| Message ID | 1353485379-6823-6-git-send-email-yang.z.zhang@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: > Ack interrupt on vmexit is required by Posted Interrupt. With it, > when external interrupt caused vmexit, the cpu will acknowledge the > interrupt controller and save the interrupt's vector in vmcs. > > There are several approaches to enable it. This patch uses a simply > way: re-generate an interrupt via self ipi. > > Signed-off-by: Yang Zhang <yang.z.zhang@intel.com> > --- > arch/x86/kvm/vmx.c | 11 ++++++++++- > 1 files changed, 10 insertions(+), 1 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 7949d21..f6ef090 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) > #ifdef CONFIG_X86_64 > min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; > #endif > - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; > + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | > + VM_EXIT_ACK_INTR_ON_EXIT; Always? Do it only if posted interrupts are actually available and going to be used. > if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS, > &_vmexit_control) < 0) > return -EIO; > @@ -4457,6 +4458,14 @@ static int handle_exception(struct kvm_vcpu *vcpu) > > static int handle_external_interrupt(struct kvm_vcpu *vcpu) > { > + unsigned int vector; > + > + vector = vmcs_read32(VM_EXIT_INTR_INFO); > + vector &= INTR_INFO_VECTOR_MASK; Valid bit is guarantied to be set here? > + > + apic_eoi(); This is way to late. handle_external_interrupt() is called longs after preemption and local irqs are enabled. vcpu process may be scheduled out and apic_eoi() will not be called for a long time leaving interrupt stuck in ISR and blocking other interrupts. > + apic->send_IPI_self(vector); For level interrupt this is not needed, no? > + > ++vcpu->stat.irq_exits; > return 1; > } > -- > 1.7.1 -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Gleb Natapov wrote on 2012-11-22: > On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: >> Ack interrupt on vmexit is required by Posted Interrupt. With it, >> when external interrupt caused vmexit, the cpu will acknowledge the >> interrupt controller and save the interrupt's vector in vmcs. >> >> There are several approaches to enable it. This patch uses a simply >> way: re-generate an interrupt via self ipi. >> >> Signed-off-by: Yang Zhang <yang.z.zhang@intel.com> >> --- >> arch/x86/kvm/vmx.c | 11 ++++++++++- >> 1 files changed, 10 insertions(+), 1 deletions(-) >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 7949d21..f6ef090 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct > vmcs_config *vmcs_conf) >> #ifdef CONFIG_X86_64 >> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; >> #endif >> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; >> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | >> + VM_EXIT_ACK_INTR_ON_EXIT; > Always? Do it only if posted interrupts are actually available > and going to be used. Right. But the currently interrupt handler path is too long: vm exit -> KVM vmexit handler(interrupt disabled) -> KVM re-enable interrupt -> cpu ack the interrupt and interrupt deliver through the host IDT This will bring extra cost for interrupt belongs to guest. After enable "acknowledge interrupt on exit", we can inject the interrupt right way after vm exit if the interrupt is for the guest(This patch doesn't do this). Since we only want to enable "acknowledge interrupt on exit" for Posted Interrupt, probably, we can enable it when PI is available. >> if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS, >> &_vmexit_control) < 0) >> return -EIO; >> @@ -4457,6 +4458,14 @@ static int handle_exception(struct kvm_vcpu *vcpu) >> >> static int handle_external_interrupt(struct kvm_vcpu *vcpu) >> { >> + unsigned int vector; >> + >> + vector = vmcs_read32(VM_EXIT_INTR_INFO); >> + vector &= INTR_INFO_VECTOR_MASK; > Valid bit is guarantied to be set here? > >> + >> + apic_eoi(); > This is way to late. handle_external_interrupt() is called longs after > preemption and local irqs are enabled. vcpu process may be scheduled out > and apic_eoi() will not be called for a long time leaving interrupt > stuck in ISR and blocking other interrupts. I will move it to vmx_complete_atomic_exit(). >> + apic->send_IPI_self(vector); > For level interrupt this is not needed, no? If we enable "ack interrupt on exit" only when apicv is available, then all interrupt is edge(interrupt remapping will setup all remap entries to deliver edge interrupt. interrupt remapping is required by x2apic, x2apic is required by PI) /* * Trigger mode in the IRTE will always be edge, and for IO-APIC, the * actual level or edge trigger will be setup in the IO-APIC * RTE. This will help simplify level triggered irq migration. * For more details, see the comments (in io_apic.c) explainig IO-APIC * irq migration in the presence of interrupt-remapping. */ >> + >> ++vcpu->stat.irq_exits; >> return 1; >> } >> -- >> 1.7.1 > > -- > Gleb. Best regards, Yang -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 11/22/2012 05:22 PM, Gleb Natapov wrote: > On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: >> Ack interrupt on vmexit is required by Posted Interrupt. With it, >> when external interrupt caused vmexit, the cpu will acknowledge the >> interrupt controller and save the interrupt's vector in vmcs. >> >> There are several approaches to enable it. This patch uses a simply >> way: re-generate an interrupt via self ipi. >> >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 7949d21..f6ef090 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) >> #ifdef CONFIG_X86_64 >> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; >> #endif >> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; >> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | >> + VM_EXIT_ACK_INTR_ON_EXIT; > Always? Do it only if posted interrupts are actually available > and going to be used. Why not always? Better to have a single code path for host interrupts (and as Yang notes, the new path is faster as well).
On Sun, Nov 25, 2012 at 02:55:26PM +0200, Avi Kivity wrote: > On 11/22/2012 05:22 PM, Gleb Natapov wrote: > > On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: > >> Ack interrupt on vmexit is required by Posted Interrupt. With it, > >> when external interrupt caused vmexit, the cpu will acknowledge the > >> interrupt controller and save the interrupt's vector in vmcs. > >> > >> There are several approaches to enable it. This patch uses a simply > >> way: re-generate an interrupt via self ipi. > >> > >> > >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > >> index 7949d21..f6ef090 100644 > >> --- a/arch/x86/kvm/vmx.c > >> +++ b/arch/x86/kvm/vmx.c > >> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) > >> #ifdef CONFIG_X86_64 > >> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; > >> #endif > >> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; > >> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | > >> + VM_EXIT_ACK_INTR_ON_EXIT; > > Always? Do it only if posted interrupts are actually available > > and going to be used. > > Why not always? Better to have a single code path for host interrupts > (and as Yang notes, the new path is faster as well). > Is it? The current path is: vm exit -> KVM vmexit handler(interrupt disabled) -> KVM re-enable interrupt -> cpu ack the interrupt and interrupt deliver through the host IDT. The proposed path is: CPU acks interrupt -> vm exit -> KVM vmexit handler(interrupt disabled) -> eoi -> self IPI -> KVM re-enable interrupt -> cpu ack the interrupt and interrupt deliver through the host IDT. Am I missing something? -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 11/25/2012 03:03 PM, Gleb Natapov wrote: > On Sun, Nov 25, 2012 at 02:55:26PM +0200, Avi Kivity wrote: >> On 11/22/2012 05:22 PM, Gleb Natapov wrote: >> > On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: >> >> Ack interrupt on vmexit is required by Posted Interrupt. With it, >> >> when external interrupt caused vmexit, the cpu will acknowledge the >> >> interrupt controller and save the interrupt's vector in vmcs. >> >> >> >> There are several approaches to enable it. This patch uses a simply >> >> way: re-generate an interrupt via self ipi. >> >> >> >> >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> >> index 7949d21..f6ef090 100644 >> >> --- a/arch/x86/kvm/vmx.c >> >> +++ b/arch/x86/kvm/vmx.c >> >> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) >> >> #ifdef CONFIG_X86_64 >> >> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; >> >> #endif >> >> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; >> >> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | >> >> + VM_EXIT_ACK_INTR_ON_EXIT; >> > Always? Do it only if posted interrupts are actually available >> > and going to be used. >> >> Why not always? Better to have a single code path for host interrupts >> (and as Yang notes, the new path is faster as well). >> > Is it? The current path is: > > vm exit -> KVM vmexit handler(interrupt disabled) -> KVM re-enable > interrupt -> cpu ack the interrupt and interrupt deliver through the > host IDT. > > The proposed path is: > > CPU acks interrupt -> vm exit -> KVM vmexit handler(interrupt disabled) > -> eoi -> self IPI -> KVM re-enable interrupt -> cpu ack the interrupt > and interrupt deliver through the host IDT. > > Am I missing something? Yes, you're missing the part where I didn't write that the new path should avoid the IDT and dispatch the interrupt directly, by emulating an interrupt frame directly. Can be as simple as pushf; push cs; call interrupt_table[vector * 8]. Of course we need to verify that no interrupt uses the IST or a task gate.
On Fri, Nov 23, 2012 at 05:41:49AM +0000, Zhang, Yang Z wrote: > Gleb Natapov wrote on 2012-11-22: > > On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: > >> Ack interrupt on vmexit is required by Posted Interrupt. With it, > >> when external interrupt caused vmexit, the cpu will acknowledge the > >> interrupt controller and save the interrupt's vector in vmcs. > >> > >> There are several approaches to enable it. This patch uses a simply > >> way: re-generate an interrupt via self ipi. > >> > >> Signed-off-by: Yang Zhang <yang.z.zhang@intel.com> > >> --- > >> arch/x86/kvm/vmx.c | 11 ++++++++++- > >> 1 files changed, 10 insertions(+), 1 deletions(-) > >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > >> index 7949d21..f6ef090 100644 > >> --- a/arch/x86/kvm/vmx.c > >> +++ b/arch/x86/kvm/vmx.c > >> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct > > vmcs_config *vmcs_conf) > >> #ifdef CONFIG_X86_64 > >> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; > >> #endif > >> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; > >> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | > >> + VM_EXIT_ACK_INTR_ON_EXIT; > > Always? Do it only if posted interrupts are actually available > > and going to be used. > > Right. > But the currently interrupt handler path is too long: > vm exit -> KVM vmexit handler(interrupt disabled) -> KVM re-enable interrupt -> cpu ack the interrupt and interrupt deliver through the host IDT > This will bring extra cost for interrupt belongs to guest. After enable "acknowledge interrupt on exit", we can inject the interrupt right way after vm exit if the interrupt is for the guest(This patch doesn't do this). > > Since we only want to enable "acknowledge interrupt on exit" for Posted Interrupt, probably, we can enable it when PI is available. > > >> if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS, > >> &_vmexit_control) < 0) > >> return -EIO; > >> @@ -4457,6 +4458,14 @@ static int handle_exception(struct kvm_vcpu *vcpu) > >> > >> static int handle_external_interrupt(struct kvm_vcpu *vcpu) > >> { > >> + unsigned int vector; > >> + > >> + vector = vmcs_read32(VM_EXIT_INTR_INFO); > >> + vector &= INTR_INFO_VECTOR_MASK; > > Valid bit is guarantied to be set here? > > > >> + > >> + apic_eoi(); > > This is way to late. handle_external_interrupt() is called longs after > > preemption and local irqs are enabled. vcpu process may be scheduled out > > and apic_eoi() will not be called for a long time leaving interrupt > > stuck in ISR and blocking other interrupts. > > I will move it to vmx_complete_atomic_exit(). > > >> + apic->send_IPI_self(vector); > > For level interrupt this is not needed, no? > > If we enable "ack interrupt on exit" only when apicv is available, then all interrupt is edge(interrupt remapping will setup all remap entries to deliver edge interrupt. interrupt remapping is required by x2apic, x2apic is required by PI) Why x2apic is required by PI? Is this architectural? Cannot find it in SDM. If interrupts will be delivered without self ipi like Avi suggests then level will not be the issue. > > /* > * Trigger mode in the IRTE will always be edge, and for IO-APIC, > the > * actual level or edge trigger will be setup in the IO-APIC > * RTE. This will help simplify level triggered irq migration. > * For more details, see the comments (in io_apic.c) explainig > IO-APIC > * irq migration in the presence of interrupt-remapping. > */ > > >> + > >> ++vcpu->stat.irq_exits; > >> return 1; > >> } > >> -- > >> 1.7.1 > > > > -- > > Gleb. > > > Best regards, > Yang > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Avi Kivity wrote on 2012-11-25: > On 11/25/2012 03:03 PM, Gleb Natapov wrote: >> On Sun, Nov 25, 2012 at 02:55:26PM +0200, Avi Kivity wrote: >>> On 11/22/2012 05:22 PM, Gleb Natapov wrote: >>>> On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: >>>>> Ack interrupt on vmexit is required by Posted Interrupt. With it, >>>>> when external interrupt caused vmexit, the cpu will acknowledge the >>>>> interrupt controller and save the interrupt's vector in vmcs. >>>>> >>>>> There are several approaches to enable it. This patch uses a simply >>>>> way: re-generate an interrupt via self ipi. >>>>> >>>>> >>>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>>>> index 7949d21..f6ef090 100644 >>>>> --- a/arch/x86/kvm/vmx.c >>>>> +++ b/arch/x86/kvm/vmx.c >>>>> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct > vmcs_config *vmcs_conf) >>>>> #ifdef CONFIG_X86_64 >>>>> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; >>>>> #endif >>>>> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; >>>>> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | >>>>> + VM_EXIT_ACK_INTR_ON_EXIT; >>>> Always? Do it only if posted interrupts are actually available >>>> and going to be used. >>> >>> Why not always? Better to have a single code path for host interrupts >>> (and as Yang notes, the new path is faster as well). >>> >> Is it? The current path is: >> >> vm exit -> KVM vmexit handler(interrupt disabled) -> KVM re-enable >> interrupt -> cpu ack the interrupt and interrupt deliver through the >> host IDT. >> >> The proposed path is: >> >> CPU acks interrupt -> vm exit -> KVM vmexit handler(interrupt disabled) >> -> eoi -> self IPI -> KVM re-enable interrupt -> cpu ack the interrupt >> and interrupt deliver through the host IDT. >> >> Am I missing something? > > Yes, you're missing the part where I didn't write that the new path > should avoid the IDT and dispatch the interrupt directly, by emulating > an interrupt frame directly. Can be as simple as pushf; push cs; call > interrupt_table[vector * 8]. Of course we need to verify that no > interrupt uses the IST or a task gate. How can we call interrupt table directly? I don't think we can expose the idt_table to a module. Anyway, to simply the implementation, I will follow gleb's suggestion: only enable "ack intr on exit" when PI is enabled and self ipi should be enough. Any comments? Best regards, Yang -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, Nov 26, 2012 at 05:44:29AM +0000, Zhang, Yang Z wrote: > Avi Kivity wrote on 2012-11-25: > > On 11/25/2012 03:03 PM, Gleb Natapov wrote: > >> On Sun, Nov 25, 2012 at 02:55:26PM +0200, Avi Kivity wrote: > >>> On 11/22/2012 05:22 PM, Gleb Natapov wrote: > >>>> On Wed, Nov 21, 2012 at 04:09:38PM +0800, Yang Zhang wrote: > >>>>> Ack interrupt on vmexit is required by Posted Interrupt. With it, > >>>>> when external interrupt caused vmexit, the cpu will acknowledge the > >>>>> interrupt controller and save the interrupt's vector in vmcs. > >>>>> > >>>>> There are several approaches to enable it. This patch uses a simply > >>>>> way: re-generate an interrupt via self ipi. > >>>>> > >>>>> > >>>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > >>>>> index 7949d21..f6ef090 100644 > >>>>> --- a/arch/x86/kvm/vmx.c > >>>>> +++ b/arch/x86/kvm/vmx.c > >>>>> @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct > > vmcs_config *vmcs_conf) > >>>>> #ifdef CONFIG_X86_64 > >>>>> min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; > >>>>> #endif > >>>>> - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; > >>>>> + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | > >>>>> + VM_EXIT_ACK_INTR_ON_EXIT; > >>>> Always? Do it only if posted interrupts are actually available > >>>> and going to be used. > >>> > >>> Why not always? Better to have a single code path for host interrupts > >>> (and as Yang notes, the new path is faster as well). > >>> > >> Is it? The current path is: > >> > >> vm exit -> KVM vmexit handler(interrupt disabled) -> KVM re-enable > >> interrupt -> cpu ack the interrupt and interrupt deliver through the > >> host IDT. > >> > >> The proposed path is: > >> > >> CPU acks interrupt -> vm exit -> KVM vmexit handler(interrupt disabled) > >> -> eoi -> self IPI -> KVM re-enable interrupt -> cpu ack the interrupt > >> and interrupt deliver through the host IDT. > >> > >> Am I missing something? > > > > Yes, you're missing the part where I didn't write that the new path > > should avoid the IDT and dispatch the interrupt directly, by emulating > > an interrupt frame directly. Can be as simple as pushf; push cs; call > > interrupt_table[vector * 8]. Of course we need to verify that no > > interrupt uses the IST or a task gate. > > How can we call interrupt table directly? I don't think we can expose the idt_table to a module. No, but we can add function to entry_(64|32).S that despatch via idt_table and expose it. Avi's idea is worth to explore before going self IPI way. > Anyway, to simply the implementation, I will follow gleb's suggestion: only enable "ack intr on exit" when PI is enabled and self ipi should be enough. Any comments? > > Best regards, > Yang > -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 7949d21..f6ef090 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2525,7 +2525,8 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf) #ifdef CONFIG_X86_64 min |= VM_EXIT_HOST_ADDR_SPACE_SIZE; #endif - opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT; + opt = VM_EXIT_SAVE_IA32_PAT | VM_EXIT_LOAD_IA32_PAT | + VM_EXIT_ACK_INTR_ON_EXIT; if (adjust_vmx_controls(min, opt, MSR_IA32_VMX_EXIT_CTLS, &_vmexit_control) < 0) return -EIO; @@ -4457,6 +4458,14 @@ static int handle_exception(struct kvm_vcpu *vcpu) static int handle_external_interrupt(struct kvm_vcpu *vcpu) { + unsigned int vector; + + vector = vmcs_read32(VM_EXIT_INTR_INFO); + vector &= INTR_INFO_VECTOR_MASK; + + apic_eoi(); + apic->send_IPI_self(vector); + ++vcpu->stat.irq_exits; return 1; }
Ack interrupt on vmexit is required by Posted Interrupt. With it, when external interrupt caused vmexit, the cpu will acknowledge the interrupt controller and save the interrupt's vector in vmcs. There are several approaches to enable it. This patch uses a simply way: re-generate an interrupt via self ipi. Signed-off-by: Yang Zhang <yang.z.zhang@intel.com> --- arch/x86/kvm/vmx.c | 11 ++++++++++- 1 files changed, 10 insertions(+), 1 deletions(-)