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Message-ID: <c510db61e36ce3b26e3a1fb7716c17f6888da095.1750176076.git.pabeni@redhat.com>
Date: Tue, 17 Jun 2025 18:12:10 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: netdev@...r.kernel.org
Cc: Willem de Bruijn <willemdebruijn.kernel@...il.com>,
Jason Wang <jasowang@...hat.com>,
Andrew Lunn <andrew+netdev@...n.ch>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
Eugenio Pérez <eperezma@...hat.com>,
Yuri Benditovich <yuri.benditovich@...nix.com>,
Akihiko Odaki <akihiko.odaki@...nix.com>
Subject: [PATCH v4 net-next 3/8] 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@...hat.com>
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
v3 -> v4:
- use a single static (lower case) constant instead of enum and old def
- simpler VHOST_GET_FEATURES_ARRAY impl
- avoid using virtio_features_and_not
v2 -> v3:
- virtio_features_t -> u64[2]
- add __counted_by annotation to vhost_features_array
v1 -> v2:
- change the ioctl to use an extensible API
---
drivers/vhost/net.c | 87 ++++++++++++++++++++++++--------
drivers/vhost/vhost.c | 2 +-
drivers/vhost/vhost.h | 4 +-
include/uapi/linux/vhost.h | 7 +++
include/uapi/linux/vhost_types.h | 5 ++
5 files changed, 82 insertions(+), 23 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 7cbfc7d718b3..126aa4ee26a8 100644
--- 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 @@ static long vhost_net_reset_owner(struct vhost_net *n)
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 @@ static long vhost_net_set_owner(struct vhost_net *n)
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, argp, sizeof(u64)))
+ 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, (count - copied) * sizeof(u64)))
+ return -EFAULT;
+ return 0;
+ case VHOST_SET_FEATURES_ARRAY:
+ if (copy_from_user(&count, argp, sizeof(u64)))
+ return -EFAULT;
+
+ virtio_features_zero(all_features);
+ for (i = 0; i < min(count, VIRTIO_FEATURES_DWORDS); ++i) {
+ argp += sizeof(u64);
+ if (copy_from_user(&all_features[i], argp,
+ sizeof(u64)))
+ return -EFAULT;
+ }
+
+ /* Any feature specified by user-space above VIRTIO_FEATURES_MAX is
+ * not supported by definition.
+ */
+ for (; i < count; ++i) {
+ if (copy_from_user(&features, argp, sizeof(u64)))
+ return -EFAULT;
+ if (features)
+ return -EOPNOTSUPP;
+ }
+
+ for (i = 1; 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 3a5ebb973dba..1094256a943c 100644
--- 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 bb75a292d50c..d1aed35c4b07 100644
--- 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 d4b3e2ae1314..d6ad01fbb8d2 100644
--- 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 d7656908f730..1c39cc5f5a31 100644
--- 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 */
--
2.49.0
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