[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 7/9] xen/gntdev: Implement dma-buf export functionality
On 06/01/2018 07:41 AM, Oleksandr Andrushchenko wrote: > From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> > > 1. Create a dma-buf from grant references provided by the foreign > domain. By default dma-buf is backed by system memory pages, but > by providing GNTDEV_DMA_FLAG_XXX flags it can also be created > as a DMA write-combine/coherent buffer, e.g. allocated with > corresponding dma_alloc_xxx API. > Export the resulting buffer as a new dma-buf. > > 2. Implement waiting for the dma-buf to be released: block until the > dma-buf with the file descriptor provided is released. > If within the time-out provided the buffer is not released then > -ETIMEDOUT error is returned. If the buffer with the file descriptor > does not exist or has already been released, then -ENOENT is > returned. For valid file descriptors this must not be treated as > error. > > Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx> > --- > drivers/xen/gntdev-dmabuf.c | 393 +++++++++++++++++++++++++++++++++++- > drivers/xen/gntdev-dmabuf.h | 9 +- > drivers/xen/gntdev.c | 90 ++++++++- > 3 files changed, 486 insertions(+), 6 deletions(-) > > diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c > index 6bedd1387bd9..f612468879b4 100644 > --- a/drivers/xen/gntdev-dmabuf.c > +++ b/drivers/xen/gntdev-dmabuf.c > @@ -3,15 +3,58 @@ > /* > * Xen dma-buf functionality for gntdev. > * > + * DMA buffer implementation is based on drivers/gpu/drm/drm_prime.c. > + * > * Copyright (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc. > */ > > +#include <linux/dma-buf.h> > #include <linux/slab.h> > > #include "gntdev-dmabuf.h" > > +struct gntdev_dmabuf { > + struct gntdev_dmabuf_priv *priv; > + struct dma_buf *dmabuf; > + struct list_head next; > + int fd; > + > + union { > + struct { > + /* Exported buffers are reference counted. */ > + struct kref refcount; > + > + struct gntdev_priv *priv; > + struct grant_map *map; > + void (*release)(struct gntdev_priv *priv, > + struct grant_map *map); > + } exp; > + } u; > + > + /* Number of pages this buffer has. */ > + int nr_pages; > + /* Pages of this buffer. */ > + struct page **pages; > +}; > + > +struct gntdev_dmabuf_wait_obj { > + struct list_head next; > + struct gntdev_dmabuf *gntdev_dmabuf; > + struct completion completion; > +}; > + > +struct gntdev_dmabuf_attachment { > + struct sg_table *sgt; > + enum dma_data_direction dir; > +}; > + > struct gntdev_dmabuf_priv { > - int dummy; > + /* List of exported DMA buffers. */ > + struct list_head exp_list; > + /* List of wait objects. */ > + struct list_head exp_wait_list; > + /* This is the lock which protects dma_buf_xxx lists. */ > + struct mutex lock; > }; > > /* ------------------------------------------------------------------ */ > @@ -22,19 +65,359 @@ struct gntdev_dmabuf_priv { > /* Implementation of wait for exported DMA buffer to be released. */ > /* ------------------------------------------------------------------ */ > > +static void dmabuf_exp_release(struct kref *kref); > + > +static struct gntdev_dmabuf_wait_obj * > +dmabuf_exp_wait_obj_new(struct gntdev_dmabuf_priv *priv, > + struct gntdev_dmabuf *gntdev_dmabuf) > +{ > + struct gntdev_dmabuf_wait_obj *obj; > + > + obj = kzalloc(sizeof(*obj), GFP_KERNEL); > + if (!obj) > + return ERR_PTR(-ENOMEM); > + > + init_completion(&obj->completion); > + obj->gntdev_dmabuf = gntdev_dmabuf; > + > + mutex_lock(&priv->lock); > + list_add(&obj->next, &priv->exp_wait_list); > + /* Put our reference and wait for gntdev_dmabuf's release to fire. */ > + kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release); > + mutex_unlock(&priv->lock); > + return obj; > +} > + > +static void dmabuf_exp_wait_obj_free(struct gntdev_dmabuf_priv *priv, > + struct gntdev_dmabuf_wait_obj *obj) > +{ > + struct gntdev_dmabuf_wait_obj *cur_obj, *q; > + > + mutex_lock(&priv->lock); > + list_for_each_entry_safe(cur_obj, q, &priv->exp_wait_list, next) > + if (cur_obj == obj) { > + list_del(&obj->next); > + kfree(obj); > + break; > + } > + mutex_unlock(&priv->lock); > +} > + > +static int dmabuf_exp_wait_obj_wait(struct gntdev_dmabuf_wait_obj *obj, > + u32 wait_to_ms) > +{ > + if (wait_for_completion_timeout(&obj->completion, > + msecs_to_jiffies(wait_to_ms)) <= 0) > + return -ETIMEDOUT; > + > + return 0; > +} > + > +static void dmabuf_exp_wait_obj_signal(struct gntdev_dmabuf_priv *priv, > + struct gntdev_dmabuf *gntdev_dmabuf) > +{ > + struct gntdev_dmabuf_wait_obj *obj, *q; > + > + list_for_each_entry_safe(obj, q, &priv->exp_wait_list, next) > + if (obj->gntdev_dmabuf == gntdev_dmabuf) { > + pr_debug("Found gntdev_dmabuf in the wait list, > wake\n"); > + complete_all(&obj->completion); break ? > + } > +} > + > +static struct gntdev_dmabuf * > +dmabuf_exp_wait_obj_get_by_fd(struct gntdev_dmabuf_priv *priv, int fd) > +{ > + struct gntdev_dmabuf *q, *gntdev_dmabuf, *ret = ERR_PTR(-ENOENT); > + > + mutex_lock(&priv->lock); > + list_for_each_entry_safe(gntdev_dmabuf, q, &priv->exp_list, next) > + if (gntdev_dmabuf->fd == fd) { > + pr_debug("Found gntdev_dmabuf in the wait list\n"); > + kref_get(&gntdev_dmabuf->u.exp.refcount); > + ret = gntdev_dmabuf; > + break; > + } > + mutex_unlock(&priv->lock); > + return ret; > +} > + > int gntdev_dmabuf_exp_wait_released(struct gntdev_dmabuf_priv *priv, int fd, > int wait_to_ms) > { > - return -EINVAL; > + struct gntdev_dmabuf *gntdev_dmabuf; > + struct gntdev_dmabuf_wait_obj *obj; > + int ret; > + > + pr_debug("Will wait for dma-buf with fd %d\n", fd); > + /* > + * Try to find the DMA buffer: if not found means that > + * either the buffer has already been released or file descriptor > + * provided is wrong. > + */ > + gntdev_dmabuf = dmabuf_exp_wait_obj_get_by_fd(priv, fd); > + if (IS_ERR(gntdev_dmabuf)) > + return PTR_ERR(gntdev_dmabuf); > + > + /* > + * gntdev_dmabuf still exists and is reference count locked by us now, > + * so prepare to wait: allocate wait object and add it to the wait list, > + * so we can find it on release. > + */ > + obj = dmabuf_exp_wait_obj_new(priv, gntdev_dmabuf); > + if (IS_ERR(obj)) { > + pr_err("Failed to setup wait object, ret %ld\n", PTR_ERR(obj)); No need for pr_err. We are out of memory. > + return PTR_ERR(obj); > +} > + > + ret = dmabuf_exp_wait_obj_wait(obj, wait_to_ms); > + dmabuf_exp_wait_obj_free(priv, obj); > + return ret; > } > > /* ------------------------------------------------------------------ */ > /* DMA buffer export support. */ > /* ------------------------------------------------------------------ */ > > +static struct sg_table * > +dmabuf_pages_to_sgt(struct page **pages, unsigned int nr_pages) > +{ > + struct sg_table *sgt; > + int ret; > + > + sgt = kmalloc(sizeof(*sgt), GFP_KERNEL); > + if (!sgt) { > + ret = -ENOMEM; > + goto out; > + } > + > + ret = sg_alloc_table_from_pages(sgt, pages, nr_pages, 0, > + nr_pages << PAGE_SHIFT, > + GFP_KERNEL); > + if (ret) > + goto out; > + > + return sgt; > + > +out: > + kfree(sgt); > + return ERR_PTR(ret); > +} > + > +static int dmabuf_exp_ops_attach(struct dma_buf *dma_buf, > + struct device *target_dev, > + struct dma_buf_attachment *attach) > +{ > + struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach; > + > + gntdev_dmabuf_attach = kzalloc(sizeof(*gntdev_dmabuf_attach), > + GFP_KERNEL); > + if (!gntdev_dmabuf_attach) > + return -ENOMEM; > + > + gntdev_dmabuf_attach->dir = DMA_NONE; > + attach->priv = gntdev_dmabuf_attach; > + /* Might need to pin the pages of the buffer now. */ Who is supposed to pin the pages? The caller? > + return 0; > +} > + > +static void dmabuf_exp_ops_detach(struct dma_buf *dma_buf, > + struct dma_buf_attachment *attach) > +{ > + struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv; > + > + if (gntdev_dmabuf_attach) { > + struct sg_table *sgt = gntdev_dmabuf_attach->sgt; > + > + if (sgt) { > + if (gntdev_dmabuf_attach->dir != DMA_NONE) > + dma_unmap_sg_attrs(attach->dev, sgt->sgl, > + sgt->nents, > + gntdev_dmabuf_attach->dir, > + DMA_ATTR_SKIP_CPU_SYNC); > + sg_free_table(sgt); > + } > + > + kfree(sgt); > + kfree(gntdev_dmabuf_attach); > + attach->priv = NULL; > + } > + /* Might need to unpin the pages of the buffer now. */ Same question. > +} > + > +static struct sg_table * > +dmabuf_exp_ops_map_dma_buf(struct dma_buf_attachment *attach, > + enum dma_data_direction dir) > +{ > + struct gntdev_dmabuf_attachment *gntdev_dmabuf_attach = attach->priv; > + struct gntdev_dmabuf *gntdev_dmabuf = attach->dmabuf->priv; > + struct sg_table *sgt; > + > + pr_debug("Mapping %d pages for dev %p\n", gntdev_dmabuf->nr_pages, > + attach->dev); > + > + if (WARN_ON(dir == DMA_NONE || !gntdev_dmabuf_attach)) WARN_ON_ONCE. Here and elsewhere. > + return ERR_PTR(-EINVAL); > + > + /* Return the cached mapping when possible. */ > + if (gntdev_dmabuf_attach->dir == dir) > + return gntdev_dmabuf_attach->sgt; > + > + /* > + * Two mappings with different directions for the same attachment are > + * not allowed. > + */ > + if (WARN_ON(gntdev_dmabuf_attach->dir != DMA_NONE)) > + return ERR_PTR(-EBUSY); > + > + sgt = dmabuf_pages_to_sgt(gntdev_dmabuf->pages, > + gntdev_dmabuf->nr_pages); > + if (!IS_ERR(sgt)) { > + if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir, > + DMA_ATTR_SKIP_CPU_SYNC)) { > + sg_free_table(sgt); > + kfree(sgt); > + sgt = ERR_PTR(-ENOMEM); > + } else { > + gntdev_dmabuf_attach->sgt = sgt; > + gntdev_dmabuf_attach->dir = dir; > + } > + } > + if (IS_ERR(sgt)) > + pr_err("Failed to map sg table for dev %p\n", attach->dev); > + return sgt; > +} > + > +static void dmabuf_exp_ops_unmap_dma_buf(struct dma_buf_attachment *attach, > + struct sg_table *sgt, > + enum dma_data_direction dir) > +{ > + /* Not implemented. The unmap is done at dmabuf_exp_ops_detach(). */ > +} > + > +static void dmabuf_exp_release(struct kref *kref) > +{ > + struct gntdev_dmabuf *gntdev_dmabuf = > + container_of(kref, struct gntdev_dmabuf, u.exp.refcount); > + > + dmabuf_exp_wait_obj_signal(gntdev_dmabuf->priv, gntdev_dmabuf); > + list_del(&gntdev_dmabuf->next); > + kfree(gntdev_dmabuf); > +} > + > +static void dmabuf_exp_ops_release(struct dma_buf *dma_buf) > +{ > + struct gntdev_dmabuf *gntdev_dmabuf = dma_buf->priv; > + struct gntdev_dmabuf_priv *priv = gntdev_dmabuf->priv; > + > + gntdev_dmabuf->u.exp.release(gntdev_dmabuf->u.exp.priv, > + gntdev_dmabuf->u.exp.map); > + mutex_lock(&priv->lock); > + kref_put(&gntdev_dmabuf->u.exp.refcount, dmabuf_exp_release); > + mutex_unlock(&priv->lock); > +} > + > +static void *dmabuf_exp_ops_kmap_atomic(struct dma_buf *dma_buf, > + unsigned long page_num) > +{ > + /* Not implemented. */ > + return NULL; > +} > + > +static void dmabuf_exp_ops_kunmap_atomic(struct dma_buf *dma_buf, > + unsigned long page_num, void *addr) > +{ > + /* Not implemented. */ > +} > + > +static void *dmabuf_exp_ops_kmap(struct dma_buf *dma_buf, > + unsigned long page_num) > +{ > + /* Not implemented. */ > + return NULL; > +} > + > +static void dmabuf_exp_ops_kunmap(struct dma_buf *dma_buf, > + unsigned long page_num, void *addr) > +{ > + /* Not implemented. */ > +} > + > +static int dmabuf_exp_ops_mmap(struct dma_buf *dma_buf, > + struct vm_area_struct *vma) > +{ > + /* Not implemented. */ > + return 0; > +} > + > +static const struct dma_buf_ops dmabuf_exp_ops = { > + .attach = dmabuf_exp_ops_attach, > + .detach = dmabuf_exp_ops_detach, > + .map_dma_buf = dmabuf_exp_ops_map_dma_buf, > + .unmap_dma_buf = dmabuf_exp_ops_unmap_dma_buf, > + .release = dmabuf_exp_ops_release, > + .map = dmabuf_exp_ops_kmap, > + .map_atomic = dmabuf_exp_ops_kmap_atomic, > + .unmap = dmabuf_exp_ops_kunmap, > + .unmap_atomic = dmabuf_exp_ops_kunmap_atomic, > + .mmap = dmabuf_exp_ops_mmap, > +}; > + > int gntdev_dmabuf_exp_from_pages(struct gntdev_dmabuf_export_args *args) > { > - return -EINVAL; > + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); > + struct gntdev_dmabuf *gntdev_dmabuf; > + int ret = 0; > + > + gntdev_dmabuf = kzalloc(sizeof(*gntdev_dmabuf), GFP_KERNEL); > + if (!gntdev_dmabuf) > + return -ENOMEM; > + > + kref_init(&gntdev_dmabuf->u.exp.refcount); > + > + gntdev_dmabuf->priv = args->dmabuf_priv; > + gntdev_dmabuf->nr_pages = args->count; > + gntdev_dmabuf->pages = args->pages; > + gntdev_dmabuf->u.exp.priv = args->priv; > + gntdev_dmabuf->u.exp.map = args->map; > + gntdev_dmabuf->u.exp.release = args->release; > + > + exp_info.exp_name = KBUILD_MODNAME; > + if (args->dev->driver && args->dev->driver->owner) > + exp_info.owner = args->dev->driver->owner; > + else > + exp_info.owner = THIS_MODULE; > + exp_info.ops = &dmabuf_exp_ops; > + exp_info.size = args->count << PAGE_SHIFT; > + exp_info.flags = O_RDWR; > + exp_info.priv = gntdev_dmabuf; > + > + gntdev_dmabuf->dmabuf = dma_buf_export(&exp_info); > + if (IS_ERR(gntdev_dmabuf->dmabuf)) { > + ret = PTR_ERR(gntdev_dmabuf->dmabuf); > + gntdev_dmabuf->dmabuf = NULL; > + goto fail; > + } > + > + ret = dma_buf_fd(gntdev_dmabuf->dmabuf, O_CLOEXEC); > + if (ret < 0) > + goto fail; > + > + gntdev_dmabuf->fd = ret; > + args->fd = ret; > + > + pr_debug("Exporting DMA buffer with fd %d\n", ret); > + > + mutex_lock(&args->dmabuf_priv->lock); > + list_add(&gntdev_dmabuf->next, &args->dmabuf_priv->exp_list); > + mutex_unlock(&args->dmabuf_priv->lock); > + return 0; > + > +fail: > + if (gntdev_dmabuf->dmabuf) > + dma_buf_put(gntdev_dmabuf->dmabuf); > + kfree(gntdev_dmabuf); > + return ret; > } > > /* ------------------------------------------------------------------ */ > @@ -66,6 +449,10 @@ struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void) > if (!priv) > return ERR_PTR(-ENOMEM); > > + mutex_init(&priv->lock); > + INIT_LIST_HEAD(&priv->exp_list); > + INIT_LIST_HEAD(&priv->exp_wait_list); > + > return priv; > } > > diff --git a/drivers/xen/gntdev-dmabuf.h b/drivers/xen/gntdev-dmabuf.h > index 040b2de904ac..95c23a24f640 100644 > --- a/drivers/xen/gntdev-dmabuf.h > +++ b/drivers/xen/gntdev-dmabuf.h > @@ -18,7 +18,14 @@ struct gntdev_dmabuf; > struct device; > > struct gntdev_dmabuf_export_args { > - int dummy; > + struct gntdev_priv *priv; > + struct grant_map *map; > + void (*release)(struct gntdev_priv *priv, struct grant_map *map); > + struct gntdev_dmabuf_priv *dmabuf_priv; > + struct device *dev; > + int count; > + struct page **pages; > + u32 fd; > }; > > struct gntdev_dmabuf_priv *gntdev_dmabuf_init(void); > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > index 7d58dfb3e5e8..cf255d45f20f 100644 > --- a/drivers/xen/gntdev.c > +++ b/drivers/xen/gntdev.c > @@ -319,6 +319,16 @@ static void gntdev_put_map(struct gntdev_priv *priv, > struct grant_map *map) > gntdev_free_map(map); > } > > +#ifdef CONFIG_XEN_GNTDEV_DMABUF > +static void gntdev_remove_map(struct gntdev_priv *priv, struct grant_map > *map) > +{ > + mutex_lock(&priv->lock); > + list_del(&map->next); > + gntdev_put_map(NULL /* already removed */, map); > + mutex_unlock(&priv->lock); > +} > +#endif > + > /* ------------------------------------------------------------------ */ > > static int find_grant_ptes(pte_t *pte, pgtable_t token, > @@ -1063,12 +1073,88 @@ static long gntdev_ioctl_grant_copy(struct > gntdev_priv *priv, void __user *u) > /* DMA buffer export support. */ > /* ------------------------------------------------------------------ */ > > +static struct grant_map * > +dmabuf_exp_alloc_backing_storage(struct gntdev_priv *priv, int dmabuf_flags, > + int count) > +{ > + struct grant_map *map; > + > + if (unlikely(count <= 0)) > + return ERR_PTR(-EINVAL); > + > + if ((dmabuf_flags & GNTDEV_DMA_FLAG_WC) && > + (dmabuf_flags & GNTDEV_DMA_FLAG_COHERENT)) { > + pr_err("Wrong dma-buf flags: either WC or coherent, not > both\n"); > + return ERR_PTR(-EINVAL); > + } > + > + map = gntdev_alloc_map(priv, count, dmabuf_flags); > + if (!map) > + return ERR_PTR(-ENOMEM); > + > + if (unlikely(atomic_add_return(count, &pages_mapped) > limit)) { > + pr_err("can't map: over limit\n"); > + gntdev_put_map(NULL, map); > + return ERR_PTR(-ENOMEM); > + } > + return map; > +} > + > int gntdev_dmabuf_exp_from_refs(struct gntdev_priv *priv, int flags, > int count, u32 domid, u32 *refs, u32 *fd) > { > - /* XXX: this will need to work with gntdev's map, so leave it here. */ > + struct grant_map *map; > + struct gntdev_dmabuf_export_args args; > + int i, ret; > + > *fd = -1; > - return -EINVAL; > + > + if (use_ptemod) { > + pr_err("Cannot provide dma-buf: use_ptemode %d\n", > + use_ptemod); No pr_err here please. This can potentially become a DoS vector as it comes directly from ioctl. I would, in fact, revisit other uses of pr_err in this file. > + return -EINVAL; > + } > + > + map = dmabuf_exp_alloc_backing_storage(priv, flags, count); @count comes from userspace. dmabuf_exp_alloc_backing_storage only checks for it to be >0. Should it be checked for some sane max value? -boris > + if (IS_ERR(map)) > + return PTR_ERR(map); > + > + for (i = 0; i < count; i++) { > + map->grants[i].domid = domid; > + map->grants[i].ref = refs[i]; > + } > + > + mutex_lock(&priv->lock); > + gntdev_add_map(priv, map); > + mutex_unlock(&priv->lock); > + > + map->flags |= GNTMAP_host_map; > +#if defined(CONFIG_X86) > + map->flags |= GNTMAP_device_map; > +#endif > + > + ret = map_grant_pages(map); > + if (ret < 0) > + goto out; > + > + args.priv = priv; > + args.map = map; > + args.release = gntdev_remove_map; > + args.dev = priv->dma_dev; > + args.dmabuf_priv = priv->dmabuf_priv; > + args.count = map->count; > + args.pages = map->pages; > + > + ret = gntdev_dmabuf_exp_from_pages(&args); > + if (ret < 0) > + goto out; > + > + *fd = args.fd; > + return 0; > + > +out: > + gntdev_remove_map(priv, map); > + return ret; > } > > /* ------------------------------------------------------------------ */ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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