vhost-net: allow configuring extended features

Use the extended feature type for 'acked_features' and implement
two new ioctls operation allowing the user-space to set/query an
unbounded amount of features.

The actual number of processed features is limited by VIRTIO_FEATURES_MAX
and attempts to set features above such limit fail with
EOPNOTSUPP.

Note that: the legacy ioctls implicitly truncate the negotiated
features to the lower 64 bits range and the 'acked_backend_features'
field don't need conversion, as the only negotiated feature there
is in the low 64 bit range.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 7cbfc7d718b3fdc09d53a1846ea5b5c701a6a41b..67d011b0d4f73f77963d5be649e235809129e7c8 100644 (file)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -69,12 +69,12 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
 
 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
 
-enum {
-       VHOST_NET_FEATURES = VHOST_FEATURES |
-                        (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
-                        (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
-                        (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
-                        (1ULL << VIRTIO_F_RING_RESET)
+static const u64 vhost_net_features[VIRTIO_FEATURES_DWORDS] = {
+       VHOST_FEATURES |
+       (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
+       (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+       (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
+       (1ULL << VIRTIO_F_RING_RESET),
 };
 
 enum {
@@ -1614,16 +1614,17 @@ done:
        return err;
 }
 
-static int vhost_net_set_features(struct vhost_net *n, u64 features)
+static int vhost_net_set_features(struct vhost_net *n, const u64 *features)
 {
        size_t vhost_hlen, sock_hlen, hdr_len;
        int i;
 
-       hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
-                              (1ULL << VIRTIO_F_VERSION_1))) ?
-                       sizeof(struct virtio_net_hdr_mrg_rxbuf) :
-                       sizeof(struct virtio_net_hdr);
-       if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
+       hdr_len = virtio_features_test_bit(features, VIRTIO_NET_F_MRG_RXBUF) ||
+                 virtio_features_test_bit(features, VIRTIO_F_VERSION_1) ?
+                 sizeof(struct virtio_net_hdr_mrg_rxbuf) :
+                 sizeof(struct virtio_net_hdr);
+
+       if (virtio_features_test_bit(features, VHOST_NET_F_VIRTIO_NET_HDR)) {
                /* vhost provides vnet_hdr */
                vhost_hlen = hdr_len;
                sock_hlen = 0;
@@ -1633,18 +1634,19 @@ static int vhost_net_set_features(struct vhost_net *n, u64 features)
                sock_hlen = hdr_len;
        }
        mutex_lock(&n->dev.mutex);
-       if ((features & (1 << VHOST_F_LOG_ALL)) &&
+       if (virtio_features_test_bit(features, VHOST_F_LOG_ALL) &&
            !vhost_log_access_ok(&n->dev))
                goto out_unlock;
 
-       if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
+       if (virtio_features_test_bit(features, VIRTIO_F_ACCESS_PLATFORM)) {
                if (vhost_init_device_iotlb(&n->dev))
                        goto out_unlock;
        }
 
        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
                mutex_lock(&n->vqs[i].vq.mutex);
-               n->vqs[i].vq.acked_features = features;
+               virtio_features_copy(n->vqs[i].vq.acked_features_array,
+                                    features);
                n->vqs[i].vhost_hlen = vhost_hlen;
                n->vqs[i].sock_hlen = sock_hlen;
                mutex_unlock(&n->vqs[i].vq.mutex);
@@ -1681,12 +1683,13 @@ out:
 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
                            unsigned long arg)
 {
+       u64 all_features[VIRTIO_FEATURES_DWORDS];
        struct vhost_net *n = f->private_data;
        void __user *argp = (void __user *)arg;
        u64 __user *featurep = argp;
        struct vhost_vring_file backend;
-       u64 features;
-       int r;
+       u64 features, count, copied;
+       int r, i;
 
        switch (ioctl) {
        case VHOST_NET_SET_BACKEND:
@@ -1694,16 +1697,60 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
                        return -EFAULT;
                return vhost_net_set_backend(n, backend.index, backend.fd);
        case VHOST_GET_FEATURES:
-               features = VHOST_NET_FEATURES;
+               features = vhost_net_features[0];
                if (copy_to_user(featurep, &features, sizeof features))
                        return -EFAULT;
                return 0;
        case VHOST_SET_FEATURES:
                if (copy_from_user(&features, featurep, sizeof features))
                        return -EFAULT;
-               if (features & ~VHOST_NET_FEATURES)
+               if (features & ~vhost_net_features[0])
                        return -EOPNOTSUPP;
-               return vhost_net_set_features(n, features);
+
+               virtio_features_from_u64(all_features, features);
+               return vhost_net_set_features(n, all_features);
+       case VHOST_GET_FEATURES_ARRAY:
+               if (copy_from_user(&count, featurep, sizeof(count)))
+                       return -EFAULT;
+
+               /* Copy the net features, up to the user-provided buffer size */
+               argp += sizeof(u64);
+               copied = min(count, VIRTIO_FEATURES_DWORDS);
+               if (copy_to_user(argp, vhost_net_features,
+                                copied * sizeof(u64)))
+                       return -EFAULT;
+
+               /* Zero the trailing space provided by user-space, if any */
+               if (clear_user(argp, size_mul(count - copied, sizeof(u64))))
+                       return -EFAULT;
+               return 0;
+       case VHOST_SET_FEATURES_ARRAY:
+               if (copy_from_user(&count, featurep, sizeof(count)))
+                       return -EFAULT;
+
+               virtio_features_zero(all_features);
+               argp += sizeof(u64);
+               copied = min(count, VIRTIO_FEATURES_DWORDS);
+               if (copy_from_user(all_features, argp, copied * sizeof(u64)))
+                       return -EFAULT;
+
+               /*
+                * Any feature specified by user-space above
+                * VIRTIO_FEATURES_MAX is not supported by definition.
+                */
+               for (i = copied; i < count; ++i) {
+                       if (copy_from_user(&features, featurep + 1 + i,
+                                          sizeof(features)))
+                               return -EFAULT;
+                       if (features)
+                               return -EOPNOTSUPP;
+               }
+
+               for (i = 0; i < VIRTIO_FEATURES_DWORDS; i++)
+                       if (all_features[i] & ~vhost_net_features[i])
+                               return -EOPNOTSUPP;
+
+               return vhost_net_set_features(n, all_features);
        case VHOST_GET_BACKEND_FEATURES:
                features = VHOST_NET_BACKEND_FEATURES;
                if (copy_to_user(featurep, &features, sizeof(features)))

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 3a5ebb973dba393738f2370fe85b857012a380bd..1094256a943c1ca1fcc181959f8c28173397b7da 100644 (file)
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -372,7 +372,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
        vq->log_used = false;
        vq->log_addr = -1ull;
        vq->private_data = NULL;
-       vq->acked_features = 0;
+       virtio_features_zero(vq->acked_features_array);
        vq->acked_backend_features = 0;
        vq->log_base = NULL;
        vq->error_ctx = NULL;

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index bb75a292d50cd3f96bc6be019574a6d6379523d6..d1aed35c4b077849777eefe71bc36172c5f6412d 100644 (file)
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -133,7 +133,7 @@ struct vhost_virtqueue {
        struct vhost_iotlb *umem;
        struct vhost_iotlb *iotlb;
        void *private_data;
-       u64 acked_features;
+       VIRTIO_DECLARE_FEATURES(acked_features);
        u64 acked_backend_features;
        /* Log write descriptors */
        void __user *log_base;
@@ -291,7 +291,7 @@ static inline void *vhost_vq_get_backend(struct vhost_virtqueue *vq)
 
 static inline bool vhost_has_feature(struct vhost_virtqueue *vq, int bit)
 {
-       return vq->acked_features & (1ULL << bit);
+       return virtio_features_test_bit(vq->acked_features_array, bit);
 }
 
 static inline bool vhost_backend_has_feature(struct vhost_virtqueue *vq, int bit)

diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index d4b3e2ae1314d1fc55f3de081ca147532d25947c..d6ad01fbb8d2ac3ec71dc65934b55d4dcd58b948 100644 (file)
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -235,4 +235,11 @@
  */
 #define VHOST_VDPA_GET_VRING_SIZE      _IOWR(VHOST_VIRTIO, 0x82,       \
                                              struct vhost_vring_state)
+
+/* Extended features manipulation */
+#define VHOST_GET_FEATURES_ARRAY _IOR(VHOST_VIRTIO, 0x83, \
+                                      struct vhost_features_array)
+#define VHOST_SET_FEATURES_ARRAY _IOW(VHOST_VIRTIO, 0x83, \
+                                      struct vhost_features_array)
+
 #endif

diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
index d7656908f7305fb7fc0977115f129924af01beff..1c39cc5f5a31b5f155983f66662ee6b7c454d516 100644 (file)
--- a/include/uapi/linux/vhost_types.h
+++ b/include/uapi/linux/vhost_types.h
@@ -110,6 +110,11 @@ struct vhost_msg_v2 {
        };
 };
 
+struct vhost_features_array {
+       __u64 count; /* number of entries present in features array */
+       __u64 features[] __counted_by(count);
+};
+
 struct vhost_memory_region {
        __u64 guest_phys_addr;
        __u64 memory_size; /* bytes */