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 5.12-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-5.12 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
@@ -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;
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-5.12/crypto-ccp-free-sev-device-if-sev-init-fails.patch
queue-5.12/kvm-lapic-accurately-guarantee-busy-wait-for-timer-t.patch
queue-5.12/kvm-x86-add-support-for-rdpid-without-rdtscp.patch
queue-5.12/kvm-x86-move-rdpid-emulation-intercept-to-its-own-enum.patch
queue-5.12/kvm-x86-emulate-rdpid-only-if-rdtscp-is-supported.patch
