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: Mon, 18 Jun 2007 13:07:16 +0300 [thread overview]
Message-ID: <46765954.60102@qumranet.com> (raw)
In-Reply-To: <20070617165201.GA23885@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 always perform the writeback stage in the
> emulation.
>
>
Unfortunately, this kills Windows XP (first run with a guest crash,
second with a host oops), so I reverted it. I'd guess some operation
which doesn't need writeback ends up in the modified code. Previously,
the check caused it to skip writeback, but now it writes back random
memory, causing a crash.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2007-06-18 10:13 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-03 21:34 [BUG] Oops with KVM-27 Luca Tettamanti
2007-06-04 9:35 ` [kvm-devel] " Avi Kivity
2007-06-04 20:22 ` Luca Tettamanti
2007-06-04 20:51 ` Avi Kivity
2007-06-04 21:22 ` Luca Tettamanti
2007-06-05 7:27 ` Avi Kivity
2007-06-07 19:16 ` Luca
2007-06-10 12:22 ` Avi Kivity
2007-06-10 20:54 ` Luca
2007-06-11 7:44 ` Avi Kivity
2007-06-11 21:06 ` Luca
2007-06-12 6:44 ` Avi Kivity
2007-06-12 17:52 ` Luca Tettamanti
2007-06-13 8:59 ` Avi Kivity
2007-06-13 20:49 ` Luca Tettamanti
2007-06-14 8:26 ` Avi Kivity
2007-06-14 22:33 ` 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 21:49 ` Luca Tettamanti
2007-06-16 7:43 ` Avi Kivity
2007-06-17 15:14 ` Luca Tettamanti
2007-06-17 15:24 ` Avi Kivity
2007-06-17 16:52 ` [PATCH 1/2] kvm: Fix x86 emulator writeback Luca Tettamanti
2007-06-17 16:58 ` Avi Kivity
2007-06-18 10:07 ` Avi Kivity [this message]
2007-06-18 11:32 ` Avi Kivity
2007-06-19 20:25 ` Luca Tettamanti
2007-06-19 20:41 ` Luca Tettamanti
2007-06-20 7:47 ` Avi Kivity
2007-06-19 20:41 ` [PATCH 2/2] kvm: avoid useless memory write when possible Luca Tettamanti
2007-06-17 16:52 ` Luca Tettamanti
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