lkml.org 
[lkml]   [2023]   [Apr]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2 10/21] KVM:x86: Add #CP support in guest exception classification
From


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)

\
 
 \ /
  Last update: 2023-04-28 08:10    [W:0.651 / U:0.352 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site