KVM: PPC: Book3S HV: Don't use compound_order to determine host mapping size

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THP paths can defer splitting compound pages until after the actual
remap and TLB flushes to split a huge PMD/PUD. This causes radix
partition scope page table mappings to get out of synch with the host
qemu page table mappings.

This results in random memory corruption in the guest when running
with THP. The easiest way to reproduce is use KVM balloon to free up
a lot of memory in the guest and then shrink the balloon to give the
memory back, while some work is being done in the guest.

Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: kvm-ppc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>

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Nicholas Piggin 2018-09-11 20:48:34 +10:00 • committed by Paul Mackerras

parent 425333bf3a

commit 71d29f43b6

1 changed files with 37 additions and 54 deletions

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arch/powerpc/kvm/book3s_64_mmu_radix.c

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