linux-kernel - [PATCH 1/2] iommu/vt-d: Preset Access bit for IOVA in FL non-leaf paging entries

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Date:   Wed, 16 Nov 2022 13:15:43 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     Tina Zhang <tina.zhang@...el.com>, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] iommu/vt-d: Preset Access bit for IOVA in FL non-leaf paging entries

From: Tina Zhang <tina.zhang@...el.com>

The A/D bits are preseted for IOVA over first level(FL) usage for both
kernel DMA (i.e, domain typs is IOMMU_DOMAIN_DMA) and user space DMA
usage (i.e., domain type is IOMMU_DOMAIN_UNMANAGED).

Presetting A bit in FL requires to preset the bit in every related paging
entries, including the non-leaf ones. Otherwise, hardware may treat this
as an error. For example, in a case of ECAP_REG.SMPWC==0, DMA faults might
occur with below DMAR fault messages (wrapped for line length) dumped.

 DMAR: DRHD: handling fault status reg 2
 DMAR: [DMA Read NO_PASID] Request device [aa:00.0] fault addr 0x10c3a6000
    [fault reason 0x90]
    SM: A/D bit update needed in first-level entry when set up in no snoop

Fixes: 289b3b005cb9 ("iommu/vt-d: Preset A/D bits for user space DMA usage")
Cc: stable@...r.kernel.org
Signed-off-by: Tina Zhang <tina.zhang@...el.com>
Link: https://lore.kernel.org/r/20221113010324.1094483-1-tina.zhang@intel.com
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel/iommu.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 48cdcd0a5cf3..996a8b5ee5ee 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -959,11 +959,9 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
 
 			domain_flush_cache(domain, tmp_page, VTD_PAGE_SIZE);
 			pteval = ((uint64_t)virt_to_dma_pfn(tmp_page) << VTD_PAGE_SHIFT) | DMA_PTE_READ | DMA_PTE_WRITE;
-			if (domain_use_first_level(domain)) {
-				pteval |= DMA_FL_PTE_XD | DMA_FL_PTE_US;
-				if (iommu_is_dma_domain(&domain->domain))
-					pteval |= DMA_FL_PTE_ACCESS;
-			}
+			if (domain_use_first_level(domain))
+				pteval |= DMA_FL_PTE_XD | DMA_FL_PTE_US | DMA_FL_PTE_ACCESS;
+
 			if (cmpxchg64(&pte->val, 0ULL, pteval))
 				/* Someone else set it while we were thinking; use theirs. */
 				free_pgtable_page(tmp_page);
-- 
2.34.1