Re: [PATCH 2/2] KVM: SVM: Set/clear CR8 write interception when AVIC is (de)activated

[Paolo Bonzini <pbonzini@redhat.com>]

On 3/10/26 23:33, Tom Lendacky wrote:
> Could we do something with virtual interrupt support? Today KVM uses the
> virtual interrupt control to detect when an IRQ window opens. We could
> do something similar by setting up the virtual interrupt priority,
> V_INTR_PRIO, at the level of the current TPR/CR8 level. When the TPR
> drops, that would trigger a #VMEXIT and allow the pending IRQ to be
> injected. Thoughts?

Yes, in fact Hyper-V uses VINTR injection and mostly doesn't bother with 
interrupt windows.  KVM does it to keep the code similar between Intel 
and AMD.

But even if you don't go all the way with VINTR, it should be possible 
to implement something akin to Intel flexpriority through V_INTR_PRIO 
and V_TPR (and keeping the VINTR intercept set to detect the moment 
V_TPR falls below V_INTR_PRIO).

Paolo