From: David Woodhouse <dwmw2@infradead.org>
To: Tom Lendacky <thomas.lendacky@amd.com>,
tglx@linutronix.de, karahmed@amazon.de, x86@kernel.org,
kvm@vger.kernel.org, torvalds@linux-foundation.org,
pbonzini@redhat.com, linux-kernel@vger.kernel.org, bp@alien8.de,
peterz@infradead.org, jmattson@google.com, rkrcmar@redhat.com,
arjan.van.de.ven@intel.com, dave.hansen@intel.com,
mingo@kernel.org
Subject: Re: [PATCH 1/4] x86/speculation: Use IBRS if available before calling into firmware
Date: Wed, 14 Feb 2018 16:53:39 +0000 [thread overview]
Message-ID: <1518627219.12890.150.camel@infradead.org> (raw)
In-Reply-To: <33d227ac-7723-5e5f-c299-4a44daa427c6@amd.com>
[-- Attachment #1: Type: text/plain, Size: 794 bytes --]
On Wed, 2018-02-14 at 10:36 -0600, Tom Lendacky wrote:
> On 2/14/2018 10:11 AM, David Woodhouse wrote:
> >
> >
> >
> > On Wed, 2018-02-14 at 10:07 -0600, Tom Lendacky wrote:
> > >
> > > Shouldn't these writes to the MSR be just for the IBRS bit? The spec
> > > also defines the STIBP bit for this MSR, and if that bit had been set by
> > > BIOS for example, these writes will clear it. And who knows what future
> > > bits may be defined and how they'll be used.
> >
> > We don't use STIBP. If one day we do decide to set it in userspace for
>
> Right, I understand the kernel doesn't use STIBP, that's why I mentioned
> BIOS as an example.
BIOS has no business setting this for us either. Either we support it
and turn it on in the kernel ourselves, or it's off.
[-- Attachment #2: smime.p7s --]
[-- Type: application/x-pkcs7-signature, Size: 5213 bytes --]
next prev parent reply other threads:[~2018-02-14 16:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-14 13:44 [PATCH 0/4] Speculation control improvements David Woodhouse
2018-02-14 13:44 ` [PATCH 1/4] x86/speculation: Use IBRS if available before calling into firmware David Woodhouse
2018-02-14 16:07 ` Tom Lendacky
2018-02-14 16:11 ` David Woodhouse
2018-02-14 16:36 ` Tom Lendacky
2018-02-14 16:53 ` David Woodhouse [this message]
2018-02-14 13:44 ` [PATCH 2/4] x86/speculation: Support "Enhanced IBRS" on future CPUs David Woodhouse
2018-02-14 13:44 ` [PATCH 3/4] Revert "x86/retpoline: Simplify vmexit_fill_RSB()" David Woodhouse
2018-02-14 13:44 ` [PATCH 4/4] x86/retpoline: Support retpoline build with Clang David Woodhouse
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1518627219.12890.150.camel@infradead.org \
--to=dwmw2@infradead.org \
--cc=arjan.van.de.ven@intel.com \
--cc=bp@alien8.de \
--cc=dave.hansen@intel.com \
--cc=jmattson@google.com \
--cc=karahmed@amazon.de \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox