From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 1/2] kvm: Fix x86 emulator writeback Date: Wed, 20 Jun 2007 10:47:24 +0300 Message-ID: <4678DB8C.4040200@qumranet.com> References: <68676e00706141627s3cb87391sa0ee6711d2f7933f@mail.gmail.com> <467256AA.1040001@qumranet.com> <20070615214915.GA10536@dreamland.darkstar.lan> <4673949B.1070505@qumranet.com> <20070617151452.GA21971@dreamland.darkstar.lan> <4675523C.9020703@qumranet.com> <20070617165201.GA23885@dreamland.darkstar.lan> <46765954.60102@qumranet.com> <46766D57.8040206@qumranet.com> <20070619202524.GA17672@dreamland.darkstar.lan> <20070619204120.GA18800@dreamland.darkstar.lan> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Luca Tettamanti Return-path: In-Reply-To: <20070619204120.GA18800-sTXFmx6KbOnUXq0IF5SVAZ4oGUkBHcCu@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 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. ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/