linux-kernel - [PATCH RESEND] iommu/amd: Fix domain flush size when syncing iotlb

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Message-ID: <20230518015054.2223833-1-pandoh@google.com>
Date:   Wed, 17 May 2023 18:50:54 -0700
From:   Jon Pan-Doh <pandoh@...gle.com>
To:     Joerg Roedel <joro@...tes.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org,
        Jon Pan-Doh <pandoh@...gle.com>, stable@...r.kernel.org,
        Gary Zibrat <gzibrat@...gle.com>,
        Sudheer Dantuluri <dantuluris@...gle.com>,
        Nadav Amit <namit@...are.com>,
        Vasant Hegde <vasant.hegde@....com>
Subject: [PATCH RESEND] 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@...r.kernel.org> # 5.15.x
Suggested-by: Gary Zibrat <gzibrat@...gle.com>
Tested-by: Sudheer Dantuluri <dantuluris@...gle.com>
Acked-by: Nadav Amit <namit@...are.com>
Reviewed-by: Vasant Hegde <vasant.hegde@....com>
Signed-off-by: Jon Pan-Doh <pandoh@...gle.com>
---
 drivers/iommu/amd/iommu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 5a505ba5467e..da45b1ab042d 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2378,7 +2378,7 @@ 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);
 }
-- 
2.40.0.634.g4ca3ef3211-goog