This is a note to let you know that I've just added the patch titled KVM: x86: Emulate RDPID only if RDTSCP is supported to the 5.11-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: kvm-x86-emulate-rdpid-only-if-rdtscp-is-supported.patch and it can be found in the queue-5.11 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 85d0011264da24be08ae907d7f29983a597ca9b1 Mon Sep 17 00:00:00 2001 From: Sean Christopherson <seanjc@xxxxxxxxxx> Date: Tue, 4 May 2021 10:17:21 -0700 Subject: KVM: x86: Emulate RDPID only if RDTSCP is supported From: Sean Christopherson <seanjc@xxxxxxxxxx> 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@xxxxxxxxxxxxxxx Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx> Message-Id: <20210504171734.1434054-3-seanjc@xxxxxxxxxx> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx> Reviewed-by: Reiji Watanabe <reijiw@xxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -573,7 +573,8 @@ 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; Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are queue-5.11/crypto-ccp-free-sev-device-if-sev-init-fails.patch queue-5.11/kvm-x86-mmu-remove-the-defunct-update_pte-paging-hook.patch queue-5.11/kvm-lapic-accurately-guarantee-busy-wait-for-timer-t.patch queue-5.11/kvm-x86-move-rdpid-emulation-intercept-to-its-own-enum.patch queue-5.11/kvm-x86-emulate-rdpid-only-if-rdtscp-is-supported.patch