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 lists.gnu.org (lists.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 11720E68160 for ; Tue, 17 Feb 2026 10:14:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vsI62-0005aM-15; Tue, 17 Feb 2026 05:14:22 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vsI5u-0005Zz-W6 for qemu-devel@nongnu.org; Tue, 17 Feb 2026 05:14:15 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vsI5q-0004Or-Kf for qemu-devel@nongnu.org; Tue, 17 Feb 2026 05:14:14 -0500 Received: from mail.maildlp.com (unknown [172.18.224.107]) by frasgout.his.huawei.com (SkyGuard) with ESMTPS id 4fFb8M0MPtzJ46Dk; Tue, 17 Feb 2026 18:13:55 +0800 (CST) Received: from dubpeml500005.china.huawei.com (unknown [7.214.145.207]) by mail.maildlp.com (Postfix) with ESMTPS id F1C6040571; Tue, 17 Feb 2026 18:14:04 +0800 (CST) Received: from localhost (10.203.177.15) by dubpeml500005.china.huawei.com (7.214.145.207) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 17 Feb 2026 10:14:04 +0000 Date: Tue, 17 Feb 2026 10:14:02 +0000 To: Alireza Sanaee CC: , , , , , , , , , , , , , , Subject: Re: [PATCH v3 2/2] hw/cxl: Add a performant (and correct) path for the non interleaved cases Message-ID: <20260217101402.00006bef@huawei.com> In-Reply-To: <20260216145219.1959-3-alireza.sanaee@huawei.com> References: <20260216145219.1959-1-alireza.sanaee@huawei.com> <20260216145219.1959-3-alireza.sanaee@huawei.com> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.203.177.15] X-ClientProxiedBy: lhrpeml500009.china.huawei.com (7.191.174.84) To dubpeml500005.china.huawei.com (7.214.145.207) Received-SPF: pass client-ip=185.176.79.56; envelope-from=jonathan.cameron@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=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: , Reply-to: Jonathan Cameron From: Jonathan Cameron via qemu development Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, 16 Feb 2026 14:52:18 +0000 Alireza Sanaee wrote: > The CXL address to device decoding logic is complex because of the need > to correctly decode fine grained interleave. The current implementation > prevents use with KVM where executed instructions may reside in that > memory and gives very slow performance even in TCG. > > In many real cases non interleaved memory configurations are useful and > for those we can use a more conventional memory region alias allowing > similar performance to other memory in the system. > > Whether this fast path is applicable can be established once the full > set of HDM decoders has been committed (in whatever order the guest > decides to commit them). As such a check is performed on each > commit/uncommit of HDM decoder to establish if the alias should be added > or removed. > > Co-developed-by: Jonathan Cameron > Signed-off-by: Jonathan Cameron > Signed-off-by: Alireza Sanaee > Tested-by: Gregory Price It might be worth a middle patch that both adds the bool to cxl_cfmws_find_device() and implements actually performing the check. The usecase for that check would then come in reduced final patch. Maybe not worth it though and just have all that stuff in the second patch of two. J