Hi,
Le lundi 27 août 2018 à 11:34 +0200, Gerd Hoffmann a écrit :
> A driver to let userspace turn memfd regions into dma-bufs.
>
> Use case: Allows qemu create dmabufs for the vga framebuffer or
> virtio-gpu ressources. Then they can be passed around to display
> those guest things on the host. To spice client for classic full
> framebuffer display, and hopefully some day to wayland server for
> seamless guest window display.
>
> qemu test branch:
> https://git.kraxel.org/cgit/qemu/log/?h=sirius/udmabuf
>
> Cc: David Airlie <airl...@linux.ie>
> Cc: Tomeu Vizoso <tomeu.viz...@collabora.com>
> Cc: Laurent Pinchart <laurent.pinch...@ideasonboard.com>
> Cc: Daniel Vetter <dan...@ffwll.ch>
> Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
> Acked-by: Daniel Vetter <daniel.vet...@ffwll.ch>
> ---
> Documentation/ioctl/ioctl-number.txt | 1 +
> include/uapi/linux/udmabuf.h | 33 +++
> drivers/dma-buf/udmabuf.c | 287
> ++++++++++++++++++++++
> tools/testing/selftests/drivers/dma-buf/udmabuf.c | 96 ++++++++
> MAINTAINERS | 16 ++
> drivers/dma-buf/Kconfig | 8 +
> drivers/dma-buf/Makefile | 1 +
> tools/testing/selftests/drivers/dma-buf/Makefile | 5 +
> 8 files changed, 447 insertions(+)
> create mode 100644 include/uapi/linux/udmabuf.h
> create mode 100644 drivers/dma-buf/udmabuf.c
> create mode 100644 tools/testing/selftests/drivers/dma-buf/udmabuf.c
> create mode 100644 tools/testing/selftests/drivers/dma-buf/Makefile
>
> diff --git a/include/uapi/linux/udmabuf.h
> b/include/uapi/linux/udmabuf.h
> new file mode 100644
> index 0000000000..46b6532ed8
> --- /dev/null
> +++ b/include/uapi/linux/udmabuf.h
> @@ -0,0 +1,33 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +#ifndef _UAPI_LINUX_UDMABUF_H
> +#define _UAPI_LINUX_UDMABUF_H
> +
> +#include <linux/types.h>
> +#include <linux/ioctl.h>
> +
> +#define UDMABUF_FLAGS_CLOEXEC 0x01
> +
> +struct udmabuf_create {
> + __u32 memfd;
> + __u32 flags;
> + __u64 offset;
> + __u64 size;
> +};
> +
> +struct udmabuf_create_item {
> + __u32 memfd;
> + __u32 __pad;
> + __u64 offset;
> + __u64 size;
> +};
> +
> +struct udmabuf_create_list {
> + __u32 flags;
> + __u32 count;
> + struct udmabuf_create_item list[];
> +};
> +
> +#define UDMABUF_CREATE _IOW('u', 0x42, struct udmabuf_create)
> +#define UDMABUF_CREATE_LIST _IOW('u', 0x43, struct
> udmabuf_create_list)
> +
> +#endif /* _UAPI_LINUX_UDMABUF_H */
> diff --git a/drivers/dma-buf/udmabuf.c b/drivers/dma-buf/udmabuf.c
> new file mode 100644
> index 0000000000..8e24204526
> --- /dev/null
> +++ b/drivers/dma-buf/udmabuf.c
> +static long udmabuf_create(struct udmabuf_create_list *head,
> + struct udmabuf_create_item *list)
> +{
> + DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> + struct file *memfd = NULL;
> + struct udmabuf *ubuf;
> + struct dma_buf *buf;
> + pgoff_t pgoff, pgcnt, pgidx, pgbuf;
> + struct page *page;
> + int seals, ret = -EINVAL;
> + u32 i, flags;
> +
> + ubuf = kzalloc(sizeof(struct udmabuf), GFP_KERNEL);
> + if (!ubuf)
> + return -ENOMEM;
> +
> + for (i = 0; i < head->count; i++) {
You need to check .__pad for unsupported value:
if (list[i].__pad) {
ret = -EINVAL;
goto err_free_ubuf;
}
> + if (!IS_ALIGNED(list[i].offset, PAGE_SIZE))
> + goto err_free_ubuf;
> + if (!IS_ALIGNED(list[i].size, PAGE_SIZE))
> + goto err_free_ubuf;
> + ubuf->pagecount += list[i].size >> PAGE_SHIFT;
> + }
> + ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(struct page
> *),
> + GFP_KERNEL);
> + if (!ubuf->pages) {
> + ret = -ENOMEM;
> + goto err_free_ubuf;
> + }
> +
> + pgbuf = 0;
> + for (i = 0; i < head->count; i++) {
> + memfd = fget(list[i].memfd);
> + if (!memfd)
> + goto err_put_pages;
> + if (!shmem_mapping(file_inode(memfd)->i_mapping))
> + goto err_put_pages;
> + seals = memfd_fcntl(memfd, F_GET_SEALS, 0);
> + if (seals == -EINVAL ||
> + (seals & SEALS_WANTED) != SEALS_WANTED ||
> + (seals & SEALS_DENIED) != 0)
> + goto err_put_pages;
> + pgoff = list[i].offset >> PAGE_SHIFT;
> + pgcnt = list[i].size >> PAGE_SHIFT;
> + for (pgidx = 0; pgidx < pgcnt; pgidx++) {
> + page = shmem_read_mapping_page(
> + file_inode(memfd)->i_mapping, pgoff +
> pgidx);
> + if (IS_ERR(page)) {
> + ret = PTR_ERR(page);
> + goto err_put_pages;
> + }
> + ubuf->pages[pgbuf++] = page;
> + }
> + fput(memfd);
> + }
> + memfd = NULL;
> +
> + exp_info.ops = &udmabuf_ops;
> + exp_info.size = ubuf->pagecount << PAGE_SHIFT;
> + exp_info.priv = ubuf;
> +
> + buf = dma_buf_export(&exp_info);
> + if (IS_ERR(buf)) {
> + ret = PTR_ERR(buf);
> + goto err_put_pages;
> + }
> +
> + flags = 0;
You need to check .flags for unsupported value:
if (head->flags & ~UDMABUF_FLAGS_CLOEXEC)
return -EINVAL;
(at the beginning of the function, of course).
> + if (head->flags & UDMABUF_FLAGS_CLOEXEC)
> + flags |= O_CLOEXEC;
> + return dma_buf_fd(buf, flags);
> +
> +err_put_pages:
> + while (pgbuf > 0)
> + put_page(ubuf->pages[--pgbuf]);
> +err_free_ubuf:
> + fput(memfd);
> + kfree(ubuf->pages);
> + kfree(ubuf);
> + return ret;
> +}
> +
Regards
--
Yann Droneaud
OPTEYA
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