iommu/vt-d: Set U/S bit in first level page table by default

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: b802d07 ("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>
Link: https://lore.kernel.org/r/20200622231345.29722-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

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;

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)