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 ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (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 887CFCE79AE for ; Wed, 20 Sep 2023 07:06:53 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id E76CE42C31 for ; Wed, 20 Sep 2023 07:06:52 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id DEEBD986675 for ; Wed, 20 Sep 2023 07:06:52 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id D4086986669; Wed, 20 Sep 2023 07:06:52 +0000 (UTC) Mailing-List: contact virtio-dev-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id C2E98986667; Wed, 20 Sep 2023 07:06:47 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-IronPort-AV: E=McAfee;i="6600,9927,10838"; a="380045501" X-IronPort-AV: E=Sophos;i="6.02,161,1688454000"; d="scan'208";a="380045501" X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10838"; a="812032857" X-IronPort-AV: E=Sophos;i="6.02,161,1688454000"; d="scan'208";a="812032857" Message-ID: <701bb67c-c52d-4eb3-a6ed-f73bd5d0ff33@intel.com> Date: Wed, 20 Sep 2023 15:06:33 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Firefox/102.0 Thunderbird/102.15.1 Content-Language: en-US To: Parav Pandit , "Chen, Jiqian" , "Michael S. Tsirkin" Cc: Gerd Hoffmann , Jason Wang , Xuan Zhuo , David Airlie , Gurchetan Singh , Chia-I Wu , =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , Robert Beckett , Mikhail Golubev-Ciuchea , "virtio-comment@lists.oasis-open.org" , "virtio-dev@lists.oasis-open.org" , "qemu-devel@nongnu.org" , "linux-kernel@vger.kernel.org" , Stefano Stabellini , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , "Deucher, Alexander" , "Koenig, Christian" , "Hildebrand, Stewart" , Xenia Ragiadakou , "Huang, Honglei1" , "Zhang, Julia" , "Huang, Ray" References: <20230919114242.2283646-1-Jiqian.Chen@amd.com> <20230919114242.2283646-2-Jiqian.Chen@amd.com> <20230919082802-mutt-send-email-mst@kernel.org> From: "Zhu, Lingshan" In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [virtio-dev] Re: [virtio-comment] Re: [VIRTIO PCI PATCH v5 1/1] transport-pci: Add freeze_mode to virtio_pci_common_cfg On 9/20/2023 2:58 PM, Parav Pandit wrote: >> From: Chen, Jiqian >> Sent: Wednesday, September 20, 2023 12:03 PM >> If driver write 0 to reset device, can the SUSPEND bit be cleared? > It must as reset operation, resets everything else and so the suspend too. > >> (pci_pm_resume->virtio_pci_restore->virtio_device_restore- >>> virtio_reset_device) >> If SUSPEND is cleared, then during the reset process in Qemu, I can't judge if >> the reset request is from guest restore process or not, and then I can't change >> the reset behavior. > Reset should not be influenced by suspend. > Suspend should do the work of suspend and reset to do the reset. > > The problem to overcome in [1] is, resume operation needs to be synchronous as it involves large part of context to resume back, and hence just asynchronously setting DRIVER_OK is not enough. > The sw must verify back that device has resumed the operation and ready to answer requests. this is not live migration, all device status and other information still stay in the device, no need to "resume" context, just resume running. Like resume from a failed LM. > > This is slightly different flow than setting the DRIVER_OK for the first time device initialization sequence as it does not involve large restoration. > > So, to merge two ideas, instead of doing DRIVER_OK to resume, the driver should clear the SUSPEND bit and verify that it is out of SUSPEND. > > Because driver is still in _OK_ driving the device flipping the SUSPEND bit. Please read the spec, it says: The driver MUST NOT clear a device status bit --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org