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| author | Sean Christopherson <seanjc@google.com> | 2024-08-02 21:55:08 +0300 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-11-01 19:22:34 +0300 |
| commit | a5d563890b8f0352c8f915c6acc75b5cd3b28d98 (patch) | |
| tree | 06f6aa0449205cd24a578176c07a73ce4f2c526c | |
| parent | a1039111192b3b8c76c3b1a334b62376df3c2885 (diff) | |
| download | linux-a5d563890b8f0352c8f915c6acc75b5cd3b28d98.tar.xz | |
KVM: x86: Reject userspace attempts to access ARCH_CAPABILITIES w/o support
Reject userspace accesses to ARCH_CAPABILITIES if the MSR isn't supposed
to exist, according to guest CPUID. However, "reject" accesses with
KVM_MSR_RET_UNSUPPORTED, so that reads get '0' and writes of '0' are
ignored if KVM advertised support ARCH_CAPABILITIES.
KVM's ABI is that userspace must set guest CPUID prior to setting MSRs,
and that setting MSRs that aren't supposed exist is disallowed (modulo the
'0' exemption).
Link: https://lore.kernel.org/r/20240802185511.305849-7-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c2802272871d..7e59d3a0801a 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3795,8 +3795,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) vcpu->arch.microcode_version = data; break; case MSR_IA32_ARCH_CAPABILITIES: - if (!msr_info->host_initiated) - return 1; + if (!msr_info->host_initiated || + !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES)) + return KVM_MSR_RET_UNSUPPORTED; vcpu->arch.arch_capabilities = data; break; case MSR_IA32_PERF_CAPABILITIES: @@ -4256,9 +4257,8 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) msr_info->data = vcpu->arch.microcode_version; break; case MSR_IA32_ARCH_CAPABILITIES: - if (!msr_info->host_initiated && - !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES)) - return 1; + if (!guest_cpuid_has(vcpu, X86_FEATURE_ARCH_CAPABILITIES)) + return KVM_MSR_RET_UNSUPPORTED; msr_info->data = vcpu->arch.arch_capabilities; break; case MSR_IA32_PERF_CAPABILITIES: |