From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NmV07-0003PD-UI for qemu-devel@nongnu.org; Tue, 02 Mar 2010 11:31:16 -0500 Received: from [199.232.76.173] (port=47218 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NmV07-0003OX-8G for qemu-devel@nongnu.org; Tue, 02 Mar 2010 11:31:15 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1NmV05-000539-If for qemu-devel@nongnu.org; Tue, 02 Mar 2010 11:31:15 -0500 Received: from thoth.sbs.de ([192.35.17.2]:16208) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NmV05-00052s-1H for qemu-devel@nongnu.org; Tue, 02 Mar 2010 11:31:13 -0500 Message-ID: <4B8D3D4D.8080601@siemens.com> Date: Tue, 02 Mar 2010 17:31:09 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <2257cac7474705fc35d74fcdff0566fb7dc0770e.1267467030.git.jan.kiszka@siemens.com> <20100302001415.GA22627@amt.cnet> <4B8CC584.1060106@web.de> <20100302115531.GA19713@amt.cnet> In-Reply-To: <20100302115531.GA19713@amt.cnet> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit 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: Marcelo Tosatti Cc: Avi Kivity , kvm@vger.kernel.org, qemu-devel@nongnu.org Marcelo Tosatti wrote: > On Tue, Mar 02, 2010 at 09:00:04AM +0100, Jan Kiszka wrote: >> 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). >>> >>> Screenshot attached. >>> >> Strange - no issues with qemu-kvm? Any special command line switch? /me >> goes scrounging for some installation XP32 CD in the meantime... > > No issues with qemu-kvm. Could not spot anything obvious. > And, of course, my WinXP installation did not trigger any reset issue, even in non-iothreaded mode. :( Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux