[PATCH v3 05/11] iommu/vt-d: Replace spin_lock_irqsave() with spin_lock()

Lu Baolu
2022-06-29T07:52:16Z

The iommu->lock is used to protect changes in root/context/pasid tables
and domain ID allocation. There's no use case to change these resources
in any interrupt context. Therefore, it's unnecessary to disable the
interrupts when the spinlock is held.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
---
drivers/iommu/intel/debugfs.c | 6 ++----
drivers/iommu/intel/iommu.c | 26 +++++++++++---------------
drivers/iommu/intel/svm.c | 6 +++---
3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c
index 6e1a3f88abc8..1f925285104e 100644
--- a/drivers/iommu/intel/debugfs.c
+++ b/drivers/iommu/intel/debugfs.c
@@ -263,10 +263,9 @@ static void ctx_tbl_walk(struct seq_file *m, struct intel_iommu *iommu, u16 bus)

static void root_tbl_walk(struct seq_file *m, struct intel_iommu *iommu)
{
- unsigned long flags;
u16 bus;

- spin_lock_irqsave(&iommu->lock, flags);
+ spin_lock(&iommu->lock);
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");
@@ -278,8 +277,7 @@ static void root_tbl_walk(struct seq_file *m, struct intel_iommu *iommu)
*/
for (bus = 0; bus < 256; bus++)
ctx_tbl_walk(m, iommu, bus);
-
- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);
}

static int dmar_translation_struct_show(struct seq_file *m, void *unused)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index ff49c9460ede..a81bdddf1091 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -797,13 +797,12 @@ static int device_context_mapped(struct intel_iommu *iommu, u8 bus, u8 devfn)
{
struct context_entry *context;
int ret = 0;
- unsigned long flags;

- spin_lock_irqsave(&iommu->lock, flags);
+ spin_lock(&iommu->lock);
context = iommu_context_addr(iommu, bus, devfn, 0);
if (context)
ret = context_present(context);
- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);
return ret;
}

@@ -2296,16 +2295,15 @@ static void domain_context_clear_one(struct device_domain_info *info, u8 bus, u8
{
struct intel_iommu *iommu = info->iommu;
struct context_entry *context;
- unsigned long flags;
u16 did_old;

if (!iommu)
return;

- spin_lock_irqsave(&iommu->lock, flags);
+ spin_lock(&iommu->lock);
context = iommu_context_addr(iommu, bus, devfn, 0);
if (!context) {
- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);
return;
}

@@ -2320,7 +2318,7 @@ static void domain_context_clear_one(struct device_domain_info *info, u8 bus, u8

context_clear_entry(context);
__iommu_flush_cache(iommu, context, sizeof(*context));
- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);
iommu->flush.flush_context(iommu,
did_old,
(((u16)bus) << 8) | devfn,
@@ -2499,7 +2497,7 @@ static int domain_add_dev_info(struct dmar_domain *domain, struct device *dev)
}

/* Setup the PASID entry for requests without PASID: */
- spin_lock_irqsave(&iommu->lock, flags);
+ spin_lock(&iommu->lock);
if (hw_pass_through && domain_type_is_si(domain))
ret = intel_pasid_setup_pass_through(iommu, domain,
dev, PASID_RID2PASID);
@@ -2509,7 +2507,7 @@ static int domain_add_dev_info(struct dmar_domain *domain, struct device *dev)
else
ret = intel_pasid_setup_second_level(iommu, domain,
dev, PASID_RID2PASID);
- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);
if (ret) {
dev_err(dev, "Setup RID2PASID failed\n");
dmar_remove_one_dev_info(dev);
@@ -2777,7 +2775,6 @@ static int copy_translation_tables(struct intel_iommu *iommu)
struct root_entry *old_rt;
phys_addr_t old_rt_phys;
int ctxt_table_entries;
- unsigned long flags;
u64 rtaddr_reg;
int bus, ret;
bool new_ext, ext;
@@ -2820,7 +2817,7 @@ static int copy_translation_tables(struct intel_iommu *iommu)
}
}

- spin_lock_irqsave(&iommu->lock, flags);
+ spin_lock(&iommu->lock);

/* Context tables are copied, now write them to the root_entry table */
for (bus = 0; bus < 256; bus++) {
@@ -2839,7 +2836,7 @@ static int copy_translation_tables(struct intel_iommu *iommu)
iommu->root_entry[bus].hi = val;
}

- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);

kfree(ctxt_tbls);

@@ -4166,7 +4163,6 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
{
struct dmar_domain *domain;
struct intel_iommu *iommu;
- unsigned long flags;

assert_spin_locked(&device_domain_lock);

@@ -4188,9 +4184,9 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)

list_del(&info->link);

- spin_lock_irqsave(&iommu->lock, flags);
+ spin_lock(&iommu->lock);
domain_detach_iommu(domain, iommu);
- spin_unlock_irqrestore(&iommu->lock, flags);
+ spin_unlock(&iommu->lock);
}

static void dmar_remove_one_dev_info(struct device *dev)
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 580713aa9e07..82288a50660d 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -328,9 +328,9 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
unsigned int flags)
{
struct device_domain_info *info = dev_iommu_priv_get(dev);
- unsigned long iflags, sflags;
struct intel_svm_dev *sdev;
struct intel_svm *svm;
+ unsigned long sflags;
int ret = 0;

svm = pasid_private_find(mm->pasid);
@@ -394,10 +394,10 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
sflags = (flags & SVM_FLAG_SUPERVISOR_MODE) ?
PASID_FLAG_SUPERVISOR_MODE : 0;
sflags |= cpu_feature_enabled(X86_FEATURE_LA57) ? PASID_FLAG_FL5LP : 0;
- spin_lock_irqsave(&iommu->lock, iflags);
+ spin_lock(&iommu->lock);
ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, mm->pasid,
FLPT_DEFAULT_DID, sflags);
- spin_unlock_irqrestore(&iommu->lock, iflags);
+ spin_unlock(&iommu->lock);

if (ret)
goto free_sdev;
--
2.25.1