (SB) is determined based on the device block size, the
* pageblock size, and the maximum allocation granularity of the buddy.
* Subblocks within a Linux memory block might either be plugged or unplugged.
* Memory is added/removed to Linux MM in Linux memory block granularity.
*
* * Big Block Mode (BBM): A Big Block (BB) spans 1..X Linux memory blocks.
* Memory is added/removed to Linux MM in Big Block granularity.
*
* The mode is determined automatically based on the Linux memory block size
* and the device block size.
*
* User space / core MM (auto onlining) is responsible for onlining added
* Linux memory blocks - and for selecting a zone. Linux Memory Blocks are
* always onlined separately, and all memory within a Linux memory block is
* onlined to the same zone - virtio-mem relies on this behavior.
*/
/*
* State of a Linux memory block in SBM.
*/
enum virtio_mem_sbm_mb_state {
/* Unplugged, not added to Linux. Can be reused later. */
VIRTIO_MEM_SBM_MB_UNUSED = 0,
/* (Partially) plugged, not added to Linux. Error on add_memory(). */
VIRTIO_MEM_SBM_MB_PLUGGED,
/* Fully plugged, fully added to Linux, offline. */
VIRTIO_MEM_SBM_MB_OFFLINE,
/* Partially plugged, fully added to Linux, offline. */
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
/* Fully plugged, fully added to Linux, onlined to a kernel zone. */
VIRTIO_MEM_SBM_MB_KERNEL,
/* Partially plugged, fully added to Linux, online to a kernel zone */
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
/* Fully plugged, fully added to Linux, onlined to ZONE_MOVABLE. */
VIRTIO_MEM_SBM_MB_MOVABLE,
/* Partially plugged, fully added to Linux, onlined to ZONE_MOVABLE. */
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
VIRTIO_MEM_SBM_MB_COUNT
};
/*
* State of a Big Block (BB) in BBM, covering 1..X Linux memory blocks.
*/
enum virtio_mem_bbm_bb_state {
/* Unplugged, not added to Linux. Can be reused later. */
VIRTIO_MEM_BBM_BB_UNUSED = 0,
/* Plugged, not added to Linux. Error on add_memory(). */
VIRTIO_MEM_BBM_BB_PLUGGED,
/* Plugged and added to Linux. */
VIRTIO_MEM_BBM_BB_ADDED,
/* All online parts are fake-offline, ready to remove. */
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE,
VIRTIO_MEM_BBM_BB_COUNT
};
struct virtio_mem {
struct virtio_device *vdev;
/* We might first have to unplug all memory when starting up. */
bool unplug_all_required;
/* Workqueue that processes the plug/unplug requests. */
struct work_struct wq;
atomic_t wq_active;
atomic_t config_changed;
/* Virtqueue for guest->host requests. */
struct virtqueue *vq;
/* Wait for a host response to a guest request. */
wait_queue_head_t host_resp;
/* Space for one guest request and the host response. */
struct virtio_mem_req req;
struct virtio_mem_resp resp;
/* The current size of the device. */
uint64_t plugged_size;
/* The requested size of the device. */
uint64_t requested_size;
/* The device block size (for communicating with the device). */
uint64_t device_block_size;
/* The determined node id for all memory of the device. */
int nid;
/* Physical start address of the memory region. */
uint64_t addr;
/* Maximum region size in bytes. */
uint64_t region_size;
/* The parent resource for all memory added via this device. */
struct resource *parent_resource;
/*
* Copy of "System RAM (virtio_mem)" to be used for
* add_memory_driver_managed().
*/
const char *resource_name;
/* Memory group identification. */
int mgid;
/*
* We don't want to add too much memory if it's not getting onlined,
* to avoid running OOM. Besides this threshold, we allow to have at
* least two offline blocks at a time (whatever is bigger).
*/
#define VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD (1024 * 1024 * 1024)
atomic64_t offline_size;
uint64_t offline_threshold;
/* If set, the driver is in SBM, otherwise in BBM. */
bool in_sbm;
union {
struct {
/* Id of the first memory block of this device. */
unsigned long first_mb_id;
/* Id of the last usable memory block of this device. */
unsigned long last_usable_mb_id;
/* Id of the next memory bock to prepare when needed. */
unsigned long next_mb_id;
/* The subblock size. */
uint64_t sb_size;
/* The number of subblocks per Linux memory block. */
uint32_t sbs_per_mb;
/* Summary of all memory block states. */
unsigned long mb_count[VIRTIO_MEM_SBM_MB_COUNT];
/*
* One byte state per memory block. Allocated via
* vmalloc(). Resized (alloc+copy+free) on demand.
*
* With 128 MiB memory blocks, we have states for 512
* GiB of memory in one 4 KiB page.
*/
uint8_t *mb_states;
/*
* Bitmap: one bit per subblock. Allocated similar to
* sbm.mb_states.
*
* A set bit means the corresponding subblock is
* plugged, otherwise it's unblocked.
*
* With 4 MiB subblocks, we manage 128 GiB of memory
* in one 4 KiB page.
*/
unsigned long *sb_states;
} sbm;
struct {
/* Id of the first big block of this device. */
unsigned long first_bb_id;
/* Id of the last usable big block of this device. */
unsigned long last_usable_bb_id;
/* Id of the next device bock to prepare when needed. */
unsigned long next_bb_id;
/* Summary of all big block states. */
unsigned long bb_count[VIRTIO_MEM_BBM_BB_COUNT];
/* One byte state per big block. See sbm.mb_states. */
uint8_t *bb_states;
/* The block size used for plugging/adding/removing. */
uint64_t bb_size;
} bbm;
};
/*
* Mutex that protects the sbm.mb_count, sbm.mb_states,
* sbm.sb_states, bbm.bb_count, and bbm.bb_states
*
* When this lock is held the pointers can't change, ONLINE and
* OFFLINE blocks can't change the state and no subblocks will get
* plugged/unplugged.
*
* In kdump mode, used to serialize requests, last_block_addr and
* last_block_plugged.
*/
struct mutex hotplug_mutex;
bool hotplug_active;
/* An error occurred we cannot handle - stop processing requests. */
bool broken;
/* Cached valued of is_kdump_kernel() when the device was probed. */
bool in_kdump;
/* The driver is being removed. */
spinlock_t removal_lock;
bool removing;
/* Timer for retrying to plug/unplug memory. */
struct hrtimer retry_timer;
unsigned int retry_timer_ms;
#define VIRTIO_MEM_RETRY_TIMER_MIN_MS 50000
#define VIRTIO_MEM_RETRY_TIMER_MAX_MS 300000
/* Memory notifier (online/offline events). */
struct notifier_block memory_notifier;
#ifdef CONFIG_PROC_VMCORE
/* vmcore callback for /proc/vmcore handling in kdump mode */
struct vmcore_cb vmcore_cb;
uint64_t last_block_addr;
bool last_block_plugged;
#endif /* CONFIG_PROC_VMCORE */
/* Next device in the list of virtio-mem devices. */
struct list_head next;
};
/*
* We have to share a single online_page callback among all virtio-mem
* devices. We use RCU to iterate the list in the callback.
*/
static DEFINE_MUTEX(virtio_mem_mutex);
static LIST_HEAD(virtio_mem_devices);
static void virtio_mem_online_page_cb(struct page *page, unsigned int order);
static void virtio_mem_fake_offline_going_offline(unsigned long pfn,
unsigned long nr_pages);
static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
unsigned long nr_pages);
static void virtio_mem_retry(struct virtio_mem *vm);
static int virtio_mem_create_resource(struct virtio_mem *vm);
static void virtio_mem_delete_resource(struct virtio_mem *vm);
/*
* Register a virtio-mem device so it will be considered for the online_page
* callback.
*/
static int register_virtio_mem_device(struct virtio_mem *vm)
{
int rc = 0;
/* First device registers the callback. */
mutex_lock(&virtio_mem_mutex);
if (list_empty(&virtio_mem_devices))
rc = set_online_page_callback(&virtio_mem_online_page_cb);
if (!rc)
list_add_rcu(&vm->next, &virtio_mem_devices);
mutex_unlock(&virtio_mem_mutex);
return rc;
}
/*
* Unregister a virtio-mem device so it will no longer be considered for the
* online_page callback.
*/
static void unregister_virtio_mem_device(struct virtio_mem *vm)
{
/* Last device unregisters the callback. */
mutex_lock(&virtio_mem_mutex);
list_del_rcu(&vm->next);
if (list_empty(&virtio_mem_devices))
restore_online_page_callback(&virtio_mem_online_page_cb);
mutex_unlock(&virtio_mem_mutex);
synchronize_rcu();
}
/*
* Calculate the memory block id of a given address.
*/
static unsigned long virtio_mem_phys_to_mb_id(unsigned long addr)
{
return addr / memory_block_size_bytes();
}
/*
* Calculate the physical start address of a given memory block id.
*/
static unsigned long virtio_mem_mb_id_to_phys(unsigned long mb_id)
{
return mb_id * memory_block_size_bytes();
}
/*
* Calculate the big block id of a given address.
*/
static unsigned long virtio_mem_phys_to_bb_id(struct virtio_mem *vm,
uint64_t addr)
{
return addr / vm->bbm.bb_size;
}
/*
* Calculate the physical start address of a given big block id.
*/
static uint64_t virtio_mem_bb_id_to_phys(struct virtio_mem *vm,
unsigned long bb_id)
{
return bb_id * vm->bbm.bb_size;
}
/*
* Calculate the subblock id of a given address.
*/
static unsigned long virtio_mem_phys_to_sb_id(struct virtio_mem *vm,
unsigned long addr)
{
const unsigned long mb_id = virtio_mem_phys_to_mb_id(addr);
const unsigned long mb_addr = virtio_mem_mb_id_to_phys(mb_id);
return (addr - mb_addr) / vm->sbm.sb_size;
}
/*
* Set the state of a big block, taking care of the state counter.
*/
static void virtio_mem_bbm_set_bb_state(struct virtio_mem *vm,
unsigned long bb_id,
enum virtio_mem_bbm_bb_state state)
{
const unsigned long idx = bb_id - vm->bbm.first_bb_id;
enum virtio_mem_bbm_bb_state old_state;
old_state = vm->bbm.bb_states[idx];
vm->bbm.bb_states[idx] = state;
BUG_ON(vm->bbm.bb_count[old_state] == 0);
vm->bbm.bb_count[old_state]--;
vm->bbm.bb_count[state]++;
}
/*
* Get the state of a big block.
*/
static enum virtio_mem_bbm_bb_state virtio_mem_bbm_get_bb_state(struct virtio_mem *vm,
unsigned long bb_id)
{
return vm->bbm.bb_states[bb_id - vm->bbm.first_bb_id];
}
/*
* Prepare the big block state array for the next big block.
*/
static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm)
{
unsigned long old_bytes = vm->bbm.next_bb_id - vm->bbm.first_bb_id;
unsigned long new_bytes = old_bytes + 1;
int old_pages = PFN_UP(old_bytes);
int new_pages = PFN_UP(new_bytes);
uint8_t *new_array;
if (vm->bbm.bb_states && old_pages == new_pages)
return 0;
new_array = vzalloc(new_pages * PAGE_SIZE);
if (!new_array)
return -ENOMEM;
mutex_lock(&vm->hotplug_mutex);
if (vm->bbm.bb_states)
memcpy(new_array, vm->bbm.bb_states, old_pages * PAGE_SIZE);
vfree(vm->bbm.bb_states);
vm->bbm.bb_states = new_array;
mutex_unlock(&vm->hotplug_mutex);
return 0;
}
#define virtio_mem_bbm_for_each_bb(_vm, _bb_id, _state) \
for (_bb_id = vm->bbm.first_bb_id; \
_bb_id < vm->bbm.next_bb_id && _vm->bbm.bb_count[_state]; \
_bb_id++) \
if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
#define virtio_mem_bbm_for_each_bb_rev(_vm, _bb_id, _state) \
for (_bb_id = vm->bbm.next_bb_id - 1; \
_bb_id >= vm->bbm.first_bb_id && _vm->bbm.bb_count[_state]; \
_bb_id--) \
if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
/*
* Set the state of a memory block, taking care of the state counter.
*/
static void virtio_mem_sbm_set_mb_state(struct virtio_mem *vm,
unsigned long mb_id, uint8_t state)
{
const unsigned long idx = mb_id - vm->sbm.first_mb_id;
uint8_t old_state;
old_state = vm->sbm.mb_states[idx];
vm->sbm.mb_states[idx] = state;
BUG_ON(vm->sbm.mb_count[old_state] == 0);
vm->sbm.mb_count[old_state]--;
vm->sbm.mb_count[state]++;
}
/*
* Get the state of a memory block.
*/
static uint8_t virtio_mem_sbm_get_mb_state(struct virtio_mem *vm,
unsigned long mb_id)
{
const unsigned long idx = mb_id - vm->sbm.first_mb_id;
return vm->sbm.mb_states[idx];
}
/*
* Prepare the state array for the next memory block.
*/
static int virtio_mem_sbm_mb_states_prepare_next_mb(struct virtio_mem *vm)
{
int old_pages = PFN_UP(vm->sbm.next_mb_id - vm->sbm.first_mb_id);
int new_pages = PFN_UP(vm->sbm.next_mb_id - vm->sbm.first_mb_id + 1);
uint8_t *new_array;
if (vm->sbm.mb_states && old_pages == new_pages)
return 0;
new_array = vzalloc(new_pages * PAGE_SIZE);
if (!new_array)
return -ENOMEM;
mutex_lock(&vm->hotplug_mutex);
if (vm->sbm.mb_states)
memcpy(new_array, vm->sbm.mb_states, old_pages * PAGE_SIZE);
vfree(vm->sbm.mb_states);
vm->sbm.mb_states = new_array;
mutex_unlock(&vm->hotplug_mutex);
return 0;
}
#define virtio_mem_sbm_for_each_mb(_vm, _mb_id, _state) \
for (_mb_id = _vm->sbm.first_mb_id; \
_mb_id < _vm->sbm.next_mb_id && _vm->sbm.mb_count[_state]; \
_mb_id++) \
if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
#define virtio_mem_sbm_for_each_mb_rev(_vm, _mb_id, _state) \
for (_mb_id = _vm->sbm.next_mb_id - 1; \
_mb_id >= _vm->sbm.first_mb_id && _vm->sbm.mb_count[_state]; \
_mb_id--) \
if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
/*
* Calculate the bit number in the subblock bitmap for the given subblock
* inside the given memory block.
*/
static int virtio_mem_sbm_sb_state_bit_nr(struct virtio_mem *vm,
unsigned long mb_id, int sb_id)
{
return (mb_id - vm->sbm.first_mb_id) * vm->sbm.sbs_per_mb + sb_id;
}
/*
* Mark all selected subblocks plugged.
*
* Will not modify the state of the memory block.
*/
static void virtio_mem_sbm_set_sb_plugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
__bitmap_set(vm->sbm.sb_states, bit, count);
}
/*
* Mark all selected subblocks unplugged.
*
* Will not modify the state of the memory block.
*/
static void virtio_mem_sbm_set_sb_unplugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
__bitmap_clear(vm->sbm.sb_states, bit, count);
}
/*
* Test if all selected subblocks are plugged.
*/
static bool virtio_mem_sbm_test_sb_plugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
if (count == 1)
return test_bit(bit, vm->sbm.sb_states);
/* TODO: Helper similar to bitmap_set() */
return find_next_zero_bit(vm->sbm.sb_states, bit + count, bit) >=
bit + count;
}
/*
* Test if all selected subblocks are unplugged.
*/
static bool virtio_mem_sbm_test_sb_unplugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
/* TODO: Helper similar to bitmap_set() */
return find_next_bit(vm->sbm.sb_states, bit + count, bit) >=
bit + count;
}
/*
* Find the first unplugged subblock. Returns vm->sbm.sbs_per_mb in case there is
* none.
*/
static int virtio_mem_sbm_first_unplugged_sb(struct virtio_mem *vm,
unsigned long mb_id)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, 0);
return find_next_zero_bit(vm->sbm.sb_states,
bit + vm->sbm.sbs_per_mb, bit) - bit;
}
/*
* Prepare the subblock bitmap for the next memory block.
*/
static int virtio_mem_sbm_sb_states_prepare_next_mb(struct virtio_mem *vm)
{
const unsigned long old_nb_mb = vm->sbm.next_mb_id - vm->sbm.first_mb_id;
const unsigned long old_nb_bits = old_nb_mb * vm->sbm.sbs_per_mb;
const unsigned long new_nb_bits = (old_nb_mb + 1) * vm->sbm.sbs_per_mb;
int old_pages = PFN_UP(BITS_TO_LONGS(old_nb_bits) * sizeof(long));
int new_pages = PFN_UP(BITS_TO_LONGS(new_nb_bits) * sizeof(long));
unsigned long *new_bitmap, *old_bitmap;
if (vm->sbm.sb_states && old_pages == new_pages)
return 0;
new_bitmap = vzalloc(new_pages * PAGE_SIZE);
if (!new_bitmap)
return -ENOMEM;
mutex_lock(&vm->hotplug_mutex);
if (new_bitmap)
memcpy(new_bitmap, vm->sbm.sb_states, old_pages * PAGE_SIZE);
old_bitmap = vm->sbm.sb_states;
vm->sbm.sb_states = new_bitmap;
mutex_unlock(&vm->hotplug_mutex);
vfree(old_bitmap);
return 0;
}
/*
* Test if we could add memory without creating too much offline memory -
* to avoid running OOM if memory is getting onlined deferred.
*/
static bool virtio_mem_could_add_memory(struct virtio_mem *vm, uint64_t size)
{
if (WARN_ON_ONCE(size > vm->offline_threshold))
return false;
return atomic64_read(&vm->offline_size) + size <= vm->offline_threshold;
}
/*
* Try adding memory to Linux. Will usually only fail if out of memory.
*
* Must not be called with the vm->hotplug_mutex held (possible deadlock with
* onlining code).
*
* Will not modify the state of memory blocks in virtio-mem.
*/
static int virtio_mem_add_memory(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
int rc;
/*
* When force-unloading the driver and we still have memory added to
* Linux, the resource name has to stay.
*/
if (!vm->resource_name) {
vm->resource_name = kstrdup_const("System RAM (virtio_mem)",
GFP_KERNEL);
if (!vm->resource_name)
return -ENOMEM;
}
dev_dbg(&vm->vdev->dev, "adding memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
/* Memory might get onlined immediately. */
atomic64_add(size, &vm->offline_size);
rc = add_memory_driver_managed(vm->mgid, addr, size, vm->resource_name,
MHP_MERGE_RESOURCE | MHP_NID_IS_MGID);
if (rc) {
atomic64_sub(size, &vm->offline_size);
dev_warn(&vm->vdev->dev, "adding memory failed: %d\n", rc);
/*
* TODO: Linux MM does not properly clean up yet in all cases
* where adding of memory failed - especially on -ENOMEM.
*/
}
return rc;
}
/*
* See virtio_mem_add_memory(): Try adding a single Linux memory block.
*/
static int virtio_mem_sbm_add_mb(struct virtio_mem *vm, unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
const uint64_t size = memory_block_size_bytes();
return virtio_mem_add_memory(vm, addr, size);
}
/*
* See virtio_mem_add_memory(): Try adding a big block.
*/
static int virtio_mem_bbm_add_bb(struct virtio_mem *vm, unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_add_memory(vm, addr, size);
}
/*
* Try removing memory from Linux. Will only fail if memory blocks aren't
* offline.
*
* Must not be called with the vm->hotplug_mutex held (possible deadlock with
* onlining code).
*
* Will not modify the state of memory blocks in virtio-mem.
*/
static int virtio_mem_remove_memory(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
int rc;
dev_dbg(&vm->vdev->dev, "removing memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
rc = remove_memory(addr, size);
if (!rc) {
atomic64_sub(size, &vm->offline_size);
/*
* We might have freed up memory we can now unplug, retry
* immediately instead of waiting.
*/
virtio_mem_retry(vm);
} else {
dev_dbg(&vm->vdev->dev, "removing memory failed: %d\n", rc);
}
return rc;
}
/*
* See virtio_mem_remove_memory(): Try removing a single Linux memory block.
*/
static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
const uint64_t size = memory_block_size_bytes();
return virtio_mem_remove_memory(vm, addr, size);
}
/*
* Try offlining and removing memory from Linux.
*
* Must not be called with the vm->hotplug_mutex held (possible deadlock with
* onlining code).
*
* Will not modify the state of memory blocks in virtio-mem.
*/
static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
uint64_t addr,
uint64_t size)
{
int rc;
dev_dbg(&vm->vdev->dev,
"offlining and removing memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
rc = offline_and_remove_memory(addr, size);
if (!rc) {
atomic64_sub(size, &vm->offline_size);
/*
* We might have freed up memory we can now unplug, retry
* immediately instead of waiting.
*/
virtio_mem_retry(vm);
} else {
dev_dbg(&vm->vdev->dev,
"offlining and removing memory failed: %d\n", rc);
}
return rc;
}
/*
* See virtio_mem_offline_and_remove_memory(): Try offlining and removing
* a single Linux memory block.
*/
static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm,
unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
const uint64_t size = memory_block_size_bytes();
return virtio_mem_offline_and_remove_memory(vm, addr, size);
}
/*
* See virtio_mem_offline_and_remove_memory(): Try to offline and remove a
* all Linux memory blocks covered by the big block.
*/
static int virtio_mem_bbm_offline_and_remove_bb(struct virtio_mem *vm,
unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_offline_and_remove_memory(vm, addr, size);
}
/*
* Trigger the workqueue so the device can perform its magic.
*/
static void virtio_mem_retry(struct virtio_mem *vm)
{
unsigned long flags;
spin_lock_irqsave(&vm->removal_lock, flags);
if (!vm->removing)
queue_work(system_freezable_wq, &vm->wq);
spin_unlock_irqrestore(&vm->removal_lock, flags);
}
static int virtio_mem_translate_node_id(struct virtio_mem *vm, uint16_t node_id)
{
int node = NUMA_NO_NODE;
#if defined(CONFIG_ACPI_NUMA)
if (virtio_has_feature(vm->vdev, VIRTIO_MEM_F_ACPI_PXM))
node = pxm_to_node(node_id);
#endif
return node;
}
/*
* Test if a virtio-mem device overlaps with the given range. Can be called
* from (notifier) callbacks lockless.
*/
static bool virtio_mem_overlaps_range(struct virtio_mem *vm, uint64_t start,
uint64_t size)
{
return start < vm->addr + vm->region_size && vm->addr < start + size;
}
/*
* Test if a virtio-mem device contains a given range. Can be called from
* (notifier) callbacks lockless.
*/
static bool virtio_mem_contains_range(struct virtio_mem *vm, uint64_t start,
uint64_t size)
{
return start >= vm->addr && start + size <= vm->addr + vm->region_size;
}
static int virtio_mem_sbm_notify_going_online(struct virtio_mem *vm,
unsigned long mb_id)
{
switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
case VIRTIO_MEM_SBM_MB_OFFLINE:
return NOTIFY_OK;
default:
break;
}
dev_warn_ratelimited(&vm->vdev->dev,
"memory block onlining denied\n");
return NOTIFY_BAD;
}
static void virtio_mem_sbm_notify_offline(struct virtio_mem *vm,
unsigned long mb_id)
{
switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
case VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL:
case VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
break;
case VIRTIO_MEM_SBM_MB_KERNEL:
case VIRTIO_MEM_SBM_MB_MOVABLE:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE);
break;
default:
BUG();
break;
}
}
static void virtio_mem_sbm_notify_online(struct virtio_mem *vm,
unsigned long mb_id,
unsigned long start_pfn)
{
const bool is_movable = page_zonenum(pfn_to_page(start_pfn)) ==
ZONE_MOVABLE;
int new_state;
switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
new_state = VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL;
if (is_movable)
new_state = VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL;
break;
case VIRTIO_MEM_SBM_MB_OFFLINE:
new_state = VIRTIO_MEM_SBM_MB_KERNEL;
if (is_movable)
new_state = VIRTIO_MEM_SBM_MB_MOVABLE;
break;
default:
BUG();
break;
}
virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
}
static void virtio_mem_sbm_notify_going_offline(struct virtio_mem *vm,
unsigned long mb_id)
{
const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size);
unsigned long pfn;
int sb_id;
for (sb_id = 0; sb_id < vm->sbm.sbs_per_mb; sb_id++) {
if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
continue;
pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
virtio_mem_fake_offline_going_offline(pfn, nr_pages);
}
}
static void virtio_mem_sbm_notify_cancel_offline(struct virtio_mem *vm,
unsigned long mb_id)
{
const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size);
unsigned long pfn;
int sb_id;
for (sb_id = 0; sb_id < vm->sbm.sbs_per_mb; sb_id++) {
if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
continue;
pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
virtio_mem_fake_offline_cancel_offline(pfn, nr_pages);
}
}
static void virtio_mem_bbm_notify_going_offline(struct virtio_mem *vm,
unsigned long bb_id,
unsigned long pfn,
unsigned long nr_pages)
{
/*
* When marked as "fake-offline", all online memory of this device block
* is allocated by us. Otherwise, we don't have any memory allocated.
*/
if (virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE)
return;
virtio_mem_fake_offline_going_offline(pfn, nr_pages);
}
static void virtio_mem_bbm_notify_cancel_offline(struct virtio_mem *vm,
unsigned long bb_id,
unsigned long pfn,
unsigned long nr_pages)
{
if (virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE)
return;
virtio_mem_fake_offline_cancel_offline(pfn, nr_pages);
}
/*
* This callback will either be called synchronously from add_memory() or
* asynchronously (e.g., triggered via user space). We have to be careful
* with locking when calling add_memory().
*/
static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,
unsigned long action, void *arg)
{
struct virtio_mem *vm = container_of(nb, struct virtio_mem,
memory_notifier);
struct memory_notify *mhp = arg;
const unsigned long start = PFN_PHYS(mhp->start_pfn);
const unsigned long size = PFN_PHYS(mhp->nr_pages);
int rc = NOTIFY_OK;
unsigned long id;
if (!virtio_mem_overlaps_range(vm, start, size))
return NOTIFY_DONE;
if (vm->in_sbm) {
id = virtio_mem_phys_to_mb_id(start);
/*
* In SBM, we add memory in separate memory blocks - we expect
* it to be onlined/offlined in the same granularity. Bail out
* if this ever changes.
*/
if (WARN_ON_ONCE(size != memory_block_size_bytes() ||
!IS_ALIGNED(start, memory_block_size_bytes())))
return NOTIFY_BAD;
} else {
id = virtio_mem_phys_to_bb_id(vm, start);
/*
* In BBM, we only care about onlining/offlining happening
* within a single big block, we don't care about the
* actual granularity as we don't track individual Linux
* memory blocks.
*/
if (WARN_ON_ONCE(id != virtio_mem_phys_to_bb_id(vm, start + size - 1)))
return NOTIFY_BAD;
}
/*
* Avoid circular locking lockdep warnings. We lock the mutex
* e.g., in MEM_GOING_ONLINE and unlock it in MEM_ONLINE. The
* blocking_notifier_call_chain() has it's own lock, which gets unlocked
* between both notifier calls and will bail out. False positive.
*/
lockdep_off();
switch (action) {
case MEM_GOING_OFFLINE:
mutex_lock(&vm->hotplug_mutex);
if (vm->removing) {
rc = notifier_from_errno(-EBUSY);
mutex_unlock(&vm->hotplug_mutex);
break;
}
vm->hotplug_active = true;
if (vm->in_sbm)
virtio_mem_sbm_notify_going_offline(vm, id);
else
virtio_mem_bbm_notify_going_offline(vm, id,
mhp->start_pfn,
mhp->nr_pages);
break;
case MEM_GOING_ONLINE:
mutex_lock(&vm->hotplug_mutex);
if (vm->removing) {
rc = notifier_from_errno(-EBUSY);
mutex_unlock(&vm->hotplug_mutex);
break;
}
vm->hotplug_active = true;
if (vm->in_sbm)
rc = virtio_mem_sbm_notify_going_online(vm, id);
break;
case MEM_OFFLINE:
if (vm->in_sbm)
virtio_mem_sbm_notify_offline(vm, id);
atomic64_add(size, &vm->offline_size);
/*
* Trigger the workqueue. Now that we have some offline memory,
* maybe we can handle pending unplug requests.
*/
if (!unplug_online)
virtio_mem_retry(vm);
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
case MEM_ONLINE:
if (vm->in_sbm)
virtio_mem_sbm_notify_online(vm, id, mhp->start_pfn);
atomic64_sub(size, &vm->offline_size);
/*
* Start adding more memory once we onlined half of our
* threshold. Don't trigger if it's possibly due to our actipn
* (e.g., us adding memory which gets onlined immediately from
* the core).
*/
if (!atomic_read(&vm->wq_active) &&
virtio_mem_could_add_memory(vm, vm->offline_threshold / 2))
virtio_mem_retry(vm);
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
case MEM_CANCEL_OFFLINE:
if (!vm->hotplug_active)
break;
if (vm->in_sbm)
virtio_mem_sbm_notify_cancel_offline(vm, id);
else
virtio_mem_bbm_notify_cancel_offline(vm, id,
mhp->start_pfn,
mhp->nr_pages);
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
case MEM_CANCEL_ONLINE:
if (!vm->hotplug_active)
break;
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
default:
break;
}
lockdep_on();
return rc;
}
/*
* Set a range of pages PG_offline. Remember pages that were never onlined
* (via generic_online_page()) using PageDirty().
*/
static void virtio_mem_set_fake_offline(unsigned long pfn,
unsigned long nr_pages, bool onlined)
{
page_offline_begin();
for (; nr_pages--; pfn++) {
struct page *page = pfn_to_page(pfn);
__SetPageOffline(page);
if (!onlined) {
SetPageDirty(page);
/* FIXME: remove after cleanups */
ClearPageReserved(page);
}
}
page_offline_end();
}
/*
* Clear PG_offline from a range of pages. If the pages were never onlined,
* (via generic_online_page()), clear PageDirty().
*/
static void virtio_mem_clear_fake_offline(unsigned long pfn,
unsigned long nr_pages, bool onlined)
{
for (; nr_pages--; pfn++) {
struct page *page = pfn_to_page(pfn);
__ClearPageOffline(page);
if (!onlined)
ClearPageDirty(page);
}
}
/*
* Release a range of fake-offline pages to the buddy, effectively
* fake-onlining them.
*/
static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
{
const unsigned long max_nr_pages = MAX_ORDER_NR_PAGES;
unsigned long i;
/*
* We are always called at least with MAX_ORDER_NR_PAGES
* granularity/alignment (e.g., the way subblocks work). All pages
* inside such a block are alike.
*/
for (i = 0; i < nr_pages; i += max_nr_pages) {
struct page *page = pfn_to_page(pfn + i);
/*
* If the page is PageDirty(), it was kept fake-offline when
* onlining the memory block. Otherwise, it was allocated
* using alloc_contig_range(). All pages in a subblock are
* alike.
*/
if (PageDirty(page)) {
virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
false);
generic_online_page(page, MAX_ORDER - 1);
} else {
virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
true);
free_contig_range(pfn + i, max_nr_pages);
adjust_managed_page_count(page, max_nr_pages);
}
}
}
/*
* Try to allocate a range, marking pages fake-offline, effectively
* fake-offlining them.
*/
static int virtio_mem_fake_offline(unsigned long pfn, unsigned long nr_pages)
{
const bool is_movable = page_zonenum(pfn_to_page(pfn)) ==
ZONE_MOVABLE;
int rc, retry_count;
/*
* TODO: We want an alloc_contig_range() mode that tries to allocate
* harder (e.g., dealing with temporarily pinned pages, PCP), especially
* with ZONE_MOVABLE. So for now, retry a couple of times with
* ZONE_MOVABLE before giving up - because that zone is supposed to give
* some guarantees.
*/
for (retry_count = 0; retry_count < 5; retry_count++) {
rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
GFP_KERNEL);
if (rc == -ENOMEM)
/* whoops, out of memory */
return rc;
else if (rc && !is_movable)
break;
else if (rc)
continue;
virtio_mem_set_fake_offline(pfn, nr_pages, true);
adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
return 0;
}
return -EBUSY;
}
/*
* Handle fake-offline pages when memory is going offline - such that the
* pages can be skipped by mm-core when offlining.
*/
static void virtio_mem_fake_offline_going_offline(unsigned long pfn,
unsigned long nr_pages)
{
struct page *page;
unsigned long i;
/*
* Drop our reference to the pages so the memory can get offlined
* and add the unplugged pages to the managed page counters (so
* offlining code can correctly subtract them again).
*/
adjust_managed_page_count(pfn_to_page(pfn), nr_pages);
/* Drop our reference to the pages so the memory can get offlined. */
for (i = 0; i < nr_pages; i++) {
page = pfn_to_page(pfn + i);
if (WARN_ON(!page_ref_dec_and_test(page)))
dump_page(page, "fake-offline page referenced");
}
}
/*
* Handle fake-offline pages when memory offlining is canceled - to undo
* what we did in virtio_mem_fake_offline_going_offline().
*/
static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
unsigned long nr_pages)
{
unsigned long i;
/*
* Get the reference we dropped when going offline and subtract the
* unplugged pages from the managed page counters.
*/
adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
for (i = 0; i < nr_pages; i++)
page_ref_inc(pfn_to_page(pfn + i));
}
static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
{
const unsigned long addr = page_to_phys(page);
unsigned long id, sb_id;
struct virtio_mem *vm;
bool do_online;
rcu_read_lock();
list_for_each_entry_rcu(vm, &virtio_mem_devices, next) {
if (!virtio_mem_contains_range(vm, addr, PFN_PHYS(1 << order)))
continue;
if (vm->in_sbm) {
/*
* We exploit here that subblocks have at least
* MAX_ORDER_NR_PAGES size/alignment - so we cannot
* cross subblocks within one call.
*/
id = virtio_mem_phys_to_mb_id(addr);
sb_id = virtio_mem_phys_to_sb_id(vm, addr);
do_online = virtio_mem_sbm_test_sb_plugged(vm, id,
sb_id, 1);
} else {
/*
* If the whole block is marked fake offline, keep
* everything that way.
*/
id = virtio_mem_phys_to_bb_id(vm, addr);
do_online = virtio_mem_bbm_get_bb_state(vm, id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE;
}
/*
* virtio_mem_set_fake_offline() might sleep, we don't need
* the device anymore. See virtio_mem_remove() how races
* between memory onlining and device removal are handled.
*/
rcu_read_unlock();
if (do_online)
generic_online_page(page, order);
else
virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
false);
return;
}
rcu_read_unlock();
/* not virtio-mem memory, but e.g., a DIMM. online it */
generic_online_page(page, order);
}
static uint64_t virtio_mem_send_request(struct virtio_mem *vm,
const struct virtio_mem_req *req)
{
struct scatterlist *sgs[2], sg_req, sg_resp;
unsigned int len;
int rc;
/* don't use the request residing on the stack (vaddr) */
vm->req = *req;
/* out: buffer for request */
sg_init_one(&sg_req, &vm->req, sizeof(vm->req));
sgs[0] = &sg_req;
/* in: buffer for response */
sg_init_one(&sg_resp, &vm->resp, sizeof(vm->resp));
sgs[1] = &sg_resp;
rc = virtqueue_add_sgs(vm->vq, sgs, 1, 1, vm, GFP_KERNEL);
if (rc < 0)
return rc;
virtqueue_kick(vm->vq);
/* wait for a response */
wait_event(vm->host_resp, virtqueue_get_buf(vm->vq, &len));
return virtio16_to_cpu(vm->vdev, vm->resp.type);
}
static int virtio_mem_send_plug_request(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
const uint64_t nb_vm_blocks = size / vm->device_block_size;
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_PLUG),
.u.plug.addr = cpu_to_virtio64(vm->vdev, addr),
.u.plug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
};
int rc = -ENOMEM;
if (atomic_read(&vm->config_changed))
return -EAGAIN;
dev_dbg(&vm->vdev->dev, "plugging memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
vm->plugged_size += size;
return 0;
case VIRTIO_MEM_RESP_NACK:
rc = -EAGAIN;
break;
case VIRTIO_MEM_RESP_BUSY:
rc = -ETXTBSY;
break;
case VIRTIO_MEM_RESP_ERROR:
rc = -EINVAL;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "plugging memory failed: %d\n", rc);
return rc;
}
static int virtio_mem_send_unplug_request(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
const uint64_t nb_vm_blocks = size / vm->device_block_size;
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG),
.u.unplug.addr = cpu_to_virtio64(vm->vdev, addr),
.u.unplug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
};
int rc = -ENOMEM;
if (atomic_read(&vm->config_changed))
return -EAGAIN;
dev_dbg(&vm->vdev->dev, "unplugging memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
vm->plugged_size -= size;
return 0;
case VIRTIO_MEM_RESP_BUSY:
rc = -ETXTBSY;
break;
case VIRTIO_MEM_RESP_ERROR:
rc = -EINVAL;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "unplugging memory failed: %d\n", rc);
return rc;
}
static int virtio_mem_send_unplug_all_request(struct virtio_mem *vm)
{
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG_ALL),
};
int rc = -ENOMEM;
dev_dbg(&vm->vdev->dev, "unplugging all memory");
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
vm->unplug_all_required = false;
vm->plugged_size = 0;
/* usable region might have shrunk */
atomic_set(&vm->config_changed, 1);
return 0;
case VIRTIO_MEM_RESP_BUSY:
rc = -ETXTBSY;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "unplugging all memory failed: %d\n", rc);
return rc;
}
/*
* Plug selected subblocks. Updates the plugged state, but not the state
* of the memory block.
*/
static int virtio_mem_sbm_plug_sb(struct virtio_mem *vm, unsigned long mb_id,
int sb_id, int count)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size;
const uint64_t size = count * vm->sbm.sb_size;
int rc;
rc = virtio_mem_send_plug_request(vm, addr, size);
if (!rc)
virtio_mem_sbm_set_sb_plugged(vm, mb_id, sb_id, count);
return rc;
}
/*
* Unplug selected subblocks. Updates the plugged state, but not the state
* of the memory block.
*/
static int virtio_mem_sbm_unplug_sb(struct virtio_mem *vm, unsigned long mb_id,
int sb_id, int count)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size;
const uint64_t size = count * vm->sbm.sb_size;
int rc;
rc = virtio_mem_send_unplug_request(vm, addr, size);
if (!rc)
virtio_mem_sbm_set_sb_unplugged(vm, mb_id, sb_id, count);
return rc;
}
/*
* Request to unplug a big block.
*
* Will not modify the state of the big block.
*/
static int virtio_mem_bbm_unplug_bb(struct virtio_mem *vm, unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_send_unplug_request(vm, addr, size);
}
/*
* Request to plug a big block.
*
* Will not modify the state of the big block.
*/
static int virtio_mem_bbm_plug_bb(struct virtio_mem *vm, unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_send_plug_request(vm, addr, size);
}
/*
* Unplug the desired number of plugged subblocks of a offline or not-added
* memory block. Will fail if any subblock cannot get unplugged (instead of
* skipping it).
*
* Will not modify the state of the memory block.
*
* Note: can fail after some subblocks were unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb_raw(struct virtio_mem *vm,
unsigned long mb_id, uint64_t *nb_sb)
{
int sb_id, count;
int rc;
sb_id = vm->sbm.sbs_per_mb - 1;
while (*nb_sb) {
/* Find the next candidate subblock */
while (sb_id >= 0 &&
virtio_mem_sbm_test_sb_unplugged(vm, mb_id, sb_id, 1))
sb_id--;
if (sb_id < 0)
break;
/* Try to unplug multiple subblocks at a time */
count = 1;
while (count < *nb_sb && sb_id > 0 &&
virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id - 1, 1)) {
count++;
sb_id--;
}
rc = virtio_mem_sbm_unplug_sb(vm, mb_id, sb_id, count);
if (rc)
return rc;
*nb_sb -= count;
sb_id--;
}
return 0;
}
/*
* Unplug all plugged subblocks of an offline or not-added memory block.
*
* Will not modify the state of the memory block.
*
* Note: can fail after some subblocks were unplugged.
*/
static int virtio_mem_sbm_unplug_mb(struct virtio_mem *vm, unsigned long mb_id)
{
uint64_t nb_sb = vm->sbm.sbs_per_mb;
return virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, &nb_sb);
}
/*
* Prepare tracking data for the next memory block.
*/
static int virtio_mem_sbm_prepare_next_mb(struct virtio_mem *vm,
unsigned long *mb_id)
{
int rc;
if (vm->sbm.next_mb_id > vm->sbm.last_usable_mb_id)
return -ENOSPC;
/* Resize the state array if required. */
rc = virtio_mem_sbm_mb_states_prepare_next_mb(vm);
if (rc)
return rc;
/* Resize the subblock bitmap if required. */
rc = virtio_mem_sbm_sb_states_prepare_next_mb(vm);
if (rc)
return rc;
vm->sbm.mb_count[VIRTIO_MEM_SBM_MB_UNUSED]++;
*mb_id = vm->sbm.next_mb_id++;
return 0;
}
/*
* Try to plug the desired number of subblocks and add the memory block
* to Linux.
*
* Will modify the state of the memory block.
*/
static int virtio_mem_sbm_plug_and_add_mb(struct virtio_mem *vm,
unsigned long mb_id, uint64_t *nb_sb)
{
const int count = min_t(int, *nb_sb, vm->sbm.sbs_per_mb);
int rc;
if (WARN_ON_ONCE(!count))
return -EINVAL;
/*
* Plug the requested number of subblocks before adding it to linux,
* so that onlining will directly online all plugged subblocks.
*/
rc = virtio_mem_sbm_plug_sb(vm, mb_id, 0, count);
if (rc)
return rc;
/*
* Mark the block properly offline before adding it to Linux,
* so the memory notifiers will find the block in the right state.
*/
if (count == vm->sbm.sbs_per_mb)
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE);
else
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
/* Add the memory block to linux - if that fails, try to unplug. */
rc = virtio_mem_sbm_add_mb(vm, mb_id);
if (rc) {
int new_state = VIRTIO_MEM_SBM_MB_UNUSED;
if (virtio_mem_sbm_unplug_sb(vm, mb_id, 0, count))
new_state = VIRTIO_MEM_SBM_MB_PLUGGED;
virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
return rc;
}
*nb_sb -= count;
return 0;
}
/*
* Try to plug the desired number of subblocks of a memory block that
* is already added to Linux.
*
* Will modify the state of the memory block.
*
* Note: Can fail after some subblocks were successfully plugged.
*/
static int virtio_mem_sbm_plug_any_sb(struct virtio_mem *vm,
unsigned long mb_id, uint64_t *nb_sb)
{
const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
unsigned long pfn, nr_pages;
int sb_id, count;
int rc;
if (WARN_ON_ONCE(!*nb_sb))
return -EINVAL;
while (*nb_sb) {
sb_id = virtio_mem_sbm_first_unplugged_sb(vm, mb_id);
if (sb_id >= vm->sbm.sbs_per_mb)
break;
count = 1;
while (count < *nb_sb &&
sb_id + count < vm->sbm.sbs_per_mb &&
!virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id + count, 1))
count++;
rc = virtio_mem_sbm_plug_sb(vm, mb_id, sb_id, count);
if (rc)
return rc;
*nb_sb -= count;
if (old_state == VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL)
continue;
/* fake-online the pages if the memory block is online */
pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
nr_pages = PFN_DOWN(count * vm->sbm.sb_size);
virtio_mem_fake_online(pfn, nr_pages);
}
if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
virtio_mem_sbm_set_mb_state(vm, mb_id, old_state - 1);
return 0;
}
static int virtio_mem_sbm_plug_request(struct virtio_mem *vm, uint64_t diff)
{
const int mb_states[] = {
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
};
uint64_t nb_sb = diff / vm->sbm.sb_size;
unsigned long mb_id;
int rc, i;
if (!nb_sb)
return 0;
/* Don't race with onlining/offlining */
mutex_lock(&vm->hotplug_mutex);
for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
virtio_mem_sbm_for_each_mb(vm, mb_id, mb_states[i]) {
rc = virtio_mem_sbm_plug_any_sb(vm, mb_id, &nb_sb);
if (rc || !nb_sb)
goto out_unlock;
cond_resched();
}
}
/*
* We won't be working on online/offline memory blocks from this point,
* so we can't race with memory onlining/offlining. Drop the mutex.
*/
mutex_unlock(&vm->hotplug_mutex);
/* Try to plug and add unused blocks */
virtio_mem_sbm_for_each_mb(vm, mb_id, VIRTIO_MEM_SBM_MB_UNUSED) {
if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
return -ENOSPC;
rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
if (rc || !nb_sb)
return rc;
cond_resched();
}
/* Try to prepare, plug and add new blocks */
while (nb_sb) {
if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
return -ENOSPC;
rc = virtio_mem_sbm_prepare_next_mb(vm, &mb_id);
if (rc)
return rc;
rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
if (rc)
return rc;
cond_resched();
}
return 0;
out_unlock:
mutex_unlock(&vm->hotplug_mutex);
return rc;
}
/*
* Plug a big block and add it to Linux.
*
* Will modify the state of the big block.
*/
static int virtio_mem_bbm_plug_and_add_bb(struct virtio_mem *vm,
unsigned long bb_id)
{
int rc;
if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_UNUSED))
return -EINVAL;
rc = virtio_mem_bbm_plug_bb(vm, bb_id);
if (rc)
return rc;
virtio_mem_bbm_set_bb_state(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED);
rc = virtio_mem_bbm_add_bb(vm, bb_id);
if (rc) {
if (!virtio_mem_bbm_unplug_bb(vm, bb_id))
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_UNUSED);
else
/* Retry from the main loop. */
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_PLUGGED);
return rc;
}
return 0;
}
/*
* Prepare tracking data for the next big block.
*/
static int virtio_mem_bbm_prepare_next_bb(struct virtio_mem *vm,
unsigned long *bb_id)
{
int rc;
if (vm->bbm.next_bb_id > vm->bbm.last_usable_bb_id)
return -ENOSPC;
/* Resize the big block state array if required. */
rc = virtio_mem_bbm_bb_states_prepare_next_bb(vm);
if (rc)
return rc;
vm->bbm.bb_count[VIRTIO_MEM_BBM_BB_UNUSED]++;
*bb_id = vm->bbm.next_bb_id;
vm->bbm.next_bb_id++;
return 0;
}
static int virtio_mem_bbm_plug_request(struct virtio_mem *vm, uint64_t diff)
{
uint64_t nb_bb = diff / vm->bbm.bb_size;
unsigned long bb_id;
int rc;
if (!nb_bb)
return 0;
/* Try to plug and add unused big blocks */
virtio_mem_bbm_for_each_bb(vm, bb_id, VIRTIO_MEM_BBM_BB_UNUSED) {
if (!virtio_mem_could_add_memory(vm, vm->bbm.bb_size))
return -ENOSPC;
rc = virtio_mem_bbm_plug_and_add_bb(vm, bb_id);
if (!rc)
nb_bb--;
if (rc || !nb_bb)
return rc;
cond_resched();
}
/* Try to prepare, plug and add new big blocks */
while (nb_bb) {
if (!virtio_mem_could_add_memory(vm, vm->bbm.bb_size))
return -ENOSPC;
rc = virtio_mem_bbm_prepare_next_bb(vm, &bb_id);
if (rc)
return rc;
rc = virtio_mem_bbm_plug_and_add_bb(vm, bb_id);
if (!rc)
nb_bb--;
if (rc)
return rc;
cond_resched();
}
return 0;
}
/*
* Try to plug the requested amount of memory.
*/
static int virtio_mem_plug_request(struct virtio_mem *vm, uint64_t diff)
{
if (vm->in_sbm)
return virtio_mem_sbm_plug_request(vm, diff);
return virtio_mem_bbm_plug_request(vm, diff);
}
/*
* Unplug the desired number of plugged subblocks of an offline memory block.
* Will fail if any subblock cannot get unplugged (instead of skipping it).
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*
* Note: Can fail after some subblocks were successfully unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb_offline(struct virtio_mem *vm,
unsigned long mb_id,
uint64_t *nb_sb)
{
int rc;
rc = virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, nb_sb);
/* some subblocks might have been unplugged even on failure */
if (!virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
if (rc)
return rc;
if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
/*
* Remove the block from Linux - this should never fail.
* Hinder the block from getting onlined by marking it
* unplugged. Temporarily drop the mutex, so
* any pending GOING_ONLINE requests can be serviced/rejected.
*/
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_UNUSED);
mutex_unlock(&vm->hotplug_mutex);
rc = virtio_mem_sbm_remove_mb(vm, mb_id);
BUG_ON(rc);
mutex_lock(&vm->hotplug_mutex);
}
return 0;
}
/*
* Unplug the given plugged subblocks of an online memory block.
*
* Will modify the state of the memory block.
*/
static int virtio_mem_sbm_unplug_sb_online(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size) * count;
const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
unsigned long start_pfn;
int rc;
start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
rc = virtio_mem_fake_offline(start_pfn, nr_pages);
if (rc)
return rc;
/* Try to unplug the allocated memory */
rc = virtio_mem_sbm_unplug_sb(vm, mb_id, sb_id, count);
if (rc) {
/* Return the memory to the buddy. */
virtio_mem_fake_online(start_pfn, nr_pages);
return rc;
}
switch (old_state) {
case VIRTIO_MEM_SBM_MB_KERNEL:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL);
break;
case VIRTIO_MEM_SBM_MB_MOVABLE:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL);
break;
}
return 0;
}
/*
* Unplug the desired number of plugged subblocks of an online memory block.
* Will skip subblock that are busy.
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*
* Note: Can fail after some subblocks were successfully unplugged. Can
* return 0 even if subblocks were busy and could not get unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb_online(struct virtio_mem *vm,
unsigned long mb_id,
uint64_t *nb_sb)
{
int rc, sb_id;
/* If possible, try to unplug the complete block in one shot. */
if (*nb_sb >= vm->sbm.sbs_per_mb &&
virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
rc = virtio_mem_sbm_unplug_sb_online(vm, mb_id, 0,
vm->sbm.sbs_per_mb);
if (!rc) {
*nb_sb -= vm->sbm.sbs_per_mb;
goto unplugged;
} else if (rc != -EBUSY)
return rc;
}
/* Fallback to single subblocks. */
for (sb_id = vm->sbm.sbs_per_mb - 1; sb_id >= 0 && *nb_sb; sb_id--) {
/* Find the next candidate subblock */
while (sb_id >= 0 &&
!virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
sb_id--;
if (sb_id < 0)
break;
rc = virtio_mem_sbm_unplug_sb_online(vm, mb_id, sb_id, 1);
if (rc == -EBUSY)
continue;
else if (rc)
return rc;
*nb_sb -= 1;
}
unplugged:
/*
* Once all subblocks of a memory block were unplugged, offline and
* remove it. This will usually not fail, as no memory is in use
* anymore - however some other notifiers might NACK the request.
*/
if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
mutex_unlock(&vm->hotplug_mutex);
rc = virtio_mem_sbm_offline_and_remove_mb(vm, mb_id);
mutex_lock(&vm->hotplug_mutex);
if (!rc)
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_UNUSED);
}
return 0;
}
/*
* Unplug the desired number of plugged subblocks of a memory block that is
* already added to Linux. Will skip subblock of online memory blocks that are
* busy (by the OS). Will fail if any subblock that's not busy cannot get
* unplugged.
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*
* Note: Can fail after some subblocks were successfully unplugged. Can
* return 0 even if subblocks were busy and could not get unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb(struct virtio_mem *vm,
unsigned long mb_id,
uint64_t *nb_sb)
{
const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
switch (old_state) {
case VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL:
case VIRTIO_MEM_SBM_MB_KERNEL:
case VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL:
case VIRTIO_MEM_SBM_MB_MOVABLE:
return virtio_mem_sbm_unplug_any_sb_online(vm, mb_id, nb_sb);
case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
case VIRTIO_MEM_SBM_MB_OFFLINE:
return virtio_mem_sbm_unplug_any_sb_offline(vm, mb_id, nb_sb);
}
return -EINVAL;
}
static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
const int mb_states[] = {
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
VIRTIO_MEM_SBM_MB_OFFLINE,
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
VIRTIO_MEM_SBM_MB_MOVABLE,
VIRTIO_MEM_SBM_MB_KERNEL,
};
uint64_t nb_sb = diff / vm->sbm.sb_size;
unsigned long mb_id;
int rc, i;
if (!nb_sb)
return 0;
/*
* We'll drop the mutex a couple of times when it is safe to do so.
* This might result in some blocks switching the state (online/offline)
* and we could miss them in this run - we will retry again later.
*/
mutex_lock(&vm->hotplug_mutex);
/*
* We try unplug from partially plugged blocks first, to try removing
* whole memory blocks along with metadata. We prioritize ZONE_MOVABLE
* as it's more reliable to unplug memory and remove whole memory
* blocks, and we don't want to trigger a zone imbalances by
* accidentially removing too much kernel memory.
*/
for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
virtio_mem_sbm_for_each_mb_rev(vm, mb_id, mb_states[i]) {
rc = virtio_mem_sbm_unplug_any_sb(vm, mb_id, &nb_sb);
if (rc || !nb_sb)
goto out_unlock;
mutex_unlock(&vm->hotplug_mutex);
cond_resched();
mutex_lock(&vm->hotplug_mutex);
}
if (!unplug_online && i == 1) {
mutex_unlock(&vm->hotplug_mutex);
return 0;
}
}
mutex_unlock(&vm->hotplug_mutex);
return nb_sb ? -EBUSY : 0;
out_unlock:
mutex_unlock(&vm->hotplug_mutex);
return rc;
}
/*
* Try to offline and remove a big block from Linux and unplug it. Will fail
* with -EBUSY if some memory is busy and cannot get unplugged.
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*/
static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm,
unsigned long bb_id)
{
const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
unsigned long end_pfn = start_pfn + nr_pages;
unsigned long pfn;
struct page *page;
int rc;
if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_ADDED))
return -EINVAL;
if (bbm_safe_unplug) {
/*
* Start by fake-offlining all memory. Once we marked the device
* block as fake-offline, all newly onlined memory will
* automatically be kept fake-offline. Protect from concurrent
* onlining/offlining until we have a consistent state.
*/
mutex_lock(&vm->hotplug_mutex);
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE);
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
page = pfn_to_online_page(pfn);
if (!page)
continue;
rc = virtio_mem_fake_offline(pfn, PAGES_PER_SECTION);
if (rc) {
end_pfn = pfn;
goto rollback_safe_unplug;
}
}
mutex_unlock(&vm->hotplug_mutex);
}
rc = virtio_mem_bbm_offline_and_remove_bb(vm, bb_id);
if (rc) {
if (bbm_safe_unplug) {
mutex_lock(&vm->hotplug_mutex);
goto rollback_safe_unplug;
}
return rc;
}
rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
if (rc)
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_PLUGGED);
else
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_UNUSED);
return rc;
rollback_safe_unplug:
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
page = pfn_to_online_page(pfn);
if (!page)
continue;
virtio_mem_fake_online(pfn, PAGES_PER_SECTION);
}
virtio_mem_bbm_set_bb_state(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED);
mutex_unlock(&vm->hotplug_mutex);
return rc;
}
/*
* Test if a big block is completely offline.
*/
static bool virtio_mem_bbm_bb_is_offline(struct virtio_mem *vm,
unsigned long bb_id)
{
const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
unsigned long pfn;
for (pfn = start_pfn; pfn < start_pfn + nr_pages;
pfn += PAGES_PER_SECTION) {
if (pfn_to_online_page(pfn))
return false;
}
return true;
}
/*
* Test if a big block is completely onlined to ZONE_MOVABLE (or offline).
*/
static bool virtio_mem_bbm_bb_is_movable(struct virtio_mem *vm,
unsigned long bb_id)
{
const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
struct page *page;
unsigned long pfn;
for (pfn = start_pfn; pfn < start_pfn + nr_pages;
pfn += PAGES_PER_SECTION) {
page = pfn_to_online_page(pfn);
if (!page)
continue;
if (page_zonenum(page) != ZONE_MOVABLE)
return false;
}
return true;
}
static int virtio_mem_bbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
uint64_t nb_bb = diff / vm->bbm.bb_size;
uint64_t bb_id;
int rc, i;
if (!nb_bb)
return 0;
/*
* Try to unplug big blocks. Similar to SBM, start with offline
* big blocks.
*/
for (i = 0; i < 3; i++) {
virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) {
cond_resched();
/*
* As we're holding no locks, these checks are racy,
* but we don't care.
*/
if (i == 0 && !virtio_mem_bbm_bb_is_offline(vm, bb_id))
continue;
if (i == 1 && !virtio_mem_bbm_bb_is_movable(vm, bb_id))
continue;
rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id);
if (rc == -EBUSY)
continue;
if (!rc)
nb_bb--;
if (rc || !nb_bb)
return rc;
}
if (i == 0 && !unplug_online)
return 0;
}
return nb_bb ? -EBUSY : 0;
}
/*
* Try to unplug the requested amount of memory.
*/
static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
if (vm->in_sbm)
return virtio_mem_sbm_unplug_request(vm, diff);
return virtio_mem_bbm_unplug_request(vm, diff);
}
/*
* Try to unplug all blocks that couldn't be unplugged before, for example,
* because the hypervisor was busy.
*/
static int virtio_mem_unplug_pending_mb(struct virtio_mem *vm)
{
unsigned long id;
int rc;
if (!vm->in_sbm) {
virtio_mem_bbm_for_each_bb(vm, id,
VIRTIO_MEM_BBM_BB_PLUGGED) {
rc = virtio_mem_bbm_unplug_bb(vm, id);
if (rc)
return rc;
virtio_mem_bbm_set_bb_state(vm, id,
VIRTIO_MEM_BBM_BB_UNUSED);
}
return 0;
}
virtio_mem_sbm_for_each_mb(vm, id, VIRTIO_MEM_SBM_MB_PLUGGED) {
rc = virtio_mem_sbm_unplug_mb(vm, id);
if (rc)
return rc;
virtio_mem_sbm_set_mb_state(vm, id,
VIRTIO_MEM_SBM_MB_UNUSED);
}
return 0;
}
/*
* Update all parts of the config that could have changed.
*/
static void virtio_mem_refresh_config(struct virtio_mem *vm)
{
const struct range pluggable_range = mhp_get_pluggable_range(true);
uint64_t new_plugged_size, usable_region_size, end_addr;
/* the plugged_size is just a reflection of what _we_ did previously */
virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
&new_plugged_size);
if (WARN_ON_ONCE(new_plugged_size != vm->plugged_size))
vm->plugged_size = new_plugged_size;
/* calculate the last usable memory block id */
virtio_cread_le(vm->vdev, struct virtio_mem_config,
usable_region_size, &usable_region_size);
end_addr = min(vm->addr + usable_region_size - 1,
pluggable_range.end);
if (vm->in_sbm) {
vm->sbm.last_usable_mb_id = virtio_mem_phys_to_mb_id(end_addr);
if (!IS_ALIGNED(end_addr + 1, memory_block_size_bytes()))
vm->sbm.last_usable_mb_id--;
} else {
vm->bbm.last_usable_bb_id = virtio_mem_phys_to_bb_id(vm,
end_addr);
if (!IS_ALIGNED(end_addr + 1, vm->bbm.bb_size))
vm->bbm.last_usable_bb_id--;
}
/*
* If we cannot plug any of our device memory (e.g., nothing in the
* usable region is addressable), the last usable memory block id will
* be smaller than the first usable memory block id. We'll stop
* attempting to add memory with -ENOSPC from our main loop.
*/
/* see if there is a request to change the size */
virtio_cread_le(vm->vdev, struct virtio_mem_config, requested_size,
&vm->requested_size);
dev_info(&vm->vdev->dev, "plugged size: 0x%llx", vm->plugged_size);
dev_info(&vm->vdev->dev, "requested size: 0x%llx", vm->requested_size);
}
/*
* Workqueue function for handling plug/unplug requests and config updates.
*/
static void virtio_mem_run_wq(struct work_struct *work)
{
struct virtio_mem *vm = container_of(work, struct virtio_mem, wq);
uint64_t diff;
int rc;
if (unlikely(vm->in_kdump)) {
dev_warn_once(&vm->vdev->dev,
"unexpected workqueue run in kdump kernel\n");
return;
}
hrtimer_cancel(&vm->retry_timer);
if (vm->broken)
return;
atomic_set(&vm->wq_active, 1);
retry:
rc = 0;
/* Make sure we start with a clean state if there are leftovers. */
if (unlikely(vm->unplug_all_required))
rc = virtio_mem_send_unplug_all_request(vm);
if (atomic_read(&vm->config_changed)) {
atomic_set(&vm->config_changed, 0);
virtio_mem_refresh_config(vm);
}
/* Unplug any leftovers from previous runs */
if (!rc)
rc = virtio_mem_unplug_pending_mb(vm);
if (!rc && vm->requested_size != vm->plugged_size) {
if (vm->requested_size > vm->plugged_size) {
diff = vm->requested_size - vm->plugged_size;
rc = virtio_mem_plug_request(vm, diff);
} else {
diff = vm->plugged_size - vm->requested_size;
rc = virtio_mem_unplug_request(vm, diff);
}
}
switch (rc) {
case 0:
vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
break;
case -ENOSPC:
/*
* We cannot add any more memory (alignment, physical limit)
* or we have too many offline memory blocks.
*/
break;
case -ETXTBSY:
/*
* The hypervisor cannot process our request right now
* (e.g., out of memory, migrating);
*/
case -EBUSY:
/*
* We cannot free up any memory to unplug it (all plugged memory
* is busy).
*/
case -ENOMEM:
/* Out of memory, try again later. */
hrtimer_start(&vm->retry_timer, ms_to_ktime(vm->retry_timer_ms),
HRTIMER_MODE_REL);
break;
case -EAGAIN:
/* Retry immediately (e.g., the config changed). */
goto retry;
default:
/* Unknown error, mark as broken */
dev_err(&vm->vdev->dev,
"unknown error, marking device broken: %d\n", rc);
vm->broken = true;
}
atomic_set(&vm->wq_active, 0);
}
static enum hrtimer_restart virtio_mem_timer_expired(struct hrtimer *timer)
{
struct virtio_mem *vm = container_of(timer, struct virtio_mem,
retry_timer);
virtio_mem_retry(vm);
vm->retry_timer_ms = min_t(unsigned int, vm->retry_timer_ms * 2,
VIRTIO_MEM_RETRY_TIMER_MAX_MS);
return HRTIMER_NORESTART;
}
static void virtio_mem_handle_response(struct virtqueue *vq)
{
struct virtio_mem *vm = vq->vdev->priv;
wake_up(&vm->host_resp);
}
static int virtio_mem_init_vq(struct virtio_mem *vm)
{
struct virtqueue *vq;
vq = virtio_find_single_vq(vm->vdev, virtio_mem_handle_response,
"guest-request");
if (IS_ERR(vq))
return PTR_ERR(vq);
vm->vq = vq;
return 0;
}
static int virtio_mem_init_hotplug(struct virtio_mem *vm)
{
const struct range pluggable_range = mhp_get_pluggable_range(true);
uint64_t unit_pages, sb_size, addr;
int rc;
/* bad device setup - warn only */
if (!IS_ALIGNED(vm->addr, memory_block_size_bytes()))
dev_warn(&vm->vdev->dev,
"The alignment of the physical start address can make some memory unusable.\n");
if (!IS_ALIGNED(vm->addr + vm->region_size, memory_block_size_bytes()))
dev_warn(&vm->vdev->dev,
"The alignment of the physical end address can make some memory unusable.\n");
if (vm->addr < pluggable_range.start ||
vm->addr + vm->region_size - 1 > pluggable_range.end)
dev_warn(&vm->vdev->dev,
"Some device memory is not addressable/pluggable. This can make some memory unusable.\n");
/* Prepare the offline threshold - make sure we can add two blocks. */
vm->offline_threshold = max_t(uint64_t, 2 * memory_block_size_bytes(),
VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);
/*
* We want subblocks to span at least MAX_ORDER_NR_PAGES and
* pageblock_nr_pages pages. This:
* - Simplifies our page onlining code (virtio_mem_online_page_cb)
* and fake page onlining code (virtio_mem_fake_online).
* - Is required for now for alloc_contig_range() to work reliably -
* it doesn't properly handle smaller granularity on ZONE_NORMAL.
*/
sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
pageblock_nr_pages) * PAGE_SIZE;
sb_size = max_t(uint64_t, vm->device_block_size, sb_size);
if (sb_size < memory_block_size_bytes() && !force_bbm) {
/* SBM: At least two subblocks per Linux memory block. */
vm->in_sbm = true;
vm->sbm.sb_size = sb_size;
vm->sbm.sbs_per_mb = memory_block_size_bytes() /
vm->sbm.sb_size;
/* Round up to the next full memory block */
addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
memory_block_size_bytes() - 1;
vm->sbm.first_mb_id = virtio_mem_phys_to_mb_id(addr);
vm->sbm.next_mb_id = vm->sbm.first_mb_id;
} else {
/* BBM: At least one Linux memory block. */
vm->bbm.bb_size = max_t(uint64_t, vm->device_block_size,
memory_block_size_bytes());
if (bbm_block_size) {
if (!is_power_of_2(bbm_block_size)) {
dev_warn(&vm->vdev->dev,
"bbm_block_size is not a power of 2");
} else if (bbm_block_size < vm->bbm.bb_size) {
dev_warn(&vm->vdev->dev,
"bbm_block_size is too small");
} else {
vm->bbm.bb_size = bbm_block_size;
}
}
/* Round up to the next aligned big block */
addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
vm->bbm.bb_size - 1;
vm->bbm.first_bb_id = virtio_mem_phys_to_bb_id(vm, addr);
vm->bbm.next_bb_id = vm->bbm.first_bb_id;
/* Make sure we can add two big blocks. */
vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size,
vm->offline_threshold);
}
dev_info(&vm->vdev->dev, "memory block size: 0x%lx",
memory_block_size_bytes());
if (vm->in_sbm)
dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
(unsigned long long)vm->sbm.sb_size);
else
dev_info(&vm->vdev->dev, "big block size: 0x%llx",
(unsigned long long)vm->bbm.bb_size);
/* create the parent resource for all memory */
rc = virtio_mem_create_resource(vm);
if (rc)
return rc;
/* use a single dynamic memory group to cover the whole memory device */
if (vm->in_sbm)
unit_pages = PHYS_PFN(memory_block_size_bytes());
else
unit_pages = PHYS_PFN(vm->bbm.bb_size);
rc = memory_group_register_dynamic(vm->nid, unit_pages);
if (rc < 0)
goto out_del_resource;
vm->mgid = rc;
/*
* If we still have memory plugged, we have to unplug all memory first.
* Registering our parent resource makes sure that this memory isn't
* actually in use (e.g., trying to reload the driver).
*/
if (vm->plugged_size) {
vm->unplug_all_required = true;
dev_info(&vm->vdev->dev, "unplugging all memory is required\n");
}
/* register callbacks */
vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
rc = register_memory_notifier(&vm->memory_notifier);
if (rc)
goto out_unreg_group;
rc = register_virtio_mem_device(vm);
if (rc)
goto out_unreg_mem;
return 0;
out_unreg_mem:
unregister_memory_notifier(&vm->memory_notifier);
out_unreg_group:
memory_group_unregister(vm->mgid);
out_del_resource:
virtio_mem_delete_resource(vm);
return rc;
}
#ifdef CONFIG_PROC_VMCORE
static int virtio_mem_send_state_request(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
const uint64_t nb_vm_blocks = size / vm->device_block_size;
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_STATE),
.u.state.addr = cpu_to_virtio64(vm->vdev, addr),
.u.state.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
};
int rc = -ENOMEM;
dev_dbg(&vm->vdev->dev, "requesting state: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
return virtio16_to_cpu(vm->vdev, vm->resp.u.state.state);
case VIRTIO_MEM_RESP_ERROR:
rc = -EINVAL;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "requesting state failed: %d\n", rc);
return rc;
}
static bool virtio_mem_vmcore_pfn_is_ram(struct vmcore_cb *cb,
unsigned long pfn)
{
struct virtio_mem *vm = container_of(cb, struct virtio_mem,
vmcore_cb);
uint64_t addr = PFN_PHYS(pfn);
bool is_ram;
int rc;
if (!virtio_mem_contains_range(vm, addr, PAGE_SIZE))
return true;
if (!vm->plugged_size)
return false;
/*
* We have to serialize device requests and access to the information
* about the block queried last.
*/
mutex_lock(&vm->hotplug_mutex);
addr = ALIGN_DOWN(addr, vm->device_block_size);
if (addr != vm->last_block_addr) {
rc = virtio_mem_send_state_request(vm, addr,
vm->device_block_size);
/* On any kind of error, we're going to signal !ram. */
if (rc == VIRTIO_MEM_STATE_PLUGGED)
vm->last_block_plugged = true;
else
vm->last_block_plugged = false;
vm->last_block_addr = addr;
}
is_ram = vm->last_block_plugged;
mutex_unlock(&vm->hotplug_mutex);
return is_ram;
}
#endif /* CONFIG_PROC_VMCORE */
static int virtio_mem_init_kdump(struct virtio_mem *vm)
{
#ifdef CONFIG_PROC_VMCORE
dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n");
vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram;
register_vmcore_cb(&vm->vmcore_cb);
return 0;
#else /* CONFIG_PROC_VMCORE */
dev_warn(&vm->vdev->dev, "disabled in kdump kernel without vmcore\n");
return -EBUSY;
#endif /* CONFIG_PROC_VMCORE */
}
static int virtio_mem_init(struct virtio_mem *vm)
{
uint16_t node_id;
if (!vm->vdev->config->get) {
dev_err(&vm->vdev->dev, "config access disabled\n");
return -EINVAL;
}
/* Fetch all properties that can't change. */
virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
&vm->plugged_size);
virtio_cread_le(vm->vdev, struct virtio_mem_config, block_size,
&vm->device_block_size);
virtio_cread_le(vm->vdev, struct virtio_mem_config, node_id,
&node_id);
vm->nid = virtio_mem_translate_node_id(vm, node_id);
virtio_cread_le(vm->vdev, struct virtio_mem_config, addr, &vm->addr);
virtio_cread_le(vm->vdev, struct virtio_mem_config, region_size,
&vm->region_size);
/* Determine the nid for the device based on the lowest address. */
if (vm->nid == NUMA_NO_NODE)
vm->nid = memory_add_physaddr_to_nid(vm->addr);
dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr);
dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size);
dev_info(&vm->vdev->dev, "device block size: 0x%llx",
(unsigned long long)vm->device_block_size);
if (vm->nid != NUMA_NO_NODE && IS_ENABLED(CONFIG_NUMA))
dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
/*
* We don't want to (un)plug or reuse any memory when in kdump. The
* memory is still accessible (but not exposed to Linux).
*/
if (vm->in_kdump)
return virtio_mem_init_kdump(vm);
return virtio_mem_init_hotplug(vm);
}
static int virtio_mem_create_resource(struct virtio_mem *vm)
{
/*
* When force-unloading the driver and removing the device, we
* could have a garbage pointer. Duplicate the string.
*/
const char *name = kstrdup(dev_name(&vm->vdev->dev), GFP_KERNEL);
if (!name)
return -ENOMEM;
/* Disallow mapping device memory via /dev/mem completely. */
vm->parent_resource = __request_mem_region(vm->addr, vm->region_size,
name, IORESOURCE_SYSTEM_RAM |
IORESOURCE_EXCLUSIVE);
if (!vm->parent_resource) {
kfree(name);
dev_warn(&vm->vdev->dev, "could not reserve device region\n");
dev_info(&vm->vdev->dev,
"reloading the driver is not supported\n");
return -EBUSY;
}
/* The memory is not actually busy - make add_memory() work. */
vm->parent_resource->flags &= ~IORESOURCE_BUSY;
return 0;
}
static void virtio_mem_delete_resource(struct virtio_mem *vm)
{
const char *name;
if (!vm->parent_resource)
return;
name = vm->parent_resource->name;
release_resource(vm->parent_resource);
kfree(vm->parent_resource);
kfree(name);
vm->parent_resource = NULL;
}
static int virtio_mem_range_has_system_ram(struct resource *res, void *arg)
{
return 1;
}
static bool virtio_mem_has_memory_added(struct virtio_mem *vm)
{
const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
return walk_iomem_res_desc(IORES_DESC_NONE, flags, vm->addr,
vm->addr + vm->region_size, NULL,
virtio_mem_range_has_system_ram) == 1;
}
static int virtio_mem_probe(struct virtio_device *vdev)
{
struct virtio_mem *vm;
int rc;
BUILD_BUG_ON(sizeof(struct virtio_mem_req) != 24);
BUILD_BUG_ON(sizeof(struct virtio_mem_resp) != 10);
vdev->priv = vm = kzalloc(sizeof(*vm), GFP_KERNEL);
if (!vm)
return -ENOMEM;
init_waitqueue_head(&vm->host_resp);
vm->vdev = vdev;
INIT_WORK(&vm->wq, virtio_mem_run_wq);
mutex_init(&vm->hotplug_mutex);
INIT_LIST_HEAD(&vm->next);
spin_lock_init(&vm->removal_lock);
hrtimer_init(&vm->retry_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
vm->retry_timer.function = virtio_mem_timer_expired;
vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
vm->in_kdump = is_kdump_kernel();
/* register the virtqueue */
rc = virtio_mem_init_vq(vm);
if (rc)
goto out_free_vm;
/* initialize the device by querying the config */
rc = virtio_mem_init(vm);
if (rc)
goto out_del_vq;
virtio_device_ready(vdev);
/* trigger a config update to start processing the requested_size */
if (!vm->in_kdump) {
atomic_set(&vm->config_changed, 1);
queue_work(system_freezable_wq, &vm->wq);
}
return 0;
out_del_vq:
vdev->config->del_vqs(vdev);
out_free_vm:
kfree(vm);
vdev->priv = NULL;
return rc;
}
static void virtio_mem_deinit_hotplug(struct virtio_mem *vm)
{
unsigned long mb_id;
int rc;
/*
* Make sure the workqueue won't be triggered anymore and no memory
* blocks can be onlined/offlined until we're finished here.
*/
mutex_lock(&vm->hotplug_mutex);
spin_lock_irq(&vm->removal_lock);
vm->removing = true;
spin_unlock_irq(&vm->removal_lock);
mutex_unlock(&vm->hotplug_mutex);
/* wait until the workqueue stopped */
cancel_work_sync(&vm->wq);
hrtimer_cancel(&vm->retry_timer);
if (vm->in_sbm) {
/*
* After we unregistered our callbacks, user space can online
* partially plugged offline blocks. Make sure to remove them.
*/
virtio_mem_sbm_for_each_mb(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL) {
rc = virtio_mem_sbm_remove_mb(vm, mb_id);
BUG_ON(rc);
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_UNUSED);
}
/*
* After we unregistered our callbacks, user space can no longer
* offline partially plugged online memory blocks. No need to
* worry about them.
*/
}
/* unregister callbacks */
unregister_virtio_mem_device(vm);
unregister_memory_notifier(&vm->memory_notifier);
/*
* There is no way we could reliably remove all memory we have added to
* the system. And there is no way to stop the driver/device from going
* away. Warn at least.
*/
if (virtio_mem_has_memory_added(vm)) {
dev_warn(&vm->vdev->dev,
"device still has system memory added\n");
} else {
virtio_mem_delete_resource(vm);
kfree_const(vm->resource_name);
memory_group_unregister(vm->mgid);
}
/* remove all tracking data - no locking needed */
if (vm->in_sbm) {
vfree(vm->sbm.mb_states);
vfree(vm->sbm.sb_states);
} else {
vfree(vm->bbm.bb_states);
}
}
static void virtio_mem_deinit_kdump(struct virtio_mem *vm)
{
#ifdef CONFIG_PROC_VMCORE
unregister_vmcore_cb(&vm->vmcore_cb);
#endif /* CONFIG_PROC_VMCORE */
}
static void virtio_mem_remove(struct virtio_device *vdev)
{
struct virtio_mem *vm = vdev->priv;
if (vm->in_kdump)
virtio_mem_deinit_kdump(</