Re: [PATCH] KVM: x86: Drop WARN on INIT/SIPI being blocked when vCPU is in Wait-For-SIPI

[Sean Christopherson]

On Thu, 22 Jan 2026 18:28:16 -0800, Sean Christopherson wrote:
> Drop the sanity check in kvm_apic_accept_events() that attempts to detect
> KVM bugs by asserting that a vCPU isn't in Wait-For-SIPI if INIT/SIPI are
> blocked, because if INIT is blocked, then it should be impossible for a
> vCPU to get into WFS in the first place.  Unfortunately, syzbot is smarter
> than KVM (and its maintainers), and circumvented the guards put in place
> by commit 0fe3e8d804fd ("KVM: x86: Move INIT_RECEIVED vs. INIT/SIPI blocked
> check to KVM_RUN") by swapping the order and stuffing VMXON after INIT, and
> then triggering kvm_apic_accept_events() by way of KVM_GET_MP_STATE.
> 
> [...]

Applied to kvm-x86 misc.

[1/1] KVM: x86: Drop WARN on INIT/SIPI being blocked when vCPU is in Wait-For-SIPI
      https://github.com/kvm-x86/linux/commit/c4a365cd4a4e

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https://github.com/kvm-x86/linux/tree/next