yang.z.zhang at intel
Aug 9, 2013, 3:32 AM
Post #3 of 9
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Re: [PATCH 2/7] Nested VMX: Allow to ack irq even virtual intr delivery is enabled
[In reply to]
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Andrew Cooper wrote on 2013-08-09:
> On 09/08/13 09:49, Yang Zhang wrote:
>> From: Yang Zhang <yang.z.zhang [at] Intel>
>>
>> In some special cases, we want to ack irq regardless of virtual
>> interrupt
> delivery.
>
> Can you explain why and when we might want to force an ack?
After vritual_vmexit, if the interrupt already is already recorded in vmcs12. Then we should clear the irr and set isr regardless APIC-v.
>
>>
>> Signed-off-by: Yang Zhang <yang.z.zhang [at] Intel>
>> ---
>> xen/arch/x86/hvm/irq.c | 2 +-
>> xen/arch/x86/hvm/vlapic.c | 4 ++--
>> xen/include/asm-x86/hvm/vlapic.h | 2 +-
>> 3 files changed, 4 insertions(+), 4 deletions(-)
>> diff --git a/xen/arch/x86/hvm/irq.c b/xen/arch/x86/hvm/irq.c index
>> 9eae5de..6a6fb68 100644
>> --- a/xen/arch/x86/hvm/irq.c
>> +++ b/xen/arch/x86/hvm/irq.c
>> @@ -437,7 +437,7 @@ struct hvm_intack hvm_vcpu_ack_pending_irq(
>> intack.vector = (uint8_t)vector;
>> break;
>> case hvm_intsrc_lapic:
>> - if ( !vlapic_ack_pending_irq(v, intack.vector) )
>> + if ( !vlapic_ack_pending_irq(v, intack.vector, 0) )
>> intack = hvm_intack_none;
>> break;
>> case hvm_intsrc_vector:
>> diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
>> index 7a154f9..20a36a0 100644
>> --- a/xen/arch/x86/hvm/vlapic.c
>> +++ b/xen/arch/x86/hvm/vlapic.c
>> @@ -1048,11 +1048,11 @@ int vlapic_has_pending_irq(struct vcpu *v)
>> return irr;
>> }
>> -int vlapic_ack_pending_irq(struct vcpu *v, int vector)
>> +int vlapic_ack_pending_irq(struct vcpu *v, int vector, int
>> +force_ack)
>> {
>> struct vlapic *vlapic = vcpu_vlapic(v);
>> - if ( vlapic_virtual_intr_delivery_enabled() )
>> + if ( vlapic_virtual_intr_delivery_enabled() && !force_ack )
>> return 1;
>
> The logic in this entire function seems quite backwards. It
> unconditionally returns 1 in all cases, and its sole callsite is in an if statement.
>
> Something like:
>
> void vlapic_ack_pending_irq(struct vcpu *v, uint8_t vector, bool_t
> force_ack) {
> struct vlapic *vlapic = vcpu_vlapic(v);
>
> if ( force_ack || !vlapic_virtual_intr_delivery_enabled() )
> {
> vlapic_set_vector(vector, &vlapic->regs->data[APIC_ISR]);
> vlapic_clear_irr(vector, vlapic);
> }
> }
>
> Seems substantially clearer.
>
> ~Andrew
>
>>
>> vlapic_set_vector(vector, &vlapic->regs->data[APIC_ISR]); diff
>> --git a/xen/include/asm-x86/hvm/vlapic.h
>> b/xen/include/asm-x86/hvm/vlapic.h
>> index 021a5f2..d8c9511 100644
>> --- a/xen/include/asm-x86/hvm/vlapic.h
>> +++ b/xen/include/asm-x86/hvm/vlapic.h
>> @@ -96,7 +96,7 @@ bool_t is_vlapic_lvtpc_enabled(struct vlapic
>> *vlapic); void vlapic_set_irq(struct vlapic *vlapic, uint8_t vec,
>> uint8_t trig);
>>
>> int vlapic_has_pending_irq(struct vcpu *v); -int
>> vlapic_ack_pending_irq(struct vcpu *v, int vector);
>> +int vlapic_ack_pending_irq(struct vcpu *v, int vector, int
>> +force_ack);
>>
>> int vlapic_init(struct vcpu *v);
>> void vlapic_destroy(struct vcpu *v);
Best regards,
Yang
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