Messages in this thread | | | Date | Thu, 19 Jun 2014 14:23:56 +0300 | From | Gleb Natapov <> | Subject | Re: [PATCH 3/3] KVM: x86: correct mwait and monitor emulation |
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On Thu, Jun 19, 2014 at 01:53:36PM +0300, Nadav Amit wrote: > > On Jun 19, 2014, at 1:18 PM, Michael S. Tsirkin <mst@redhat.com> wrote: > > > On Wed, Jun 18, 2014 at 02:46:01PM -0400, Gabriel L. Somlo wrote: > >> On Wed, Jun 18, 2014 at 10:59:14AM -0700, Eric Northup wrote: > >>> On Wed, Jun 18, 2014 at 7:19 AM, Nadav Amit <namit@cs.technion.ac.il> wrote: > >>>> mwait and monitor are currently handled as nop. Considering this behavior, they > >>>> should still be handled correctly, i.e., check execution conditions and generate > >>>> exceptions when required. mwait and monitor may also be executed in real-mode > >>>> and are not handled in that case. This patch performs the emulation of > >>>> monitor-mwait according to Intel SDM (other than checking whether interrupt can > >>>> be used as a break event). > >>>> > >>>> Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> > >> > >> How about this instead (details in the commit log below) ? Please let > >> me know what you think, and if you'd prefer me to send it out as a > >> separate patch rather than a reply to this thread. > >> > >> Thanks, > >> --Gabriel > > > > If there's an easy workaround, I'm inclined to agree. > > We can always go back to Gabriel's patch (and then we'll need > > Nadav's one too) but if we release a kernel with this > > support it becomes an ABI and we can't go back. > > > > So let's be careful here, and revert the hack for 3.16. > > > > > > Acked-by: Michael S. Tsirkin <mst@redhat.com> > > > Personally, I got a custom guest which requires mwait for executing correctly. Can you elaborate on this guest a little bit. With nop implementation for mwait the guest will hog a host cpu. Do you consider this to be "executing correctly?"
-- Gleb.
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