From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Andy Lutomirski <luto@amacapital.net>,
Kyle Huey <me@kylehuey.com>,
Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
John Stultz <john.stultz@linaro.org>,
Ingo Molnar <mingo@redhat.com>, Michal Hocko <mhocko@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Michael S. Tsirkin" <mst@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Aravind Gopalakrishnan <Aravind.Gopalakrishnan@amd.com>,
Vlastimil Babka <vbabka@suse.cz>,
"Luis R. Rodriguez" <mcgrof@kernel.org>,
Mateusz Guzik <mguzik@redhat.com>,
Alex Thorlton <athorlton@sgi.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Dmitry Vyukov <dvyukov@google.com>,
Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>,
Jiri Slaby <jslaby@suse.cz>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Ben Segall <bsegall@google.com>,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, Denys Vlasenko <dvlasenk@redhat.com>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
"Robert O'Callahan" <robert@ocallahan.org>,
"open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<linux-kernel@vger.kernel.org>, Juergen Gross <jgross@suse.com>,
Linux API <linux-api@vger.kernel.org>,
Fenghua Yu <fenghua.yu@intel.com>,
Kees Cook <keescook@chromium.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Borislav Petkov <bp@suse.de>, Len Brown <len.brown@intel.com>,
Huang Rui <ray.huang@amd.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH] prctl,x86 Add PR_[GET|SET]_CPUID for controlling the CPUID instruction.
Date: Wed, 14 Sep 2016 15:23:44 -0400 [thread overview]
Message-ID: <e7b0b419-ed32-e35b-2f7b-eee71834fafd@oracle.com> (raw)
In-Reply-To: <CALCETrWo2XcOvnWOwU4oS-pU1+KL2PnoHa0pdFX=PA3xeM7eqg@mail.gmail.com>
On 09/14/2016 02:52 PM, Andy Lutomirski wrote:
> On Tue, Sep 13, 2016 at 11:13 PM, Kyle Huey <me@kylehuey.com> wrote:
>> On Mon, Sep 12, 2016 at 9:56 AM, Andy Lutomirski <luto@amacapital.net> wrote:
>>> You should explicitly check that, if the
>>> feature is set under Xen PV, then the MSR actually works as
>>> advertised. This may require talking to the Xen folks to make sure
>>> you're testing the right configuration.
>> This is interesting. When running under Xen PV the kernel is allowed
>> to read the real value of MSR_PLATFORM_INFO and see that CPUID
>> faulting is supported. But as you suggested, writing to
>> MSR_MISC_FEATURES_ENABLES doesn't actually enable CPUID faulting, at
>> least not in any way that works.
>>
>> It's not obvious to me how to test this, because when this feature
>> works, CPUID only faults in userspace, not in the kernel. Is there
>> existing code somewhere that runs tests like this in userspace?
>>
> Andrew, Boris: should we expect Xen PV to do anything sensible when we
> write to MSR_PLATFORM_INFO to turn on CPUID faulting? Should the Xen
> PV rdmsr hooks or perhaps the hypervisor mask out the feature if it
> isn't going to be supported?
The hypervisor uses CPUID faulting so we shouldn't advertise this
feature to guests.
-boris
next prev parent reply other threads:[~2016-09-14 19:25 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-12 0:29 [PATCH] prctl,x86 Add PR_[GET|SET]_CPUID for controlling the CPUID instruction Kyle Huey
2016-09-12 9:07 ` Borislav Petkov
2016-09-12 14:15 ` Kyle Huey
2016-09-12 14:34 ` Borislav Petkov
2016-09-13 18:42 ` Kyle Huey
2016-09-12 16:56 ` Andy Lutomirski
2016-09-12 17:18 ` Borislav Petkov
2016-09-12 17:56 ` Jann Horn
2016-09-12 21:07 ` Andy Lutomirski
2016-09-14 6:13 ` Kyle Huey
2016-09-14 18:52 ` Andy Lutomirski
2016-09-14 19:22 ` Andrew Cooper
2016-09-14 19:23 ` Boris Ostrovsky [this message]
2016-09-14 19:28 ` Andrew Cooper
2016-09-14 19:36 ` Andy Lutomirski
2016-09-14 19:42 ` Andrew Cooper
2016-09-12 17:37 ` Andi Kleen
2016-09-12 18:25 ` Henrique de Moraes Holschuh
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=e7b0b419-ed32-e35b-2f7b-eee71834fafd@oracle.com \
--to=boris.ostrovsky@oracle.com \
--cc=Aravind.Gopalakrishnan@amd.com \
--cc=akpm@linux-foundation.org \
--cc=alexander.shishkin@linux.intel.com \
--cc=andrew.cooper3@citrix.com \
--cc=aryabinin@virtuozzo.com \
--cc=athorlton@sgi.com \
--cc=bp@suse.de \
--cc=bsegall@google.com \
--cc=dvlasenk@redhat.com \
--cc=dvyukov@google.com \
--cc=fenghua.yu@intel.com \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=john.stultz@linaro.org \
--cc=jslaby@suse.cz \
--cc=keescook@chromium.org \
--cc=len.brown@intel.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@amacapital.net \
--cc=mcgrof@kernel.org \
--cc=me@kylehuey.com \
--cc=mguzik@redhat.com \
--cc=mhocko@suse.com \
--cc=mingo@redhat.com \
--cc=mst@redhat.com \
--cc=paul.gortmaker@windriver.com \
--cc=peterz@infradead.org \
--cc=rafael.j.wysocki@intel.com \
--cc=ray.huang@amd.com \
--cc=robert@ocallahan.org \
--cc=srinivas.pandruvada@linux.intel.com \
--cc=tglx@linutronix.de \
--cc=vbabka@suse.cz \
--cc=vladimir_zapolskiy@mentor.com \
--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;
as well as URLs for NNTP newsgroup(s).