diff mbox series

[v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active

Message ID 20211103094255.426573-1-mlevitsk@redhat.com (mailing list archive)
State New, archived
Headers show
Series [v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active | expand

Commit Message

Maxim Levitsky Nov. 3, 2021, 9:42 a.m. UTC
KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using
standard kvm's inject_pending_event, and not via APICv/AVIC.

Since this is a debug feature, just inhibit it while it
is in use.

Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 arch/x86/include/asm/kvm_host.h | 1 +
 arch/x86/kvm/svm/avic.c         | 3 ++-
 arch/x86/kvm/vmx/vmx.c          | 3 ++-
 arch/x86/kvm/x86.c              | 3 +++
 4 files changed, 8 insertions(+), 2 deletions(-)

Comments

Vitaly Kuznetsov Nov. 3, 2021, 1:28 p.m. UTC | #1
Maxim Levitsky <mlevitsk@redhat.com> writes:

> KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using
> standard kvm's inject_pending_event, and not via APICv/AVIC.
>
> Since this is a debug feature, just inhibit it while it
> is in use.
>
> Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")
>
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  arch/x86/include/asm/kvm_host.h | 1 +
>  arch/x86/kvm/svm/avic.c         | 3 ++-
>  arch/x86/kvm/vmx/vmx.c          | 3 ++-
>  arch/x86/kvm/x86.c              | 3 +++
>  4 files changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 88fce6ab4bbd7..8f6e15b95a4d8 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1034,6 +1034,7 @@ struct kvm_x86_msr_filter {
>  #define APICV_INHIBIT_REASON_IRQWIN     3
>  #define APICV_INHIBIT_REASON_PIT_REINJ  4
>  #define APICV_INHIBIT_REASON_X2APIC	5
> +#define APICV_INHIBIT_REASON_BLOCKIRQ	6
>  
>  struct kvm_arch {
>  	unsigned long n_used_mmu_pages;
> diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> index 8052d92069e01..affc0ea98d302 100644
> --- a/arch/x86/kvm/svm/avic.c
> +++ b/arch/x86/kvm/svm/avic.c
> @@ -904,7 +904,8 @@ bool svm_check_apicv_inhibit_reasons(ulong bit)
>  			  BIT(APICV_INHIBIT_REASON_NESTED) |
>  			  BIT(APICV_INHIBIT_REASON_IRQWIN) |
>  			  BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
> -			  BIT(APICV_INHIBIT_REASON_X2APIC);
> +			  BIT(APICV_INHIBIT_REASON_X2APIC) |
> +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
>  
>  	return supported & BIT(bit);
>  }
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 71f54d85f104c..e4fc9ff7cd944 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7565,7 +7565,8 @@ static void hardware_unsetup(void)
>  static bool vmx_check_apicv_inhibit_reasons(ulong bit)
>  {
>  	ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
> -			  BIT(APICV_INHIBIT_REASON_HYPERV);
> +			  BIT(APICV_INHIBIT_REASON_HYPERV) |
> +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
>  
>  	return supported & BIT(bit);
>  }
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index ac83d873d65b0..dccf927baa4dd 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10747,6 +10747,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
>  	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
>  		vcpu->arch.singlestep_rip = kvm_get_linear_rip(vcpu);
>  
> +	kvm_request_apicv_update(vcpu->kvm,
> +				 !(vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ),
> +				 APICV_INHIBIT_REASON_BLOCKIRQ);
>  	/*
>  	 * Trigger an rflags update that will inject or remove the trace
>  	 * flags.

This fixes the problem for me!

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Maxim Levitsky Nov. 3, 2021, 1:49 p.m. UTC | #2
On Wed, 2021-11-03 at 14:28 +0100, Vitaly Kuznetsov wrote:
> Maxim Levitsky <mlevitsk@redhat.com> writes:
> 
> > KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using
> > standard kvm's inject_pending_event, and not via APICv/AVIC.
> > 
> > Since this is a debug feature, just inhibit it while it
> > is in use.
> > 
> > Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")
> > 
> > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> > ---
> >  arch/x86/include/asm/kvm_host.h | 1 +
> >  arch/x86/kvm/svm/avic.c         | 3 ++-
> >  arch/x86/kvm/vmx/vmx.c          | 3 ++-
> >  arch/x86/kvm/x86.c              | 3 +++
> >  4 files changed, 8 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 88fce6ab4bbd7..8f6e15b95a4d8 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1034,6 +1034,7 @@ struct kvm_x86_msr_filter {
> >  #define APICV_INHIBIT_REASON_IRQWIN     3
> >  #define APICV_INHIBIT_REASON_PIT_REINJ  4
> >  #define APICV_INHIBIT_REASON_X2APIC	5
> > +#define APICV_INHIBIT_REASON_BLOCKIRQ	6
> >  
> >  struct kvm_arch {
> >  	unsigned long n_used_mmu_pages;
> > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> > index 8052d92069e01..affc0ea98d302 100644
> > --- a/arch/x86/kvm/svm/avic.c
> > +++ b/arch/x86/kvm/svm/avic.c
> > @@ -904,7 +904,8 @@ bool svm_check_apicv_inhibit_reasons(ulong bit)
> >  			  BIT(APICV_INHIBIT_REASON_NESTED) |
> >  			  BIT(APICV_INHIBIT_REASON_IRQWIN) |
> >  			  BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
> > -			  BIT(APICV_INHIBIT_REASON_X2APIC);
> > +			  BIT(APICV_INHIBIT_REASON_X2APIC) |
> > +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
> >  
> >  	return supported & BIT(bit);
> >  }
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index 71f54d85f104c..e4fc9ff7cd944 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -7565,7 +7565,8 @@ static void hardware_unsetup(void)
> >  static bool vmx_check_apicv_inhibit_reasons(ulong bit)
> >  {
> >  	ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
> > -			  BIT(APICV_INHIBIT_REASON_HYPERV);
> > +			  BIT(APICV_INHIBIT_REASON_HYPERV) |
> > +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
> >  
> >  	return supported & BIT(bit);
> >  }
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index ac83d873d65b0..dccf927baa4dd 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -10747,6 +10747,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> >  	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
> >  		vcpu->arch.singlestep_rip = kvm_get_linear_rip(vcpu);
> >  
> > +	kvm_request_apicv_update(vcpu->kvm,
> > +				 !(vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ),
> > +				 APICV_INHIBIT_REASON_BLOCKIRQ);
> >  	/*
> >  	 * Trigger an rflags update that will inject or remove the trace
> >  	 * flags.
> 
> This fixes the problem for me!
> 
> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Cool!
> 

Now that I think about it, since guest debug flags are per-vcpu, this code won't
work if there are multiple vCPUs and you enable KVM_GUESTDBG_BLOCKIRQ on all of them
and then disable on this flag on just one of vCPUs, because this code will re-enable APICv/AVIC in this case.
A counter is needed, like you did in synic/autoeoi case.

I'll send a V3 soon.


Best regards,
	Maxim Levitsky
Vitaly Kuznetsov Nov. 3, 2021, 2 p.m. UTC | #3
Maxim Levitsky <mlevitsk@redhat.com> writes:

> On Wed, 2021-11-03 at 14:28 +0100, Vitaly Kuznetsov wrote:
>> Maxim Levitsky <mlevitsk@redhat.com> writes:
>> 
>> > KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using
>> > standard kvm's inject_pending_event, and not via APICv/AVIC.
>> > 
>> > Since this is a debug feature, just inhibit it while it
>> > is in use.
>> > 
>> > Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")
>> > 
>> > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
>> > ---
>> >  arch/x86/include/asm/kvm_host.h | 1 +
>> >  arch/x86/kvm/svm/avic.c         | 3 ++-
>> >  arch/x86/kvm/vmx/vmx.c          | 3 ++-
>> >  arch/x86/kvm/x86.c              | 3 +++
>> >  4 files changed, 8 insertions(+), 2 deletions(-)
>> > 
>> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> > index 88fce6ab4bbd7..8f6e15b95a4d8 100644
>> > --- a/arch/x86/include/asm/kvm_host.h
>> > +++ b/arch/x86/include/asm/kvm_host.h
>> > @@ -1034,6 +1034,7 @@ struct kvm_x86_msr_filter {
>> >  #define APICV_INHIBIT_REASON_IRQWIN     3
>> >  #define APICV_INHIBIT_REASON_PIT_REINJ  4
>> >  #define APICV_INHIBIT_REASON_X2APIC	5
>> > +#define APICV_INHIBIT_REASON_BLOCKIRQ	6
>> >  
>> >  struct kvm_arch {
>> >  	unsigned long n_used_mmu_pages;
>> > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
>> > index 8052d92069e01..affc0ea98d302 100644
>> > --- a/arch/x86/kvm/svm/avic.c
>> > +++ b/arch/x86/kvm/svm/avic.c
>> > @@ -904,7 +904,8 @@ bool svm_check_apicv_inhibit_reasons(ulong bit)
>> >  			  BIT(APICV_INHIBIT_REASON_NESTED) |
>> >  			  BIT(APICV_INHIBIT_REASON_IRQWIN) |
>> >  			  BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
>> > -			  BIT(APICV_INHIBIT_REASON_X2APIC);
>> > +			  BIT(APICV_INHIBIT_REASON_X2APIC) |
>> > +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
>> >  
>> >  	return supported & BIT(bit);
>> >  }
>> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> > index 71f54d85f104c..e4fc9ff7cd944 100644
>> > --- a/arch/x86/kvm/vmx/vmx.c
>> > +++ b/arch/x86/kvm/vmx/vmx.c
>> > @@ -7565,7 +7565,8 @@ static void hardware_unsetup(void)
>> >  static bool vmx_check_apicv_inhibit_reasons(ulong bit)
>> >  {
>> >  	ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
>> > -			  BIT(APICV_INHIBIT_REASON_HYPERV);
>> > +			  BIT(APICV_INHIBIT_REASON_HYPERV) |
>> > +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
>> >  
>> >  	return supported & BIT(bit);
>> >  }
>> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> > index ac83d873d65b0..dccf927baa4dd 100644
>> > --- a/arch/x86/kvm/x86.c
>> > +++ b/arch/x86/kvm/x86.c
>> > @@ -10747,6 +10747,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
>> >  	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
>> >  		vcpu->arch.singlestep_rip = kvm_get_linear_rip(vcpu);
>> >  
>> > +	kvm_request_apicv_update(vcpu->kvm,
>> > +				 !(vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ),
>> > +				 APICV_INHIBIT_REASON_BLOCKIRQ);
>> >  	/*
>> >  	 * Trigger an rflags update that will inject or remove the trace
>> >  	 * flags.
>> 
>> This fixes the problem for me!
>> 
>> Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> Cool!
>> 
>
> Now that I think about it, since guest debug flags are per-vcpu, this code won't
> work if there are multiple vCPUs and you enable KVM_GUESTDBG_BLOCKIRQ on all of them
> and then disable on this flag on just one of vCPUs, because this code will re-enable APICv/AVIC in this case.
> A counter is needed, like you did in synic/autoeoi case.
>

Right, I completely forgot about this peculiarity!
Maxim Levitsky Nov. 3, 2021, 2:39 p.m. UTC | #4
On Wed, 2021-11-03 at 15:00 +0100, Vitaly Kuznetsov wrote:
> Maxim Levitsky <mlevitsk@redhat.com> writes:
> 
> > On Wed, 2021-11-03 at 14:28 +0100, Vitaly Kuznetsov wrote:
> > > Maxim Levitsky <mlevitsk@redhat.com> writes:
> > > 
> > > > KVM_GUESTDBG_BLOCKIRQ relies on interrupts being injected using
> > > > standard kvm's inject_pending_event, and not via APICv/AVIC.
> > > > 
> > > > Since this is a debug feature, just inhibit it while it
> > > > is in use.
> > > > 
> > > > Fixes: 61e5f69ef0837 ("KVM: x86: implement KVM_GUESTDBG_BLOCKIRQ")
> > > > 
> > > > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> > > > ---
> > > >  arch/x86/include/asm/kvm_host.h | 1 +
> > > >  arch/x86/kvm/svm/avic.c         | 3 ++-
> > > >  arch/x86/kvm/vmx/vmx.c          | 3 ++-
> > > >  arch/x86/kvm/x86.c              | 3 +++
> > > >  4 files changed, 8 insertions(+), 2 deletions(-)
> > > > 
> > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > > > index 88fce6ab4bbd7..8f6e15b95a4d8 100644
> > > > --- a/arch/x86/include/asm/kvm_host.h
> > > > +++ b/arch/x86/include/asm/kvm_host.h
> > > > @@ -1034,6 +1034,7 @@ struct kvm_x86_msr_filter {
> > > >  #define APICV_INHIBIT_REASON_IRQWIN     3
> > > >  #define APICV_INHIBIT_REASON_PIT_REINJ  4
> > > >  #define APICV_INHIBIT_REASON_X2APIC	5
> > > > +#define APICV_INHIBIT_REASON_BLOCKIRQ	6
> > > >  
> > > >  struct kvm_arch {
> > > >  	unsigned long n_used_mmu_pages;
> > > > diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
> > > > index 8052d92069e01..affc0ea98d302 100644
> > > > --- a/arch/x86/kvm/svm/avic.c
> > > > +++ b/arch/x86/kvm/svm/avic.c
> > > > @@ -904,7 +904,8 @@ bool svm_check_apicv_inhibit_reasons(ulong bit)
> > > >  			  BIT(APICV_INHIBIT_REASON_NESTED) |
> > > >  			  BIT(APICV_INHIBIT_REASON_IRQWIN) |
> > > >  			  BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
> > > > -			  BIT(APICV_INHIBIT_REASON_X2APIC);
> > > > +			  BIT(APICV_INHIBIT_REASON_X2APIC) |
> > > > +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
> > > >  
> > > >  	return supported & BIT(bit);
> > > >  }
> > > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > > > index 71f54d85f104c..e4fc9ff7cd944 100644
> > > > --- a/arch/x86/kvm/vmx/vmx.c
> > > > +++ b/arch/x86/kvm/vmx/vmx.c
> > > > @@ -7565,7 +7565,8 @@ static void hardware_unsetup(void)
> > > >  static bool vmx_check_apicv_inhibit_reasons(ulong bit)
> > > >  {
> > > >  	ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
> > > > -			  BIT(APICV_INHIBIT_REASON_HYPERV);
> > > > +			  BIT(APICV_INHIBIT_REASON_HYPERV) |
> > > > +			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
> > > >  
> > > >  	return supported & BIT(bit);
> > > >  }
> > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > > > index ac83d873d65b0..dccf927baa4dd 100644
> > > > --- a/arch/x86/kvm/x86.c
> > > > +++ b/arch/x86/kvm/x86.c
> > > > @@ -10747,6 +10747,9 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
> > > >  	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
> > > >  		vcpu->arch.singlestep_rip = kvm_get_linear_rip(vcpu);
> > > >  
> > > > +	kvm_request_apicv_update(vcpu->kvm,
> > > > +				 !(vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ),
> > > > +				 APICV_INHIBIT_REASON_BLOCKIRQ);
> > > >  	/*
> > > >  	 * Trigger an rflags update that will inject or remove the trace
> > > >  	 * flags.
> > > 
> > > This fixes the problem for me!
> > > 
> > > Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> > 
> > Cool!
> > 
> > Now that I think about it, since guest debug flags are per-vcpu, this code won't
> > work if there are multiple vCPUs and you enable KVM_GUESTDBG_BLOCKIRQ on all of them
> > and then disable on this flag on just one of vCPUs, because this code will re-enable APICv/AVIC in this case.
> > A counter is needed, like you did in synic/autoeoi case.
> > 
> 
> Right, I completely forgot about this peculiarity!

I am sending v3 of this patch, I decided to avoid a counter and instead just use 
kvm_for_each_vcpu to see if other vCPUs have that bit set, on the ground of
this feature beeing only a debug feature.

Best regards,
	Maxim Levitsky

>
diff mbox series

Patch

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 88fce6ab4bbd7..8f6e15b95a4d8 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1034,6 +1034,7 @@  struct kvm_x86_msr_filter {
 #define APICV_INHIBIT_REASON_IRQWIN     3
 #define APICV_INHIBIT_REASON_PIT_REINJ  4
 #define APICV_INHIBIT_REASON_X2APIC	5
+#define APICV_INHIBIT_REASON_BLOCKIRQ	6
 
 struct kvm_arch {
 	unsigned long n_used_mmu_pages;
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c
index 8052d92069e01..affc0ea98d302 100644
--- a/arch/x86/kvm/svm/avic.c
+++ b/arch/x86/kvm/svm/avic.c
@@ -904,7 +904,8 @@  bool svm_check_apicv_inhibit_reasons(ulong bit)
 			  BIT(APICV_INHIBIT_REASON_NESTED) |
 			  BIT(APICV_INHIBIT_REASON_IRQWIN) |
 			  BIT(APICV_INHIBIT_REASON_PIT_REINJ) |
-			  BIT(APICV_INHIBIT_REASON_X2APIC);
+			  BIT(APICV_INHIBIT_REASON_X2APIC) |
+			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
 
 	return supported & BIT(bit);
 }
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 71f54d85f104c..e4fc9ff7cd944 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7565,7 +7565,8 @@  static void hardware_unsetup(void)
 static bool vmx_check_apicv_inhibit_reasons(ulong bit)
 {
 	ulong supported = BIT(APICV_INHIBIT_REASON_DISABLE) |
-			  BIT(APICV_INHIBIT_REASON_HYPERV);
+			  BIT(APICV_INHIBIT_REASON_HYPERV) |
+			  BIT(APICV_INHIBIT_REASON_BLOCKIRQ);
 
 	return supported & BIT(bit);
 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac83d873d65b0..dccf927baa4dd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10747,6 +10747,9 @@  int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
 	if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP)
 		vcpu->arch.singlestep_rip = kvm_get_linear_rip(vcpu);
 
+	kvm_request_apicv_update(vcpu->kvm,
+				 !(vcpu->guest_debug & KVM_GUESTDBG_BLOCKIRQ),
+				 APICV_INHIBIT_REASON_BLOCKIRQ);
 	/*
 	 * Trigger an rflags update that will inject or remove the trace
 	 * flags.