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iommu/vt-d: Don't free parent pagetable of the PTE we're adding 

When adding a large scatterlist entry that covers more than the L3
superpage size (1GB) but has an alignment such that we must use L2
superpages (2MB) , we give dma_pte_free_level() a range that causes it
to free the L3 pagetable we're about to populate. We fix this by telling
dma_pte_free_pagetable() about the pagetable level we're about to populate
to prevent freeing it.

For example, mapping a scatterlist with entry lengths 854MB and 1194MB
at IOVA 0xffff80000000 would, when processing the 2MB-aligned second
entry, cause pfn_to_dma_pte() to create a L3 directory to hold L2
superpages for the mapping at IOVA 0xffffc0000000. We would previously
call dma_pte_free_pagetable(domain, 0xffffc0000, 0xfffffffff), which
would free the L3 directory pfn_to_dma_pte() just created for IO PFN
0xffffc0000. Telling dma_pte_free_pagetable() to retain the L3
directories while using L2 superpages avoids the erroneous free.

Signed-off-by: David Dillow <dillow@google.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
zero-colors
David Dillow 2017-06-28 19:42:23 -07:00 committed by Joerg Roedel
parent 01e1932a17
commit bc24c57159
1 changed files with 26 additions and 12 deletions
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38
drivers/iommu/intel-iommu.c
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@ -1137,8 +1137,9 @@ static void dma_pte_clear_range(struct dmar_domain *domain,
}
static void dma_pte_free_level(struct dmar_domain *domain, int level,
struct dma_pte *pte, unsigned long pfn,
unsigned long start_pfn, unsigned long last_pfn)
int retain_level, struct dma_pte *pte,
unsigned long pfn, unsigned long start_pfn,
unsigned long last_pfn)
{
pfn = max(start_pfn, pfn);
pte = &pte[pfn_level_offset(pfn, level)];
@ -1153,12 +1154,17 @@ static void dma_pte_free_level(struct dmar_domain *domain, int level,
level_pfn = pfn & level_mask(level);
level_pte = phys_to_virt(dma_pte_addr(pte));
if (level > 2)
dma_pte_free_level(domain, level - 1, level_pte,
level_pfn, start_pfn, last_pfn);
if (level > 2) {
dma_pte_free_level(domain, level - 1, retain_level,
level_pte, level_pfn, start_pfn,
last_pfn);
}
/* If range covers entire pagetable, free it */
if (!(start_pfn > level_pfn ||
/*
* Free the page table if we're below the level we want to
* retain and the range covers the entire table.
*/
if (level < retain_level && !(start_pfn > level_pfn ||
last_pfn < level_pfn + level_size(level) - 1)) {
dma_clear_pte(pte);
domain_flush_cache(domain, pte, sizeof(*pte));
@ -1169,10 +1175,14 @@ next:
} while (!first_pte_in_page(++pte) && pfn <= last_pfn);
}
/* clear last level (leaf) ptes and free page table pages. */
/*
* clear last level (leaf) ptes and free page table pages below the
* level we wish to keep intact.
*/
static void dma_pte_free_pagetable(struct dmar_domain *domain,
unsigned long start_pfn,
unsigned long last_pfn)
unsigned long last_pfn,
int retain_level)
{
BUG_ON(!domain_pfn_supported(domain, start_pfn));
BUG_ON(!domain_pfn_supported(domain, last_pfn));
@ -1181,7 +1191,7 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain,
dma_pte_clear_range(domain, start_pfn, last_pfn);
/* We don't need lock here; nobody else touches the iova range */
dma_pte_free_level(domain, agaw_to_level(domain->agaw),
dma_pte_free_level(domain, agaw_to_level(domain->agaw), retain_level,
domain->pgd, 0, start_pfn, last_pfn);
/* free pgd */
@ -2274,8 +2284,11 @@ static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
/*
* Ensure that old small page tables are
* removed to make room for superpage(s).
* We're adding new large pages, so make sure
* we don't remove their parent tables.
*/
dma_pte_free_pagetable(domain, iov_pfn, end_pfn);
dma_pte_free_pagetable(domain, iov_pfn, end_pfn,
largepage_lvl + 1);
} else {
pteval &= ~(uint64_t)DMA_PTE_LARGE_PAGE;
}
@ -3935,7 +3948,8 @@ static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nele
ret = domain_sg_mapping(domain, start_vpfn, sglist, size, prot);
if (unlikely(ret)) {
dma_pte_free_pagetable(domain, start_vpfn,
start_vpfn + size - 1);
start_vpfn + size - 1,
agaw_to_level(domain->agaw) + 1);
free_iova_fast(&domain->iovad, iova_pfn, dma_to_mm_pfn(size));
return 0;
}