mbox series

[0/2] KVM: x86: Acquire SRCU in fastpath handler

Message ID 20230721224337.2335137-1-seanjc@google.com
Headers
Series KVM: x86: Acquire SRCU in fastpath handler |

Message

Sean Christopherson July 21, 2023, 10:43 p.m. UTC 
  Acquire SRCU for read when handling fastpath MSR writes so that side
effects like

Note, the PMU case could (and should) also be fixed by making the PMU
filter code smarter, e.g. by snapshotting which PMC events need to be
emulated, thus avoiding the filter lookup entirely.  But acquiring SRCU
is relatively cheap, and this isn't the first bug of this nature.

Which is a perfect segue into patch 2, which reverts a hack-a-fix to
fudge around SVM needing to do the front half of emulation when skipping
the WRMSR.

Note #2, the fastpath also doesn't honor the MSR filter for TSC_DEADLINE.
That's a problem for another day.

Sean Christopherson (2):
  KVM: x86: Acquire SRCU read lock when handling fastpath MSR writes
  Revert "KVM: SVM: Skip WRMSR fastpath on VM-Exit if next RIP isn't
    valid"

 arch/x86/kvm/svm/svm.c | 10 ++--------
 arch/x86/kvm/x86.c     |  4 ++++
 2 files changed, 6 insertions(+), 8 deletions(-)


base-commit: fdf0eaf11452d72945af31804e2a1048ee1b574c

Comments

Paolo Bonzini July 29, 2023, 2:57 p.m. UTC | #1 
Queued, thanks.

Paolo