From: Avi Kivity <avi@qumranet.com>
To: Luca Tettamanti <kronos.it@gmail.com>
Cc: kvm-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] kvm: Fix x86 emulator writeback
Date: Wed, 20 Jun 2007 10:47:24 +0300 [thread overview]
Message-ID: <4678DB8C.4040200@qumranet.com> (raw)
In-Reply-To: <20070619204120.GA18800@dreamland.darkstar.lan>
Luca Tettamanti wrote:
> When the old value and new one are the same the emulator skips the
> write; this is undesiderable when the destination is a MMIO area and the
> write shall be performed regardless of the previous value. This
> optimization breaks e.g. a Linux guest APIC compiled without
> X86_GOOD_APIC.
>
> Remove the check and perform the writeback stage in the emulation unless
> it's explicitly disabled (currently push and some 2 bytes instructions
> may disable the writeback).
>
>
Applied both, thanks.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Luca Tettamanti <kronos.it-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 1/2] kvm: Fix x86 emulator writeback
Date: Wed, 20 Jun 2007 10:47:24 +0300 [thread overview]
Message-ID: <4678DB8C.4040200@qumranet.com> (raw)
In-Reply-To: <20070619204120.GA18800-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
Luca Tettamanti wrote:
> When the old value and new one are the same the emulator skips the
> write; this is undesiderable when the destination is a MMIO area and the
> write shall be performed regardless of the previous value. This
> optimization breaks e.g. a Linux guest APIC compiled without
> X86_GOOD_APIC.
>
> Remove the check and perform the writeback stage in the emulation unless
> it's explicitly disabled (currently push and some 2 bytes instructions
> may disable the writeback).
>
>
Applied both, thanks.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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next prev parent reply other threads:[~2007-06-20 7:57 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-03 21:34 [BUG] Oops with KVM-27 Luca Tettamanti
2007-06-03 21:34 ` Luca Tettamanti
2007-06-04 9:35 ` [kvm-devel] " Avi Kivity
2007-06-04 9:35 ` Avi Kivity
2007-06-04 20:22 ` [kvm-devel] " Luca Tettamanti
[not found] ` <20070604202248.GA18668-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-04 20:51 ` Avi Kivity
2007-06-04 20:51 ` [kvm-devel] " Avi Kivity
2007-06-04 21:22 ` Luca Tettamanti
2007-06-04 21:22 ` Luca Tettamanti
2007-06-05 7:27 ` [kvm-devel] " Avi Kivity
2007-06-05 7:27 ` Avi Kivity
2007-06-07 19:16 ` [kvm-devel] " Luca
2007-06-07 19:16 ` Luca
[not found] ` <68676e00706071216i4bd051c5hb1c114f3c13ab97f-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-10 12:22 ` Avi Kivity
2007-06-10 12:22 ` [kvm-devel] " Avi Kivity
2007-06-10 20:54 ` Luca
[not found] ` <68676e00706101354n5fe7e1a9y12cb690cae2924e3-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-11 7:44 ` Avi Kivity
2007-06-11 7:44 ` [kvm-devel] " Avi Kivity
2007-06-11 21:06 ` Luca
2007-06-12 6:44 ` Avi Kivity
[not found] ` <68676e00706111406r16eafd0eseaf1fb24f5c0d075-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-12 6:44 ` Avi Kivity
2007-06-12 17:52 ` [kvm-devel] " Luca Tettamanti
[not found] ` <20070612175246.GA5864-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-13 8:59 ` Avi Kivity
2007-06-13 8:59 ` [kvm-devel] " Avi Kivity
2007-06-13 20:49 ` Luca Tettamanti
2007-06-13 20:49 ` Luca Tettamanti
2007-06-14 8:26 ` [kvm-devel] " Avi Kivity
2007-06-14 8:26 ` Avi Kivity
[not found] ` <4670FBB5.70707-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-14 22:33 ` Luca Tettamanti
2007-06-14 22:33 ` [kvm-devel] " Luca Tettamanti
2007-06-14 22:53 ` Luca Tettamanti
2007-06-14 23:13 ` Luca Tettamanti
2007-06-14 23:27 ` Luca
2007-06-15 9:06 ` Avi Kivity
2007-06-15 9:06 ` Avi Kivity
2007-06-15 21:49 ` [kvm-devel] " Luca Tettamanti
2007-06-16 7:43 ` Avi Kivity
2007-06-16 7:43 ` Avi Kivity
2007-06-17 15:14 ` [kvm-devel] " Luca Tettamanti
2007-06-17 15:14 ` Luca Tettamanti
2007-06-17 15:24 ` [kvm-devel] " Avi Kivity
2007-06-17 16:52 ` [PATCH 1/2] kvm: Fix x86 emulator writeback Luca Tettamanti
2007-06-17 16:58 ` Avi Kivity
2007-06-17 16:58 ` Avi Kivity
2007-06-18 10:07 ` Avi Kivity
2007-06-18 10:07 ` Avi Kivity
2007-06-18 11:32 ` Avi Kivity
2007-06-18 11:32 ` Avi Kivity
2007-06-19 20:25 ` Luca Tettamanti
2007-06-19 20:25 ` Luca Tettamanti
2007-06-19 20:41 ` Luca Tettamanti
2007-06-19 20:41 ` Luca Tettamanti
2007-06-20 7:47 ` Avi Kivity [this message]
2007-06-20 7:47 ` Avi Kivity
2007-06-19 20:41 ` [PATCH 2/2] kvm: avoid useless memory write when possible Luca Tettamanti
2007-06-19 20:41 ` Luca Tettamanti
2007-06-17 16:52 ` Luca Tettamanti
[not found] ` <466CFD6D.2080201-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-11 21:06 ` [BUG] Oops with KVM-27 Luca
2007-06-12 17:52 ` Luca Tettamanti
[not found] ` <466BED18.5040708-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-10 20:54 ` Luca
[not found] ` <4663DCE9.3000107-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-04 20:22 ` Luca Tettamanti
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