From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58431) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a6iKD-0006Fn-S6 for qemu-devel@nongnu.org; Wed, 09 Dec 2015 12:14:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a6iKA-0002JT-0O for qemu-devel@nongnu.org; Wed, 09 Dec 2015 12:14:45 -0500 Received: from mail-io0-x22d.google.com ([2607:f8b0:4001:c06::22d]:33965) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a6iK9-0002JG-SC for qemu-devel@nongnu.org; Wed, 09 Dec 2015 12:14:41 -0500 Received: by ioir85 with SMTP id r85so66599033ioi.1 for ; Wed, 09 Dec 2015 09:14:41 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <56685631.50700@intel.com> References: <1448372127-28115-1-git-send-email-tianyu.lan@intel.com> <20151207165039.GA20210@redhat.com> <56685631.50700@intel.com> Date: Wed, 9 Dec 2015 09:14:41 -0800 Message-ID: From: Alexander Duyck Content-Type: text/plain; charset=UTF-8 Subject: Re: [Qemu-devel] live migration vs device assignment (motivation) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Lan, Tianyu" Cc: qemu-devel@nongnu.org, "Tantilov, Emil S" , kvm@vger.kernel.org, Ard Biesheuvel , aik@ozlabs.ru, "Skidmore, Donald C" , "Michael S. Tsirkin" , "Dong, Eddie" , "Jani, Nrupal" , quintela@redhat.com, Alexander Graf , Blue Swirl , cornelia.huck@de.ibm.com, Alex Williamson , kraxel@redhat.com, Anthony Liguori , amit.shah@redhat.com, Paolo Bonzini , "Rustad, Mark D" , lcapitulino@redhat.com, Or Gerlitz On Wed, Dec 9, 2015 at 8:26 AM, Lan, Tianyu wrote: > For other kind of devices, it's hard to work. > We are also adding migration support for QAT(QuickAssist Technology) device. > > QAT device user case introduction. > Server, networking, big data, and storage applications use QuickAssist > Technology to offload servers from handling compute-intensive operations, > such as: > 1) Symmetric cryptography functions including cipher operations and > authentication operations > 2) Public key functions including RSA, Diffie-Hellman, and elliptic curve > cryptography > 3) Compression and decompression functions including DEFLATE and LZS > > PCI hotplug will not work for such devices during migration and these > operations will fail when unplug device. I assume the problem is that with a PCI hotplug event you are losing the state information for the device, do I have that right? Looking over the QAT drivers it doesn't seem like any of them support the suspend/resume PM calls. I would imagine it makes it difficult for a system with a QAT card in it to be able to drop the system to a low power state. You might want to try enabling suspend/resume support for the devices on bare metal before you attempt to take on migration as it would provide you with a good testing framework to see what needs to be saved/restored within the device and in what order before you attempt to do the same while migrating from one system to another. - Alex