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KVM: x86: ensure all MSRs can always be KVM_GET/SET_MSR'd

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Some of the MSRs returned by GET_MSR_INDEX_LIST currently cannot be sent back
to KVM_GET_MSR and/or KVM_SET_MSR; either they can never be sent back, or you
they are only accepted under special conditions.  This makes the API a pain to
use.

To avoid this pain, this patch makes it so that the result of the get-list
ioctl can always be used for host-initiated get and set.  Since we don't have
a separate way to check for read-only MSRs, this means some Hyper-V MSRs are
ignored when written.  Arguably they should not even be in the result of
GET_MSR_INDEX_LIST, but I am leaving there in case userspace is using the
outcome of GET_MSR_INDEX_LIST to derive the support for the corresponding
Hyper-V feature.

Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini
2018-07-26 13:01:52 +02:00
parent cf81a7e580
commit 44883f01fe
3 changed files with 30 additions and 14 deletions
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2
arch/x86/kvm/hyperv.h
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@@ -48,7 +48,7 @@ static inline struct kvm_vcpu *synic_to_vcpu(struct kvm_vcpu_hv_synic *synic)
}
int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host);
int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host);
bool kvm_hv_hypercall_enabled(struct kvm *kvm);
int kvm_hv_hypercall(struct kvm_vcpu *vcpu);