[PATCH 08/12] iommu/vt-d: Replace spin_lock_irqsave() with spin_lock()

Lu Baolu
2022-05-27T06:34:25Z

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. Hence there's no need to disable interrupts
when helding the spinlock.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/intel/debugfs.c | 6 ++----
drivers/iommu/intel/iommu.c | 17 +++++++----------
2 files changed, 9 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c
index eea8727aa7bc..ca1adceeba19 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 ccf3c7fa26f1..2e195a639502 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;
}

@@ -2287,16 +2286,15 @@ 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;
}

@@ -2311,7 +2309,7 @@ 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,
@@ -2764,7 +2762,6 @@ 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;
@@ -2807,7 +2804,7 @@ 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++) {
@@ -2826,7 +2823,7 @@ 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);

--
2.25.1