* [PATCH] KVM: x86: zero apic_arb_prio on reset
@ 2015-10-30 14:48 Radim Krčmář
2015-11-02 11:57 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Radim Krčmář @ 2015-10-30 14:48 UTC (permalink / raw)
To: linux-kernel; +Cc: kvm, Paolo Bonzini, Yuki Shibuya
BSP doesn't get INIT so its apic_arb_prio isn't zeroed after reboot.
BSP won't get lowest priority interrupts until other VCPUs get enough
interrupts to match their pre-reboot apic_arb_prio.
That behavior doesn't fit into KVM's round-robin-like interpretation of
lowest priority delivery ... userspace should KVM_SET_LAPIC on reset, so
just zero apic_arb_prio there.
Reported-by: Yuki Shibuya <shibuya.yk@ncos.nec.co.jp>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/lapic.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 1b02c44c7b8b..08655020417d 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1924,6 +1924,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
kvm_make_request(KVM_REQ_EVENT, vcpu);
if (ioapic_in_kernel(vcpu->kvm))
kvm_rtc_eoi_tracking_restore_one(vcpu);
+
+ vcpu->arch.apic_arb_prio = 0;
}
void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
--
2.5.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: x86: zero apic_arb_prio on reset
2015-10-30 14:48 [PATCH] KVM: x86: zero apic_arb_prio on reset Radim Krčmář
@ 2015-11-02 11:57 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2015-11-02 11:57 UTC (permalink / raw)
To: Radim Krčmář, linux-kernel; +Cc: kvm, Yuki Shibuya
On 30/10/2015 15:48, Radim Krčmář wrote:
> BSP doesn't get INIT so its apic_arb_prio isn't zeroed after reboot.
> BSP won't get lowest priority interrupts until other VCPUs get enough
> interrupts to match their pre-reboot apic_arb_prio.
>
> That behavior doesn't fit into KVM's round-robin-like interpretation of
> lowest priority delivery ... userspace should KVM_SET_LAPIC on reset, so
> just zero apic_arb_prio there.
>
> Reported-by: Yuki Shibuya <shibuya.yk@ncos.nec.co.jp>
> Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
> ---
> arch/x86/kvm/lapic.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 1b02c44c7b8b..08655020417d 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -1924,6 +1924,8 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
> kvm_make_request(KVM_REQ_EVENT, vcpu);
> if (ioapic_in_kernel(vcpu->kvm))
> kvm_rtc_eoi_tracking_restore_one(vcpu);
> +
> + vcpu->arch.apic_arb_prio = 0;
> }
>
> void __kvm_migrate_apic_timer(struct kvm_vcpu *vcpu)
>
Applied, thanks.
Paolo
^ permalink raw reply [flat|nested] 2+ messages in thread
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2015-11-02 11:57 ` Paolo Bonzini
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