From 3269ee0bd6686baf86630300d528500ac5b516d7 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Sat, 15 Jun 2013 10:27:19 -0600 Subject: [PATCH] intel-iommu: Fix leaks in pagetable freeing At best the current code only seems to free the leaf pagetables and the root. If you're unlucky enough to have a large gap (like any QEMU guest with more than 3G of memory), only the first chunk of leaf pagetables are freed (plus the root). This is a massive memory leak. This patch re-writes the pagetable freeing function to use a recursive algorithm and manages to not only free all the pagetables, but does it without any apparent performance loss versus the current broken version. Signed-off-by: Alex Williamson Cc: stable@vger.kernel.org Reviewed-by: Marcelo Tosatti Signed-off-by: Joerg Roedel --- drivers/iommu/intel-iommu.c | 72 ++++++++++++++++++------------------- 1 file changed, 35 insertions(+), 37 deletions(-) diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index eec0d3e04bf5..15e9b57e9cf0 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -890,56 +890,54 @@ static int dma_pte_clear_range(struct dmar_domain *domain, return order; } +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) +{ + pfn = max(start_pfn, pfn); + pte = &pte[pfn_level_offset(pfn, level)]; + + do { + unsigned long level_pfn; + struct dma_pte *level_pte; + + if (!dma_pte_present(pte) || dma_pte_superpage(pte)) + goto next; + + level_pfn = pfn & level_mask(level - 1); + 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 range covers entire pagetable, free it */ + if (!(start_pfn > level_pfn || + last_pfn < level_pfn + level_size(level))) { + dma_clear_pte(pte); + domain_flush_cache(domain, pte, sizeof(*pte)); + free_pgtable_page(level_pte); + } +next: + pfn += level_size(level); + } while (!first_pte_in_page(++pte) && pfn <= last_pfn); +} + /* free page table pages. last level pte should already be cleared */ static void dma_pte_free_pagetable(struct dmar_domain *domain, unsigned long start_pfn, unsigned long last_pfn) { int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT; - struct dma_pte *first_pte, *pte; - int total = agaw_to_level(domain->agaw); - int level; - unsigned long tmp; - int large_page = 2; BUG_ON(addr_width < BITS_PER_LONG && start_pfn >> addr_width); BUG_ON(addr_width < BITS_PER_LONG && last_pfn >> addr_width); BUG_ON(start_pfn > last_pfn); /* We don't need lock here; nobody else touches the iova range */ - level = 2; - while (level <= total) { - tmp = align_to_level(start_pfn, level); - - /* If we can't even clear one PTE at this level, we're done */ - if (tmp + level_size(level) - 1 > last_pfn) - return; - - do { - large_page = level; - first_pte = pte = dma_pfn_level_pte(domain, tmp, level, &large_page); - if (large_page > level) - level = large_page + 1; - if (!pte) { - tmp = align_to_level(tmp + 1, level + 1); - continue; - } - do { - if (dma_pte_present(pte)) { - free_pgtable_page(phys_to_virt(dma_pte_addr(pte))); - dma_clear_pte(pte); - } - pte++; - tmp += level_size(level); - } while (!first_pte_in_page(pte) && - tmp + level_size(level) - 1 <= last_pfn); + dma_pte_free_level(domain, agaw_to_level(domain->agaw), + domain->pgd, 0, start_pfn, last_pfn); - domain_flush_cache(domain, first_pte, - (void *)pte - (void *)first_pte); - - } while (tmp && tmp + level_size(level) - 1 <= last_pfn); - level++; - } /* free pgd */ if (start_pfn == 0 && last_pfn == DOMAIN_MAX_PFN(domain->gaw)) { free_pgtable_page(domain->pgd); -- GitLab