| From 85d0011264da24be08ae907d7f29983a597ca9b1 Mon Sep 17 00:00:00 2001 |
| From: Sean Christopherson <seanjc@google.com> |
| Date: Tue, 4 May 2021 10:17:21 -0700 |
| Subject: KVM: x86: Emulate RDPID only if RDTSCP is supported |
| |
| 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 |
| @@ -572,7 +572,8 @@ 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; |
