From patchwork Tue Sep 19 16:08:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mattias Nissler X-Patchwork-Id: 13391592 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 8B2BBCE79A9 for ; Tue, 19 Sep 2023 16:10:20 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qidHS-0001ox-9G; Tue, 19 Sep 2023 12:08:54 -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 1qidHL-0001nH-QQ for qemu-devel@nongnu.org; Tue, 19 Sep 2023 12:08:47 -0400 Received: from mail-pl1-x62c.google.com ([2607:f8b0:4864:20::62c]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1qidHG-0004gC-Ke for qemu-devel@nongnu.org; Tue, 19 Sep 2023 12:08:44 -0400 Received: by mail-pl1-x62c.google.com with SMTP id d9443c01a7336-1c43166b7e5so40513175ad.3 for ; Tue, 19 Sep 2023 09:08:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rivosinc-com.20230601.gappssmtp.com; s=20230601; t=1695139720; x=1695744520; 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=p6Dfw5nXdG1KaTAXJxxWtlHGXg9g55Oz1nL1iQCVLII=; b=sj2H+zCB7SN6usjCUb8N15cuPmpI5tA8/ows9Q0dH+tXzunkV0xcwOZKv0PAc1U4ay JTwPaQYqEx2dGNeBlQ1aKddMj+xWvgVeRbL0mNPx0brzlHkh7l9l7N73JXbWuTtruXEu j9zTAH0+0znkBrnIeGosIK5QHepllty8zwxfPuW7F3TQ+hbHrGtvL36xvNNWq9NCDou9 tV3Xh4L/+8FH5KTjjOKXlltLUA76HO3VlwNzgFoCFqfYrGi8q5un2CM4h86SkReYOfZ4 aDAFapOHTbr0tdZQLbDNwFu6Ak/q/huv52EocKtYzEro50JxGtSLxCf1QRO7XHGkbOXa sTfg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1695139720; x=1695744520; 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=p6Dfw5nXdG1KaTAXJxxWtlHGXg9g55Oz1nL1iQCVLII=; b=NBfe4P6I49Ijssf1CuHz3Wj5uhEErOicHrhbO+nt/T9sYymD0pqA6UXYTIKQyC39zS xrtpCfpJ9a9aLvfRf6WXMh+1juoX+tvvriNZ7m0d337Y6bJ/+FkGe4l5g3dWEfL0Tw1F oTjdMs1KLcXIJUeH0mlvVN3jjESf/3PpVQ1yy+LUCF9+ca9hiruI4cxkXJ0lseFNfiyz R2M2BhUCHNXaLhsc7FX/qgI05esR8r9y9lBhSRLf3aIJrR7Pe1V9nJYIsSVS5sf4xLKo tTyKPTSizeBM9NPshtfvxvb1qkmlt2+x3QP3C8Dr6aLC8Xa4rHspc+Pj36mDQq9wQ+Yl Glww== X-Gm-Message-State: AOJu0YyymSTlcSbrJQ5/4o7QvBWvU2h+ThE6fLMFjMIqUGF6dUEjyRzl wcNxECmVg/57wpsSDaDCO9eCS31bzBaIIc8yPFA= X-Google-Smtp-Source: AGHT+IETLhW1Fut5+eOnAyzrkY4B7disx5+mUBEQ1iT4KmnIaU8GOIdRWkfJGRfl1A+3Q1Af6x2c2w== X-Received: by 2002:a17:902:9684:b0:1b8:8af0:416f with SMTP id n4-20020a170902968400b001b88af0416fmr11306642plp.1.1695139720283; Tue, 19 Sep 2023 09:08:40 -0700 (PDT) Received: from mnissler.ba.rivosinc.com ([66.220.2.162]) by smtp.gmail.com with ESMTPSA id l9-20020a170902d34900b001b8a1a25e6asm8086308plk.128.2023.09.19.09.08.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Sep 2023 09:08:39 -0700 (PDT) From: Mattias Nissler To: qemu-devel@nongnu.org Cc: john.levon@nutanix.com, stefanha@redhat.com, Richard Henderson , Elena Ufimtseva , "Michael S. Tsirkin" , Paolo Bonzini , Jagannathan Raman , Peter Xu , David Hildenbrand , Marcel Apfelbaum , =?utf-8?q?Philippe_Mathieu-D?= =?utf-8?q?aud=C3=A9?= , Mattias Nissler Subject: [PATCH v4 0/5] Support message-based DMA in vfio-user server Date: Tue, 19 Sep 2023 09:08:08 -0700 Message-Id: <20230919160814.3343727-1-mnissler@rivosinc.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::62c; envelope-from=mnissler@rivosinc.com; helo=mail-pl1-x62c.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 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. 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 | 88 ++++++++++++++++++-- include/exec/cpu-common.h | 2 - include/exec/memory.h | 41 +++++++++- include/hw/pci/pci_device.h | 3 + softmmu/dma-helpers.c | 4 +- softmmu/memory.c | 8 ++ softmmu/physmem.c | 149 ++++++++++++++++++---------------- subprojects/libvfio-user.wrap | 2 +- 10 files changed, 221 insertions(+), 86 deletions(-)