From: "Joerg Roedel" <joerg.roedel-5C7GfCeVMHo@public.gmane.org>
To: "Avi Kivity" <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: Re: [PATCH] SVM: forbid guest to execute monitor/mwait
Date: Thu, 22 Mar 2007 12:56:02 +0100 [thread overview]
Message-ID: <20070322115602.GF20139@amd.com> (raw)
In-Reply-To: <46026B2A.2080501-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
On Thu, Mar 22, 2007 at 01:40:26PM +0200, Avi Kivity wrote:
> Joerg Roedel wrote:
> >Right. But it is possible for userspace to enable monitor bit for the
> >guest. Without virtualization of these 2 instructions the guest would
> >idle in the guest state after calling mwait and prevent other processes
> >and guests from running in that time.
>
> Won't an interrupt during mwait cause a vmexit?
Yes, an interrupt would cause an vmexit. But depending on the HZ value
of the host it may be a lot of time until the next interrupt. And over
time this will sum up and slow down other tasks.
Joerg
--
Joerg Roedel
Operating System Research Center
AMD Saxony LLC & Co. KG
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next prev parent reply other threads:[~2007-03-22 11:56 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-21 18:47 [PATCH] SVM: forbid guest to execute monitor/mwait Joerg Roedel
[not found] ` <20070321184700.GA20139-5C7GfCeVMHo@public.gmane.org>
2007-03-22 7:38 ` Avi Kivity
[not found] ` <46023264.4010105-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-22 9:56 ` Joerg Roedel
[not found] ` <20070322095605.GB20139-5C7GfCeVMHo@public.gmane.org>
2007-03-22 10:06 ` Avi Kivity
[not found] ` <46025528.5010707-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-22 10:17 ` Joerg Roedel
[not found] ` <20070322101729.GC20139-5C7GfCeVMHo@public.gmane.org>
2007-03-22 10:42 ` Avi Kivity
[not found] ` <46025D94.8050606-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-22 11:07 ` Joerg Roedel
[not found] ` <20070322110733.GE20139-5C7GfCeVMHo@public.gmane.org>
2007-03-22 11:40 ` Avi Kivity
[not found] ` <46026B2A.2080501-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-22 11:56 ` Joerg Roedel [this message]
[not found] ` <20070322115602.GF20139-5C7GfCeVMHo@public.gmane.org>
2007-03-22 12:01 ` Avi Kivity
[not found] ` <4602700E.1030500-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-22 12:22 ` Joerg Roedel
[not found] ` <20070322122249.GG20139-5C7GfCeVMHo@public.gmane.org>
2007-03-22 12:33 ` Avi Kivity
[not found] ` <460277AE.9040403-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-22 12:46 ` Joerg Roedel
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