iommu/amd: Fix domain flush size when syncing iotlb

When running on an AMD vIOMMU, we observed multiple invalidations (of
decreasing power of 2 aligned sizes) when unmapping a single page.

Domain flush takes gather bounds (end-start) as size param. However,
gather->end is defined as the last inclusive address (start + size - 1).
This leads to an off by 1 error.

With this patch, verified that 1 invalidation occurs when unmapping a
single page.

Fixes: a270be1b3fdf ("iommu/amd: Use only natural aligned flushes in a VM")
Cc: stable@vger.kernel.org # >= 5.15
Signed-off-by: Jon Pan-Doh <pandoh@google.com>
Tested-by: Sudheer Dantuluri <dantuluris@google.com>
Suggested-by: Gary Zibrat <gzibrat@google.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Acked-by: Nadav Amit <namit@vmware.com>
Link: https://lore.kernel.org/r/20230426203256.237116-1-pandoh@google.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 3797e35df0357574d8e232228e2095f9863d7fc6..0f3ac4b489d673ea30fc228be2ffb41648cc71e4 100644 (file)
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2398,7 +2398,7 @@ static void amd_iommu_iotlb_sync(struct iommu_domain *domain,
        unsigned long flags;
 
        spin_lock_irqsave(&dom->lock, flags);
-       domain_flush_pages(dom, gather->start, gather->end - gather->start, 1);
+       domain_flush_pages(dom, gather->start, gather->end - gather->start + 1, 1);
        amd_iommu_domain_flush_complete(dom);
        spin_unlock_irqrestore(&dom->lock, flags);
 }