vhost: add unlikely annotations to error path
[deliverable/linux.git] / drivers / vhost / vhost.c
index c6fb8e968f219c504a90bbbca9e8e56e5af1fe5a..0b99783083f61504bd77fc353e9c9f99a09f7bfb 100644 (file)
@@ -320,10 +320,8 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
 {
        struct vhost_memory mem, *newmem, *oldmem;
        unsigned long size = offsetof(struct vhost_memory, regions);
-       long r;
-       r = copy_from_user(&mem, m, size);
-       if (r)
-               return r;
+       if (copy_from_user(&mem, m, size))
+               return -EFAULT;
        if (mem.padding)
                return -EOPNOTSUPP;
        if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS)
@@ -333,15 +331,16 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
                return -ENOMEM;
 
        memcpy(newmem, &mem, size);
-       r = copy_from_user(newmem->regions, m->regions,
-                          mem.nregions * sizeof *m->regions);
-       if (r) {
+       if (copy_from_user(newmem->regions, m->regions,
+                          mem.nregions * sizeof *m->regions)) {
                kfree(newmem);
-               return r;
+               return -EFAULT;
        }
 
-       if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL)))
+       if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) {
+               kfree(newmem);
                return -EFAULT;
+       }
        oldmem = d->memory;
        rcu_assign_pointer(d->memory, newmem);
        synchronize_rcu();
@@ -374,7 +373,7 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
        r = get_user(idx, idxp);
        if (r < 0)
                return r;
-       if (idx > d->nvqs)
+       if (idx >= d->nvqs)
                return -ENOBUFS;
 
        vq = d->vqs + idx;
@@ -389,9 +388,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
                        r = -EBUSY;
                        break;
                }
-               r = copy_from_user(&s, argp, sizeof s);
-               if (r < 0)
+               if (copy_from_user(&s, argp, sizeof s)) {
+                       r = -EFAULT;
                        break;
+               }
                if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) {
                        r = -EINVAL;
                        break;
@@ -405,9 +405,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
                        r = -EBUSY;
                        break;
                }
-               r = copy_from_user(&s, argp, sizeof s);
-               if (r < 0)
+               if (copy_from_user(&s, argp, sizeof s)) {
+                       r = -EFAULT;
                        break;
+               }
                if (s.num > 0xffff) {
                        r = -EINVAL;
                        break;
@@ -419,12 +420,14 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
        case VHOST_GET_VRING_BASE:
                s.index = idx;
                s.num = vq->last_avail_idx;
-               r = copy_to_user(argp, &s, sizeof s);
+               if (copy_to_user(argp, &s, sizeof s))
+                       r = -EFAULT;
                break;
        case VHOST_SET_VRING_ADDR:
-               r = copy_from_user(&a, argp, sizeof a);
-               if (r < 0)
+               if (copy_from_user(&a, argp, sizeof a)) {
+                       r = -EFAULT;
                        break;
+               }
                if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) {
                        r = -EOPNOTSUPP;
                        break;
@@ -477,9 +480,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
                vq->used = (void __user *)(unsigned long)a.used_user_addr;
                break;
        case VHOST_SET_VRING_KICK:
-               r = copy_from_user(&f, argp, sizeof f);
-               if (r < 0)
+               if (copy_from_user(&f, argp, sizeof f)) {
+                       r = -EFAULT;
                        break;
+               }
                eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
                if (IS_ERR(eventfp)) {
                        r = PTR_ERR(eventfp);
@@ -492,9 +496,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
                        filep = eventfp;
                break;
        case VHOST_SET_VRING_CALL:
-               r = copy_from_user(&f, argp, sizeof f);
-               if (r < 0)
+               if (copy_from_user(&f, argp, sizeof f)) {
+                       r = -EFAULT;
                        break;
+               }
                eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
                if (IS_ERR(eventfp)) {
                        r = PTR_ERR(eventfp);
@@ -510,9 +515,10 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
                        filep = eventfp;
                break;
        case VHOST_SET_VRING_ERR:
-               r = copy_from_user(&f, argp, sizeof f);
-               if (r < 0)
+               if (copy_from_user(&f, argp, sizeof f)) {
+                       r = -EFAULT;
                        break;
+               }
                eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
                if (IS_ERR(eventfp)) {
                        r = PTR_ERR(eventfp);
@@ -575,9 +581,10 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg)
                r = vhost_set_memory(d, argp);
                break;
        case VHOST_SET_LOG_BASE:
-               r = copy_from_user(&p, argp, sizeof p);
-               if (r < 0)
+               if (copy_from_user(&p, argp, sizeof p)) {
+                       r = -EFAULT;
                        break;
+               }
                if ((u64)(unsigned long)p != p) {
                        r = -EFAULT;
                        break;
@@ -729,12 +736,12 @@ static int translate_desc(struct vhost_dev *dev, u64 addr, u32 len,
        mem = rcu_dereference(dev->memory);
        while ((u64)len > s) {
                u64 size;
-               if (ret >= iov_size) {
+               if (unlikely(ret >= iov_size)) {
                        ret = -ENOBUFS;
                        break;
                }
                reg = find_region(mem, addr, len);
-               if (!reg) {
+               if (unlikely(!reg)) {
                        ret = -EFAULT;
                        break;
                }
@@ -773,18 +780,18 @@ static unsigned next_desc(struct vring_desc *desc)
        return next;
 }
 
-static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
-                            struct iovec iov[], unsigned int iov_size,
-                            unsigned int *out_num, unsigned int *in_num,
-                            struct vhost_log *log, unsigned int *log_num,
-                            struct vring_desc *indirect)
+static int get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
+                       struct iovec iov[], unsigned int iov_size,
+                       unsigned int *out_num, unsigned int *in_num,
+                       struct vhost_log *log, unsigned int *log_num,
+                       struct vring_desc *indirect)
 {
        struct vring_desc desc;
        unsigned int i = 0, count, found = 0;
        int ret;
 
        /* Sanity check */
-       if (indirect->len % sizeof desc) {
+       if (unlikely(indirect->len % sizeof desc)) {
                vq_err(vq, "Invalid length in indirect descriptor: "
                       "len 0x%llx not multiple of 0x%zx\n",
                       (unsigned long long)indirect->len,
@@ -794,7 +801,7 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
 
        ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect,
                             ARRAY_SIZE(vq->indirect));
-       if (ret < 0) {
+       if (unlikely(ret < 0)) {
                vq_err(vq, "Translation failure %d in indirect.\n", ret);
                return ret;
        }
@@ -806,7 +813,7 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
        count = indirect->len / sizeof desc;
        /* Buffers are chained via a 16 bit next field, so
         * we can have at most 2^16 of these. */
-       if (count > USHRT_MAX + 1) {
+       if (unlikely(count > USHRT_MAX + 1)) {
                vq_err(vq, "Indirect buffer length too big: %d\n",
                       indirect->len);
                return -E2BIG;
@@ -814,19 +821,19 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
 
        do {
                unsigned iov_count = *in_num + *out_num;
-               if (++found > count) {
+               if (unlikely(++found > count)) {
                        vq_err(vq, "Loop detected: last one at %u "
                               "indirect size %u\n",
                               i, count);
                        return -EINVAL;
                }
-               if (memcpy_fromiovec((unsigned char *)&desc, vq->indirect,
-                                    sizeof desc)) {
+               if (unlikely(memcpy_fromiovec((unsigned char *)&desc, vq->indirect,
+                                             sizeof desc))) {
                        vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n",
                               i, (size_t)indirect->addr + i * sizeof desc);
                        return -EINVAL;
                }
-               if (desc.flags & VRING_DESC_F_INDIRECT) {
+               if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
                        vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n",
                               i, (size_t)indirect->addr + i * sizeof desc);
                        return -EINVAL;
@@ -834,7 +841,7 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
 
                ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
                                     iov_size - iov_count);
-               if (ret < 0) {
+               if (unlikely(ret < 0)) {
                        vq_err(vq, "Translation failure %d indirect idx %d\n",
                               ret, i);
                        return ret;
@@ -850,7 +857,7 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
                } else {
                        /* If it's an output descriptor, they're all supposed
                         * to come before any input descriptors. */
-                       if (*in_num) {
+                       if (unlikely(*in_num)) {
                                vq_err(vq, "Indirect descriptor "
                                       "has out after in: idx %d\n", i);
                                return -EINVAL;
@@ -866,12 +873,13 @@ static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq,
  * number of output then some number of input descriptors, it's actually two
  * iovecs, but we pack them into one and note how many of each there were.
  *
- * This function returns the descriptor number found, or vq->num (which
- * is never a valid descriptor number) if none was found. */
-unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
-                          struct iovec iov[], unsigned int iov_size,
-                          unsigned int *out_num, unsigned int *in_num,
-                          struct vhost_log *log, unsigned int *log_num)
+ * This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found.  A negative code is
+ * returned on error. */
+int vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
+                     struct iovec iov[], unsigned int iov_size,
+                     unsigned int *out_num, unsigned int *in_num,
+                     struct vhost_log *log, unsigned int *log_num)
 {
        struct vring_desc desc;
        unsigned int i, head, found = 0;
@@ -880,16 +888,16 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
 
        /* Check it isn't doing very strange things with descriptor numbers. */
        last_avail_idx = vq->last_avail_idx;
-       if (get_user(vq->avail_idx, &vq->avail->idx)) {
+       if (unlikely(get_user(vq->avail_idx, &vq->avail->idx))) {
                vq_err(vq, "Failed to access avail idx at %p\n",
                       &vq->avail->idx);
-               return vq->num;
+               return -EFAULT;
        }
 
-       if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) {
+       if (unlikely((u16)(vq->avail_idx - last_avail_idx) > vq->num)) {
                vq_err(vq, "Guest moved used index from %u to %u",
                       last_avail_idx, vq->avail_idx);
-               return vq->num;
+               return -EFAULT;
        }
 
        /* If there's nothing new since last we looked, return invalid. */
@@ -901,18 +909,19 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
 
        /* Grab the next descriptor number they're advertising, and increment
         * the index we've seen. */
-       if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) {
+       if (unlikely(get_user(head,
+                             &vq->avail->ring[last_avail_idx % vq->num]))) {
                vq_err(vq, "Failed to read head: idx %d address %p\n",
                       last_avail_idx,
                       &vq->avail->ring[last_avail_idx % vq->num]);
-               return vq->num;
+               return -EFAULT;
        }
 
        /* If their number is silly, that's an error. */
-       if (head >= vq->num) {
+       if (unlikely(head >= vq->num)) {
                vq_err(vq, "Guest says index %u > %u is available",
                       head, vq->num);
-               return vq->num;
+               return -EINVAL;
        }
 
        /* When we start there are none of either input nor output. */
@@ -923,41 +932,41 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
        i = head;
        do {
                unsigned iov_count = *in_num + *out_num;
-               if (i >= vq->num) {
+               if (unlikely(i >= vq->num)) {
                        vq_err(vq, "Desc index is %u > %u, head = %u",
                               i, vq->num, head);
-                       return vq->num;
+                       return -EINVAL;
                }
-               if (++found > vq->num) {
+               if (unlikely(++found > vq->num)) {
                        vq_err(vq, "Loop detected: last one at %u "
                               "vq size %u head %u\n",
                               i, vq->num, head);
-                       return vq->num;
+                       return -EINVAL;
                }
                ret = copy_from_user(&desc, vq->desc + i, sizeof desc);
-               if (ret) {
+               if (unlikely(ret)) {
                        vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
                               i, vq->desc + i);
-                       return vq->num;
+                       return -EFAULT;
                }
                if (desc.flags & VRING_DESC_F_INDIRECT) {
                        ret = get_indirect(dev, vq, iov, iov_size,
                                           out_num, in_num,
                                           log, log_num, &desc);
-                       if (ret < 0) {
+                       if (unlikely(ret < 0)) {
                                vq_err(vq, "Failure detected "
                                       "in indirect descriptor at idx %d\n", i);
-                               return vq->num;
+                               return ret;
                        }
                        continue;
                }
 
                ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count,
                                     iov_size - iov_count);
-               if (ret < 0) {
+               if (unlikely(ret < 0)) {
                        vq_err(vq, "Translation failure %d descriptor idx %d\n",
                               ret, i);
-                       return vq->num;
+                       return ret;
                }
                if (desc.flags & VRING_DESC_F_WRITE) {
                        /* If this is an input descriptor,
@@ -971,10 +980,10 @@ unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq,
                } else {
                        /* If it's an output descriptor, they're all supposed
                         * to come before any input descriptors. */
-                       if (*in_num) {
+                       if (unlikely(*in_num)) {
                                vq_err(vq, "Descriptor has out after in: "
                                       "idx %d\n", i);
-                               return vq->num;
+                               return -EINVAL;
                        }
                        *out_num += ret;
                }
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