Re: [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul

Maxim Levitsky
2021-12-09T14:48:37Z

On Thu, 2021-12-09 at 15:29 +0100, Paolo Bonzini wrote:
> On 12/9/21 01:02, Sean Christopherson wrote:
> > RDX, a.k.a. ir_data is NULL. This check in svm_ir_list_add()
> >
> > if (pi->ir_data && (pi->prev_ga_tag != 0)) {
> >
> > implies pi->ir_data can be NULL, but neither avic_update_iommu_vcpu_affinity()
> > nor amd_iommu_update_ga() check ir->data for NULL.
> >
> > amd_ir_set_vcpu_affinity() returns "success" without clearing pi.is_guest_mode
> >
> > /* Note:
> > * This device has never been set up for guest mode.
> > * we should not modify the IRTE
> > */
> > if (!dev_data || !dev_data->use_vapic)
> > return 0;
> >
> > so it's plausible svm_ir_list_add() could add to the list with a NULL pi->ir_data.
> >
> > But none of the relevant code has seen any meaningful changes since 5.15, so odds
> > are good I broke something :-/

Doesn't reproduce here yet even with my iommu changes :-(
Oh well.

Best regards,
Maxim Levitsky

> >
>
> Ok, I'll take this.
>
> Paolo
>