From 6f820bb995b657ad69197679b4d626cf226bfd35 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Fri, 9 Nov 2018 12:07:11 +0100 Subject: [PATCH] iommu/amd: Allow to upgrade page-size Before this patch the iommu_map_page() function failed when it tried to map a huge-page where smaller mappings existed before. With this change the page-table pages of the old mappings are teared down, so that the huge-page can be mapped. Signed-off-by: Joerg Roedel --- drivers/iommu/amd_iommu.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c index c539b2a59019..71797b3d67e5 100644 --- a/drivers/iommu/amd_iommu.c +++ b/drivers/iommu/amd_iommu.c @@ -1557,6 +1557,25 @@ static u64 *fetch_pte(struct protection_domain *domain, return pte; } +static struct page *free_clear_pte(u64 *pte, u64 pteval, struct page *freelist) +{ + unsigned long pt; + int mode; + + while (cmpxchg64(pte, pteval, 0) != pteval) { + pr_warn("AMD-Vi: IOMMU pte changed since we read it\n"); + pteval = *pte; + } + + if (!IOMMU_PTE_PRESENT(pteval)) + return freelist; + + pt = (unsigned long)IOMMU_PTE_PAGE(pteval); + mode = IOMMU_PTE_MODE(pteval); + + return free_sub_pt(pt, mode, freelist); +} + /* * Generic mapping functions. It maps a physical address into a DMA * address space. It allocates the page table pages if necessary. @@ -1571,6 +1590,7 @@ static int iommu_map_page(struct protection_domain *dom, int prot, gfp_t gfp) { + struct page *freelist = NULL; u64 __pte, *pte; int i, count; @@ -1587,8 +1607,10 @@ static int iommu_map_page(struct protection_domain *dom, return -ENOMEM; for (i = 0; i < count; ++i) - if (IOMMU_PTE_PRESENT(pte[i])) - return -EBUSY; + freelist = free_clear_pte(&pte[i], pte[i], freelist); + + if (freelist != NULL) + dom->updated = true; if (count > 1) { __pte = PAGE_SIZE_PTE(__sme_set(phys_addr), page_size); @@ -1606,6 +1628,9 @@ static int iommu_map_page(struct protection_domain *dom, update_domain(dom); + /* Everything flushed out, free pages now */ + free_page_list(freelist); + return 0; }