| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.12 329/363] KVM: x86: Emulate RDPID only if RDTSCP is supported | Date | Mon, 17 May 2021 16:03:15 +0200 |
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From: Sean Christopherson <seanjc@google.com>
commit 85d0011264da24be08ae907d7f29983a597ca9b1 upstream.
Do not advertise emulation support for RDPID if RDTSCP is unsupported. RDPID emulation subtly relies on MSR_TSC_AUX to exist in hardware, as both vmx_get_msr() and svm_get_msr() will return an error if the MSR is unsupported, i.e. ctxt->ops->get_msr() will fail and the emulator will inject a #UD.
Note, RDPID emulation also relies on RDTSCP being enabled in the guest, but this is a KVM bug and will eventually be fixed.
Fixes: fb6d4d340e05 ("KVM: x86: emulate RDPID") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20210504171734.1434054-3-seanjc@google.com> Reviewed-by: Jim Mattson <jmattson@google.com> Reviewed-by: Reiji Watanabe <reijiw@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/x86/kvm/cpuid.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -589,7 +589,8 @@ static int __do_cpuid_func_emulated(stru case 7: entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX; entry->eax = 0; - entry->ecx = F(RDPID); + if (kvm_cpu_cap_has(X86_FEATURE_RDTSCP)) + entry->ecx = F(RDPID); ++array->nent; default: break;
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