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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 365B0CE7B1A for ; Thu, 28 Sep 2023 18:42:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232178AbjI1Sm3 (ORCPT ); Thu, 28 Sep 2023 14:42:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231376AbjI1Sm2 (ORCPT ); Thu, 28 Sep 2023 14:42:28 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3A9111F for ; Thu, 28 Sep 2023 11:42:26 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EB518C433C7; Thu, 28 Sep 2023 18:42:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695926546; bh=4hpytdvRSL30OvRAK9aQteOIrJ4N4j+nW6AYJp3bba8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SEqjMMZlcpbl2xclT8khFZkc4L9ubcPnG8YOyIOAdrccm4LQZq7NAMB2Tich+AoNp 3cKCGEMD982eXenrNtfd9052Rcn9k1zZAL5UPlepZ+yvYr3E/PE9rbowUTL1soJNfT uNBQsXCWO+Qxze5hPP2wAWhcvvulv3QvjGrt366+ZcoZ0pWQP5PqLub7+zV3nyyX1t kpoeF7oTE5Xz3BvU9HF3QZmSTuwmbj1MNx9TtgwPR89M6wYgKaF1RPUI+omSpFznj4 WV82v6phhRtFxiArXMuj3npNLgB5eaoMOe48h7tt71HAnRtg9u2hjy4ys88khrOrmw BayHq7z7sTjJg== Date: Thu, 28 Sep 2023 21:42:22 +0300 From: Leon Romanovsky To: Alex Williamson Cc: Yishai Hadas , Jason Gunthorpe , kvm@vger.kernel.org, kevin.tian@intel.com, joao.m.martins@oracle.com, maorg@nvidia.com Subject: Re: [PATCH vfio 0/9] Add chunk mode support for mlx5 driver Message-ID: <20230928184222.GV1642130@unreal> References: <20230911093856.81910-1-yishaih@nvidia.com> <20230920183123.GJ13733@nvidia.com> <78298eea-b264-1739-9ded-7d8fa9c7208e@nvidia.com> <20230927161023.7e13c06f.alex.williamson@redhat.com> <20230928110808.GT1642130@unreal> <20230928122952.31af1d67.alex.williamson@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230928122952.31af1d67.alex.williamson@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Sep 28, 2023 at 12:29:52PM -0600, Alex Williamson wrote: > On Thu, 28 Sep 2023 14:08:08 +0300 > Leon Romanovsky wrote: > > > On Wed, Sep 27, 2023 at 04:10:23PM -0600, Alex Williamson wrote: > > > On Wed, 27 Sep 2023 13:59:06 +0300 > > > Yishai Hadas wrote: > > > > > > > On 20/09/2023 21:31, Jason Gunthorpe wrote: > > > > > On Mon, Sep 11, 2023 at 12:38:47PM +0300, Yishai Hadas wrote: > > > > >> This series adds 'chunk mode' support for mlx5 driver upon the migration > > > > >> flow. > > > > >> > > > > >> Before this series, we were limited to 4GB state size, as of the 4 bytes > > > > >> max value based on the device specification for the query/save/load > > > > >> commands. > > > > >> > > > > >> Once the device supports 'chunk mode' the driver can support state size > > > > >> which is larger than 4GB. > > > > >> > > > > >> In that case, the device has the capability to split a single image to > > > > >> multiple chunks as long as the software provides a buffer in the minimum > > > > >> size reported by the device. > > > > >> > > > > >> The driver should query for the minimum buffer size required using > > > > >> QUERY_VHCA_MIGRATION_STATE command with the 'chunk' bit set in its > > > > >> input, in that case, the output will include both the minimum buffer > > > > >> size and also the remaining total size to be reported/used where it will > > > > >> be applicable. > > > > >> > > > > >> Upon chunk mode, there may be multiple images that will be read from the > > > > >> device upon STOP_COPY. The driver will read ahead from the firmware the > > > > >> full state in small/optimized chunks while letting QEMU/user space read > > > > >> in parallel the available data. > > > > >> > > > > >> The chunk buffer size is picked up based on the minimum size that > > > > >> firmware requires, the total full size and some max value in the driver > > > > >> code which was set to 8MB to achieve some optimized downtime in the > > > > >> general case. > > > > >> > > > > >> With that series in place, we could migrate successfully a device state > > > > >> with a larger size than 4GB, while even improving the downtime in some > > > > >> scenarios. > > > > >> > > > > >> Note: > > > > >> As the first patch should go to net/mlx5 we may need to send it as a > > > > >> pull request format to VFIO to avoid conflicts before acceptance. > > > > >> > > > > >> Yishai > > > > >> > > > > >> Yishai Hadas (9): > > > > >> net/mlx5: Introduce ifc bits for migration in a chunk mode > > > > >> vfio/mlx5: Wake up the reader post of disabling the SAVING migration > > > > >> file > > > > >> vfio/mlx5: Refactor the SAVE callback to activate a work only upon an > > > > >> error > > > > >> vfio/mlx5: Enable querying state size which is > 4GB > > > > >> vfio/mlx5: Rename some stuff to match chunk mode > > > > >> vfio/mlx5: Pre-allocate chunks for the STOP_COPY phase > > > > >> vfio/mlx5: Add support for SAVING in chunk mode > > > > >> vfio/mlx5: Add support for READING in chunk mode > > > > >> vfio/mlx5: Activate the chunk mode functionality > > > > > I didn't check in great depth but this looks OK to me > > > > > > > > > > Reviewed-by: Jason Gunthorpe > > > > > > > > Thanks Jason > > > > > > > > > > > > > > I think this is a good design to start motivating more qmeu > > > > > improvements, eg using io_uring as we could go further in the driver > > > > > to optimize with that kind of support. > > > > > > > > > > Jason > > > > > > > > Alex, > > > > > > > > Can we move forward with the series and send a PR for the first patch > > > > that needs to go also to net/mlx5 ? > > > > > > Yeah, I don't spot any issues with it either. Thanks, > > > > Hi Alex, > > > > I uploaded the first patch to shared branch, can you please pull it? > > https://git.kernel.org/pub/scm/linux/kernel/git/mellanox/linux.git/log/?h=mlx5-vfio > > Yep, got it. Thanks. > > Yishai, were you planning to resend the remainder or do you just want > me to pull 2-9 from this series? Thanks, Just pull, like I did with b4 :) ~/src/b4/b4.sh shazam -l -s https://lore.kernel.org/kvm/20230911093856.81910-1-yishaih@nvidia.com/ -P 2-9 -t Thanks > > Alex >