linux-kernel - [PATCH v2 08/12] iommu/vt-d: Replace spin_lock_irqsave() with spin

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Date:   Tue, 14 Jun 2022 10:51:33 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>, Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        Jason Gunthorpe <jgg@...dia.com>
Cc:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH v2 08/12] iommu/vt-d: Replace spin_lock_irqsave() with spin_lock()

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@...ux.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 5ebfe32265d5..104f9d77b3f0 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 12cd12fc86a4..aec33599c7f7 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;
 }
 
@@ -2295,16 +2294,15 @@ 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;
 	}
 
@@ -2319,7 +2317,7 @@ 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,
@@ -2772,7 +2770,6 @@ 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;
@@ -2815,7 +2812,7 @@ 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++) {
@@ -2834,7 +2831,7 @@ 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