From: Gleb Natapov <gleb@redhat.com>
To: Jan Beulich <JBeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
KVM list <kvm@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Peter Anvin <hpa@zytor.com>
Subject: Re: [PATCH, RFC] x86-64: properly handle FPU code/data selectors
Date: Thu, 17 Oct 2013 12:27:27 +0300 [thread overview]
Message-ID: <20131017092727.GN15657@redhat.com> (raw)
In-Reply-To: <525ED75402000078000FB95B@nat28.tlf.novell.com>
On Wed, Oct 16, 2013 at 05:13:40PM +0100, Jan Beulich wrote:
> > It preserves *less* state, because the upper 32 bits of rip are now
> > corrupted. Any 64-bit application that actually looks at the FP
> > rip/rdp fields now get the WRONG VALUES.
>
> But again - this isn't being done for ordinary 64-bit applications,
> this is only happening for KVM guests. And there not being a
> protocol for telling the caller whether a certain context hold
> 64-bit offsets or selector/offset pairs shouldn't be a reason to
> think of a solution to the problem.
>
KVM knows what mode guest vcpu is in. is_long_mode(vcpu) will tell you
if it is in long mode or not. No need to guess it.
--
Gleb.
next prev parent reply other threads:[~2013-10-17 9:27 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-16 12:00 [PATCH, RFC] x86-64: properly handle FPU code/data selectors Jan Beulich
2013-10-16 15:19 ` Linus Torvalds
2013-10-16 15:36 ` Jan Beulich
2013-10-16 15:50 ` Linus Torvalds
2013-10-16 16:13 ` Jan Beulich
2013-10-16 18:43 ` Linus Torvalds
2013-10-17 7:09 ` Jan Beulich
2013-10-17 9:27 ` Gleb Natapov [this message]
2013-10-17 9:33 ` Jan Beulich
2013-10-17 9:41 ` Gleb Natapov
2013-10-17 9:51 ` Jan Beulich
2013-10-17 10:23 ` Gleb Natapov
2013-10-17 10:37 ` Jan Beulich
2013-10-17 10:39 ` Gleb Natapov
2013-10-16 15:39 ` H. Peter Anvin
2013-10-16 16:07 ` Jan Beulich
2013-10-16 17:13 ` H. Peter Anvin
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=20131017092727.GN15657@redhat.com \
--to=gleb@redhat.com \
--cc=JBeulich@suse.com \
--cc=hpa@zytor.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.