From: Eduardo Habkost <ehabkost@redhat.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
kvm@vger.kernel.org, "Jim Mattson" <jmattson@google.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
"KarimAllah Ahmed" <karahmed@amazon.de>,
"David Woodhouse" <dwmw2@infradead.org>
Subject: Re: [PATCH] kvm: x86: Report STIBP on GET_SUPPORTED_CPUID
Date: Fri, 7 Dec 2018 14:48:37 -0200 [thread overview]
Message-ID: <20181207164837.GE7395@habkost.net> (raw)
In-Reply-To: <20181205220206.GA16013@char.us.oracle.com>
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
next prev parent reply other threads:[~2018-12-07 16:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 19:19 [PATCH] kvm: x86: Report STIBP on GET_SUPPORTED_CPUID Eduardo Habkost
2018-12-05 19:36 ` Jim Mattson
2018-12-05 22:02 ` Konrad Rzeszutek Wilk
2018-12-05 22:47 ` Jim Mattson
2018-12-07 16:48 ` Eduardo Habkost [this message]
2018-12-14 10:55 ` Paolo Bonzini
2022-05-17 0:35 ` Jim Mattson
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