[PATCH v3 4/5] iommu/amd: Do not Invalidate IRT when IRTE caching is disabled

[Suravee Suthikulpanit]

With the Interrupt Remapping Table cache disabled, there is no need to
issue invalidate IRT and wait for its completion. Therefore, add logic
to bypass the operation.

Reviewed-by: Jerry Snitselaar <jsnitsel@xxxxxxxxxx>
Suggested-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
 drivers/iommu/amd/iommu.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 0c4a2796bb0a..51c2b018433d 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -1273,12 +1273,24 @@ static void amd_iommu_flush_irt_all(struct amd_iommu *iommu)
 	u32 devid;
 	u16 last_bdf = iommu->pci_seg->last_bdf;
 
+	if (iommu->irtcachedis_enabled)
+		return;
+
 	for (devid = 0; devid <= last_bdf; devid++)
 		iommu_flush_irt(iommu, devid);
 
 	iommu_completion_wait(iommu);
 }
 
+static void iommu_flush_irt_and_complete(struct amd_iommu *iommu, u16 devid)
+{
+	if (iommu->irtcachedis_enabled)
+		return;
+
+	iommu_flush_irt(iommu, devid);
+	iommu_completion_wait(iommu);
+}
+
 void iommu_flush_all_caches(struct amd_iommu *iommu)
 {
 	if (iommu_feature(iommu, FEATURE_IA)) {
@@ -3028,8 +3040,7 @@ static int modify_irte_ga(struct amd_iommu *iommu, u16 devid, int index,
 
 	raw_spin_unlock_irqrestore(&table->lock, flags);
 
-	iommu_flush_irt(iommu, devid);
-	iommu_completion_wait(iommu);
+	iommu_flush_irt_and_complete(iommu, devid);
 
 	return 0;
 }
@@ -3048,8 +3059,7 @@ static int modify_irte(struct amd_iommu *iommu,
 	table->table[index] = irte->val;
 	raw_spin_unlock_irqrestore(&table->lock, flags);
 
-	iommu_flush_irt(iommu, devid);
-	iommu_completion_wait(iommu);
+	iommu_flush_irt_and_complete(iommu, devid);
 
 	return 0;
 }
@@ -3067,8 +3077,7 @@ static void free_irte(struct amd_iommu *iommu, u16 devid, int index)
 	iommu->irte_ops->clear_allocated(table, index);
 	raw_spin_unlock_irqrestore(&table->lock, flags);
 
-	iommu_flush_irt(iommu, devid);
-	iommu_completion_wait(iommu);
+	iommu_flush_irt_and_complete(iommu, devid);
 }
 
 static void irte_prepare(void *entry,
-- 
2.31.1