From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aurelien Jarno Subject: Re: KVM: Fix the invlpg instruction emulation on AMD64 Date: Tue, 16 Oct 2007 11:46:15 +0200 Message-ID: <47148867.9070600@aurel32.net> References: <20071015190823.GA11333@hall.aurel32.net> <47148403.6010603@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Avi Kivity Return-path: In-Reply-To: <47148403.6010603-atKUWr5tajBWk0Htik3J/w@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Avi Kivity a =E9crit : > Aurelien Jarno wrote: >> The patch below removes the check for c->modrm_reg =3D=3D 7 to detect th= e = >> invlpg instruction, as it was the case before before commit = >> aa38840d3d2e0a804e628077df8d8879b496d741. This fixes the boot of FreeBSD >> on an AMD64 CPU. >> >> It also moves the assignation of c->src.bytes after the test as it is >> not needed for the invlpg instruction. >> >> Signed-off-by: Aurelien Jarno >> >> diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c >> index fa33fcd..01aa952 100644 >> --- a/drivers/kvm/x86_emulate.c >> +++ b/drivers/kvm/x86_emulate.c >> @@ -824,12 +824,10 @@ modrm_done: >> c->src.bytes =3D 4; >> goto srcmem_common; >> case SrcMem: >> - c->src.bytes =3D (c->d & ByteOp) ? 1 : >> - c->op_bytes; >> /* Don't fetch the address for invlpg: it could be unmapped. */ >> - if (c->twobyte && c->b =3D=3D 0x01 >> - && c->modrm_reg =3D=3D 7) >> + if (c->twobyte && c->b =3D=3D 0x01) >> break; >> + c->src.bytes =3D (c->d & ByteOp) ? 1 : c->op_bytes; >> >> = > = > I don't understand why this helps. All of the other instructions in = > this group either have modrm_mod =3D=3D 3 or do require evaluation of the = ^^^^^^^^^ The test actually concerns modrm_reg and not modrm_mod. Maybe it is wrong? > source. invlpg is the only one that doesn't. I have marked the invlpg instruction the same way as it is done in kvm-37 to know what happens. I get either modrm_reg =3D 4 or =3D 6 when the invlpg instruction is executed, but never =3D 7. > It looks like this patch would break lgdt and lidt (which are only = > needed on Intel). > = I admit I haven't tried on Intel. -- = .''`. Aurelien Jarno | GPG: 1024D/F1BCDB73 : :' : Debian developer | Electrical Engineer `. `' aurel32-8fiUuRrzOP0dnm+yROfE0A@public.gmane.org | aurelien-rXXEIb44qovR7s880joybQ@public.gmane.org `- people.debian.org/~aurel32 | www.aurel32.net ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/