From: Chris Lalancette <clalance@redhat.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andrew Morton <akpm@osdl.org>,
Eduardo Habkost <ehabkost@redhat.com>,
kvm@vger.kernel.org, kexec@lists.infradead.org,
Haren Myneni <hbabu@us.ibm.com>,
Simon Horman <horms@verge.net.au>, Avi Kivity <avi@redhat.com>,
Vivek Goyal <vgoyal@redhat.com>
Subject: Re: [PATCH 0/2] kvm: disable virtualization on kdump
Date: Thu, 30 Oct 2008 08:35:59 +0100 [thread overview]
Message-ID: <490963DF.90703@redhat.com> (raw)
In-Reply-To: <m1bpx23lzg.fsf@frodo.ebiederm.org>
Eric W. Biederman wrote:
>>>> svm can writeback into memory at odd times if we don't do this, and the cost
>> is
>>>> small - clear a bit in EFER. There's no reason to be lazy.
>>>>
>>> Especially if we can clear that bit unconditionally (when
>>> EFER is present) I'm all for it.
>>>
>> That is the case.
>
> Cool. I forget if we have to test for EFER on 32bit, or if we can just wrmsr
> and be done with it. Regardless that sounds easy to do on the kexec path.
I'm pretty sure you have to test for it first; pre-64 bit x86 hardware doesn't
have the EFER register, so you'll fault on access. On the other hand pre-64 bit
x86 hardware doesn't usually (ever?) have VT extensions either.
--
Chris Lalancette
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WARNING: multiple messages have this Message-ID (diff)
From: Chris Lalancette <clalance-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: "Eric W. Biederman" <ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
Cc: Andrew Morton <akpm-3NddpPZAyC0@public.gmane.org>,
Eduardo Habkost
<ehabkost-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org,
Haren Myneni <hbabu-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>,
Simon Horman <horms-/R6kz+dDXgpPR4JQBCEnsQ@public.gmane.org>,
Avi Kivity <avi-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 0/2] kvm: disable virtualization on kdump
Date: Thu, 30 Oct 2008 08:35:59 +0100 [thread overview]
Message-ID: <490963DF.90703@redhat.com> (raw)
In-Reply-To: <m1bpx23lzg.fsf-B27657KtZYmhTnVgQlOflh2eb7JE58TQ@public.gmane.org>
Eric W. Biederman wrote:
>>>> svm can writeback into memory at odd times if we don't do this, and the cost
>> is
>>>> small - clear a bit in EFER. There's no reason to be lazy.
>>>>
>>> Especially if we can clear that bit unconditionally (when
>>> EFER is present) I'm all for it.
>>>
>> That is the case.
>
> Cool. I forget if we have to test for EFER on 32bit, or if we can just wrmsr
> and be done with it. Regardless that sounds easy to do on the kexec path.
I'm pretty sure you have to test for it first; pre-64 bit x86 hardware doesn't
have the EFER register, so you'll fault on access. On the other hand pre-64 bit
x86 hardware doesn't usually (ever?) have VT extensions either.
--
Chris Lalancette
next prev parent reply other threads:[~2008-10-30 7:37 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-20 15:01 [PATCH 0/2] kvm: disable virtualization on kdump Eduardo Habkost
2008-10-20 15:01 ` Eduardo Habkost
2008-10-20 15:01 ` [PATCH 1/2] kdump: crash-time CPU halt notifier interface Eduardo Habkost
2008-10-20 15:01 ` Eduardo Habkost
2008-10-20 15:01 ` [PATCH 2/2] kvm: disable virtualization when halting CPUs on crash Eduardo Habkost
2008-10-20 15:01 ` Eduardo Habkost
2008-10-22 23:28 ` [PATCH 0/2] kvm: disable virtualization on kdump Simon Horman
2008-10-22 23:28 ` Simon Horman
2008-10-23 19:41 ` Eduardo Habkost
2008-10-23 19:41 ` Eduardo Habkost
2008-10-23 22:29 ` Simon Horman
2008-10-23 22:29 ` Simon Horman
2008-10-24 1:00 ` Eric W. Biederman
2008-10-24 1:00 ` Eric W. Biederman
2008-10-26 12:49 ` Avi Kivity
2008-10-26 12:49 ` Avi Kivity
2008-10-26 14:46 ` Eric W. Biederman
2008-10-26 14:46 ` Eric W. Biederman
2008-10-26 15:07 ` Avi Kivity
2008-10-26 15:07 ` Avi Kivity
2008-10-26 21:39 ` Eduardo Habkost
2008-10-26 21:39 ` Eduardo Habkost
2008-10-27 2:08 ` Eric W. Biederman
2008-10-27 2:08 ` Eric W. Biederman
2008-10-27 9:13 ` Avi Kivity
2008-10-27 9:13 ` Avi Kivity
2008-10-27 12:28 ` Eduardo Habkost
2008-10-27 12:28 ` Eduardo Habkost
2008-10-27 14:02 ` Avi Kivity
2008-10-27 14:02 ` Avi Kivity
2008-10-27 17:32 ` Eric W. Biederman
2008-10-27 17:32 ` Eric W. Biederman
2008-10-28 19:45 ` Eduardo Habkost
2008-10-28 19:45 ` Eduardo Habkost
2008-10-28 20:13 ` Eric W. Biederman
2008-10-28 20:13 ` Eric W. Biederman
2008-10-29 9:41 ` Avi Kivity
2008-10-29 9:41 ` Avi Kivity
2008-10-29 14:54 ` Eric W. Biederman
2008-10-29 14:54 ` Eric W. Biederman
2008-10-29 17:03 ` Avi Kivity
2008-10-29 17:03 ` Avi Kivity
2008-10-30 1:33 ` Eric W. Biederman
2008-10-30 1:33 ` Eric W. Biederman
2008-10-30 7:35 ` Chris Lalancette [this message]
2008-10-30 7:35 ` Chris Lalancette
2008-10-30 7:43 ` Avi Kivity
2008-10-30 7:43 ` Avi Kivity
2008-10-30 7:52 ` Avi Kivity
2008-10-30 7:52 ` Avi Kivity
2008-10-29 9:31 ` Avi Kivity
2008-10-29 9:31 ` Avi Kivity
2008-10-27 15:05 ` Eric W. Biederman
2008-10-27 15:05 ` Eric W. Biederman
2008-10-27 15:50 ` Eduardo Habkost
2008-10-27 15:50 ` Eduardo Habkost
2008-10-27 8:54 ` Avi Kivity
2008-10-27 8:54 ` Avi Kivity
2008-10-27 13:09 ` Vivek Goyal
2008-10-27 13:09 ` Vivek Goyal
2008-10-27 14:04 ` Avi Kivity
2008-10-27 14:04 ` Avi Kivity
2008-10-29 20:10 ` Eduardo Habkost
2008-10-29 20:10 ` Eduardo Habkost
2008-10-29 20:29 ` Avi Kivity
2008-10-29 20:29 ` Avi Kivity
2008-10-29 21:05 ` Vivek Goyal
2008-10-29 21:05 ` Vivek Goyal
2008-10-30 0:58 ` Eric W. Biederman
2008-10-30 0:58 ` Eric W. Biederman
2008-10-26 21:47 ` Eric W. Biederman
2008-10-26 21:47 ` Eric W. Biederman
2008-10-27 8:59 ` Avi Kivity
2008-10-27 8:59 ` Avi Kivity
2008-10-27 15:02 ` Eric W. Biederman
2008-10-27 15:02 ` Eric W. Biederman
2008-10-27 15:38 ` Eduardo Habkost
2008-10-27 15:38 ` Eduardo Habkost
2008-10-26 12:46 ` Avi Kivity
2008-10-26 12:46 ` Avi Kivity
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