On Tue, May 29, 2018 at 10:23:27AM +0200, Daniel Vetter wrote: > 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; Can/should we test here that the memfd has a locked down size here? I do think yes (otherwise the dma-buf operations need to take that into account, and all kinds of funny things might happen), but I'm not sure whether your userspace can cope with that. On that: Link to userspace patches/git tree using this would be nice. -Daniel > > + > > + 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 -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
