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Subject[PATCH 2/2] iommu/vt-d: Set U/S bit in first level page table by default
Date
When using first-level translation for IOVA, currently the U/S bit in the
page table is cleared which implies DMA requests with user privilege are
blocked. As the result, following error messages might be observed when
passing through a device to user level:

DMAR: DRHD: handling fault status reg 3
DMAR: [DMA Read] Request device [41:00.0] PASID 1 fault addr 7ecdcd000
[fault reason 129] SM: U/S set 0 for first-level translation
with user privilege

This fixes it by setting U/S bit in the first level page table and makes
IOVA over first level compatible with previous second-level translation.

Fixes: b802d070a52a1 ("iommu/vt-d: Use iova over first level")
Reported-by: Xin Zeng <xin.zeng@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/intel-iommu.c | 5 ++---
include/linux/intel-iommu.h | 1 +
2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 648a785e078a..d148712466b4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -921,7 +921,7 @@ 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;
+ pteval |= DMA_FL_PTE_XD | DMA_FL_PTE_US;
if (cmpxchg64(&pte->val, 0ULL, pteval))
/* Someone else set it while we were thinking; use theirs. */
free_pgtable_page(tmp_page);
@@ -1951,7 +1951,6 @@ static inline void
context_set_sm_rid2pasid(struct context_entry *context, unsigned long pasid)
{
context->hi |= pasid & ((1 << 20) - 1);
- context->hi |= (1 << 20);
}

/*
@@ -2243,7 +2242,7 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,

attr = prot & (DMA_PTE_READ | DMA_PTE_WRITE | DMA_PTE_SNP);
if (domain_use_first_level(domain))
- attr |= DMA_FL_PTE_PRESENT | DMA_FL_PTE_XD;
+ attr |= DMA_FL_PTE_PRESENT | DMA_FL_PTE_XD | DMA_FL_PTE_US;

if (!sg) {
sg_res = nr_pages;
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index 4100bd224f5c..3e8fa1c7a1e6 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -41,6 +41,7 @@
#define DMA_PTE_SNP BIT_ULL(11)

#define DMA_FL_PTE_PRESENT BIT_ULL(0)
+#define DMA_FL_PTE_US BIT_ULL(2)
#define DMA_FL_PTE_XD BIT_ULL(63)

#define ADDR_WIDTH_5LEVEL (57)
--
2.17.1
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