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Message-ID: <b9b60ed5865958b9d169adc3b0196c21a50f6bca.1748614223.git.pabeni@redhat.com>
Date: Fri, 30 May 2025 16:49:19 +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: [RFC PATCH v2 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_t
size, 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.
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
v1 -> v2:
- change the ioctl to use an extensible API
---
drivers/vhost/net.c | 61 ++++++++++++++++++++++++++++++--
drivers/vhost/vhost.h | 2 +-
include/uapi/linux/vhost.h | 7 ++++
include/uapi/linux/vhost_types.h | 5 +++
4 files changed, 71 insertions(+), 4 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 7cbfc7d718b3..f53294440695 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -77,6 +77,8 @@ enum {
(1ULL << VIRTIO_F_RING_RESET)
};
+#define VHOST_NET_ALL_FEATURES VHOST_NET_FEATURES
+
enum {
VHOST_NET_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
};
@@ -1614,7 +1616,7 @@ 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, virtio_features_t features)
{
size_t vhost_hlen, sock_hlen, hdr_len;
int i;
@@ -1685,8 +1687,9 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
void __user *argp = (void __user *)arg;
u64 __user *featurep = argp;
struct vhost_vring_file backend;
- u64 features;
- int r;
+ virtio_features_t all_features;
+ u64 features, count;
+ int r, i;
switch (ioctl) {
case VHOST_NET_SET_BACKEND:
@@ -1704,6 +1707,58 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
if (features & ~VHOST_NET_FEATURES)
return -EOPNOTSUPP;
return vhost_net_set_features(n, 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 */
+ all_features = VHOST_NET_ALL_FEATURES;
+ for (i = 0; i < min(VIRTIO_FEATURES_WORDS / 2, count); ++i) {
+ argp += sizeof(u64);
+ features = all_features >> (64 * i);
+ if (copy_to_user(argp, &features, sizeof(u64)))
+ return -EFAULT;
+ }
+
+ /* Zero the trailing space provided by user-space, if any */
+ features = 0;
+ for (; i < count; ++i) {
+ argp += sizeof(u64);
+ if (copy_to_user(argp, &features, sizeof(u64)))
+ return -EFAULT;
+ }
+ return 0;
+ }
+ case VHOST_SET_FEATURES_ARRAY:
+ {
+ if (copy_from_user(&count, argp, sizeof(u64)))
+ return -EFAULT;
+
+ all_features = 0;
+ for (i = 0; i < min(count, VIRTIO_FEATURES_WORDS / 2); ++i) {
+ argp += sizeof(u64);
+ if (copy_from_user(&features, argp, sizeof(u64)))
+ return -EFAULT;
+
+ all_features |= ((virtio_features_t)features) << (64 * i);
+ }
+
+ /* 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;
+ }
+
+ if (all_features & ~VHOST_NET_ALL_FEATURES)
+ 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.h b/drivers/vhost/vhost.h
index bb75a292d50c..ef1c7fd6f4e1 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_features_t acked_features;
u64 acked_backend_features;
/* Log write descriptors */
void __user *log_base;
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..3f227114c557 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[];
+};
+
struct vhost_memory_region {
__u64 guest_phys_addr;
__u64 memory_size; /* bytes */
--
2.49.0
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