From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CE4B9C43458 for ; Mon, 6 Jul 2026 13:05:36 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wgj0c-0002MF-QF; Mon, 06 Jul 2026 09:05:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wgj0X-0002LA-L9 for qemu-devel@nongnu.org; Mon, 06 Jul 2026 09:05:09 -0400 Received: from linux.microsoft.com ([13.77.154.182]) by eggs.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wgj0V-0002Ue-Tm for qemu-devel@nongnu.org; Mon, 06 Jul 2026 09:05:09 -0400 Received: from example.com (unknown [167.220.208.42]) by linux.microsoft.com (Postfix) with ESMTPSA id D353F20B716B; Mon, 6 Jul 2026 06:04:59 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com D353F20B716B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1783343102; bh=42ZU0Iw+ebDa0/X5YhAcUnBEM087OQr1GBPIsBa3FnA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=nZ9OJYHR63/bEOzubXphlQMJ7E1M4wExiXdSbfdHvzASazJByZiZh792Q+8afv4z8 DdfFlS9aaPFEOH4tHQP6l1IYG0EUAMIMpvsiOCz855WIkcbXFONjUx4JPRkLfXyxLY 0F/HyOZdF6HEJXz4mkwRo6IICRFtyJMhKYNbVTAQ= Date: Mon, 6 Jul 2026 15:05:00 +0200 From: Magnus Kulke To: Paolo Bonzini Cc: qemu-devel , kvm , Magnus Kulke , Wei Liu , "Michael S. Tsirkin" , =?iso-8859-1?Q?C=E9dric?= Le Goater , Zhao Liu , Richard Henderson , Wei Liu , Alex Williamson , Marcel Apfelbaum , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= , Marcelo Tosatti Subject: Re: [PATCH 26/34] accel/mshv: introduce SaveVMHandler Message-ID: References: <20260417105618.3621-1-magnuskulke@linux.microsoft.com> <20260417105618.3621-27-magnuskulke@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Received-SPF: pass client-ip=13.77.154.182; envelope-from=magnuskulke@linux.microsoft.com; helo=linux.microsoft.com X-Spam_score_int: -19 X-Spam_score: -2.0 X-Spam_bar: -- X-Spam_report: (-2.0 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, Jul 03, 2026 at 07:50:43PM +0200, Paolo Bonzini wrote: > There are different "schools of thought" for that. Freezing introduces an > incorrect timing on the destination, not freezing introduces a jump. > > If you choose to freeze that's fine, QEMU does the same for KVM even though > KVM has alternative ioctls that allow not freezing. > > But currently it's the wrong > > place. I'll find some more fitting place to perform this ceremony. > > > > KVM uses a device for that, see kvnclock.c. Makes sense, kvmclock looks like a good template. I'll use a similar object. > > Curiously the time-frozen source was obscuring another potentially more > > serious bug. The mshv vcpu dispatch loop currently does not honor a > > cpu->exit_request > > > Was that related to the other patch that was touching the vcpu thread loop? > yup, we need the same here, I'll address it as part of a migration-pt2 series. we only need to check for cpu->exit_request and break the loop if set. best, magnus