From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Npnl1-0006ei-50 for qemu-devel@nongnu.org; Thu, 11 Mar 2010 14:09:19 -0500 Received: from [199.232.76.173] (port=39331 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Npnl0-0006di-JV for qemu-devel@nongnu.org; Thu, 11 Mar 2010 14:09:18 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Npnky-0000nO-Qw for qemu-devel@nongnu.org; Thu, 11 Mar 2010 14:09:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:59224) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Npnky-0000n8-BT for qemu-devel@nongnu.org; Thu, 11 Mar 2010 14:09:16 -0500 Date: Thu, 11 Mar 2010 15:49:51 -0300 From: Marcelo Tosatti Message-ID: <20100311184951.GB17264@amt.cnet> References: <2257cac7474705fc35d74fcdff0566fb7dc0770e.1267467030.git.jan.kiszka@siemens.com> <20100302001415.GA22627@amt.cnet> <4B98AAB2.7020202@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B98AAB2.7020202@redhat.com> Subject: [Qemu-devel] Re: [PATCH 2/4] KVM: Rework VCPU state writeback API List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Jan Kiszka , qemu-devel@nongnu.org, kvm@vger.kernel.org On Thu, Mar 11, 2010 at 10:32:50AM +0200, Avi Kivity wrote: > On 03/02/2010 02:14 AM, Marcelo Tosatti wrote: > >On Mon, Mar 01, 2010 at 07:10:30PM +0100, Jan Kiszka wrote: > >>This grand cleanup drops all reset and vmsave/load related > >>synchronization points in favor of four(!) generic hooks: > >> > >>- cpu_synchronize_all_states in qemu_savevm_state_complete > >> (initial sync from kernel before vmsave) > >>- cpu_synchronize_all_post_init in qemu_loadvm_state > >> (writeback after vmload) > >>- cpu_synchronize_all_post_init in main after machine init > >>- cpu_synchronize_all_post_reset in qemu_system_reset > >> (writeback after system reset) > >> > >>These writeback points + the existing one of VCPU exec after > >>cpu_synchronize_state map on three levels of writeback: > >> > >>- KVM_PUT_RUNTIME_STATE (during runtime, other VCPUs continue to run) > >>- KVM_PUT_RESET_STATE (on synchronous system reset, all VCPUs stopped) > >>- KVM_PUT_FULL_STATE (on init or vmload, all VCPUs stopped as well) > >> > >>This level is passed to the arch-specific VCPU state writing function > >>that will decide which concrete substates need to be written. That way, > >>no writer of load, save or reset functions that interact with in-kernel > >>KVM states will ever have to worry about synchronization again. That > >>also means that a lot of reasons for races, segfaults and deadlocks are > >>eliminated. > >> > >>cpu_synchronize_state remains untouched, just as Anthony suggested. We > >>continue to need it before reading or writing of VCPU states that are > >>also tracked by in-kernel KVM subsystems. > >> > >>Consequently, this patch removes many cpu_synchronize_state calls that > >>are now redundant, just like remaining explicit register syncs. > >> > >>Signed-off-by: Jan Kiszka > >Jan, > > > >This patch breaks system reset of WinXP.32 install (more easily > >reproducible without iothread enabled). > > > > What's the conclusion here? The patch is innocent of the regression? Yes, it is. The problem was caused by a recent seabios change, now fixed.