From: Eduardo Habkost <ehabkost@redhat.com>
To: David Dunn <ddunn@vmware.com>
Cc: "Jim Mattson" <jmattson@google.com>,
"Andi Kleen" <ak@linux.intel.com>,
"Arjan van de Ven" <arjan@linux.intel.com>,
"KarimAllah Ahmed" <karahmed@amazon.de>,
"Wilson, Matt" <msw@amazon.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Andrea Arcangeli" <aarcange@redhat.com>,
"Andy Lutomirski" <luto@kernel.org>,
"Ashok Raj" <ashok.raj@intel.com>,
"Asit Mallick" <asit.k.mallick@intel.com>,
"Borislav Petkov" <bp@suse.de>,
"Dan Williams" <dan.j.williams@intel.com>,
"Dave Hansen" <dave.hansen@intel.com>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
"H . Peter Anvin" <hpa@zytor.com>,
"Ingo Molnar" <mingo@redhat.com>,
"Janakarajan Natarajan" <Janakarajan.Natarajan@amd.com>,
"Joerg Roedel" <joro@8bytes.org>,
"Jun Nakajima" <jun.nakajima@intel.com>,
"Laura Abbott" <labbott@redhat.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Masami Hiramatsu" <mhiramat@kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Peter Zijlstra" <peterz@infradead.org>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
"Tim Chen" <tim.c.chen@linux.intel.com>,
"Tom Lendacky" <thomas.lendacky@amd.com>,
"Jorgensen, Bryan" <bryan.jorgensen@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"x86@kernel.org" <x86@kernel.org>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Fred Jacobs" <fjacobs@vmware.com>,
"David Woodhouse" <dwmw2@infradead.org>
Subject: Re: [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure
Date: Mon, 29 Jan 2018 23:30:14 -0200 [thread overview]
Message-ID: <20180130013014.GE21702@localhost.localdomain> (raw)
In-Reply-To: <30A89AF5-51E6-4D7F-B669-63C2B3191302@vmware.com>
On Tue, Jan 30, 2018 at 01:20:52AM +0000, David Dunn wrote:
> Eduardo,
>
> This is why it would be good to have a CPUID bit that says:
> "apply SkyLake RSB stuffing." That's preferable to "trust FMS"
> for VMware.
Agreed it would be more useful than "trust FMS". However, I
believe a "no need to apply Skylake RSB stuffing" bit (which I
called "we promise we won't migrate to Skylake" previously) would
allow guests to enable safer behavior by default under older
hypervisors that don't support this bit.
>
> If Intel defines such a feature flag, sets it on SkyLake, and
> Linux uses it... that would be very helpful for VMware.
>
> I won't speak for GCE and AWS. But hopefully they can indicate
> whether it would help them as well.
I agree that having a standard flag on the CPUID space to specify
that would be very helpful.
>
> If Intel cannot define/implement such a flag on SkyLake, then
> maybe the engineers on this email could define a flag in the
> hypervisor specific CPUID space. Linux would need to query
> that flag if it sees CPUID[1].ECX[31] set. That's not as nice
> since it makes detection on bare metal and virtualization
> platforms different, but it better than keying off FMS.
Agreed.
--
Eduardo
next prev parent reply other threads:[~2018-01-30 1:30 UTC|newest]
Thread overview: 75+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-29 22:29 [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure David Dunn
2018-01-29 22:41 ` Andi Kleen
2018-01-29 22:49 ` Jim Mattson
2018-01-30 1:10 ` Eduardo Habkost
2018-01-30 1:20 ` David Dunn
2018-01-30 1:30 ` Eduardo Habkost [this message]
2018-01-29 23:51 ` Fred Jacobs
2018-01-30 1:08 ` Eduardo Habkost
-- strict thread matches above, loose matches on Subject: below --
2018-01-20 19:22 [RFC 00/10] Speculation Control feature support KarimAllah Ahmed
2018-01-20 19:22 ` [RFC 05/10] x86/speculation: Add basic IBRS support infrastructure KarimAllah Ahmed
2018-01-21 14:31 ` Thomas Gleixner
2018-01-21 14:56 ` Borislav Petkov
2018-01-22 9:51 ` Peter Zijlstra
2018-01-22 12:06 ` Borislav Petkov
2018-01-22 13:30 ` Greg Kroah-Hartman
2018-01-22 13:37 ` Woodhouse, David
2018-01-21 15:25 ` David Woodhouse
2018-01-23 20:58 ` David Woodhouse
2018-01-23 22:43 ` Johannes Erdfelt
2018-01-24 8:47 ` Peter Zijlstra
2018-01-24 9:02 ` David Woodhouse
2018-01-24 9:10 ` Greg Kroah-Hartman
2018-01-24 15:09 ` Arjan van de Ven
2018-01-24 15:18 ` David Woodhouse
2018-01-24 9:34 ` Peter Zijlstra
2018-01-24 10:49 ` Henrique de Moraes Holschuh
2018-01-24 12:30 ` David Woodhouse
2018-01-24 12:14 ` David Woodhouse
2018-01-24 12:29 ` Peter Zijlstra
2018-01-24 12:58 ` David Woodhouse
2018-01-29 20:14 ` [RFC,05/10] " Eduardo Habkost
2018-01-29 20:17 ` David Woodhouse
2018-01-29 20:42 ` Eduardo Habkost
2018-01-29 20:44 ` Arjan van de Ven
2018-01-29 21:02 ` David Woodhouse
2018-01-29 21:37 ` Jim Mattson
2018-01-29 21:50 ` Eduardo Habkost
2018-01-29 22:12 ` Jim Mattson
2018-01-30 1:22 ` Eduardo Habkost
2018-01-29 22:25 ` Andi Kleen
2018-01-30 1:37 ` Eduardo Habkost
2018-01-29 21:37 ` Andi Kleen
2018-01-29 21:44 ` Eduardo Habkost
2018-01-29 22:10 ` Konrad Rzeszutek Wilk
2018-01-30 1:12 ` Eduardo Habkost
2018-01-30 0:23 ` Linus Torvalds
2018-01-30 1:03 ` Jim Mattson
2018-01-30 3:13 ` Andi Kleen
2018-01-31 15:03 ` Paolo Bonzini
2018-01-31 15:07 ` Dr. David Alan Gilbert
2018-01-30 1:32 ` Arjan van de Ven
2018-01-30 3:32 ` Linus Torvalds
2018-01-30 12:04 ` Eduardo Habkost
2018-01-30 13:54 ` Arjan van de Ven
2018-01-30 8:22 ` David Woodhouse
2018-01-30 11:35 ` David Woodhouse
2018-01-30 11:56 ` Dr. David Alan Gilbert
2018-01-30 12:11 ` Christian Borntraeger
2018-01-30 14:46 ` Christophe de Dinechin
2018-01-30 14:52 ` Christian Borntraeger
2018-01-30 14:56 ` Christophe de Dinechin
2018-01-30 15:33 ` Christian Borntraeger
2018-01-30 20:46 ` Alan Cox
2018-01-31 10:05 ` Christophe de Dinechin
2018-01-31 10:15 ` Thomas Gleixner
2018-01-31 11:04 ` Dr. David Alan Gilbert
2018-01-31 11:52 ` Borislav Petkov
2018-01-31 12:30 ` Dr. David Alan Gilbert
2018-01-31 13:18 ` Borislav Petkov
2018-01-31 14:04 ` Dr. David Alan Gilbert
2018-01-31 14:44 ` Eduardo Habkost
2018-01-31 16:28 ` Borislav Petkov
2018-01-31 11:07 ` Christophe de Dinechin
2018-01-31 15:00 ` Eduardo Habkost
2018-01-31 15:11 ` Arjan van de Ven
2018-01-31 10:03 ` [RFC 05/10] " Christophe de Dinechin
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=20180130013014.GE21702@localhost.localdomain \
--to=ehabkost@redhat.com \
--cc=Janakarajan.Natarajan@amd.com \
--cc=aarcange@redhat.com \
--cc=ak@linux.intel.com \
--cc=arjan@linux.intel.com \
--cc=ashok.raj@intel.com \
--cc=asit.k.mallick@intel.com \
--cc=bp@suse.de \
--cc=bryan.jorgensen@intel.com \
--cc=dan.j.williams@intel.com \
--cc=dave.hansen@intel.com \
--cc=ddunn@vmware.com \
--cc=dgilbert@redhat.com \
--cc=dwmw2@infradead.org \
--cc=fjacobs@vmware.com \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=jun.nakajima@intel.com \
--cc=karahmed@amazon.de \
--cc=kvm@vger.kernel.org \
--cc=labbott@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mhiramat@kernel.org \
--cc=mingo@redhat.com \
--cc=msw@amazon.com \
--cc=pbonzini@redhat.com \
--cc=peterz@infradead.org \
--cc=rkrcmar@redhat.com \
--cc=tglx@linutronix.de \
--cc=thomas.lendacky@amd.com \
--cc=tim.c.chen@linux.intel.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;
as well as URLs for NNTP newsgroup(s).