linux-kernel - [PATCH 1/1] iommu/vt-d: Unconditionally flush device TLB for pasid table updates

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Message-Id: <20240820030208.20020-1-baolu.lu@linux.intel.com>
Date: Tue, 20 Aug 2024 11:02:08 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Kevin Tian <kevin.tian@...el.com>,
	Yi Liu <yi.l.liu@...el.com>
Cc: iommu@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 1/1] iommu/vt-d: Unconditionally flush device TLB for pasid table updates

The caching mode of an IOMMU is irrelevant to the behavior of the device
TLB. Previously, commit <304b3bde24b5> ("iommu/vt-d: Remove caching mode
check before device TLB flush") removed this redundant check in the
domain unmap path.

Checking the caching mode before flushing the device TLB after a pasid
table entry is updated is unnecessary and can lead to inconsistent
behavior.

Extends this consistency by removing the caching mode check in the pasid
table update path.

Suggested-by: Yi Liu <yi.l.liu@...el.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/pasid.c | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index 5792c817cefa..dc00eac6be31 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -264,9 +264,7 @@ void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev,
 	else
 		iommu->flush.flush_iotlb(iommu, did, 0, 0, DMA_TLB_DSI_FLUSH);
 
-	/* Device IOTLB doesn't need to be flushed in caching mode. */
-	if (!cap_caching_mode(iommu->cap))
-		devtlb_invalidation_with_pasid(iommu, dev, pasid);
+	devtlb_invalidation_with_pasid(iommu, dev, pasid);
 }
 
 /*
@@ -493,9 +491,7 @@ int intel_pasid_setup_dirty_tracking(struct intel_iommu *iommu,
 
 	iommu->flush.flush_iotlb(iommu, did, 0, 0, DMA_TLB_DSI_FLUSH);
 
-	/* Device IOTLB doesn't need to be flushed in caching mode. */
-	if (!cap_caching_mode(iommu->cap))
-		devtlb_invalidation_with_pasid(iommu, dev, pasid);
+	devtlb_invalidation_with_pasid(iommu, dev, pasid);
 
 	return 0;
 }
@@ -572,9 +568,7 @@ void intel_pasid_setup_page_snoop_control(struct intel_iommu *iommu,
 	pasid_cache_invalidation_with_pasid(iommu, did, pasid);
 	qi_flush_piotlb(iommu, did, pasid, 0, -1, 0);
 
-	/* Device IOTLB doesn't need to be flushed in caching mode. */
-	if (!cap_caching_mode(iommu->cap))
-		devtlb_invalidation_with_pasid(iommu, dev, pasid);
+	devtlb_invalidation_with_pasid(iommu, dev, pasid);
 }
 
 /**
-- 
2.34.1