[PATCH v2 0/3] KVM: x86/mmu: Fix TLB flushing bugs in TDP MMU

Sean Christopherson
2021-03-25T20:02:25Z

Two bug fixes and a clean up involving the TDP MMU, found by inspection.

Patch 1 fixes a bug where KVM yields, e.g. due to lock contention, without
performing a pending TLB flush that was required from a previous root.

Patch 2 fixes a much more egregious bug where it fails to handle TDP MMU
flushes in NX huge page recovery.

Patch 3 explicitly disallows yielding in the TDP MMU to prevent a similar
bug to patch 1 from sneaking in.

v2:
- Collect a review. [Ben]
- Disallowing yielding instead of feeding "flush" into the TDP MMU. [Ben]
- Move the yielding logic to a separate patch since it's not strictly a
bug fix and it's standalone anyways (the flush feedback loop was not).

v1:
- https://lkml.kernel.org/r/20210319232006.3468382-1-seanjc@google.com

Sean Christopherson (3):
KVM: x86/mmu: Ensure TLBs are flushed when yielding during GFN range
zap
KVM: x86/mmu: Ensure TLBs are flushed for TDP MMU during NX zapping
KVM: x86/mmu: Don't allow TDP MMU to yield when recovering NX pages

arch/x86/kvm/mmu/mmu.c | 9 +++++----
arch/x86/kvm/mmu/tdp_mmu.c | 26 ++++++++++++++------------
arch/x86/kvm/mmu/tdp_mmu.h | 23 ++++++++++++++++++++++-
3 files changed, 41 insertions(+), 17 deletions(-)

--
2.31.0.291.g576ba9dcdaf-goog