From patchwork Wed Nov 1 13:16:06 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mattias Nissler X-Patchwork-Id: 13442829 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 0FA5BC4332F for ; Wed, 1 Nov 2023 13:17:25 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qyB5D-0000G2-Fg; Wed, 01 Nov 2023 09:16:31 -0400 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 1qyB5C-0000Fk-3e for qemu-devel@nongnu.org; Wed, 01 Nov 2023 09:16:30 -0400 Received: from mail-oo1-xc2a.google.com ([2607:f8b0:4864:20::c2a]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qyB59-0003cf-T4 for qemu-devel@nongnu.org; Wed, 01 Nov 2023 09:16:29 -0400 Received: by mail-oo1-xc2a.google.com with SMTP id 006d021491bc7-586cf3eccbeso2592118eaf.2 for ; Wed, 01 Nov 2023 06:16:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1698844586; x=1699449386; darn=nongnu.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=BtHevg6SDFOZoCNQO78iStIGCiDAqZmXuTORjfVCjXM=; b=zKlZguybxE1MkoRb2+lLk9McqvFXVYPzUErSYMnoDHTSzo4EyJn31dBcssE/HVwicU lxF1ECgH0HE2geKB0R1Mas5O4ZvxrZcf1aICFGQC8TxuYJgvNGmD76QVb6R4AgI+XUoS HLrPhdp+ZC7tz7IQGqZgKBGWT+PaujtI+PaTeGm2QEH7yiekKkDyVc+rjiR9b4r5EfEH qo3x26Fknvy/Sb2nu6NRCHp6Gt/niGD119F2WJ/I81J0CsMD8BfErRIowloEg8m0SbtG EOaSqxi91bhT5AsuhM5jcqxe/qoBrn83QKahwwej8uI2oX/hfpSfxpXd5sMLu2VLRWxm 7DgA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698844586; x=1699449386; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=BtHevg6SDFOZoCNQO78iStIGCiDAqZmXuTORjfVCjXM=; b=V77nF8jvahsafhxDWLIfwW86xSi9ijSsVZ0mO5czxTPmcuVF6NjvJDCkJyBjqZU1Ea R9Mr3Bct9q+7sMKHE2Q1558i3E3V4jYNlgVXwcZ4rchGupxQiwJfqUpREshlcJXyYuYS evQzkr0lLj6OFkkZM/le3Or3/XvZZ7qVcjFKb7bJovUZzK7P3cPY8Aar1gqt01cgTn5E S0aFKpv5YYmDTMTp1z2LURi9fslPYQkAWAYqsA7DOxH/7FlMI/0UKIF//EN4p2yhcKKX RT7WEysIT+BExKbF6Y+OHJJHMPkGO2uw+WnOZgX/oTM0Q2OtNyZpC8IkGNA/NycEuMbV dsrA== X-Gm-Message-State: AOJu0YzQn+zGUJvvTR/465JAi+rsx9LY4LlAtr3Laxj9eMVykL33APFN 2qJeP+TB3R7gHu0SbyKO1Sp4BQ== X-Google-Smtp-Source: AGHT+IEWcwEttcp/vEkEDPC+rJ6YQAUaO0TftteSe8V284vBlMfSAZ8xiDsUuk0aivNs8Fg6p1rLng== X-Received: by 2002:a05:6870:4154:b0:1e9:a050:3d60 with SMTP id r20-20020a056870415400b001e9a0503d60mr15680135oad.48.1698844586150; Wed, 01 Nov 2023 06:16:26 -0700 (PDT) Received: from mnissler.ba.rivosinc.com ([64.71.180.162]) by smtp.gmail.com with ESMTPSA id y6-20020a056870e3c600b001d4d8efa7f9sm238148oad.4.2023.11.01.06.16.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 01 Nov 2023 06:16:25 -0700 (PDT) From: Mattias Nissler To: stefanha@redhat.com, jag.raman@oracle.com, qemu-devel@nongnu.org, peterx@redhat.com Cc: john.levon@nutanix.com, David Hildenbrand , Marcel Apfelbaum , Paolo Bonzini , "Michael S. Tsirkin" , =?utf-8?q?Philippe_Mathieu-Daud=C3=A9?= , Elena Ufimtseva , Richard Henderson , Mattias Nissler Subject: [PATCH v6 0/5] Support message-based DMA in vfio-user server Date: Wed, 1 Nov 2023 06:16:06 -0700 Message-Id: <20231101131611.775299-1-mnissler@rivosinc.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::c2a; envelope-from=mnissler@rivosinc.com; helo=mail-oo1-xc2a.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org This series adds basic support for message-based DMA in qemu's vfio-user server. This is useful for cases where the client does not provide file descriptors for accessing system memory via memory mappings. My motivating use case is to hook up device models as PCIe endpoints to a hardware design. This works by bridging the PCIe transaction layer to vfio-user, and the endpoint does not access memory directly, but sends memory requests TLPs to the hardware design in order to perform DMA. Note that more work is needed to make message-based DMA work well: qemu currently breaks down DMA accesses into chunks of size 8 bytes at maximum, each of which will be handled in a separate vfio-user DMA request message. This is quite terrible for large DMA accesses, such as when nvme reads and writes page-sized blocks for example. Thus, I would like to improve qemu to be able to perform larger accesses, at least for indirect memory regions. I have something working locally, but since this will likely result in more involved surgery and discussion, I am leaving this to be addressed in a separate patch. Changes from v1: * Address Stefan's review comments. In particular, enforce an allocation limit and don't drop the map client callbacks given that map requests can fail when hitting size limits. * libvfio-user version bump now included in the series. * Tested as well on big-endian s390x. This uncovered another byte order issue in vfio-user server code that I've included a fix for. Changes from v2: * Add a preparatory patch to make bounce buffering an AddressSpace-specific concept. * The total buffer size limit parameter is now per AdressSpace and can be configured for PCIDevice via a property. * Store a magic value in first bytes of bounce buffer struct as a best effort measure to detect invalid pointers in address_space_unmap. Changes from v3: * libvfio-user now supports twin-socket mode which uses separate sockets for client->server and server->client commands, respectively. This addresses the concurrent command bug triggered by server->client DMA access commands. See https://github.com/nutanix/libvfio-user/issues/279 for details. * Add missing teardown code in do_address_space_destroy. * Fix bounce buffer size bookkeeping race condition. * Generate unmap notification callbacks unconditionally. * Some cosmetic fixes. Changes from v4: * Fix accidentally dropped memory_region_unref, control flow restored to match previous code to simplify review. * Some cosmetic fixes. Changes from v5: * Unregister indirect memory region in libvfio-user dma_unregister callback. I believe all patches in the series have been reviewed appropriately, so my hope is that this will be the final iteration. Stefan, Peter, Jag, thanks for your feedback, let me know if there's anything else needed from my side before this can get merged. Mattias Nissler (5): softmmu: Per-AddressSpace bounce buffering softmmu: Support concurrent bounce buffers Update subprojects/libvfio-user vfio-user: Message-based DMA support vfio-user: Fix config space access byte order hw/pci/pci.c | 8 ++ hw/remote/trace-events | 2 + hw/remote/vfio-user-obj.c | 104 +++++++++++++++++++++---- include/exec/cpu-common.h | 2 - include/exec/memory.h | 41 +++++++++- include/hw/pci/pci_device.h | 3 + subprojects/libvfio-user.wrap | 2 +- system/dma-helpers.c | 4 +- system/memory.c | 8 ++ system/physmem.c | 141 ++++++++++++++++++---------------- 10 files changed, 226 insertions(+), 89 deletions(-)