KVM: x86: check PIR even for vCPUs with disabled APICv
The IRTE for an assigned device can trigger a POSTED_INTR_VECTOR even
if APICv is disabled on the vCPU that receives it. In that case, the
interrupt will just cause a vmexit and leave the ON bit set together
with the PIR bit corresponding to the interrupt.
Right now, the interrupt would not be delivered until APICv is re-enabled.
However, fixing this is just a matter of always doing the PIR->IRR
synchronization, even if the vCPU has temporarily disabled APICv.
This is not a problem for performance, or if anything it is an
improvement. First, in the common case where vcpu->arch.apicv_active is
true, one fewer check has to be performed. Second, static_call_cond will
elide the function call if APICv is not present or disabled. Finally,
in the case for AMD hardware we can remove the sync_pir_to_irr callback:
it is only needed for apic_has_interrupt_for_ppr, and that function
already has a fallback for !APICv.
Co-developed-by: Sean Christopherson <firstname.lastname@example.org>
Signed-off-by: Sean Christopherson <email@example.com>
Reviewed-by: Maxim Levitsky <firstname.lastname@example.org>
Reviewed-by: David Matlack <email@example.com>
Signed-off-by: Paolo Bonzini <firstname.lastname@example.org>
3 files changed