[PATCH 10/14] iommu/vt-d: Unconditionally flush device TLB for pasid table updates

Lu Baolu
2024-09-02T02:31:38Z

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@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20240820030208.20020-1-baolu.lu@linux.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 b51fc268dc84..2e5fa0a23299 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