blob: 62e23ff3c987e1658fe44483716aa74b709227d8 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright © 2018 Intel Corporation.
*
* Authors: Gayatri Kammela <gayatri.kammela@intel.com>
* Sohil Mehta <sohil.mehta@intel.com>
* Jacob Pan <jacob.jun.pan@linux.intel.com>
* Lu Baolu <baolu.lu@linux.intel.com>
*/
#include <linux/debugfs.h>
#include <linux/dmar.h>
#include <linux/intel-iommu.h>
#include <linux/pci.h>
#include <asm/irq_remapping.h>
#include "pasid.h"
#include "perf.h"
struct tbl_walk {
u16 bus;
u16 devfn;
u32 pasid;
struct root_entry *rt_entry;
struct context_entry *ctx_entry;
struct pasid_entry *pasid_tbl_entry;
};
struct iommu_regset {
int offset;
const char *regs;
};
#define DEBUG_BUFFER_SIZE 1024
static char debug_buf[DEBUG_BUFFER_SIZE];
#define IOMMU_REGSET_ENTRY(_reg_) \
{ DMAR_##_reg_##_REG, __stringify(_reg_) }
static const struct iommu_regset iommu_regs_32[] = {
IOMMU_REGSET_ENTRY(VER),
IOMMU_REGSET_ENTRY(GCMD),
IOMMU_REGSET_ENTRY(GSTS),
IOMMU_REGSET_ENTRY(FSTS),
IOMMU_REGSET_ENTRY(FECTL),
IOMMU_REGSET_ENTRY(FEDATA),
IOMMU_REGSET_ENTRY(FEADDR),
IOMMU_REGSET_ENTRY(FEUADDR),
IOMMU_REGSET_ENTRY(PMEN),
IOMMU_REGSET_ENTRY(PLMBASE),
IOMMU_REGSET_ENTRY(PLMLIMIT),
IOMMU_REGSET_ENTRY(ICS),
IOMMU_REGSET_ENTRY(PRS),
IOMMU_REGSET_ENTRY(PECTL),
IOMMU_REGSET_ENTRY(PEDATA),
IOMMU_REGSET_ENTRY(PEADDR),
IOMMU_REGSET_ENTRY(PEUADDR),
};
static const struct iommu_regset iommu_regs_64[] = {
IOMMU_REGSET_ENTRY(CAP),
IOMMU_REGSET_ENTRY(ECAP),
IOMMU_REGSET_ENTRY(RTADDR),
IOMMU_REGSET_ENTRY(CCMD),
IOMMU_REGSET_ENTRY(AFLOG),
IOMMU_REGSET_ENTRY(PHMBASE),
IOMMU_REGSET_ENTRY(PHMLIMIT),
IOMMU_REGSET_ENTRY(IQH),
IOMMU_REGSET_ENTRY(IQT),
IOMMU_REGSET_ENTRY(IQA),
IOMMU_REGSET_ENTRY(IRTA),
IOMMU_REGSET_ENTRY(PQH),
IOMMU_REGSET_ENTRY(PQT),
IOMMU_REGSET_ENTRY(PQA),
IOMMU_REGSET_ENTRY(MTRRCAP),
IOMMU_REGSET_ENTRY(MTRRDEF),
IOMMU_REGSET_ENTRY(MTRR_FIX64K_00000),
IOMMU_REGSET_ENTRY(MTRR_FIX16K_80000),
IOMMU_REGSET_ENTRY(MTRR_FIX16K_A0000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_C0000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_C8000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_D0000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_D8000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_E0000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_E8000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_F0000),
IOMMU_REGSET_ENTRY(MTRR_FIX4K_F8000),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE0),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK0),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE1),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK1),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE2),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK2),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE3),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK3),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE4),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK4),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE5),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK5),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE6),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK6),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE7),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK7),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE8),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK8),
IOMMU_REGSET_ENTRY(MTRR_PHYSBASE9),
IOMMU_REGSET_ENTRY(MTRR_PHYSMASK9),
IOMMU_REGSET_ENTRY(VCCAP),
IOMMU_REGSET_ENTRY(VCMD),
IOMMU_REGSET_ENTRY(VCRSP),
};
static int iommu_regset_show(struct seq_file *m, void *unused)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
unsigned long flag;
int i, ret = 0;
u64 value;
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
if (!drhd->reg_base_addr) {
seq_puts(m, "IOMMU: Invalid base address\n");
ret = -EINVAL;
goto out;
}
seq_printf(m, "IOMMU: %s Register Base Address: %llx\n",
iommu->name, drhd->reg_base_addr);
seq_puts(m, "Name\t\t\tOffset\t\tContents\n");
/*
* Publish the contents of the 64-bit hardware registers
* by adding the offset to the pointer (virtual address).
*/
raw_spin_lock_irqsave(&iommu->register_lock, flag);
for (i = 0 ; i < ARRAY_SIZE(iommu_regs_32); i++) {
value = dmar_readl(iommu->reg + iommu_regs_32[i].offset);
seq_printf(m, "%-16s\t0x%02x\t\t0x%016llx\n",
iommu_regs_32[i].regs, iommu_regs_32[i].offset,
value);
}
for (i = 0 ; i < ARRAY_SIZE(iommu_regs_64); i++) {
value = dmar_readq(iommu->reg + iommu_regs_64[i].offset);
seq_printf(m, "%-16s\t0x%02x\t\t0x%016llx\n",
iommu_regs_64[i].regs, iommu_regs_64[i].offset,
value);
}
raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
seq_putc(m, '\n');
}
out:
rcu_read_unlock();
return ret;
}
DEFINE_SHOW_ATTRIBUTE(iommu_regset);
static inline void print_tbl_walk(struct seq_file *m)
{
struct tbl_walk *tbl_wlk = m->private;
seq_printf(m, "%02x:%02x.%x\t0x%016llx:0x%016llx\t0x%016llx:0x%016llx\t",
tbl_wlk->bus, PCI_SLOT(tbl_wlk->devfn),
PCI_FUNC(tbl_wlk->devfn), tbl_wlk->rt_entry->hi,
tbl_wlk->rt_entry->lo, tbl_wlk->ctx_entry->hi,
tbl_wlk->ctx_entry->lo);
/*
* A legacy mode DMAR doesn't support PASID, hence default it to -1
* indicating that it's invalid. Also, default all PASID related fields
* to 0.
*/
if (!tbl_wlk->pasid_tbl_entry)
seq_printf(m, "%-6d\t0x%016llx:0x%016llx:0x%016llx\n", -1,
(u64)0, (u64)0, (u64)0);
else
seq_printf(m, "%-6d\t0x%016llx:0x%016llx:0x%016llx\n",
tbl_wlk->pasid, tbl_wlk->pasid_tbl_entry->val[2],
tbl_wlk->pasid_tbl_entry->val[1],
tbl_wlk->pasid_tbl_entry->val[0]);
}
static void pasid_tbl_walk(struct seq_file *m, struct pasid_entry *tbl_entry,
u16 dir_idx)
{
struct tbl_walk *tbl_wlk = m->private;
u8 tbl_idx;
for (tbl_idx = 0; tbl_idx < PASID_TBL_ENTRIES; tbl_idx++) {
if (pasid_pte_is_present(tbl_entry)) {
tbl_wlk->pasid_tbl_entry = tbl_entry;
tbl_wlk->pasid = (dir_idx << PASID_PDE_SHIFT) + tbl_idx;
print_tbl_walk(m);
}
tbl_entry++;
}
}
static void pasid_dir_walk(struct seq_file *m, u64 pasid_dir_ptr,
u16 pasid_dir_size)
{
struct pasid_dir_entry *dir_entry = phys_to_virt(pasid_dir_ptr);
struct pasid_entry *pasid_tbl;
u16 dir_idx;
for (dir_idx = 0; dir_idx < pasid_dir_size; dir_idx++) {
pasid_tbl = get_pasid_table_from_pde(dir_entry);
if (pasid_tbl)
pasid_tbl_walk(m, pasid_tbl, dir_idx);
dir_entry++;
}
}
static void ctx_tbl_walk(struct seq_file *m, struct intel_iommu *iommu, u16 bus)
{
struct context_entry *context;
u16 devfn, pasid_dir_size;
u64 pasid_dir_ptr;
for (devfn = 0; devfn < 256; devfn++) {
struct tbl_walk tbl_wlk = {0};
/*
* Scalable mode root entry points to upper scalable mode
* context table and lower scalable mode context table. Each
* scalable mode context table has 128 context entries where as
* legacy mode context table has 256 context entries. So in
* scalable mode, the context entries for former 128 devices are
* in the lower scalable mode context table, while the latter
* 128 devices are in the upper scalable mode context table.
* In scalable mode, when devfn > 127, iommu_context_addr()
* automatically refers to upper scalable mode context table and
* hence the caller doesn't have to worry about differences
* between scalable mode and non scalable mode.
*/
context = iommu_context_addr(iommu, bus, devfn, 0);
if (!context)
return;
if (!context_present(context))
continue;
tbl_wlk.bus = bus;
tbl_wlk.devfn = devfn;
tbl_wlk.rt_entry = &iommu->root_entry[bus];
tbl_wlk.ctx_entry = context;
m->private = &tbl_wlk;
if (dmar_readq(iommu->reg + DMAR_RTADDR_REG) & DMA_RTADDR_SMT) {
pasid_dir_ptr = context->lo & VTD_PAGE_MASK;
pasid_dir_size = get_pasid_dir_size(context);
pasid_dir_walk(m, pasid_dir_ptr, pasid_dir_size);
continue;
}
print_tbl_walk(m);
}
}
static void root_tbl_walk(struct seq_file *m, struct intel_iommu *iommu)
{
unsigned long flags;
u16 bus;
spin_lock_irqsave(&iommu->lock, flags);
seq_printf(m, "IOMMU %s: Root Table Address: 0x%llx\n", iommu->name,
(u64)virt_to_phys(iommu->root_entry));
seq_puts(m, "B.D.F\tRoot_entry\t\t\t\tContext_entry\t\t\t\tPASID\tPASID_table_entry\n");
/*
* No need to check if the root entry is present or not because
* iommu_context_addr() performs the same check before returning
* context entry.
*/
for (bus = 0; bus < 256; bus++)
ctx_tbl_walk(m, iommu, bus);
spin_unlock_irqrestore(&iommu->lock, flags);
}
static int dmar_translation_struct_show(struct seq_file *m, void *unused)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
u32 sts;
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
sts = dmar_readl(iommu->reg + DMAR_GSTS_REG);
if (!(sts & DMA_GSTS_TES)) {
seq_printf(m, "DMA Remapping is not enabled on %s\n",
iommu->name);
continue;
}
root_tbl_walk(m, iommu);
seq_putc(m, '\n');
}
rcu_read_unlock();
return 0;
}
DEFINE_SHOW_ATTRIBUTE(dmar_translation_struct);
static inline unsigned long level_to_directory_size(int level)
{
return BIT_ULL(VTD_PAGE_SHIFT + VTD_STRIDE_SHIFT * (level - 1));
}
static inline void
dump_page_info(struct seq_file *m, unsigned long iova, u64 *path)
{
seq_printf(m, "0x%013lx |\t0x%016llx\t0x%016llx\t0x%016llx\t0x%016llx\t0x%016llx\n",
iova >> VTD_PAGE_SHIFT, path[5], path[4],
path[3], path[2], path[1]);
}
static void pgtable_walk_level(struct seq_file *m, struct dma_pte *pde,
int level, unsigned long start,
u64 *path)
{
int i;
if (level > 5 || level < 1)
return;
for (i = 0; i < BIT_ULL(VTD_STRIDE_SHIFT);
i++, pde++, start += level_to_directory_size(level)) {
if (!dma_pte_present(pde))
continue;
path[level] = pde->val;
if (dma_pte_superpage(pde) || level == 1)
dump_page_info(m, start, path);
else
pgtable_walk_level(m, phys_to_virt(dma_pte_addr(pde)),
level - 1, start, path);
path[level] = 0;
}
}
static int show_device_domain_translation(struct device *dev, void *data)
{
struct dmar_domain *domain = find_domain(dev);
struct seq_file *m = data;
u64 path[6] = { 0 };
if (!domain)
return 0;
seq_printf(m, "Device %s with pasid %d @0x%llx\n",
dev_name(dev), domain->default_pasid,
(u64)virt_to_phys(domain->pgd));
seq_puts(m, "IOVA_PFN\t\tPML5E\t\t\tPML4E\t\t\tPDPE\t\t\tPDE\t\t\tPTE\n");
pgtable_walk_level(m, domain->pgd, domain->agaw + 2, 0, path);
seq_putc(m, '\n');
return 0;
}
static int domain_translation_struct_show(struct seq_file *m, void *unused)
{
unsigned long flags;
int ret;
spin_lock_irqsave(&device_domain_lock, flags);
ret = bus_for_each_dev(&pci_bus_type, NULL, m,
show_device_domain_translation);
spin_unlock_irqrestore(&device_domain_lock, flags);
return ret;
}
DEFINE_SHOW_ATTRIBUTE(domain_translation_struct);
static void invalidation_queue_entry_show(struct seq_file *m,
struct intel_iommu *iommu)
{
int index, shift = qi_shift(iommu);
struct qi_desc *desc;
int offset;
if (ecap_smts(iommu->ecap))
seq_puts(m, "Index\t\tqw0\t\t\tqw1\t\t\tqw2\t\t\tqw3\t\t\tstatus\n");
else
seq_puts(m, "Index\t\tqw0\t\t\tqw1\t\t\tstatus\n");
for (index = 0; index < QI_LENGTH; index++) {
offset = index << shift;
desc = iommu->qi->desc + offset;
if (ecap_smts(iommu->ecap))
seq_printf(m, "%5d\t%016llx\t%016llx\t%016llx\t%016llx\t%016x\n",
index, desc->qw0, desc->qw1,
desc->qw2, desc->qw3,
iommu->qi->desc_status[index]);
else
seq_printf(m, "%5d\t%016llx\t%016llx\t%016x\n",
index, desc->qw0, desc->qw1,
iommu->qi->desc_status[index]);
}
}
static int invalidation_queue_show(struct seq_file *m, void *unused)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
unsigned long flags;
struct q_inval *qi;
int shift;
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
qi = iommu->qi;
shift = qi_shift(iommu);
if (!qi || !ecap_qis(iommu->ecap))
continue;
seq_printf(m, "Invalidation queue on IOMMU: %s\n", iommu->name);
raw_spin_lock_irqsave(&qi->q_lock, flags);
seq_printf(m, " Base: 0x%llx\tHead: %lld\tTail: %lld\n",
(u64)virt_to_phys(qi->desc),
dmar_readq(iommu->reg + DMAR_IQH_REG) >> shift,
dmar_readq(iommu->reg + DMAR_IQT_REG) >> shift);
invalidation_queue_entry_show(m, iommu);
raw_spin_unlock_irqrestore(&qi->q_lock, flags);
seq_putc(m, '\n');
}
rcu_read_unlock();
return 0;
}
DEFINE_SHOW_ATTRIBUTE(invalidation_queue);
#ifdef CONFIG_IRQ_REMAP
static void ir_tbl_remap_entry_show(struct seq_file *m,
struct intel_iommu *iommu)
{
struct irte *ri_entry;
unsigned long flags;
int idx;
seq_puts(m, " Entry SrcID DstID Vct IRTE_high\t\tIRTE_low\n");
raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
for (idx = 0; idx < INTR_REMAP_TABLE_ENTRIES; idx++) {
ri_entry = &iommu->ir_table->base[idx];
if (!ri_entry->present || ri_entry->p_pst)
continue;
seq_printf(m, " %-5d %02x:%02x.%01x %08x %02x %016llx\t%016llx\n",
idx, PCI_BUS_NUM(ri_entry->sid),
PCI_SLOT(ri_entry->sid), PCI_FUNC(ri_entry->sid),
ri_entry->dest_id, ri_entry->vector,
ri_entry->high, ri_entry->low);
}
raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
}
static void ir_tbl_posted_entry_show(struct seq_file *m,
struct intel_iommu *iommu)
{
struct irte *pi_entry;
unsigned long flags;
int idx;
seq_puts(m, " Entry SrcID PDA_high PDA_low Vct IRTE_high\t\tIRTE_low\n");
raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
for (idx = 0; idx < INTR_REMAP_TABLE_ENTRIES; idx++) {
pi_entry = &iommu->ir_table->base[idx];
if (!pi_entry->present || !pi_entry->p_pst)
continue;
seq_printf(m, " %-5d %02x:%02x.%01x %08x %08x %02x %016llx\t%016llx\n",
idx, PCI_BUS_NUM(pi_entry->sid),
PCI_SLOT(pi_entry->sid), PCI_FUNC(pi_entry->sid),
pi_entry->pda_h, pi_entry->pda_l << 6,
pi_entry->vector, pi_entry->high,
pi_entry->low);
}
raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
}
/*
* For active IOMMUs go through the Interrupt remapping
* table and print valid entries in a table format for
* Remapped and Posted Interrupts.
*/
static int ir_translation_struct_show(struct seq_file *m, void *unused)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
u64 irta;
u32 sts;
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
if (!ecap_ir_support(iommu->ecap))
continue;
seq_printf(m, "Remapped Interrupt supported on IOMMU: %s\n",
iommu->name);
sts = dmar_readl(iommu->reg + DMAR_GSTS_REG);
if (iommu->ir_table && (sts & DMA_GSTS_IRES)) {
irta = virt_to_phys(iommu->ir_table->base);
seq_printf(m, " IR table address:%llx\n", irta);
ir_tbl_remap_entry_show(m, iommu);
} else {
seq_puts(m, "Interrupt Remapping is not enabled\n");
}
seq_putc(m, '\n');
}
seq_puts(m, "****\n\n");
for_each_active_iommu(iommu, drhd) {
if (!cap_pi_support(iommu->cap))
continue;
seq_printf(m, "Posted Interrupt supported on IOMMU: %s\n",
iommu->name);
if (iommu->ir_table) {
irta = virt_to_phys(iommu->ir_table->base);
seq_printf(m, " IR table address:%llx\n", irta);
ir_tbl_posted_entry_show(m, iommu);
} else {
seq_puts(m, "Interrupt Remapping is not enabled\n");
}
seq_putc(m, '\n');
}
rcu_read_unlock();
return 0;
}
DEFINE_SHOW_ATTRIBUTE(ir_translation_struct);
#endif
static void latency_show_one(struct seq_file *m, struct intel_iommu *iommu,
struct dmar_drhd_unit *drhd)
{
int ret;
seq_printf(m, "IOMMU: %s Register Base Address: %llx\n",
iommu->name, drhd->reg_base_addr);
ret = dmar_latency_snapshot(iommu, debug_buf, DEBUG_BUFFER_SIZE);
if (ret < 0)
seq_puts(m, "Failed to get latency snapshot");
else
seq_puts(m, debug_buf);
seq_puts(m, "\n");
}
static int latency_show(struct seq_file *m, void *v)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
rcu_read_lock();
for_each_active_iommu(iommu, drhd)
latency_show_one(m, iommu, drhd);
rcu_read_unlock();
return 0;
}
static int dmar_perf_latency_open(struct inode *inode, struct file *filp)
{
return single_open(filp, latency_show, NULL);
}
static ssize_t dmar_perf_latency_write(struct file *filp,
const char __user *ubuf,
size_t cnt, loff_t *ppos)
{
struct dmar_drhd_unit *drhd;
struct intel_iommu *iommu;
int counting;
char buf[64];
if (cnt > 63)
cnt = 63;
if (copy_from_user(&buf, ubuf, cnt))
return -EFAULT;
buf[cnt] = 0;
if (kstrtoint(buf, 0, &counting))
return -EINVAL;
switch (counting) {
case 0:
rcu_read_lock();
for_each_active_iommu(iommu, drhd) {
dmar_latency_disable(iommu, DMAR_LATENCY_INV_IOTLB);
dmar_latency_disable(iommu, DMAR_LATENCY_INV_DEVTLB);
dmar_latency_disable(iommu, DMAR_LATENCY_INV_IEC);
dmar_latency_disable(iommu, DMAR_LATENCY_PRQ);
}
rcu_read_unlock();
break;
case 1:
rcu_read_lock();
for_each_active_iommu(iommu, drhd)
dmar_latency_enable(iommu, DMAR_LATENCY_INV_IOTLB);
rcu_read_unlock();
break;
case 2:
rcu_read_lock();
for_each_active_iommu(iommu, drhd)
dmar_latency_enable(iommu, DMAR_LATENCY_INV_DEVTLB);
rcu_read_unlock();
break;
case 3:
rcu_read_lock();
for_each_active_iommu(iommu, drhd)
dmar_latency_enable(iommu, DMAR_LATENCY_INV_IEC);
rcu_read_unlock();
break;
case 4:
rcu_read_lock();
for_each_active_iommu(iommu, drhd)
dmar_latency_enable(iommu, DMAR_LATENCY_PRQ);
rcu_read_unlock();
break;
default:
return -EINVAL;
}
*ppos += cnt;
return cnt;
}
static const struct file_operations dmar_perf_latency_fops = {
.open = dmar_perf_latency_open,
.write = dmar_perf_latency_write,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
void __init intel_iommu_debugfs_init(void)
{
struct dentry *intel_iommu_debug = debugfs_create_dir("intel",
iommu_debugfs_dir);
debugfs_create_file("iommu_regset", 0444, intel_iommu_debug, NULL,
&iommu_regset_fops);
debugfs_create_file("dmar_translation_struct", 0444, intel_iommu_debug,
NULL, &dmar_translation_struct_fops);
debugfs_create_file("domain_translation_struct", 0444,
intel_iommu_debug, NULL,
&domain_translation_struct_fops);
debugfs_create_file("invalidation_queue", 0444, intel_iommu_debug,
NULL, &invalidation_queue_fops);
#ifdef CONFIG_IRQ_REMAP
debugfs_create_file("ir_translation_struct", 0444, intel_iommu_debug,
NULL, &ir_translation_struct_fops);
#endif
debugfs_create_file("dmar_perf_latency", 0644, intel_iommu_debug,
NULL, &dmar_perf_latency_fops);
}