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SubjectRe: [PATCH v15 04/14] KVM: x86: Add #CP support in guest exception dispatch
On Thu, Feb 04, 2021, Paolo Bonzini wrote:
> On 03/02/21 22:46, Sean Christopherson wrote:
> >
> > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> > index dbca1687ae8e..0b6dab6915a3 100644
> > --- a/arch/x86/kvm/vmx/nested.c
> > +++ b/arch/x86/kvm/vmx/nested.c
> > @@ -2811,7 +2811,7 @@ static int nested_check_vm_entry_controls(struct kvm_vcpu *vcpu,
> > /* VM-entry interruption-info field: deliver error code */
> > should_have_error_code =
> > intr_type == INTR_TYPE_HARD_EXCEPTION && prot_mode &&
> > - x86_exception_has_error_code(vector);
> > + x86_exception_has_error_code(vcpu, vector);
> > if (CC(has_error_code != should_have_error_code))
> > return -EINVAL;
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 28fea7ff7a86..0288d6a364bd 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -437,17 +437,20 @@ EXPORT_SYMBOL_GPL(kvm_spurious_fault);
> > #define EXCPT_CONTRIBUTORY 1
> > #define EXCPT_PF 2
> >
> > -static int exception_class(int vector)
> > +static int exception_class(struct kvm_vcpu *vcpu, int vector)
> > {
> > switch (vector) {
> > case PF_VECTOR:
> > return EXCPT_PF;
> > + case CP_VECTOR:
> > + if (vcpu->arch.cr4_guest_rsvd_bits & X86_CR4_CET)
> > + return EXCPT_BENIGN;
> > + return EXCPT_CONTRIBUTORY;
> > case DE_VECTOR:
> > case TS_VECTOR:
> > case NP_VECTOR:
> > case SS_VECTOR:
> > case GP_VECTOR:
> > - case CP_VECTOR:

This removal got lost when squasing.

arch/x86/kvm/x86.c: In function ‘exception_class’:
arch/x86/kvm/x86.c:455:2: error: duplicate case value
455 | case CP_VECTOR:
| ^~~~
arch/x86/kvm/x86.c:446:2: note: previously used here
446 | case CP_VECTOR:
| ^~~~

> > return EXCPT_CONTRIBUTORY;
> > default:
> > break;
> > @@ -588,8 +591,8 @@ static void kvm_multiple_exception(struct kvm_vcpu *vcpu,
> > kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu);
> > return;
> > }
> > - class1 = exception_class(prev_nr);
> > - class2 = exception_class(nr);
> > + class1 = exception_class(vcpu, prev_nr);
> > + class2 = exception_class(vcpu, nr);
> > if ((class1 == EXCPT_CONTRIBUTORY && class2 == EXCPT_CONTRIBUTORY)
> > || (class1 == EXCPT_PF && class2 != EXCPT_BENIGN)) {
> > /*
> > diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> > index a14da36a30ed..dce756ffb577 100644
> > --- a/arch/x86/kvm/x86.h
> > +++ b/arch/x86/kvm/x86.h
> > @@ -120,12 +120,16 @@ static inline bool is_la57_mode(struct kvm_vcpu *vcpu)
> > #endif
> > }
> >
> > -static inline bool x86_exception_has_error_code(unsigned int vector)
> > +static inline bool x86_exception_has_error_code(struct kvm_vcpu *vcpu,
> > + unsigned int vector)
> > {
> > static u32 exception_has_error_code = BIT(DF_VECTOR) | BIT(TS_VECTOR) |
> > BIT(NP_VECTOR) | BIT(SS_VECTOR) | BIT(GP_VECTOR) |
> > BIT(PF_VECTOR) | BIT(AC_VECTOR) | BIT(CP_VECTOR);
> >
> > + if (vector == CP_VECTOR && (vcpu->arch.cr4_guest_rsvd_bits & X86_CR4_CET))
> > + return false;
> > +
> > return (1U << vector) & exception_has_error_code;
> > }
> >
> >
> >
> >
>
> Squashed, thanks. I made a small change to the last hunk:
>
> if (!((1U << vector) & exception_has_error_code))
> return false;
>
> if (vector == CP_VECTOR)
> return !(vcpu->arch.cr4_guest_rsvd_bits & X86_CR4_CET);
>
> return true;

Ha, I guessed wrong, that was my first pass at it :-)

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