* [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active
@ 2021-11-03 9:42 Maxim Levitsky
2021-11-03 13:28 ` Vitaly Kuznetsov
0 siblings, 1 reply; 5+ messages in thread
From: Maxim Levitsky @ 2021-11-03 9:42 UTC (permalink / raw)
To: kvm
Cc: Paolo Bonzini, Maxim Levitsky, Wanpeng Li, Jim Mattson,
Joerg Roedel, open list:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Borislav Petkov, Thomas Gleixner, Vitaly Kuznetsov,
H. Peter Anvin, maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Ingo Molnar, Sean Christopherson
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.
--
2.26.3
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active
2021-11-03 9:42 [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active Maxim Levitsky
@ 2021-11-03 13:28 ` Vitaly Kuznetsov
2021-11-03 13:49 ` Maxim Levitsky
0 siblings, 1 reply; 5+ messages in thread
From: Vitaly Kuznetsov @ 2021-11-03 13:28 UTC (permalink / raw)
To: Maxim Levitsky, kvm
Cc: Paolo Bonzini, Maxim Levitsky, Wanpeng Li, Jim Mattson,
Joerg Roedel, open list:X86 ARCHITECTURE (32-BIT AND 64-BIT),
Borislav Petkov, Thomas Gleixner, H. Peter Anvin,
maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT), Ingo Molnar,
Sean Christopherson
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>
--
Vitaly
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active
2021-11-03 13:28 ` Vitaly Kuznetsov
@ 2021-11-03 13:49 ` Maxim Levitsky
2021-11-03 14:00 ` Vitaly Kuznetsov
0 siblings, 1 reply; 5+ messages in thread
From: Maxim Levitsky @ 2021-11-03 13:49 UTC (permalink / raw)
To: Vitaly Kuznetsov, kvm
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Joerg Roedel,
open list:X86 ARCHITECTURE (32-BIT AND 64-BIT), Borislav Petkov,
Thomas Gleixner, H. Peter Anvin,
maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT), Ingo Molnar,
Sean Christopherson
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
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active
2021-11-03 13:49 ` Maxim Levitsky
@ 2021-11-03 14:00 ` Vitaly Kuznetsov
2021-11-03 14:39 ` Maxim Levitsky
0 siblings, 1 reply; 5+ messages in thread
From: Vitaly Kuznetsov @ 2021-11-03 14:00 UTC (permalink / raw)
To: Maxim Levitsky, kvm
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Joerg Roedel,
open list:X86 ARCHITECTURE (32-BIT AND 64-BIT), Borislav Petkov,
Thomas Gleixner, H. Peter Anvin,
maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT), Ingo Molnar,
Sean Christopherson
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!
--
Vitaly
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active
2021-11-03 14:00 ` Vitaly Kuznetsov
@ 2021-11-03 14:39 ` Maxim Levitsky
0 siblings, 0 replies; 5+ messages in thread
From: Maxim Levitsky @ 2021-11-03 14:39 UTC (permalink / raw)
To: Vitaly Kuznetsov, kvm
Cc: Paolo Bonzini, Wanpeng Li, Jim Mattson, Joerg Roedel,
open list:X86 ARCHITECTURE (32-BIT AND 64-BIT), Borislav Petkov,
Thomas Gleixner, H. Peter Anvin,
maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT), Ingo Molnar,
Sean Christopherson
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
>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-11-03 14:39 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2021-11-03 9:42 [PATCH v2] KVM: x86: inhibit APICv when KVM_GUESTDBG_BLOCKIRQ active Maxim Levitsky
2021-11-03 13:28 ` Vitaly Kuznetsov
2021-11-03 13:49 ` Maxim Levitsky
2021-11-03 14:00 ` Vitaly Kuznetsov
2021-11-03 14:39 ` Maxim Levitsky
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