Paul Mackerras ad9940e377 KVM: PPC: Book3S HV: Close race with page faults around memslot flushes
[ Upstream commit 11362b1befeadaae4d159a8cddcdaf6b8afe08f9 ]

There is a potential race condition between hypervisor page faults
and flushing a memslot.  It is possible for a page fault to read the
memslot before a memslot is updated and then write a PTE to the
partition-scoped page tables after kvmppc_radix_flush_memslot has
completed.  (Note that this race has never been explicitly observed.)

To close this race, it is sufficient to increment the MMU sequence
number while the kvm->mmu_lock is held.  That will cause
mmu_notifier_retry() to return true, and the page fault will then
return to the guest without inserting a PTE.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01 13:18:05 +02:00
..
2020-10-01 13:17:39 +02:00
2020-05-10 10:31:31 +02:00
2020-09-23 12:40:42 +02:00
2019-09-27 13:02:19 -07:00