Marc,
On 20/03/2019 10:11, Marc Zyngier wrote:
On Wed, 20 Mar 2019 09:44:38 +0000
Suzuki K Poulose <suzuki.poulose@xxxxxxx> wrote:
Hi Marc,
On 20/03/2019 08:15, Marc Zyngier wrote:
Hi Suzuki,
On Tue, 19 Mar 2019 14:11:08 +0000,
Suzuki K Poulose <suzuki.poulose@xxxxxxx> wrote:
We rely on the mmu_notifier call backs to handle the split/merge
of huge pages and thus we are guaranteed that, while creating a
block mapping, either the entire block is unmapped at stage2 or it
is missing permission.
However, we miss a case where the block mapping is split for dirty
logging case and then could later be made block mapping, if we cancel the
dirty logging. This not only creates inconsistent TLB entries for
the pages in the the block, but also leakes the table pages for
PMD level.
Handle this corner case for the huge mappings at stage2 by
unmapping the non-huge mapping for the block. This could potentially
release the upper level table. So we need to restart the table walk
once we unmap the range.
Fixes : ad361f093c1e31d ("KVM: ARM: Support hugetlbfs backed huge pages")
Reported-by: Zheng Xiang <zhengxiang9@xxxxxxxxxx>
Cc: Zheng Xiang <zhengxiang9@xxxxxxxxxx>
Cc: Zhengui Yu <yuzenghui@xxxxxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
Signed-off-by: Suzuki K Poulose ...
+ if (!pmd_thp_or_huge(old_pmd)) {
+ unmap_stage2_range(kvm, addr & S2_PMD_MASK, S2_PMD_SIZE);
+ goto retry;
+ if (!stage2_pud_huge(kvm, old_pud)) {
+ unmap_stage2_range(kvm, addr & S2_PUD_MASK, S2_PUD_SIZE);
We should really get rid of the S2_P{U/M}D_* definitions, as they are
always the same as the host. The only thing that changes is the PGD size
which varies according to the IPA and the concatenation.
Also what do you think about using P{M,U}D_* instead of S2_P{M,U}D_*
above ? I could make that change with the respin.
Sure, feel free to send a fixed version. I'll drop the currently queued
patch.
Thanks. Sorry for the trouble.
Cheers
Suzuki
