From 22d169bdd2849fe6bd18c2643742e1c02be6451c Mon Sep 17 00:00:00 2001 From: Dmytro Maluka Date: Thu, 22 Jan 2026 09:48:52 +0800 Subject: [PATCH] iommu/vt-d: Flush cache for PASID table before using it When writing the address of a freshly allocated zero-initialized PASID table to a PASID directory entry, do that after the CPU cache flush for this PASID table, not before it, to avoid the time window when this PASID table may be already used by non-coherent IOMMU hardware while its contents in RAM is still some random old data, not zero-initialized. Fixes: 194b3348bdbb ("iommu/vt-d: Fix PASID directory pointer coherency") Signed-off-by: Dmytro Maluka Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20251221123508.37495-1-dmaluka@chromium.org Signed-off-by: Lu Baolu Signed-off-by: Joerg Roedel --- drivers/iommu/intel/pasid.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c index 99692f88b8834..6379b211f12b0 100644 --- a/drivers/iommu/intel/pasid.c +++ b/drivers/iommu/intel/pasid.c @@ -153,6 +153,9 @@ retry: if (!entries) return NULL; + if (!ecap_coherent(info->iommu->ecap)) + clflush_cache_range(entries, VTD_PAGE_SIZE); + /* * The pasid directory table entry won't be freed after * allocation. No worry about the race with free and @@ -165,10 +168,8 @@ retry: iommu_free_pages(entries); goto retry; } - if (!ecap_coherent(info->iommu->ecap)) { - clflush_cache_range(entries, VTD_PAGE_SIZE); + if (!ecap_coherent(info->iommu->ecap)) clflush_cache_range(&dir[dir_index].val, sizeof(*dir)); - } } return &entries[index]; -- 2.47.3