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Thu, 03 Aug 2023 16:55:15 -0700 (PDT) Received: from gurchetansingh0.mtv.corp.google.com ([2620:15c:a7:2:9efb:b80c:dd5c:56c9]) by smtp.gmail.com with ESMTPSA id d8-20020a63a708000000b0055387ffef10sm364329pgf.24.2023.08.03.16.55.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Aug 2023 16:55:15 -0700 (PDT) From: Gurchetan Singh X-Google-Original-From: Gurchetan Singh To: qemu-devel@nongnu.org Cc: kraxel@redhat.com, marcandre.lureau@redhat.com, akihiko.odaki@gmail.com, dmitry.osipenko@collabora.com, ray.huang@amd.com, alex.bennee@linaro.org, shentey@gmail.com, hi@alyssa.is Subject: [PATCH v3 9/9] docs/system: add basic virtio-gpu documentation Date: Thu, 3 Aug 2023 16:55:02 -0700 Message-Id: <20230803235502.373-10-gurchetansingh@google.com> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20230803235502.373-1-gurchetansingh@google.com> References: <20230803235502.373-1-gurchetansingh@google.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::c2c; envelope-from=gurchetansingh@chromium.org; helo=mail-oo1-xc2c.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-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+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Gurchetan Singh This adds basic documentation for virtio-gpu. Suggested-by: Akihiko Odaki Signed-off-by: Gurchetan Singh --- v2: - Incorporated suggestions by Akihiko Odaki - Listed the currently supported capset_names (Bernard) v3: - Incorporated suggestions by Akihiko Odaki and Alyssa Ross docs/system/device-emulation.rst | 1 + docs/system/devices/virtio-gpu.rst | 115 +++++++++++++++++++++++++++++ 2 files changed, 116 insertions(+) create mode 100644 docs/system/devices/virtio-gpu.rst diff --git a/docs/system/device-emulation.rst b/docs/system/device-emulation.rst index 4491c4cbf7..1167f3a9f2 100644 --- a/docs/system/device-emulation.rst +++ b/docs/system/device-emulation.rst @@ -91,6 +91,7 @@ Emulated Devices devices/nvme.rst devices/usb.rst devices/vhost-user.rst + devices/virtio-gpu.rst devices/virtio-pmem.rst devices/vhost-user-rng.rst devices/canokey.rst diff --git a/docs/system/devices/virtio-gpu.rst b/docs/system/devices/virtio-gpu.rst new file mode 100644 index 0000000000..2b8ecdac32 --- /dev/null +++ b/docs/system/devices/virtio-gpu.rst @@ -0,0 +1,115 @@ +.. + SPDX-License-Identifier: GPL-2.0 + +virtio-gpu +========== + +This document explains the setup and usage of the virtio-gpu device. +The virtio-gpu device paravirtualizes the GPU and display controller. + +Linux kernel support +-------------------- + +virtio-gpu requires a guest Linux kernel built with the +``CONFIG_DRM_VIRTIO_GPU`` option. + +QEMU virtio-gpu variants +------------------------ + +QEMU virtio-gpu device variants come in the following form: + + * ``virtio-vga[-BACKEND]`` + * ``virtio-gpu[-BACKEND][-INTERFACE]`` + * ``vhost-user-vga`` + * ``vhost-user-pci`` + +**Backends:** QEMU provides a 2D virtio-gpu backend, and two accelerated +backends: virglrenderer ('gl' device label) and rutabaga_gfx ('rutabaga' +device label). There is a vhost-user backend that runs the graphics stack +in a separate process for improved isolation. + +**Interfaces:** QEMU further categorizes virtio-gpu device variants based +on the interface exposed to the guest. The interfaces can be classified +into VGA and non-VGA variants. The VGA ones are prefixed with virtio-vga +or vhost-user-vga while the non-VGA ones are prefixed with virtio-gpu or +vhost-user-gpu. + +The VGA ones always use the PCI interface, but for the non-VGA ones, the +user can further pick between MMIO or PCI. For MMIO, the user can suffix +the device name with -device, though vhost-user-gpu does not support MMIO. +For PCI, the user can suffix it with -pci. Without these suffixes, the +platform default will be chosen. + +This document uses the PCI interface in examples. + +virtio-gpu 2d +------------- + +The default 2D backend only performs 2D operations. The guest needs to +employ a software renderer for 3D graphics. + +Typically, the software renderer is provided by `Mesa`_ or `SwiftShader`_. +Mesa's implementations (LLVMpipe, Lavapipe and virgl below) work out of box +on typical modern Linux distributions. + +.. parsed-literal:: + -device virtio-gpu-pci + +.. _Mesa: https://www.mesa3d.org/ +.. _SwiftShader: https://github.com/google/swiftshader + +virtio-gpu virglrenderer +------------------------ + +When using virgl accelerated graphics mode in the guest, OpenGL API calls +are translated into an intermediate representation (see `Gallium3D`_). The +intermediate representation is communicated to the host and the +`virglrenderer`_ library on the host translates the intermediate +representation back to OpenGL API calls. + +.. parsed-literal:: + -device virtio-gpu-gl-pci + +.. _Gallium3D: https://www.freedesktop.org/wiki/Software/gallium/ +.. _virglrenderer: https://gitlab.freedesktop.org/virgl/virglrenderer/ + +virtio-gpu rutabaga +------------------- + +virtio-gpu can also leverage `rutabaga_gfx`_ to provide `gfxstream`_ +rendering and `Wayland display passthrough`_. With the gfxstream rendering +mode, GLES and Vulkan calls are forwarded to the host with minimal +modification. + +The crosvm book provides directions on how to build a `gfxstream-enabled +rutabaga`_ and launch a `guest Wayland proxy`_. + +This device does require host blob support (``hostmem`` field below). The +``hostmem`` field specifies the size of virtio-gpu host memory window. +This is typically between 256M and 8G. + +Atleast one capset (see colon separated ``capset_names`` below) must be +specified when starting the device. The currently supported +``capset_names`` are ``gfxstream-vulkan`` and ``cross-domain`` on Linux +guests. For Android guests, ``gfxstream-gles`` is also supported. + +The device will try to auto-detect the wayland socket path if the +``cross-domain`` capset name is set. The user may optionally specify +``wayland_socket_path`` for non-standard paths. + +The ``wsi`` option can be set to ``surfaceless`` or ``headless``. +Surfaceless doesn't create a native window surface, but does copy from the +render target to the Pixman buffer if a virtio-gpu 2D hypercall is issued. +Headless is like surfaceless, but doesn't copy to the Pixman buffer. +Surfaceless is the default if ``wsi`` is not specified. + +.. parsed-literal:: + -device virtio-gpu-rutabaga-pci,capset_names=gfxstream-vulkan:cross-domain, + hostmem=8G,wayland_socket_path="$XDG_RUNTIME_DIR/$WAYLAND_DISPLAY", + wsi=headless + +.. _rutabaga_gfx: https://github.com/google/crosvm/blob/main/rutabaga_gfx/ffi/src/include/rutabaga_gfx_ffi.h +.. _gfxstream: https://android.googlesource.com/platform/hardware/google/gfxstream/ +.. _Wayland display passthrough: https://www.youtube.com/watch?v=OZJiHMtIQ2M +.. _gfxstream-enabled rutabaga: https://crosvm.dev/book/appendix/rutabaga_gfx.html +.. _guest Wayland proxy: https://crosvm.dev/book/devices/wayland.html