From: David Woodhouse Date: Tue, 27 Feb 2024 11:49:17 +0000 (+0000) Subject: KVM: x86/xen: remove WARN_ON_ONCE() with false positives in evtchn delivery X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=66e3cf729b1ea017cad643415ade319556862b68;p=linux.git KVM: x86/xen: remove WARN_ON_ONCE() with false positives in evtchn delivery The kvm_xen_inject_vcpu_vector() function has a comment saying "the fast version will always work for physical unicast", justifying its use of kvm_irq_delivery_to_apic_fast() and the WARN_ON_ONCE() when that fails. In fact that assumption isn't true if X2APIC isn't in use by the guest and there is (8-bit x)APIC ID aliasing. A single "unicast" destination APIC ID *may* then be delivered to multiple vCPUs. Remove the warning, and in fact it might as well just call kvm_irq_delivery_to_apic(). Reported-by: Michal Luczaj Fixes: fde0451be8fb3 ("KVM: x86/xen: Support per-vCPU event channel upcall via local APIC") Signed-off-by: David Woodhouse Reviewed-by: Paul Durrant Link: https://lore.kernel.org/r/20240227115648.3104-4-dwmw2@infradead.org Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 5c24c92588cf3..54c4ced96b694 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -10,7 +10,7 @@ #include "x86.h" #include "xen.h" #include "hyperv.h" -#include "lapic.h" +#include "irq.h" #include #include @@ -570,7 +570,6 @@ void kvm_xen_update_runstate(struct kvm_vcpu *v, int state) void kvm_xen_inject_vcpu_vector(struct kvm_vcpu *v) { struct kvm_lapic_irq irq = { }; - int r; irq.dest_id = v->vcpu_id; irq.vector = v->arch.xen.upcall_vector; @@ -579,8 +578,7 @@ void kvm_xen_inject_vcpu_vector(struct kvm_vcpu *v) irq.delivery_mode = APIC_DM_FIXED; irq.level = 1; - /* The fast version will always work for physical unicast */ - WARN_ON_ONCE(!kvm_irq_delivery_to_apic_fast(v->kvm, NULL, &irq, &r, NULL)); + kvm_irq_delivery_to_apic(v->kvm, NULL, &irq, NULL); } /*