Messages in this thread | | | Date | Fri, 7 Dec 2018 14:48:37 -0200 | From | Eduardo Habkost <> | Subject | Re: [PATCH] kvm: x86: Report STIBP on GET_SUPPORTED_CPUID |
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On Wed, Dec 05, 2018 at 05:02:06PM -0500, Konrad Rzeszutek Wilk wrote: > On Wed, Dec 05, 2018 at 05:19:56PM -0200, Eduardo Habkost wrote: > > Months ago, we have added code to allow direct access to MSR_IA32_SPEC_CTRL > > to the guest, which makes STIBP available to guests. This was implemented > > by commits d28b387fb74d ("KVM/VMX: Allow direct access to > > MSR_IA32_SPEC_CTRL") and b2ac58f90540 ("KVM/SVM: Allow direct access to > > MSR_IA32_SPEC_CTRL"). > > > > However, we never updated GET_SUPPORTED_CPUID to let userspace know that > > STIBP can be enabled in CPUID. Fix that by updating > > Ooops! > > kvm_cpuid_8000_0008_ebx_x86_features and kvm_cpuid_7_0_edx_x86_features. > > Shouldn't there also be a patch in QEMU to use it? (aka, +stibp).
I will submit the QEMU patch soon.
A patch exists on some downstream QEMU distributions, already, but it was never merged upstream because GET_SUPPORTED_CPUID never supported STIBP in the upstream kernel. (And because in the end it was not used for mitigating Spectre)
> > Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Thanks!
-- Eduardo
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