linux-kernel - Re: 2.6.23-rc1, KVM-AMD problem

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Message-Id: <200708041517.37895.prakash@punnoor.de>
Date:	Sat, 4 Aug 2007 15:17:34 +0200
From:	Prakash Punnoor <prakash@...noor.de>
To:	Avi Kivity <avi@...ranet.com>
Cc:	Alistair John Strachan <alistair@...zero.co.uk>,
	kvm-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Subject: Re: 2.6.23-rc1, KVM-AMD problem

Am Montag 30 Juli 2007 schrieb Avi Kivity:
> Alistair John Strachan wrote:
[...]
> > Basically, the installer seems to work fine, but Windows seemed to have
> > problems after installing post-SP2 updates. Maybe that's why not
> > everybody is seeing it yet.
>
> How about the attached patch? (I haven't yet tried to reproduce, but
> this can cause an AMD-only oops).

commit 80917728e43e248155c019f743655806b582b099
Author: Avi Kivity <avi@...ranet.com>
Date:   Mon Jul 30 15:56:36 2007 +0300

    KVM: x86 emulator: disable writeback for debug register instructions
    
    These are handled internally by the instruction.
    
    Signed-off-by: Avi Kivity <avi@...ranet.com>

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 1a90ba0..2136da5 100644
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -1222,11 +1222,13 @@ twobyte_insn:
                }
                break;
        case 0x21: /* mov from dr to reg */
+               no_wb = 1;
                if (modrm_mod != 3)
                        goto cannot_emulate;
                rc = emulator_get_dr(ctxt, modrm_reg, &_regs[modrm_rm]);
                break;
        case 0x23: /* mov from reg to dr */
+               no_wb = 1;
                if (modrm_mod != 3)
                        goto cannot_emulate;
                rc = emulator_set_dr(ctxt, modrm_reg, _regs[modrm_rm]);


Unfortunately this doesn't seem to have made it into 2.6.23-rc2. I need it as 
well, to make Windows XP boot up w/o hanging or reebooting my host machine.

Cheers,
-- 
(°=                 =°)
//\ Prakash Punnoor /\\
V_/                 \_V

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