From: Gleb Natapov <gleb@redhat.com>
To: Jan Kiszka <jan.kiszka@web.de>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>, kvm <kvm@vger.kernel.org>
Subject: Re: [PATCH] qemu-kvm: x86: Fix mismerge in cpu_post_load
Date: Sun, 6 Dec 2009 12:56:15 +0200 [thread overview]
Message-ID: <20091206105615.GL20102@redhat.com> (raw)
In-Reply-To: <4B1B89DA.6030004@web.de>
On Sun, Dec 06, 2009 at 11:39:22AM +0100, Jan Kiszka wrote:
> >> Unlike the other states we discussed, this one
> >> is not "fixable" in the kernel. So I tend to think there is a real need
> >> for my write-back scope abstraction - which would also be able to handle
> >> the other states cleanly, both in upstream and here.
> >>
> >
> > Yes. Gleb suggested treating mpstate/nmi as part of the APIC state
> > (which makes sense), which would work, as APIC state is not
> > automatically written back. But the tsc msr would need special treatment.
>
> (just realized that I forgot to answer him)
>
> While this would make sense for mpstate, NMIs are not coupled to the
> APICs. The APIC just happens to be one source for them (though a common
> one). So if there is no in-kernel APIC state, there would never be a
> write-back of the NMI state, which is bad.
>
I agree about NMI. We never do RMW to NMI anyway. Mpstate/sipi_vector belong
to APIC state though.
--
Gleb.
next prev parent reply other threads:[~2009-12-06 10:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-12-03 18:21 [PATCH] qemu-kvm: x86: Fix mismerge in cpu_post_load Jan Kiszka
2009-12-06 9:54 ` Avi Kivity
2009-12-06 10:39 ` Jan Kiszka
2009-12-06 10:41 ` Avi Kivity
2009-12-06 10:56 ` Gleb Natapov [this message]
2009-12-06 10:33 ` Gleb Natapov
2009-12-06 10:44 ` Jan Kiszka
2009-12-06 10:49 ` Gleb Natapov
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