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iommu/amd: Check PM_LEVEL_SIZE() condition in locked section

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The increase_address_space() function has to check the PM_LEVEL_SIZE()
condition again under the domain->lock to avoid a false trigger of the
WARN_ON_ONCE() and to avoid that the address space is increase more
often than necessary.

Reported-by: Qian Cai <cai@lca.pw>
Fixes: 754265bcab ("iommu/amd: Fix race in increase_address_space()")
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Joerg Roedel 2019-10-18 11:34:22 +02:00
parent ec21f17a94
commit 46ac18c347
1 changed files with 4 additions and 3 deletions
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7
drivers/iommu/amd_iommu.c
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@ -1464,6 +1464,7 @@ static void free_pagetable(struct protection_domain *domain)
* to 64 bits.
*/
static bool increase_address_space(struct protection_domain *domain,
unsigned long address,
gfp_t gfp)
{
unsigned long flags;
@ -1472,8 +1473,8 @@ static bool increase_address_space(struct protection_domain *domain,
spin_lock_irqsave(&domain->lock, flags);
if (WARN_ON_ONCE(domain->mode == PAGE_MODE_6_LEVEL))
/* address space already 64 bit large */
if (address <= PM_LEVEL_SIZE(domain->mode) ||
WARN_ON_ONCE(domain->mode == PAGE_MODE_6_LEVEL))
goto out;
pte = (void *)get_zeroed_page(gfp);
@ -1506,7 +1507,7 @@ static u64 *alloc_pte(struct protection_domain *domain,
BUG_ON(!is_power_of_2(page_size));
while (address > PM_LEVEL_SIZE(domain->mode))
*updated = increase_address_space(domain, gfp) || *updated;
*updated = increase_address_space(domain, address, gfp) || *updated;
level = domain->mode - 1;
pte = &domain->pt_root[PM_LEVEL_INDEX(level, address)];