From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9360F5DF1D for ; Wed, 6 Mar 2024 14:58:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.176.79.56 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709737108; cv=none; b=oeeiort6id6Ixy9Tqkf6NKLohjdkq43RoG9I8UNBPFw9kmq/2E2HHlkDFLeDmmOZiN9dsfEvIdHl6hTdU9PYa2gMxqhxSYA3EzU3l5uC/BGfo2I3h4rA98jEJlITLtc7ARykKIIhPxFrjIIQoq686nWwI7iGxUO3A+Bcjyb23qI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709737108; c=relaxed/simple; bh=8xEGWgreU7mf+tbvnw8cS5ihC7lnADfy4Dcl+gE17PE=; h=Date:From:To:CC:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=LAN4f0e9MszzHP8XJMTBCjZQveOaylfXGdPLnp9837sWWejUskVka5SWZNrLRa9T5VqU1Vpgrc8XhjNT8efLIZvZ+iysHSc5V56CxMjBC3yW6aJ17Qwl+z//wW0vhFAXvUImnaPGFZAMnODZr2vHbMzrq0E63LBsi7V08FjFxfk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=185.176.79.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=Huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Tqb691fKtz6K62Z; Wed, 6 Mar 2024 22:53:37 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 79DFD140DDC; Wed, 6 Mar 2024 22:58:24 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.35; Wed, 6 Mar 2024 14:58:23 +0000 Date: Wed, 6 Mar 2024 14:58:23 +0000 From: Jonathan Cameron To: fan CC: , , , , , , , , , Fan Ni Subject: Re: [PATCH v4 08/10] hw/cxl/cxl-mailbox-utils: Add mailbox commands to support add/release dynamic capacity response Message-ID: <20240306145823.000028ee@Huawei.com> In-Reply-To: References: <20240221182020.1086096-1-nifan.cxl@gmail.com> <20240221182020.1086096-9-nifan.cxl@gmail.com> <20240226180417.00004dc4@Huawei.com> <20240227103909.00002a92@Huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-cxl@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: lhrpeml500004.china.huawei.com (7.191.163.9) To lhrpeml500005.china.huawei.com (7.191.163.240) ... > > > I cannot find anything specific to this in the specification either. > > > Since we have already detected the case where the extent range across > > > multiple regions, the only case we need to capture here is one/multiple > > > portions of an extents getting released and causing extent overflow. > > > I think we can handle it after we introduce the bitmaps (PATCH 10) which > > > indicates DPA ranges mapped by valid extents in the device. > > > > > > With that, The release workflow would be > > > > > > 1) detecting malformed extent lists; if passed > > > 2) do cxl_detect_extent_overflow { > > > delta = 0; > > > make a copy of the bitmap as bitmap_copy; > > > for each extent in the updated_extent_list; do > > > if (extent range not fully set in the bitmap_copy) > > > return error; > > > else { > > > if gap at the front based on the bitmap_copy: > > > delta += 1; > > > if gap at the end based on the bitmap_copy: > > > delta += 1; > > > delta -= 1; > > > // NOTE: current_extent_count will not be updated in the > > > // loop since delta will track the whole loop > > > if (delta + current_extent_count > max_extent_count) > > > return resource exhausted; > > > update bitmap_copy to clear the range covered by the extent > > > under consideration; > > > } > > > done > > > > > > }; if pass > > > 3. do real release: in the pass, we will not need to detect extent > > > errors; > > > > > > Does the above solution sound reasonable? If so, do we want to go this > > > way? do we need to introduce the bitmap earlier in the series? > > > > Yes, something along these lines should work nicely. > > > > Jonathan > > Hi Jonathan, > I updated the code based on your feedback and now we can process extent > release request more flexible. Excellent! > We can now support superset release (actually it can do even more, > as long as the DPA range is coverd by accepted extents, we can release). > > I have run following tests and the code works as expected, > 1. Add multiple extents, and removing them one by one, passed; > 2. Superset release: add multiple extents with continuous DPA ranges, and > remove all of them with a single release request with an extent covering the > whole DPA range, passed; > 3. Partial extent release: add a large extent and release only part of it, > passed; > 4. Partial+superset release: add multiple extents,and release it with some > leftover with one request with an extent. For example, add extents [0-128M] > and [128M-256M], release [64M-256M]. Passed; > 5. Release extent not aligned to block size, failed as expected; > 6. Extents have overlaps, fail the request as expected; > 7. Extent has uncovered DPA range, skip the extent as expected; > > The only limitation is that for superset release case, if we find > part of its DPA range is still pending to add, while the other is > accepted, we reject it through QMP interface. I think that is a reasonable limitation as we don't expect people to do that crazy on QMP side. Maybe long term we'll want a 'release all' type command (I'm thinking virtualized device usecases) but we can deal with that later. > > The latest code is https://github.com/moking/qemu/tree/dcd-v5. > > The main changes are in the last three commits. > Btw, in the last commit, I introduce new QMP interfaces to print out > accepted and pending-to-add list in the device to a file "/tmp/qmp.txt", > do we want it? If yes, I can polish it a little bit, otherwise I will > keep it for my own test purpose. Ah. I missed this mail and replied directly. That needs a rethink as the thread has concluded I think. I'll carry it on my tree, but not look to upstream it. > > I will test more and send out v5 if the above looks reasonable to you. > Sorry for slow reply - I'm a bit behind with mailing lists. Great you sent it out in the meantime. Jonathan