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From:   Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
To:     <linux-kernel@vger.kernel.org>, <iommu@lists.linux.dev>
CC:     <joro@8bytes.org>, <joao.m.martins@oracle.com>,
        <alejandro.j.jimenez@oracle.com>, <boris.ostrovsky@oracle.com>,
        <jon.grimm@amd.com>, <santosh.shukla@amd.com>,
        <vasant.hegde@amd.com>, <kishon.vijayabraham@amd.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: [PATCH v2 4/5] iommu/amd: Do not Invalidate IRT when disable IRTE caching
Date:   Thu, 18 May 2023 20:55:28 -0400
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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.

Suggested-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
---
 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