e5cd6cbe02
This patch adds a new virtgpu feature that allows directly mapping host allocated resources. This is based on virtio shared memory regions, which allows querying for memory regions using PCI transport. Each shared memory region has an associated "shmid", the meaning of which is device specific. For virtio-gpu, we can define the shared memory region with id VIRTIO_GPU_SHM_ID_HOST_VISIBLE to be the "host visible memory region". The presence of the host visible memory region means the following hypercalls are supported: 1) VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB This hypercall tells the host to inject the host resource's mapping in an offset into virtio-gpu's PCI address space. This is typically done via KVM_SET_USER_MEMORY_REGION on Linux hosts. On success, VIRTIO_GPU_RESP_OK_MAP_INFO is returned, which specifies the host buffer's caching type and possibly in the future performance hints about the buffer.. 2) VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB This hypercall tells the host to remove the host resource's mapping from the guest VM. Signed-off-by: Gerd Hoffmann <kraxel@redhat.com> Acked-by: Tomeu Vizoso <tomeu.vizoso@collabora.com> Acked-by: Lingfeng Yang <lfy@google.com> Link: http://patchwork.freedesktop.org/patch/msgid/20200924003214.662-4-gurchetansingh@chromium.org Co-developed-by: Gurchetan Singh <gurchetansingh@chromium.org> Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.