diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/xen/gntdev.c | 1165 |
1 files changed, 1165 insertions, 0 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c new file mode 100644 index 000000000..16acddaff --- /dev/null +++ b/drivers/xen/gntdev.c @@ -0,0 +1,1165 @@ +/****************************************************************************** + * gntdev.c + * + * Device for accessing (in user-space) pages that have been granted by other + * domains. + * + * Copyright (c) 2006-2007, D G Murray. + * (c) 2009 Gerd Hoffmann <kraxel@redhat.com> + * (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ + +#undef DEBUG + +#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt + +#include <linux/dma-mapping.h> +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/miscdevice.h> +#include <linux/fs.h> +#include <linux/uaccess.h> +#include <linux/sched.h> +#include <linux/sched/mm.h> +#include <linux/spinlock.h> +#include <linux/slab.h> +#include <linux/highmem.h> +#include <linux/refcount.h> +#include <linux/workqueue.h> + +#include <xen/xen.h> +#include <xen/grant_table.h> +#include <xen/balloon.h> +#include <xen/gntdev.h> +#include <xen/events.h> +#include <xen/page.h> +#include <asm/xen/hypervisor.h> +#include <asm/xen/hypercall.h> + +#include "gntdev-common.h" +#ifdef CONFIG_XEN_GNTDEV_DMABUF +#include "gntdev-dmabuf.h" +#endif + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, " + "Gerd Hoffmann <kraxel@redhat.com>"); +MODULE_DESCRIPTION("User-space granted page access driver"); + +static unsigned int limit = 64*1024; +module_param(limit, uint, 0644); +MODULE_PARM_DESC(limit, + "Maximum number of grants that may be mapped by one mapping request"); + +/* True in PV mode, false otherwise */ +static int use_ptemod; + +static void unmap_grant_pages(struct gntdev_grant_map *map, + int offset, int pages); + +static struct miscdevice gntdev_miscdev; + +/* ------------------------------------------------------------------ */ + +bool gntdev_test_page_count(unsigned int count) +{ + return !count || count > limit; +} + +static void gntdev_print_maps(struct gntdev_priv *priv, + char *text, int text_index) +{ +#ifdef DEBUG + struct gntdev_grant_map *map; + + pr_debug("%s: maps list (priv %p)\n", __func__, priv); + list_for_each_entry(map, &priv->maps, next) + pr_debug(" index %2d, count %2d %s\n", + map->index, map->count, + map->index == text_index && text ? text : ""); +#endif +} + +static void gntdev_free_map(struct gntdev_grant_map *map) +{ + if (map == NULL) + return; + +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC + if (map->dma_vaddr) { + struct gnttab_dma_alloc_args args; + + args.dev = map->dma_dev; + args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT); + args.nr_pages = map->count; + args.pages = map->pages; + args.frames = map->frames; + args.vaddr = map->dma_vaddr; + args.dev_bus_addr = map->dma_bus_addr; + + gnttab_dma_free_pages(&args); + } else +#endif + if (map->pages) + gnttab_free_pages(map->count, map->pages); + +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC + kvfree(map->frames); +#endif + kvfree(map->pages); + kvfree(map->grants); + kvfree(map->map_ops); + kvfree(map->unmap_ops); + kvfree(map->kmap_ops); + kvfree(map->kunmap_ops); + kvfree(map->being_removed); + kfree(map); +} + +struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count, + int dma_flags) +{ + struct gntdev_grant_map *add; + int i; + + add = kzalloc(sizeof(*add), GFP_KERNEL); + if (NULL == add) + return NULL; + + add->grants = kvcalloc(count, sizeof(add->grants[0]), GFP_KERNEL); + add->map_ops = kvcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL); + add->unmap_ops = kvcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL); + add->kmap_ops = kvcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL); + add->kunmap_ops = kvcalloc(count, + sizeof(add->kunmap_ops[0]), GFP_KERNEL); + add->pages = kvcalloc(count, sizeof(add->pages[0]), GFP_KERNEL); + add->being_removed = + kvcalloc(count, sizeof(add->being_removed[0]), GFP_KERNEL); + if (NULL == add->grants || + NULL == add->map_ops || + NULL == add->unmap_ops || + NULL == add->kmap_ops || + NULL == add->kunmap_ops || + NULL == add->pages || + NULL == add->being_removed) + goto err; + +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC + add->dma_flags = dma_flags; + + /* + * Check if this mapping is requested to be backed + * by a DMA buffer. + */ + if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) { + struct gnttab_dma_alloc_args args; + + add->frames = kvcalloc(count, sizeof(add->frames[0]), + GFP_KERNEL); + if (!add->frames) + goto err; + + /* Remember the device, so we can free DMA memory. */ + add->dma_dev = priv->dma_dev; + + args.dev = priv->dma_dev; + args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT); + args.nr_pages = count; + args.pages = add->pages; + args.frames = add->frames; + + if (gnttab_dma_alloc_pages(&args)) + goto err; + + add->dma_vaddr = args.vaddr; + add->dma_bus_addr = args.dev_bus_addr; + } else +#endif + if (gnttab_alloc_pages(count, add->pages)) + goto err; + + for (i = 0; i < count; i++) { + add->map_ops[i].handle = -1; + add->unmap_ops[i].handle = -1; + add->kmap_ops[i].handle = -1; + add->kunmap_ops[i].handle = -1; + } + + add->index = 0; + add->count = count; + refcount_set(&add->users, 1); + + return add; + +err: + gntdev_free_map(add); + return NULL; +} + +void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add) +{ + struct gntdev_grant_map *map; + + list_for_each_entry(map, &priv->maps, next) { + if (add->index + add->count < map->index) { + list_add_tail(&add->next, &map->next); + goto done; + } + add->index = map->index + map->count; + } + list_add_tail(&add->next, &priv->maps); + +done: + gntdev_print_maps(priv, "[new]", add->index); +} + +static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv, + int index, int count) +{ + struct gntdev_grant_map *map; + + list_for_each_entry(map, &priv->maps, next) { + if (map->index != index) + continue; + if (count && map->count != count) + continue; + return map; + } + return NULL; +} + +void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map) +{ + if (!map) + return; + + if (!refcount_dec_and_test(&map->users)) + return; + + if (map->pages && !use_ptemod) { + /* + * Increment the reference count. This ensures that the + * subsequent call to unmap_grant_pages() will not wind up + * re-entering itself. It *can* wind up calling + * gntdev_put_map() recursively, but such calls will be with a + * reference count greater than 1, so they will return before + * this code is reached. The recursion depth is thus limited to + * 1. Do NOT use refcount_inc() here, as it will detect that + * the reference count is zero and WARN(). + */ + refcount_set(&map->users, 1); + + /* + * Unmap the grants. This may or may not be asynchronous, so it + * is possible that the reference count is 1 on return, but it + * could also be greater than 1. + */ + unmap_grant_pages(map, 0, map->count); + + /* Check if the memory now needs to be freed */ + if (!refcount_dec_and_test(&map->users)) + return; + + /* + * All pages have been returned to the hypervisor, so free the + * map. + */ + } + + if (use_ptemod && map->notifier_init) + mmu_interval_notifier_remove(&map->notifier); + + if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { + notify_remote_via_evtchn(map->notify.event); + evtchn_put(map->notify.event); + } + gntdev_free_map(map); +} + +/* ------------------------------------------------------------------ */ + +static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data) +{ + struct gntdev_grant_map *map = data; + unsigned int pgnr = (addr - map->pages_vm_start) >> PAGE_SHIFT; + int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte | + (1 << _GNTMAP_guest_avail0); + u64 pte_maddr; + + BUG_ON(pgnr >= map->count); + pte_maddr = arbitrary_virt_to_machine(pte).maddr; + + gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, + map->grants[pgnr].ref, + map->grants[pgnr].domid); + gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags, + -1 /* handle */); + return 0; +} + +int gntdev_map_grant_pages(struct gntdev_grant_map *map) +{ + size_t alloced = 0; + int i, err = 0; + + if (!use_ptemod) { + /* Note: it could already be mapped */ + if (map->map_ops[0].handle != -1) + return 0; + for (i = 0; i < map->count; i++) { + unsigned long addr = (unsigned long) + pfn_to_kaddr(page_to_pfn(map->pages[i])); + gnttab_set_map_op(&map->map_ops[i], addr, map->flags, + map->grants[i].ref, + map->grants[i].domid); + gnttab_set_unmap_op(&map->unmap_ops[i], addr, + map->flags, -1 /* handle */); + } + } else { + /* + * Setup the map_ops corresponding to the pte entries pointing + * to the kernel linear addresses of the struct pages. + * These ptes are completely different from the user ptes dealt + * with find_grant_ptes. + * Note that GNTMAP_device_map isn't needed here: The + * dev_bus_addr output field gets consumed only from ->map_ops, + * and by not requesting it when mapping we also avoid needing + * to mirror dev_bus_addr into ->unmap_ops (and holding an extra + * reference to the page in the hypervisor). + */ + unsigned int flags = (map->flags & ~GNTMAP_device_map) | + GNTMAP_host_map; + + for (i = 0; i < map->count; i++) { + unsigned long address = (unsigned long) + pfn_to_kaddr(page_to_pfn(map->pages[i])); + BUG_ON(PageHighMem(map->pages[i])); + + gnttab_set_map_op(&map->kmap_ops[i], address, flags, + map->grants[i].ref, + map->grants[i].domid); + gnttab_set_unmap_op(&map->kunmap_ops[i], address, + flags, -1); + } + } + + pr_debug("map %d+%d\n", map->index, map->count); + err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, + map->pages, map->count); + + for (i = 0; i < map->count; i++) { + if (map->map_ops[i].status == GNTST_okay) { + map->unmap_ops[i].handle = map->map_ops[i].handle; + alloced++; + } else if (!err) + err = -EINVAL; + + if (map->flags & GNTMAP_device_map) + map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr; + + if (use_ptemod) { + if (map->kmap_ops[i].status == GNTST_okay) { + alloced++; + map->kunmap_ops[i].handle = map->kmap_ops[i].handle; + } else if (!err) + err = -EINVAL; + } + } + atomic_add(alloced, &map->live_grants); + return err; +} + +static void __unmap_grant_pages_done(int result, + struct gntab_unmap_queue_data *data) +{ + unsigned int i; + struct gntdev_grant_map *map = data->data; + unsigned int offset = data->unmap_ops - map->unmap_ops; + int successful_unmaps = 0; + int live_grants; + + for (i = 0; i < data->count; i++) { + if (map->unmap_ops[offset + i].status == GNTST_okay && + map->unmap_ops[offset + i].handle != -1) + successful_unmaps++; + + WARN_ON(map->unmap_ops[offset+i].status && + map->unmap_ops[offset+i].handle != -1); + pr_debug("unmap handle=%d st=%d\n", + map->unmap_ops[offset+i].handle, + map->unmap_ops[offset+i].status); + map->unmap_ops[offset+i].handle = -1; + if (use_ptemod) { + if (map->kunmap_ops[offset + i].status == GNTST_okay && + map->kunmap_ops[offset + i].handle != -1) + successful_unmaps++; + + WARN_ON(map->kunmap_ops[offset+i].status && + map->kunmap_ops[offset+i].handle != -1); + pr_debug("kunmap handle=%u st=%d\n", + map->kunmap_ops[offset+i].handle, + map->kunmap_ops[offset+i].status); + map->kunmap_ops[offset+i].handle = -1; + } + } + + /* + * Decrease the live-grant counter. This must happen after the loop to + * prevent premature reuse of the grants by gnttab_mmap(). + */ + live_grants = atomic_sub_return(successful_unmaps, &map->live_grants); + if (WARN_ON(live_grants < 0)) + pr_err("%s: live_grants became negative (%d) after unmapping %d pages!\n", + __func__, live_grants, successful_unmaps); + + /* Release reference taken by __unmap_grant_pages */ + gntdev_put_map(NULL, map); +} + +static void __unmap_grant_pages(struct gntdev_grant_map *map, int offset, + int pages) +{ + if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { + int pgno = (map->notify.addr >> PAGE_SHIFT); + + if (pgno >= offset && pgno < offset + pages) { + /* No need for kmap, pages are in lowmem */ + uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); + + tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; + map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; + } + } + + map->unmap_data.unmap_ops = map->unmap_ops + offset; + map->unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; + map->unmap_data.pages = map->pages + offset; + map->unmap_data.count = pages; + map->unmap_data.done = __unmap_grant_pages_done; + map->unmap_data.data = map; + refcount_inc(&map->users); /* to keep map alive during async call below */ + + gnttab_unmap_refs_async(&map->unmap_data); +} + +static void unmap_grant_pages(struct gntdev_grant_map *map, int offset, + int pages) +{ + int range; + + if (atomic_read(&map->live_grants) == 0) + return; /* Nothing to do */ + + pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); + + /* It is possible the requested range will have a "hole" where we + * already unmapped some of the grants. Only unmap valid ranges. + */ + while (pages) { + while (pages && map->being_removed[offset]) { + offset++; + pages--; + } + range = 0; + while (range < pages) { + if (map->being_removed[offset + range]) + break; + map->being_removed[offset + range] = true; + range++; + } + if (range) + __unmap_grant_pages(map, offset, range); + offset += range; + pages -= range; + } +} + +/* ------------------------------------------------------------------ */ + +static void gntdev_vma_open(struct vm_area_struct *vma) +{ + struct gntdev_grant_map *map = vma->vm_private_data; + + pr_debug("gntdev_vma_open %p\n", vma); + refcount_inc(&map->users); +} + +static void gntdev_vma_close(struct vm_area_struct *vma) +{ + struct gntdev_grant_map *map = vma->vm_private_data; + struct file *file = vma->vm_file; + struct gntdev_priv *priv = file->private_data; + + pr_debug("gntdev_vma_close %p\n", vma); + + vma->vm_private_data = NULL; + gntdev_put_map(priv, map); +} + +static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, + unsigned long addr) +{ + struct gntdev_grant_map *map = vma->vm_private_data; + + return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; +} + +static const struct vm_operations_struct gntdev_vmops = { + .open = gntdev_vma_open, + .close = gntdev_vma_close, + .find_special_page = gntdev_vma_find_special_page, +}; + +/* ------------------------------------------------------------------ */ + +static bool gntdev_invalidate(struct mmu_interval_notifier *mn, + const struct mmu_notifier_range *range, + unsigned long cur_seq) +{ + struct gntdev_grant_map *map = + container_of(mn, struct gntdev_grant_map, notifier); + unsigned long mstart, mend; + unsigned long map_start, map_end; + + if (!mmu_notifier_range_blockable(range)) + return false; + + map_start = map->pages_vm_start; + map_end = map->pages_vm_start + (map->count << PAGE_SHIFT); + + /* + * If the VMA is split or otherwise changed the notifier is not + * updated, but we don't want to process VA's outside the modified + * VMA. FIXME: It would be much more understandable to just prevent + * modifying the VMA in the first place. + */ + if (map_start >= range->end || map_end <= range->start) + return true; + + mstart = max(range->start, map_start); + mend = min(range->end, map_end); + pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", + map->index, map->count, map_start, map_end, + range->start, range->end, mstart, mend); + unmap_grant_pages(map, (mstart - map_start) >> PAGE_SHIFT, + (mend - mstart) >> PAGE_SHIFT); + + return true; +} + +static const struct mmu_interval_notifier_ops gntdev_mmu_ops = { + .invalidate = gntdev_invalidate, +}; + +/* ------------------------------------------------------------------ */ + +static int gntdev_open(struct inode *inode, struct file *flip) +{ + struct gntdev_priv *priv; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + INIT_LIST_HEAD(&priv->maps); + mutex_init(&priv->lock); + +#ifdef CONFIG_XEN_GNTDEV_DMABUF + priv->dmabuf_priv = gntdev_dmabuf_init(flip); + if (IS_ERR(priv->dmabuf_priv)) { + int ret = PTR_ERR(priv->dmabuf_priv); + + kfree(priv); + return ret; + } +#endif + + flip->private_data = priv; +#ifdef CONFIG_XEN_GRANT_DMA_ALLOC + priv->dma_dev = gntdev_miscdev.this_device; + dma_coerce_mask_and_coherent(priv->dma_dev, DMA_BIT_MASK(64)); +#endif + pr_debug("priv %p\n", priv); + + return 0; +} + +static int gntdev_release(struct inode *inode, struct file *flip) +{ + struct gntdev_priv *priv = flip->private_data; + struct gntdev_grant_map *map; + + pr_debug("priv %p\n", priv); + + mutex_lock(&priv->lock); + while (!list_empty(&priv->maps)) { + map = list_entry(priv->maps.next, + struct gntdev_grant_map, next); + list_del(&map->next); + gntdev_put_map(NULL /* already removed */, map); + } + mutex_unlock(&priv->lock); + +#ifdef CONFIG_XEN_GNTDEV_DMABUF + gntdev_dmabuf_fini(priv->dmabuf_priv); +#endif + + kfree(priv); + return 0; +} + +static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, + struct ioctl_gntdev_map_grant_ref __user *u) +{ + struct ioctl_gntdev_map_grant_ref op; + struct gntdev_grant_map *map; + int err; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, add %d\n", priv, op.count); + if (unlikely(gntdev_test_page_count(op.count))) + return -EINVAL; + + err = -ENOMEM; + map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */); + if (!map) + return err; + + if (copy_from_user(map->grants, &u->refs, + sizeof(map->grants[0]) * op.count) != 0) { + gntdev_put_map(NULL, map); + return -EFAULT; + } + + mutex_lock(&priv->lock); + gntdev_add_map(priv, map); + op.index = map->index << PAGE_SHIFT; + mutex_unlock(&priv->lock); + + if (copy_to_user(u, &op, sizeof(op)) != 0) + return -EFAULT; + + return 0; +} + +static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, + struct ioctl_gntdev_unmap_grant_ref __user *u) +{ + struct ioctl_gntdev_unmap_grant_ref op; + struct gntdev_grant_map *map; + int err = -ENOENT; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); + + mutex_lock(&priv->lock); + map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); + if (map) { + list_del(&map->next); + err = 0; + } + mutex_unlock(&priv->lock); + if (map) + gntdev_put_map(priv, map); + return err; +} + +static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, + struct ioctl_gntdev_get_offset_for_vaddr __user *u) +{ + struct ioctl_gntdev_get_offset_for_vaddr op; + struct vm_area_struct *vma; + struct gntdev_grant_map *map; + int rv = -EINVAL; + + if (copy_from_user(&op, u, sizeof(op)) != 0) + return -EFAULT; + pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); + + mmap_read_lock(current->mm); + vma = find_vma(current->mm, op.vaddr); + if (!vma || vma->vm_ops != &gntdev_vmops) + goto out_unlock; + + map = vma->vm_private_data; + if (!map) + goto out_unlock; + + op.offset = map->index << PAGE_SHIFT; + op.count = map->count; + rv = 0; + + out_unlock: + mmap_read_unlock(current->mm); + + if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) + return -EFAULT; + return rv; +} + +static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) +{ + struct ioctl_gntdev_unmap_notify op; + struct gntdev_grant_map *map; + int rc; + int out_flags; + evtchn_port_t out_event; + + if (copy_from_user(&op, u, sizeof(op))) + return -EFAULT; + + if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) + return -EINVAL; + + /* We need to grab a reference to the event channel we are going to use + * to send the notify before releasing the reference we may already have + * (if someone has called this ioctl twice). This is required so that + * it is possible to change the clear_byte part of the notification + * without disturbing the event channel part, which may now be the last + * reference to that event channel. + */ + if (op.action & UNMAP_NOTIFY_SEND_EVENT) { + if (evtchn_get(op.event_channel_port)) + return -EINVAL; + } + + out_flags = op.action; + out_event = op.event_channel_port; + + mutex_lock(&priv->lock); + + list_for_each_entry(map, &priv->maps, next) { + uint64_t begin = map->index << PAGE_SHIFT; + uint64_t end = (map->index + map->count) << PAGE_SHIFT; + if (op.index >= begin && op.index < end) + goto found; + } + rc = -ENOENT; + goto unlock_out; + + found: + if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && + (map->flags & GNTMAP_readonly)) { + rc = -EINVAL; + goto unlock_out; + } + + out_flags = map->notify.flags; + out_event = map->notify.event; + + map->notify.flags = op.action; + map->notify.addr = op.index - (map->index << PAGE_SHIFT); + map->notify.event = op.event_channel_port; + + rc = 0; + + unlock_out: + mutex_unlock(&priv->lock); + + /* Drop the reference to the event channel we did not save in the map */ + if (out_flags & UNMAP_NOTIFY_SEND_EVENT) + evtchn_put(out_event); + + return rc; +} + +#define GNTDEV_COPY_BATCH 16 + +struct gntdev_copy_batch { + struct gnttab_copy ops[GNTDEV_COPY_BATCH]; + struct page *pages[GNTDEV_COPY_BATCH]; + s16 __user *status[GNTDEV_COPY_BATCH]; + unsigned int nr_ops; + unsigned int nr_pages; + bool writeable; +}; + +static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, + unsigned long *gfn) +{ + unsigned long addr = (unsigned long)virt; + struct page *page; + unsigned long xen_pfn; + int ret; + + ret = pin_user_pages_fast(addr, 1, batch->writeable ? FOLL_WRITE : 0, &page); + if (ret < 0) + return ret; + + batch->pages[batch->nr_pages++] = page; + + xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); + *gfn = pfn_to_gfn(xen_pfn); + + return 0; +} + +static void gntdev_put_pages(struct gntdev_copy_batch *batch) +{ + unpin_user_pages_dirty_lock(batch->pages, batch->nr_pages, batch->writeable); + batch->nr_pages = 0; + batch->writeable = false; +} + +static int gntdev_copy(struct gntdev_copy_batch *batch) +{ + unsigned int i; + + gnttab_batch_copy(batch->ops, batch->nr_ops); + gntdev_put_pages(batch); + + /* + * For each completed op, update the status if the op failed + * and all previous ops for the segment were successful. + */ + for (i = 0; i < batch->nr_ops; i++) { + s16 status = batch->ops[i].status; + s16 old_status; + + if (status == GNTST_okay) + continue; + + if (__get_user(old_status, batch->status[i])) + return -EFAULT; + + if (old_status != GNTST_okay) + continue; + + if (__put_user(status, batch->status[i])) + return -EFAULT; + } + + batch->nr_ops = 0; + return 0; +} + +static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, + struct gntdev_grant_copy_segment *seg, + s16 __user *status) +{ + uint16_t copied = 0; + + /* + * Disallow local -> local copies since there is only space in + * batch->pages for one page per-op and this would be a very + * expensive memcpy(). + */ + if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) + return -EINVAL; + + /* Can't cross page if source/dest is a grant ref. */ + if (seg->flags & GNTCOPY_source_gref) { + if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) + return -EINVAL; + } + if (seg->flags & GNTCOPY_dest_gref) { + if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) + return -EINVAL; + } + + if (put_user(GNTST_okay, status)) + return -EFAULT; + + while (copied < seg->len) { + struct gnttab_copy *op; + void __user *virt; + size_t len, off; + unsigned long gfn; + int ret; + + if (batch->nr_ops >= GNTDEV_COPY_BATCH) { + ret = gntdev_copy(batch); + if (ret < 0) + return ret; + } + + len = seg->len - copied; + + op = &batch->ops[batch->nr_ops]; + op->flags = 0; + + if (seg->flags & GNTCOPY_source_gref) { + op->source.u.ref = seg->source.foreign.ref; + op->source.domid = seg->source.foreign.domid; + op->source.offset = seg->source.foreign.offset + copied; + op->flags |= GNTCOPY_source_gref; + } else { + virt = seg->source.virt + copied; + off = (unsigned long)virt & ~XEN_PAGE_MASK; + len = min(len, (size_t)XEN_PAGE_SIZE - off); + batch->writeable = false; + + ret = gntdev_get_page(batch, virt, &gfn); + if (ret < 0) + return ret; + + op->source.u.gmfn = gfn; + op->source.domid = DOMID_SELF; + op->source.offset = off; + } + + if (seg->flags & GNTCOPY_dest_gref) { + op->dest.u.ref = seg->dest.foreign.ref; + op->dest.domid = seg->dest.foreign.domid; + op->dest.offset = seg->dest.foreign.offset + copied; + op->flags |= GNTCOPY_dest_gref; + } else { + virt = seg->dest.virt + copied; + off = (unsigned long)virt & ~XEN_PAGE_MASK; + len = min(len, (size_t)XEN_PAGE_SIZE - off); + batch->writeable = true; + + ret = gntdev_get_page(batch, virt, &gfn); + if (ret < 0) + return ret; + + op->dest.u.gmfn = gfn; + op->dest.domid = DOMID_SELF; + op->dest.offset = off; + } + + op->len = len; + copied += len; + + batch->status[batch->nr_ops] = status; + batch->nr_ops++; + } + + return 0; +} + +static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) +{ + struct ioctl_gntdev_grant_copy copy; + struct gntdev_copy_batch batch; + unsigned int i; + int ret = 0; + + if (copy_from_user(©, u, sizeof(copy))) + return -EFAULT; + + batch.nr_ops = 0; + batch.nr_pages = 0; + + for (i = 0; i < copy.count; i++) { + struct gntdev_grant_copy_segment seg; + + if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { + ret = -EFAULT; + goto out; + } + + ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status); + if (ret < 0) + goto out; + + cond_resched(); + } + if (batch.nr_ops) + ret = gntdev_copy(&batch); + return ret; + + out: + gntdev_put_pages(&batch); + return ret; +} + +static long gntdev_ioctl(struct file *flip, + unsigned int cmd, unsigned long arg) +{ + struct gntdev_priv *priv = flip->private_data; + void __user *ptr = (void __user *)arg; + + switch (cmd) { + case IOCTL_GNTDEV_MAP_GRANT_REF: + return gntdev_ioctl_map_grant_ref(priv, ptr); + + case IOCTL_GNTDEV_UNMAP_GRANT_REF: + return gntdev_ioctl_unmap_grant_ref(priv, ptr); + + case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: + return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); + + case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: + return gntdev_ioctl_notify(priv, ptr); + + case IOCTL_GNTDEV_GRANT_COPY: + return gntdev_ioctl_grant_copy(priv, ptr); + +#ifdef CONFIG_XEN_GNTDEV_DMABUF + case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS: + return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr); + + case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED: + return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr); + + case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS: + return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr); + + case IOCTL_GNTDEV_DMABUF_IMP_RELEASE: + return gntdev_ioctl_dmabuf_imp_release(priv, ptr); +#endif + + default: + pr_debug("priv %p, unknown cmd %x\n", priv, cmd); + return -ENOIOCTLCMD; + } + + return 0; +} + +static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) +{ + struct gntdev_priv *priv = flip->private_data; + int index = vma->vm_pgoff; + int count = vma_pages(vma); + struct gntdev_grant_map *map; + int err = -EINVAL; + + if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) + return -EINVAL; + + pr_debug("map %d+%d at %lx (pgoff %lx)\n", + index, count, vma->vm_start, vma->vm_pgoff); + + mutex_lock(&priv->lock); + map = gntdev_find_map_index(priv, index, count); + if (!map) + goto unlock_out; + if (!atomic_add_unless(&map->in_use, 1, 1)) + goto unlock_out; + + refcount_inc(&map->users); + + vma->vm_ops = &gntdev_vmops; + + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP; + + if (use_ptemod) + vma->vm_flags |= VM_DONTCOPY; + + vma->vm_private_data = map; + if (map->flags) { + if ((vma->vm_flags & VM_WRITE) && + (map->flags & GNTMAP_readonly)) + goto out_unlock_put; + } else { + map->flags = GNTMAP_host_map; + if (!(vma->vm_flags & VM_WRITE)) + map->flags |= GNTMAP_readonly; + } + + map->pages_vm_start = vma->vm_start; + + if (use_ptemod) { + err = mmu_interval_notifier_insert_locked( + &map->notifier, vma->vm_mm, vma->vm_start, + vma->vm_end - vma->vm_start, &gntdev_mmu_ops); + if (err) + goto out_unlock_put; + + map->notifier_init = true; + } + mutex_unlock(&priv->lock); + + if (use_ptemod) { + /* + * gntdev takes the address of the PTE in find_grant_ptes() and + * passes it to the hypervisor in gntdev_map_grant_pages(). The + * purpose of the notifier is to prevent the hypervisor pointer + * to the PTE from going stale. + * + * Since this vma's mappings can't be touched without the + * mmap_lock, and we are holding it now, there is no need for + * the notifier_range locking pattern. + */ + mmu_interval_read_begin(&map->notifier); + + err = apply_to_page_range(vma->vm_mm, vma->vm_start, + vma->vm_end - vma->vm_start, + find_grant_ptes, map); + if (err) { + pr_warn("find_grant_ptes() failure.\n"); + goto out_put_map; + } + } + + err = gntdev_map_grant_pages(map); + if (err) + goto out_put_map; + + if (!use_ptemod) { + err = vm_map_pages_zero(vma, map->pages, map->count); + if (err) + goto out_put_map; + } + + return 0; + +unlock_out: + mutex_unlock(&priv->lock); + return err; + +out_unlock_put: + mutex_unlock(&priv->lock); +out_put_map: + if (use_ptemod) + unmap_grant_pages(map, 0, map->count); + gntdev_put_map(priv, map); + return err; +} + +static const struct file_operations gntdev_fops = { + .owner = THIS_MODULE, + .open = gntdev_open, + .release = gntdev_release, + .mmap = gntdev_mmap, + .unlocked_ioctl = gntdev_ioctl +}; + +static struct miscdevice gntdev_miscdev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "xen/gntdev", + .fops = &gntdev_fops, +}; + +/* ------------------------------------------------------------------ */ + +static int __init gntdev_init(void) +{ + int err; + + if (!xen_domain()) + return -ENODEV; + + use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); + + err = misc_register(&gntdev_miscdev); + if (err != 0) { + pr_err("Could not register gntdev device\n"); + return err; + } + return 0; +} + +static void __exit gntdev_exit(void) +{ + misc_deregister(&gntdev_miscdev); +} + +module_init(gntdev_init); +module_exit(gntdev_exit); + +/* ------------------------------------------------------------------ */ |