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intel-iommu: Fix leaks in pagetable freeing

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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 <alex.williamson@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>
This commit is contained in:
Alex Williamson 2013-06-15 10:27:19 -06:00 committed by Joerg Roedel
parent d4e4ab86bc
commit 3269ee0bd6
1 changed files with 35 additions and 37 deletions
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72
drivers/iommu/intel-iommu.c
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@ -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);
dma_pte_free_level(domain, agaw_to_level(domain->agaw),
domain->pgd, 0, start_pfn, last_pfn);
/* 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);
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);