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@xxxxxxxxx>
---
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)
