* [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state
@ 2016-09-14 21:48 Paolo Bonzini
2016-09-15 15:25 ` Radim Krčmář
2016-09-19 13:16 ` Joerg Roedel
0 siblings, 2 replies; 3+ messages in thread
From: Paolo Bonzini @ 2016-09-14 21:48 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Joerg Roedel, David Gilbert, Radim Krčmář
When userspace sends KVM_SET_LAPIC, KVM schedules a check between
the vCPU's IRR and ISR and the IOAPIC redirection table, in order
to re-establish the IOAPIC's dest_map (the list of CPUs servicing
the real-time clock interrupt with the corresponding vectors).
However, __rtc_irq_eoi_tracking_restore_one was forgetting to
set dest_map->vectors. Because of this, the IOAPIC did not process
the real-time clock interrupt EOI, ioapic->rtc_status.pending_eoi
got stuck at a non-zero value, and further RTC interrupts were
reported to userspace as coalesced.
Fixes: 9e4aabe2bb3454c83dac8139cf9974503ee044db
Fixes: 4d99ba898dd0c521ca6cdfdde55c9b58aea3cb3d
Cc: Joerg Roedel <jroedel@suse.de>
Cc: David Gilbert <dgilbert@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/ioapic.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index 5f42d038fcb4..c7220ba94aa7 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -109,6 +109,7 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
{
bool new_val, old_val;
struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
+ struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
union kvm_ioapic_redirect_entry *e;
e = &ioapic->redirtbl[RTC_GSI];
@@ -117,16 +118,17 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
return;
new_val = kvm_apic_pending_eoi(vcpu, e->fields.vector);
- old_val = test_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
+ old_val = test_bit(vcpu->vcpu_id, dest_map->map);
if (new_val == old_val)
return;
if (new_val) {
- __set_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
+ __set_bit(vcpu->vcpu_id, dest_map->map);
+ dest_map->vectors[vcpu->vcpu_id] = e->fields.vector;
ioapic->rtc_status.pending_eoi++;
} else {
- __clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
+ __clear_bit(vcpu->vcpu_id, dest_map->map);
ioapic->rtc_status.pending_eoi--;
rtc_status_pending_eoi_check_valid(ioapic);
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state
2016-09-14 21:48 [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state Paolo Bonzini
@ 2016-09-15 15:25 ` Radim Krčmář
2016-09-19 13:16 ` Joerg Roedel
1 sibling, 0 replies; 3+ messages in thread
From: Radim Krčmář @ 2016-09-15 15:25 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm, Joerg Roedel, David Gilbert
2016-09-14 23:48+0200, Paolo Bonzini:
> When userspace sends KVM_SET_LAPIC, KVM schedules a check between
> the vCPU's IRR and ISR and the IOAPIC redirection table, in order
> to re-establish the IOAPIC's dest_map (the list of CPUs servicing
> the real-time clock interrupt with the corresponding vectors).
>
> However, __rtc_irq_eoi_tracking_restore_one was forgetting to
> set dest_map->vectors. Because of this, the IOAPIC did not process
> the real-time clock interrupt EOI, ioapic->rtc_status.pending_eoi
> got stuck at a non-zero value, and further RTC interrupts were
> reported to userspace as coalesced.
>
> Fixes: 9e4aabe2bb3454c83dac8139cf9974503ee044db
> Fixes: 4d99ba898dd0c521ca6cdfdde55c9b58aea3cb3d
> Cc: Joerg Roedel <jroedel@suse.de>
> Cc: David Gilbert <dgilbert@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
Nice catch,
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
(It is sad that the RTC EOI tracking exists ...)
> arch/x86/kvm/ioapic.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index 5f42d038fcb4..c7220ba94aa7 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -109,6 +109,7 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
> {
> bool new_val, old_val;
> struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
> + struct dest_map *dest_map = &ioapic->rtc_status.dest_map;
> union kvm_ioapic_redirect_entry *e;
>
> e = &ioapic->redirtbl[RTC_GSI];
> @@ -117,16 +118,17 @@ static void __rtc_irq_eoi_tracking_restore_one(struct kvm_vcpu *vcpu)
> return;
>
> new_val = kvm_apic_pending_eoi(vcpu, e->fields.vector);
> - old_val = test_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
> + old_val = test_bit(vcpu->vcpu_id, dest_map->map);
>
> if (new_val == old_val)
> return;
>
> if (new_val) {
> - __set_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
> + __set_bit(vcpu->vcpu_id, dest_map->map);
> + dest_map->vectors[vcpu->vcpu_id] = e->fields.vector;
> ioapic->rtc_status.pending_eoi++;
> } else {
> - __clear_bit(vcpu->vcpu_id, ioapic->rtc_status.dest_map.map);
> + __clear_bit(vcpu->vcpu_id, dest_map->map);
> ioapic->rtc_status.pending_eoi--;
> rtc_status_pending_eoi_check_valid(ioapic);
> }
> --
> 1.8.3.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state
2016-09-14 21:48 [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state Paolo Bonzini
2016-09-15 15:25 ` Radim Krčmář
@ 2016-09-19 13:16 ` Joerg Roedel
1 sibling, 0 replies; 3+ messages in thread
From: Joerg Roedel @ 2016-09-19 13:16 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, David Gilbert, Radim Krčmář
On Wed, Sep 14, 2016 at 11:48:32PM +0200, Paolo Bonzini wrote:
> When userspace sends KVM_SET_LAPIC, KVM schedules a check between
> the vCPU's IRR and ISR and the IOAPIC redirection table, in order
> to re-establish the IOAPIC's dest_map (the list of CPUs servicing
> the real-time clock interrupt with the corresponding vectors).
>
> However, __rtc_irq_eoi_tracking_restore_one was forgetting to
> set dest_map->vectors. Because of this, the IOAPIC did not process
> the real-time clock interrupt EOI, ioapic->rtc_status.pending_eoi
> got stuck at a non-zero value, and further RTC interrupts were
> reported to userspace as coalesced.
>
> Fixes: 9e4aabe2bb3454c83dac8139cf9974503ee044db
> Fixes: 4d99ba898dd0c521ca6cdfdde55c9b58aea3cb3d
> Cc: Joerg Roedel <jroedel@suse.de>
> Cc: David Gilbert <dgilbert@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Good catch, thanks for fixing this.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-09-14 21:48 [PATCH] kvm: x86: correctly reset dest_map->vector when restoring LAPIC state Paolo Bonzini
2016-09-15 15:25 ` Radim Krčmář
2016-09-19 13:16 ` Joerg Roedel
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