From patchwork Thu Mar 7 15:53:03 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 13585959 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 437E9C48BF6 for ; Thu, 7 Mar 2024 15:53:57 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1riG3U-0001Fp-7F; Thu, 07 Mar 2024 10:53:12 -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 1riG3S-0001FW-4Z for qemu-devel@nongnu.org; Thu, 07 Mar 2024 10:53:10 -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 1riG3O-00018L-AE for qemu-devel@nongnu.org; Thu, 07 Mar 2024 10:53:09 -0500 Received: from mail.maildlp.com (unknown [172.18.186.231]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4TrDNC2tlHz6D8dw; Thu, 7 Mar 2024 23:52:59 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id BC884140D1D; Thu, 7 Mar 2024 23:53:02 +0800 (CST) Received: from SecurePC-101-06.china.huawei.com (10.122.247.231) 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; Thu, 7 Mar 2024 15:53:02 +0000 To: Paolo Bonzini , Eduardo Habkost , , CC: Peter Maydell , Gregory Price , =?utf-8?q?Alex_Benn=C3=A9e?= , Subject: [PATCH v3 0/1] target/i386: Fix page walking from MMIO memory. Date: Thu, 7 Mar 2024 15:53:03 +0000 Message-ID: <20240307155304.31241-1-Jonathan.Cameron@huawei.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-Originating-IP: [10.122.247.231] X-ClientProxiedBy: lhrpeml500002.china.huawei.com (7.191.160.78) To lhrpeml500005.china.huawei.com (7.191.163.240) 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, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-to: Jonathan Cameron X-Patchwork-Original-From: Jonathan Cameron via From: Jonathan Cameron Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Previously: tcg/i386: Page tables in MMIO memory fixes (CXL) Richard Henderson picked up patches 1 and 3 which were architecture independent leaving just this x86 specific patch. No change to the patch. Resending because it's hard to spot individual unapplied patches in a larger series. Original cover letter (edited). CXL memory is interleaved at granularities as fine as 64 bytes. To emulate this each read and write access undergoes address translation similar to that used in physical hardware. This is done using cfmws_ops for a memory region per CXL Fixed Memory Window (the PA address range in the host that is interleaved across host bridges and beyond. The OS programs interleaved decoders in the CXL Root Bridges, switch upstream ports and the corresponding decoders CXL type 3 devices who have to know the Host PA to Device PA mappings). Unfortunately this CXL memory may be used as normal memory and anything that can end up in RAM can be placed within it. As Linux has become more capable of handling this memory we've started to get quite a few bug reports for the QEMU support. However terrible the performance is people seem to like running actual software stacks on it :( This doesn't work for KVM - so for now CXL emulation remains TCG only. (unless you are very careful on how it is used!) I plan to add some safety guards at a later date to make it slightly harder for people to shoot themselves in the foot + a more limited set of CXL functionality that is safe (no interleaving!) Previously we had some issues with TCG reading instructions from CXL memory but that is now all working. This time the issues are around the Page Tables being in the CXL memory + DMA buffers being placed in it. The test setup I've been using is simple 2 way interleave via 2 root ports below a single CXL root complex. After configuration in Linux these are mapped to their own Numa Node and numactl --membind=1 ls followed by powering down the machine is sufficient to hit all the bugs addressed in this series. Thanks to Gregory, Peter and Alex for their help figuring this lot out. Whilst thread started back at: https://lore.kernel.org/all/CAAg4PaqsGZvkDk_=PH+Oz-yeEUVcVsrumncAgegRKuxe_YoFhA@mail.gmail.com/ The QEMU part is from. https://lore.kernel.org/all/20240201130438.00001384@Huawei.com/ Gregory Price (1): target/i386: Enable page walking from MMIO memory target/i386/tcg/sysemu/excp_helper.c | 57 +++++++++++++++------------- 1 file changed, 30 insertions(+), 27 deletions(-)