KVM: x86: nSVM: disallow userspace setting of MSR_AMD64_TSC_RATIO to non default value when tsc scaling disabled
If nested tsc scaling is disabled, MSR_AMD64_TSC_RATIO should
never have non default value.
Due to way nested tsc scaling support was implmented in qemu,
it would set this msr to 0 when nested tsc scaling was disabled.
Ignore that value for now, as it causes no harm.
Fixes: 5228eb96a4
("KVM: x86: nSVM: implement nested TSC scaling")
Cc: stable@vger.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220223115649.319134-1-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Родитель
6f3c1fc53d
Коммит
e910a53fb4
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@ -2693,8 +2693,23 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
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u64 data = msr->data;
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switch (ecx) {
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case MSR_AMD64_TSC_RATIO:
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if (!msr->host_initiated && !svm->tsc_scaling_enabled)
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return 1;
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if (!svm->tsc_scaling_enabled) {
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if (!msr->host_initiated)
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return 1;
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/*
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* In case TSC scaling is not enabled, always
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* leave this MSR at the default value.
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*
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* Due to bug in qemu 6.2.0, it would try to set
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* this msr to 0 if tsc scaling is not enabled.
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* Ignore this value as well.
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*/
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if (data != 0 && data != svm->tsc_ratio_msr)
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return 1;
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break;
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}
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if (data & TSC_RATIO_RSVD)
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return 1;
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