KVM: arm64: Wake-up from WFI when iqrchip is in userspace

It appears that there is nothing in the wake-up path that
evaluates whether the in-kernel interrupts are pending unless
we have a vgic.

This means that the userspace irqchip support has been broken for
about four years, and nobody noticed. It was also broken before
as we wouldn't wake-up on a PMU interrupt, but hey, who cares...

It is probably time to remove the feature altogether, because it
was a terrible idea 10 years ago, and it still is.

Fixes: b57de4ffd7c6d ("KVM: arm64: Simplify kvm_cpu_has_pending_timer()")
Link: https://patch.msgid.link/20260423163607.486345-1-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 176cbe8baad30c60e534b9a62d4b7d835699fafd..8bb2c7422cc8b0ad1c6952047cbb878af57fcaca 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -824,6 +824,10 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
 {
        bool irq_lines = *vcpu_hcr(v) & (HCR_VI | HCR_VF | HCR_VSE);
 
+       irq_lines |= (!irqchip_in_kernel(v->kvm) &&
+                     (kvm_timer_should_notify_user(v) ||
+                      kvm_pmu_should_notify_user(v)));
+
        return ((irq_lines || kvm_vgic_vcpu_pending_irq(v))
                && !kvm_arm_vcpu_stopped(v) && !v->arch.pause);
 }