[PATCH v4 3/7] iommu/vt-d: Fix PASID devTLB invalidation

Jacob Pan
2020-07-07T00:06:27Z

DevTLB flush can be used for both DMA request with and without PASIDs.
The former uses PASID#0 (RID2PASID), latter uses non-zero PASID for SVA
usage.

This patch adds a check for PASID value such that devTLB flush with
PASID is used for SVA case. This is more efficient in that multiple
PASIDs can be used by a single device, when tearing down a PASID entry
we shall flush only the devTLB specific to a PASID.

Fixes: 6f7db75e1c46 ("iommu/vt-d: Add second level page table")
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
drivers/iommu/intel/pasid.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c
index c81f0f17c6ba..fa0154cce537 100644
--- a/drivers/iommu/intel/pasid.c
+++ b/drivers/iommu/intel/pasid.c
@@ -486,7 +486,16 @@ devtlb_invalidation_with_pasid(struct intel_iommu *iommu,
qdep = info->ats_qdep;
pfsid = info->pfsid;

- qi_flush_dev_iotlb(iommu, sid, pfsid, qdep, 0, 64 - VTD_PAGE_SHIFT);
+ /*
+ * When PASID 0 is used, it indicates RID2PASID(DMA request w/o PASID),
+ * devTLB flush w/o PASID should be used. For non-zero PASID under
+ * SVA usage, device could do DMA with multiple PASIDs. It is more
+ * efficient to flush devTLB specific to the PASID.
+ */
+ if (pasid == PASID_RID2PASID)
+ qi_flush_dev_iotlb(iommu, sid, pfsid, qdep, 0, 64 - VTD_PAGE_SHIFT);
+ else
+ qi_flush_dev_iotlb_pasid(iommu, sid, pfsid, pasid, qdep, 0, 64 - VTD_PAGE_SHIFT);
}

void intel_pasid_tear_down_entry(struct intel_iommu *iommu, struct device *dev,