All of lore.kernel.org
 help / color / mirror / Atom feed
From: Avi Kivity <avi@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>, kvm <kvm@vger.kernel.org>,
	qemu-devel <qemu-devel@nongnu.org>
Subject: Re: [PATCH v2][uq/master] kvm: x86: Save/restore FPU OP, IP and DP
Date: Sun, 19 Jun 2011 15:58:53 +0300	[thread overview]
Message-ID: <4DFDF28D.3030206@redhat.com> (raw)
In-Reply-To: <4DF8B0E6.1080806@siemens.com>

On 06/15/2011 04:17 PM, Jan Kiszka wrote:
> These FPU states are properly maintained by KVM but not yet by TCG. So
> far we unconditionally set them to 0 in the guest which may cause
> state corruptions, though not with modern guests.
>
> To avoid breaking backward migration, use a conditional subsection that
> is only written if any of the three fields is non-zero. The guest's
> FNINIT clears them frequently, and cleared IA32_MISC_ENABLE MSR[2]
> reduces the probability of non-zero values further so that this
> subsection is not expected to restrict migration in any common scenario.

Thanks, applied to uq/master.  A test migration showed that the 
subsection in fact did not show up.

-- 
error compiling committee.c: too many arguments to function


WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>, kvm <kvm@vger.kernel.org>
Subject: Re: [Qemu-devel] [PATCH v2][uq/master] kvm: x86: Save/restore FPU OP, IP and DP
Date: Sun, 19 Jun 2011 15:58:53 +0300	[thread overview]
Message-ID: <4DFDF28D.3030206@redhat.com> (raw)
In-Reply-To: <4DF8B0E6.1080806@siemens.com>

On 06/15/2011 04:17 PM, Jan Kiszka wrote:
> These FPU states are properly maintained by KVM but not yet by TCG. So
> far we unconditionally set them to 0 in the guest which may cause
> state corruptions, though not with modern guests.
>
> To avoid breaking backward migration, use a conditional subsection that
> is only written if any of the three fields is non-zero. The guest's
> FNINIT clears them frequently, and cleared IA32_MISC_ENABLE MSR[2]
> reduces the probability of non-zero values further so that this
> subsection is not expected to restrict migration in any common scenario.

Thanks, applied to uq/master.  A test migration showed that the 
subsection in fact did not show up.

-- 
error compiling committee.c: too many arguments to function

  parent reply	other threads:[~2011-06-19 12:59 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-06-11  9:23 [PATCH][uq/master] kvm: x86: Save/restore FPU OP, IP and DP Jan Kiszka
2011-06-11  9:23 ` [Qemu-devel] " Jan Kiszka
2011-06-13  8:45 ` Avi Kivity
2011-06-13  8:45   ` [Qemu-devel] " Avi Kivity
2011-06-14  6:10   ` Jan Kiszka
2011-06-14  6:10     ` [Qemu-devel] " Jan Kiszka
2011-06-14  8:23     ` Avi Kivity
2011-06-14  8:23       ` [Qemu-devel] " Avi Kivity
2011-06-14  8:28       ` Jan Kiszka
2011-06-14  8:28         ` [Qemu-devel] " Jan Kiszka
2011-06-15  9:10     ` Avi Kivity
2011-06-15  9:10       ` [Qemu-devel] " Avi Kivity
2011-06-15 10:20       ` Jan Kiszka
2011-06-15 10:20         ` [Qemu-devel] " Jan Kiszka
2011-06-15 10:39         ` Jan Kiszka
2011-06-15 10:39           ` [Qemu-devel] " Jan Kiszka
2011-06-15 11:26         ` Avi Kivity
2011-06-15 11:26           ` [Qemu-devel] " Avi Kivity
2011-06-15 11:32           ` Jan Kiszka
2011-06-15 11:32             ` [Qemu-devel] " Jan Kiszka
2011-06-15 11:33             ` Avi Kivity
2011-06-15 11:33               ` [Qemu-devel] " Avi Kivity
2011-06-15 11:45               ` Jan Kiszka
2011-06-15 11:45                 ` [Qemu-devel] " Jan Kiszka
2011-06-15 13:17 ` [PATCH v2][uq/master] " Jan Kiszka
2011-06-15 13:17   ` [Qemu-devel] " Jan Kiszka
2011-06-16  9:42   ` Christophe Fergeau
2011-06-16  9:42     ` Christophe Fergeau
2011-06-19 12:58   ` Avi Kivity [this message]
2011-06-19 12:58     ` Avi Kivity
2011-06-16  9:35 ` [PATCH][uq/master] " Christophe Fergeau
2011-06-16  9:35   ` [Qemu-devel] " Christophe Fergeau

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=4DFDF28D.3030206@redhat.com \
    --to=avi@redhat.com \
    --cc=jan.kiszka@siemens.com \
    --cc=kvm@vger.kernel.org \
    --cc=mtosatti@redhat.com \
    --cc=qemu-devel@nongnu.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.