diff options
| -rw-r--r-- | drivers/xen/gntdev.c | 203 | ||||
| -rw-r--r-- | include/uapi/xen/gntdev.h | 50 |
2 files changed, 253 insertions, 0 deletions
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c index cbd3836ec8fa..dc495383ad73 100644 --- a/drivers/xen/gntdev.c +++ b/drivers/xen/gntdev.c @@ -748,6 +748,206 @@ static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) return rc; } +#define GNTDEV_COPY_BATCH 24 + +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; +}; + +static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, + bool writeable, unsigned long *gfn) +{ + unsigned long addr = (unsigned long)virt; + struct page *page; + unsigned long xen_pfn; + int ret; + + ret = get_user_pages_fast(addr, 1, writeable, &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) +{ + unsigned int i; + + for (i = 0; i < batch->nr_pages; i++) + put_page(batch->pages[i]); + batch->nr_pages = 0; +} + +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); + + ret = gntdev_get_page(batch, virt, false, &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); + + ret = gntdev_get_page(batch, virt, true, &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) { @@ -767,6 +967,9 @@ static long gntdev_ioctl(struct file *flip, case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: return gntdev_ioctl_notify(priv, ptr); + case IOCTL_GNTDEV_GRANT_COPY: + return gntdev_ioctl_grant_copy(priv, ptr); + default: pr_debug("priv %p, unknown cmd %x\n", priv, cmd); return -ENOIOCTLCMD; diff --git a/include/uapi/xen/gntdev.h b/include/uapi/xen/gntdev.h index aa7610a9b867..d0661977667e 100644 --- a/include/uapi/xen/gntdev.h +++ b/include/uapi/xen/gntdev.h @@ -144,6 +144,56 @@ struct ioctl_gntdev_unmap_notify { __u32 event_channel_port; }; +struct gntdev_grant_copy_segment { + union { + void __user *virt; + struct { + grant_ref_t ref; + __u16 offset; + domid_t domid; + } foreign; + } source, dest; + __u16 len; + + __u16 flags; /* GNTCOPY_* */ + __s16 status; /* GNTST_* */ +}; + +/* + * Copy between grant references and local buffers. + * + * The copy is split into @count @segments, each of which can copy + * to/from one grant reference. + * + * Each segment is similar to struct gnttab_copy in the hypervisor ABI + * except the local buffer is specified using a virtual address + * (instead of a GFN and offset). + * + * The local buffer may cross a Xen page boundary -- the driver will + * split segments into multiple ops if required. + * + * Returns 0 if all segments have been processed and @status in each + * segment is valid. Note that one or more segments may have failed + * (status != GNTST_okay). + * + * If the driver had to split a segment into two or more ops, @status + * includes the status of the first failed op for that segment (or + * GNTST_okay if all ops were successful). + * + * If -1 is returned, the status of all segments is undefined. + * + * EINVAL: A segment has local buffers for both source and + * destination. + * EINVAL: A segment crosses the boundary of a foreign page. + * EFAULT: A segment's local buffer is not accessible. + */ +#define IOCTL_GNTDEV_GRANT_COPY \ + _IOC(_IOC_NONE, 'G', 8, sizeof(struct ioctl_gntdev_grant_copy)) +struct ioctl_gntdev_grant_copy { + unsigned int count; + struct gntdev_grant_copy_segment __user *segments; +}; + /* Clear (set to zero) the byte specified by index */ #define UNMAP_NOTIFY_CLEAR_BYTE 0x1 /* Send an interrupt on the indicated event channel */ |