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kvm: svm: Only propagate next_rip when guest supports it

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Currently we always write the next_rip of the shadow vmcb to
the guests vmcb when we emulate a vmexit. This could confuse
the guest when its cpuid indicated no support for the
next_rip feature.

Fix this by only propagating next_rip if the guest actually
supports it.

Cc: Bandan Das <bsd@redhat.com>
Cc: Dirk Mueller <dmueller@suse.com>
Tested-By: Dirk Mueller <dmueller@suse.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Joerg Roedel 2015-10-14 15:10:54 +02:00 committed by Paolo Bonzini
parent 951f9fd74f
commit 6092d3d3e6
2 changed files with 31 additions and 1 deletions
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21
arch/x86/kvm/cpuid.h
View File

@ -149,4 +149,25 @@ static inline bool guest_cpuid_has_rdtscp(struct kvm_vcpu *vcpu)
best = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
return best && (best->edx & bit(X86_FEATURE_RDTSCP));
}
/*
* NRIPS is provided through cpuidfn 0x8000000a.edx bit 3
*/
#define BIT_NRIPS 3
static inline bool guest_cpuid_has_nrips(struct kvm_vcpu *vcpu)
{
struct kvm_cpuid_entry2 *best;
best = kvm_find_cpuid_entry(vcpu, 0x8000000a, 0);
/*
* NRIPS is a scattered cpuid feature, so we can't use
* X86_FEATURE_NRIPS here (X86_FEATURE_NRIPS would be bit
* position 8, not 3).
*/
return best && (best->edx & bit(BIT_NRIPS));
}
#undef BIT_NRIPS
#endif

11
arch/x86/kvm/svm.c
View File

@ -159,6 +159,9 @@ struct vcpu_svm {
u32 apf_reason;
u64 tsc_ratio;
/* cached guest cpuid flags for faster access */
bool nrips_enabled : 1;
};
static DEFINE_PER_CPU(u64, current_tsc_ratio);
@ -2365,7 +2368,9 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
nested_vmcb->control.exit_info_2 = vmcb->control.exit_info_2;
nested_vmcb->control.exit_int_info = vmcb->control.exit_int_info;
nested_vmcb->control.exit_int_info_err = vmcb->control.exit_int_info_err;
nested_vmcb->control.next_rip = vmcb->control.next_rip;
if (svm->nrips_enabled)
nested_vmcb->control.next_rip = vmcb->control.next_rip;
/*
* If we emulate a VMRUN/#VMEXIT in the same host #vmexit cycle we have
@ -4085,6 +4090,10 @@ static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
static void svm_cpuid_update(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
/* Update nrips enabled cache */
svm->nrips_enabled = !!guest_cpuid_has_nrips(&svm->vcpu);
}
static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)