[0/2] KVM: arm/arm64: Fix guest's PMR synchronization when blocking on WFI

Message

Marc Zyngier Aug. 2, 2019, 10:37 a.m. UTC

It recently came to light that if we run a guest that actively uses
interrupt priorities to block interrupts, vcpus can end-up being
blocked while they shouldn't, leading to an unresponsive guest (a
slightly less than desirable outcome).

Patch #1 fixes the issue (which has been with us since 4.12), which I plan
to take in for 5.3 with immediate backport to stable.

Patch #2 is more of an RFC, as it also impacts the SVN AVIC support. It
moves the kvm_arch_vcpu_blocking callback to happen earlier, leading to
much better performances on ARM, and leading to the above fix to be
applied at the best possible spot. I'd welcome any comment/testing on
this, specially on non-ARM systems.

Marc Zyngier (2):
  KVM: arm/arm64: Sync ICH_VMCR_EL2 back when about to block
  KVM: Call kvm_arch_vcpu_blocking early into the blocking sequence

 include/kvm/arm_vgic.h      |  1 +
 virt/kvm/arm/arm.c          | 11 +++++++++++
 virt/kvm/arm/vgic/vgic-v2.c |  9 ++++++++-
 virt/kvm/arm/vgic/vgic-v3.c |  7 ++++++-
 virt/kvm/arm/vgic/vgic.c    | 11 +++++++++++
 virt/kvm/arm/vgic/vgic.h    |  2 ++
 virt/kvm/kvm_main.c         |  7 +++----
 7 files changed, 42 insertions(+), 6 deletions(-)