Messages in this thread | | | Date | Fri, 28 Apr 2023 14:09:43 +0800 | Subject | Re: [PATCH v2 10/21] KVM:x86: Add #CP support in guest exception classification | From | Binbin Wu <> |
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On 4/21/2023 9:46 PM, Yang Weijiang wrote: > Add handling for Control Protection (#CP) exceptions(vector 21). > The new vector is introduced for Intel's Control-Flow Enforcement > Technology (CET) relevant violation cases. > See Intel's SDM for details. > > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> > --- > arch/x86/include/uapi/asm/kvm.h | 1 + > arch/x86/kvm/vmx/nested.c | 2 +- > arch/x86/kvm/x86.c | 10 +++++++--- > arch/x86/kvm/x86.h | 13 ++++++++++--- > 4 files changed, 19 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h > index 7f467fe05d42..1c002abe2be8 100644 > --- a/arch/x86/include/uapi/asm/kvm.h > +++ b/arch/x86/include/uapi/asm/kvm.h > @@ -33,6 +33,7 @@ > #define MC_VECTOR 18 > #define XM_VECTOR 19 > #define VE_VECTOR 20 > +#define CP_VECTOR 21 > > /* Select x86 specific features in <linux/kvm.h> */ > #define __KVM_HAVE_PIT > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c > index 96ede74a6067..7bc62cd72748 100644 > --- a/arch/x86/kvm/vmx/nested.c > +++ b/arch/x86/kvm/vmx/nested.c > @@ -2850,7 +2850,7 @@ 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 7788646bbf1f..a768cbf3fbb7 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -520,11 +520,15 @@ 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; By definition, #CP is Contributory. Can you explain more about this change here which treats #CP as EXCPT_BENIGN when CET is not enabled in guest?
In current KVM code, there is suppose no #CP triggered in guest if CET is not enalbed in guest, right? > case DE_VECTOR: > case TS_VECTOR: > case NP_VECTOR: > @@ -707,8 +711,8 @@ 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 c544602d07a3..2ba7c7fc4846 100644 > --- a/arch/x86/kvm/x86.h > +++ b/arch/x86/kvm/x86.h > @@ -171,13 +171,20 @@ static inline bool is_64_bit_hypercall(struct kvm_vcpu *vcpu) > return vcpu->arch.guest_state_protected || is_64_bit_mode(vcpu); > } > > -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(PF_VECTOR) | BIT(AC_VECTOR) | BIT(CP_VECTOR); > > - return (1U << vector) & exception_has_error_code; > + 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; > } > > static inline bool mmu_is_nested(struct kvm_vcpu *vcpu)
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