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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: Mon, 18 Jun 2007 13:07:16 +0300	[thread overview]
Message-ID: <46765954.60102@qumranet.com> (raw)
In-Reply-To: <20070617165201.GA23885-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 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


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  parent reply	other threads:[~2007-06-18 10:07 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
     [not found] ` <20070603213432.GA3075-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-04  9:35   ` Avi Kivity
     [not found]     ` <4663DCE9.3000107-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-04 20:22       ` Luca Tettamanti
     [not found]     ` <20070604202248.GA18668@dreamland.darkstar.lan>
     [not found]       ` <20070604202248.GA18668-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-04 20:51         ` Avi Kivity
     [not found]       ` <46647B3E.2090205@qumranet.com>
     [not found]         ` <46647B3E.2090205-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-04 21:22           ` Luca Tettamanti
     [not found]             ` <20070604212207.GA22365-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-05  7:27               ` Avi Kivity
     [not found]                 ` <46651069.5040003-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-07 19:16                   ` Luca
     [not found]                     ` <68676e00706071216i4bd051c5hb1c114f3c13ab97f-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-10 12:22                       ` Avi Kivity
     [not found]                     ` <466BED18.5040708@qumranet.com>
     [not found]                       ` <466BED18.5040708-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-10 20:54                         ` Luca
     [not found]                       ` <68676e00706101354n5fe7e1a9y12cb690cae2924e3@mail.gmail.com>
     [not found]                         ` <68676e00706101354n5fe7e1a9y12cb690cae2924e3-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-11  7:44                           ` Avi Kivity
     [not found]                         ` <466CFD6D.2080201@qumranet.com>
     [not found]                           ` <466CFD6D.2080201-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-11 21:06                             ` Luca
2007-06-12 17:52                             ` Luca Tettamanti
     [not found]                           ` <68676e00706111406r16eafd0eseaf1fb24f5c0d075@mail.gmail.com>
     [not found]                             ` <68676e00706111406r16eafd0eseaf1fb24f5c0d075-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-12  6:44                               ` Avi Kivity
     [not found]                           ` <20070612175246.GA5864@dreamland.darkstar.lan>
     [not found]                             ` <20070612175246.GA5864-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-13  8:59                               ` Avi Kivity
     [not found]                             ` <466FB1ED.3090905@qumranet.com>
     [not found]                               ` <466FB1ED.3090905-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-13 20:49                                 ` Luca Tettamanti
     [not found]                                   ` <20070613204948.GA14710-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
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 22:53                                       ` [kvm-devel] " Luca Tettamanti
2007-06-14 23:13                                         ` Luca Tettamanti
2007-06-14 23:27                                           ` Luca
     [not found]                                             ` <68676e00706141627s3cb87391sa0ee6711d2f7933f-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2007-06-15  9:06                                               ` Avi Kivity
2007-06-15 21:49                                                 ` [kvm-devel] " Luca Tettamanti
     [not found]                                                   ` <20070615214915.GA10536-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-16  7:43                                                     ` Avi Kivity
     [not found]                                                       ` <4673949B.1070505-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
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
     [not found]                                                               ` <20070617165201.GA23885-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-17 16:58                                                                 ` Avi Kivity
2007-06-18 10:07                                                                 ` Avi Kivity [this message]
     [not found]                                                                   ` <46765954.60102-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-18 11:32                                                                     ` Avi Kivity
     [not found]                                                                       ` <46766D57.8040206-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-06-19 20:25                                                                         ` Luca Tettamanti
     [not found]                                                                           ` <20070619202524.GA17672-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
2007-06-19 20:41                                                                             ` Luca Tettamanti
     [not found]                                                                               ` <20070619204120.GA18800-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@public.gmane.org>
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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