On Fri, May 25, 2018 at 04:08:08PM +0200, Gerd Hoffmann wrote: > 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. > > Note: Initial revision which supports a single region only so it > can't handle virtio-gpu ressources yet. > > qemu test branch: > https://git.kraxel.org/cgit/qemu/log/?h=sirius/udmabuf > > Cc: David Airlie <airlied@xxxxxxxx> > Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx> > Cc: Daniel Vetter <daniel@xxxxxxxx> > Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx> > --- > include/uapi/linux/udmabuf.h | 19 ++ > drivers/dma-buf/udmabuf.c | 240 ++++++++++++++++++++++ > tools/testing/selftests/drivers/dma-buf/udmabuf.c | 95 +++++++++ > drivers/dma-buf/Kconfig | 7 + > drivers/dma-buf/Makefile | 1 + > tools/testing/selftests/drivers/dma-buf/Makefile | 5 + > 6 files changed, 367 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..2fbe69cf05 > --- /dev/null > +++ b/include/uapi/linux/udmabuf.h > @@ -0,0 +1,19 @@ > +/* 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; > +}; > + > +#define UDMABUF_CREATE _IOW(0x42, 0x23, struct udmabuf_create) > + > +#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..f9600dc985 > --- /dev/null > +++ b/drivers/dma-buf/udmabuf.c > @@ -0,0 +1,240 @@ > +/* > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + */ > +#include <linux/init.h> > +#include <linux/module.h> > +#include <linux/device.h> > +#include <linux/kernel.h> > +#include <linux/slab.h> > +#include <linux/miscdevice.h> > +#include <linux/dma-buf.h> > +#include <linux/highmem.h> > +#include <linux/cred.h> > +#include <linux/shmem_fs.h> > + > +#include <uapi/linux/udmabuf.h> > + > +struct udmabuf { > + struct file *filp; > + u32 pagecount; > + struct page **pages; > +}; > + > +static int udmabuf_vm_fault(struct vm_fault *vmf) > +{ > + struct vm_area_struct *vma = vmf->vma; > + struct udmabuf *ubuf = vma->vm_private_data; > + > + if (WARN_ON(vmf->pgoff >= ubuf->pagecount)) > + return VM_FAULT_SIGBUS; > + > + vmf->page = ubuf->pages[vmf->pgoff]; > + get_page(vmf->page); > + return 0; > +} > + > +static const struct vm_operations_struct udmabuf_vm_ops = { > + .fault = udmabuf_vm_fault, > +}; > + > +static int mmap_udmabuf(struct dma_buf *buf, struct vm_area_struct *vma) > +{ > + struct udmabuf *ubuf = buf->priv; > + > + if ((vma->vm_flags & VM_SHARED) == 0) > + return -EINVAL; > + > + vma->vm_ops = &udmabuf_vm_ops; > + vma->vm_private_data = ubuf; > + return 0; > +} > + > +static struct sg_table *map_udmabuf(struct dma_buf_attachment *at, > + enum dma_data_direction direction) > +{ > + struct udmabuf *ubuf = at->dmabuf->priv; > + struct sg_table *sg; > + > + sg = kzalloc(sizeof(*sg), GFP_KERNEL); > + if (!sg) > + goto err1; > + if (sg_alloc_table_from_pages(sg, ubuf->pages, ubuf->pagecount, > + 0, ubuf->pagecount << PAGE_SHIFT, > + GFP_KERNEL) < 0) > + goto err2; > + if (!dma_map_sg(at->dev, sg->sgl, sg->nents, direction)) > + goto err3; > + > + return sg; > + > +err3: > + sg_free_table(sg); > +err2: > + kfree(sg); > +err1: > + return ERR_PTR(-ENOMEM); > +} > + > +static void unmap_udmabuf(struct dma_buf_attachment *at, > + struct sg_table *sg, > + enum dma_data_direction direction) > +{ > + sg_free_table(sg); > + kfree(sg); > +} > + > +static void release_udmabuf(struct dma_buf *buf) > +{ > + struct udmabuf *ubuf = buf->priv; > + pgoff_t pg; > + > + for (pg = 0; pg < ubuf->pagecount; pg++) > + put_page(ubuf->pages[pg]); > + fput(ubuf->filp); > + kfree(ubuf->pages); > + kfree(ubuf); > +} > + > +static void *kmap_atomic_udmabuf(struct dma_buf *buf, unsigned long page_num) > +{ > + struct udmabuf *ubuf = buf->priv; > + struct page *page = ubuf->pages[page_num]; > + > + return kmap_atomic(page); > +} > + > +static void *kmap_udmabuf(struct dma_buf *buf, unsigned long page_num) > +{ > + struct udmabuf *ubuf = buf->priv; > + struct page *page = ubuf->pages[page_num]; > + > + return kmap(page); > +} The above leaks like mad since no kunamp? Also I think we have 0 users of the kmap atomic interfaces ... so not sure whether it's worth it to implement those. -Daniel > + > +static struct dma_buf_ops udmabuf_ops = { > + .map_dma_buf = map_udmabuf, > + .unmap_dma_buf = unmap_udmabuf, > + .release = release_udmabuf, > + .map_atomic = kmap_atomic_udmabuf, > + .map = kmap_udmabuf, > + .mmap = mmap_udmabuf, > +}; > + > +static long udmabuf_ioctl_create(struct file *filp, unsigned long arg) > +{ > + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); > + struct udmabuf_create create; > + struct udmabuf *ubuf; > + struct dma_buf *buf; > + pgoff_t pgoff, pgidx; > + struct page *page; > + int ret = -EINVAL; > + u32 flags; > + > + if (copy_from_user(&create, (void __user *)arg, > + sizeof(struct udmabuf_create))) > + return -EFAULT; > + > + if (!IS_ALIGNED(create.offset, PAGE_SIZE)) > + return -EINVAL; > + if (!IS_ALIGNED(create.size, PAGE_SIZE)) > + return -EINVAL; > + > + ubuf = kzalloc(sizeof(struct udmabuf), GFP_KERNEL); > + if (!ubuf) > + return -ENOMEM; > + > + ubuf->filp = fget(create.memfd); > + if (!ubuf->filp) > + goto err_free_ubuf; > + if (!shmem_mapping(file_inode(ubuf->filp)->i_mapping)) > + goto err_free_ubuf; > + > + ubuf->pagecount = create.size >> PAGE_SHIFT; > + ubuf->pages = kmalloc_array(ubuf->pagecount, sizeof(struct page*), > + GFP_KERNEL); > + if (!ubuf->pages) { > + ret = -ENOMEM; > + goto err_free_ubuf; > + } > + > + pgoff = create.offset >> PAGE_SHIFT; > + for (pgidx = 0; pgidx < ubuf->pagecount; pgidx++) { > + page = shmem_read_mapping_page( > + file_inode(ubuf->filp)->i_mapping, pgoff + pgidx); > + if (IS_ERR(page)) { > + ret = PTR_ERR(buf); > + goto err_put_pages; > + } > + ubuf->pages[pgidx] = page; > + } > + > + 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; > + if (create.flags & UDMABUF_FLAGS_CLOEXEC) > + flags |= O_CLOEXEC; > + return dma_buf_fd(buf, flags); > + > +err_put_pages: > + while (pgidx > 0) > + put_page(ubuf->pages[--pgidx]); > +err_free_ubuf: > + fput(ubuf->filp); > + kfree(ubuf->pages); > + kfree(ubuf); > + return ret; > +} > + > +static long udmabuf_ioctl(struct file *filp, unsigned int ioctl, > + unsigned long arg) > +{ > + long ret; > + > + switch (ioctl) { > + case UDMABUF_CREATE: > + ret = udmabuf_ioctl_create(filp, arg); > + break; > + default: > + ret = -EINVAL; > + break; > + } > + return ret; > +} > + > +static const struct file_operations udmabuf_fops = { > + .owner = THIS_MODULE, > + .unlocked_ioctl = udmabuf_ioctl, > +}; > + > +static struct miscdevice udmabuf_misc = { > + .minor = MISC_DYNAMIC_MINOR, > + .name = "udmabuf", > + .fops = &udmabuf_fops, > +}; > + > +static int __init udmabuf_dev_init(void) > +{ > + return misc_register(&udmabuf_misc); > +} > + > +static void __exit udmabuf_dev_exit(void) > +{ > + misc_deregister(&udmabuf_misc); > +} > + > +module_init(udmabuf_dev_init) > +module_exit(udmabuf_dev_exit) > + > +MODULE_AUTHOR("Gerd Hoffmann <kraxel@xxxxxxxxxx>"); > +MODULE_LICENSE("GPL v2"); > diff --git a/tools/testing/selftests/drivers/dma-buf/udmabuf.c b/tools/testing/selftests/drivers/dma-buf/udmabuf.c > new file mode 100644 > index 0000000000..d46c58b0dd > --- /dev/null > +++ b/tools/testing/selftests/drivers/dma-buf/udmabuf.c > @@ -0,0 +1,95 @@ > +#include <stdio.h> > +#include <stdlib.h> > +#include <unistd.h> > +#include <string.h> > +#include <errno.h> > +#include <fcntl.h> > +#include <malloc.h> > + > +#include <sys/ioctl.h> > +#include <sys/syscall.h> > +#include <linux/memfd.h> > +#include <linux/udmabuf.h> > + > +#define TEST_PREFIX "drivers/dma-buf/udmabuf" > +#define NUM_PAGES 4 > + > +static int memfd_create(const char *name, unsigned int flags) > +{ > + return syscall(__NR_memfd_create, name, flags); > +} > + > +int main(int argc, char *argv[]) > +{ > + struct udmabuf_create create; > + int devfd, memfd, buf, ret; > + off_t size; > + void *mem; > + > + devfd = open("/dev/udmabuf", O_RDWR); > + if (devfd < 0) { > + printf("%s: [skip,no-udmabuf]\n", TEST_PREFIX); > + exit(77); > + } > + > + memfd = memfd_create("udmabuf-test", MFD_CLOEXEC); > + if (memfd < 0) { > + printf("%s: [skip,no-memfd]\n", TEST_PREFIX); > + exit(77); > + } > + > + size = getpagesize() * NUM_PAGES; > + ret = ftruncate(memfd, size); > + if (ret == -1) { > + printf("%s: [FAIL,memfd-truncate]\n", TEST_PREFIX); > + exit(1); > + } > + > + memset(&create, 0, sizeof(create)); > + > + /* should fail (offset not page aligned) */ > + create.memfd = memfd; > + create.offset = getpagesize()/2; > + create.size = getpagesize(); > + buf = ioctl(devfd, UDMABUF_CREATE, &create); > + if (buf >= 0) { > + printf("%s: [FAIL,test-1]\n", TEST_PREFIX); > + exit(1); > + } > + > + /* should fail (size not multiple of page) */ > + create.memfd = memfd; > + create.offset = 0; > + create.size = getpagesize()/2; > + buf = ioctl(devfd, UDMABUF_CREATE, &create); > + if (buf >= 0) { > + printf("%s: [FAIL,test-2]\n", TEST_PREFIX); > + exit(1); > + } > + > + /* should fail (not memfd) */ > + create.memfd = 0; /* stdin */ > + create.offset = 0; > + create.size = size; > + buf = ioctl(devfd, UDMABUF_CREATE, &create); > + if (buf >= 0) { > + printf("%s: [FAIL,test-3]\n", TEST_PREFIX); > + exit(1); > + } > + > + /* should work */ > + create.memfd = memfd; > + create.offset = 0; > + create.size = size; > + buf = ioctl(devfd, UDMABUF_CREATE, &create); > + if (buf < 0) { > + printf("%s: [FAIL,test-4]\n", TEST_PREFIX); > + exit(1); > + } > + > + fprintf(stderr, "%s: ok\n", TEST_PREFIX); > + close(buf); > + close(memfd); > + close(devfd); > + return 0; > +} > diff --git a/drivers/dma-buf/Kconfig b/drivers/dma-buf/Kconfig > index ed3b785bae..19be3ec62d 100644 > --- a/drivers/dma-buf/Kconfig > +++ b/drivers/dma-buf/Kconfig > @@ -30,4 +30,11 @@ config SW_SYNC > WARNING: improper use of this can result in deadlocking kernel > drivers from userspace. Intended for test and debug only. > > +config UDMABUF > + bool "userspace dmabuf misc driver" > + default n > + depends on DMA_SHARED_BUFFER > + ---help--- > + A driver to let userspace turn iovs into dma-bufs. > + > endmenu > diff --git a/drivers/dma-buf/Makefile b/drivers/dma-buf/Makefile > index c33bf88631..0913a6ccab 100644 > --- a/drivers/dma-buf/Makefile > +++ b/drivers/dma-buf/Makefile > @@ -1,3 +1,4 @@ > obj-y := dma-buf.o dma-fence.o dma-fence-array.o reservation.o seqno-fence.o > obj-$(CONFIG_SYNC_FILE) += sync_file.o > obj-$(CONFIG_SW_SYNC) += sw_sync.o sync_debug.o > +obj-$(CONFIG_UDMABUF) += udmabuf.o > diff --git a/tools/testing/selftests/drivers/dma-buf/Makefile b/tools/testing/selftests/drivers/dma-buf/Makefile > new file mode 100644 > index 0000000000..4154c3d7aa > --- /dev/null > +++ b/tools/testing/selftests/drivers/dma-buf/Makefile > @@ -0,0 +1,5 @@ > +CFLAGS += -I../../../../../usr/include/ > + > +TEST_GEN_PROGS := udmabuf > + > +include ../../lib.mk > -- > 2.9.3 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
