kernel/linux.git/include/linux/virtio_vsock.h, branch v7.0-rc7

vsock: add netns support to virtio transports

2026-01-27T09:45:38+00:00

Add netns support to loopback and vhost. Keep netns disabled for virtio-vsock, but add necessary changes to comply with common API updates. This is the patch in the series when vhost-vsock namespaces actually come online. Reviewed-by: Stefano Garzarella Signed-off-by: Bobby Eshleman Link: https://patch.msgid.link/20260121-vsock-vmtest-v16-3-2859a7512097@meta.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni

vsock: add netns to vsock core

2026-01-27T09:45:38+00:00

Add netns logic to vsock core. Additionally, modify transport hook prototypes to be used by later transport-specific patches (e.g., *_seqpacket_allow()). Namespaces are supported primarily by changing socket lookup functions (e.g., vsock_find_connected_socket()) to take into account the socket namespace and the namespace mode before considering a candidate socket a "match". This patch also introduces the sysctl /proc/sys/net/vsock/ns_mode to report the mode and /proc/sys/net/vsock/child_ns_mode to set the mode for new namespaces. Add netns functionality (initialization, passing to transports, procfs, etc...) to the af_vsock socket layer. Later patches that add netns support to transports depend on this patch. This patch changes the allocation of random ports for connectible vsocks in order to avoid leaking the random port range starting point to other namespaces. dgram_allow(), stream_allow(), and seqpacket_allow() callbacks are modified to take a vsk in order to perform logic on namespace modes. In future patches, the net will also be used for socket lookups in these functions. Reviewed-by: Stefano Garzarella Signed-off-by: Bobby Eshleman Link: https://patch.msgid.link/20260121-vsock-vmtest-v16-1-2859a7512097@meta.com Acked-by: Michael S. Tsirkin Signed-off-by: Paolo Abeni

vsock/virtio: Rename virtio_vsock_skb_rx_put()

2025-08-01T13:11:09+00:00

In preparation for using virtio_vsock_skb_rx_put() when populating SKBs on the vsock TX path, rename virtio_vsock_skb_rx_put() to virtio_vsock_skb_put(). No functional change. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-9-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vhost/vsock: Allocate nonlinear SKBs for handling large receive buffers

2025-08-01T13:11:09+00:00

When receiving a packet from a guest, vhost_vsock_handle_tx_kick() calls vhost_vsock_alloc_linear_skb() to allocate and fill an SKB with the receive data. Unfortunately, these are always linear allocations and can therefore result in significant pressure on kmalloc() considering that the maximum packet size (VIRTIO_VSOCK_MAX_PKT_BUF_SIZE + VIRTIO_VSOCK_SKB_HEADROOM) is a little over 64KiB, resulting in a 128KiB allocation for each packet. Rework the vsock SKB allocation so that, for sizes with page order greater than PAGE_ALLOC_COSTLY_ORDER, a nonlinear SKB is allocated instead with the packet header in the SKB and the receive data in the fragments. Finally, add a debug warning if virtio_vsock_skb_rx_put() is ever called on an SKB with a non-zero length, as this would be destructive for the nonlinear case. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-8-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Move SKB allocation lower-bound check to callers

2025-08-01T13:11:09+00:00

virtio_vsock_alloc_linear_skb() checks that the requested size is at least big enough for the packet header (VIRTIO_VSOCK_SKB_HEADROOM). Of the three callers of virtio_vsock_alloc_linear_skb(), only vhost_vsock_alloc_skb() can potentially pass a packet smaller than the header size and, as it already has a check against the maximum packet size, extend its bounds checking to consider the minimum packet size and remove the check from virtio_vsock_alloc_linear_skb(). Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-7-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Rename virtio_vsock_alloc_skb()

2025-08-01T13:11:09+00:00

In preparation for nonlinear allocations for large SKBs, rename virtio_vsock_alloc_skb() to virtio_vsock_alloc_linear_skb() to indicate that it returns linear SKBs unconditionally and switch all callers over to this new interface for now. No functional change. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-6-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page

2025-08-01T13:11:09+00:00

When allocating receive buffers for the vsock virtio RX virtqueue, an SKB is allocated with a 4140 data payload (the 44-byte packet header + VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE). Even when factoring in the SKB overhead, the resulting 8KiB allocation thanks to the rounding in kmalloc_reserve() is wasteful (~3700 unusable bytes) and results in a higher-order page allocation on systems with 4KiB pages just for the sake of a few hundred bytes of packet data. Limit the vsock virtio RX buffers to 4KiB per SKB, resulting in much better memory utilisation and removing the need to allocate higher-order pages entirely. Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-5-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: Move length check to callers of virtio_vsock_skb_rx_put()

2025-08-01T13:11:09+00:00

virtio_vsock_skb_rx_put() only calls skb_put() if the length in the packet header is not zero even though skb_put() handles this case gracefully. Remove the functionally redundant check from virtio_vsock_skb_rx_put() and, on the assumption that this is a worthwhile optimisation for handling credit messages, augment the existing length checks in virtio_transport_rx_work() to elide the call for zero-length payloads. Since the callers all have the length, extend virtio_vsock_skb_rx_put() to take it as an additional parameter rather than fish it back out of the packet header. Note that the vhost code already has similar logic in vhost_vsock_alloc_skb(). Reviewed-by: Stefano Garzarella Signed-off-by: Will Deacon Message-Id: <20250717090116.11987-4-will@kernel.org> Signed-off-by: Michael S. Tsirkin

vsock/virtio: fix `rx_bytes` accounting for stream sockets

2025-05-26T17:04:21+00:00

In `struct virtio_vsock_sock`, we maintain two counters: - `rx_bytes`: used internally to track how many bytes have been read. This supports mechanisms like .stream_has_data() and sock_rcvlowat(). - `fwd_cnt`: used for the credit mechanism to inform available receive buffer space to the remote peer. These counters are updated via virtio_transport_inc_rx_pkt() and virtio_transport_dec_rx_pkt(). Since the beginning with commit 06a8fc78367d ("VSOCK: Introduce virtio_vsock_common.ko"), we call virtio_transport_dec_rx_pkt() in virtio_transport_stream_do_dequeue() only when we consume the entire packet, so partial reads, do not update `rx_bytes` and `fwd_cnt`. This is fine for `fwd_cnt`, because we still have space used for the entire packet, and we don't want to update the credit for the other peer until we free the space of the entire packet. However, this causes `rx_bytes` to be stale on partial reads. Previously, this didn’t cause issues because `rx_bytes` was used only by .stream_has_data(), and any unread portion of a packet implied data was still available. However, since commit 93b808876682 ("virtio/vsock: fix logic which reduces credit update messages"), we now rely on `rx_bytes` to determine if a credit update should be sent when the data in the RX queue drops below SO_RCVLOWAT value. This patch fixes the accounting by updating `rx_bytes` with the number of bytes actually read, even on partial reads, while leaving `fwd_cnt` untouched until the packet is fully consumed. Also introduce a new `buf_used` counter to check that the remote peer is honoring the given credit; this was previously done via `rx_bytes`. Fixes: 93b808876682 ("virtio/vsock: fix logic which reduces credit update messages") Signed-off-by: Stefano Garzarella Link: https://patch.msgid.link/20250521121705.196379-1-sgarzare@redhat.com Signed-off-by: Paolo Abeni

vsock/virtio: add SIOCOUTQ support for all virtio based transports

2024-08-02T08:20:28+00:00

Introduce support for virtio_transport_unsent_bytes ioctl for virtio_transport, vhost_vsock and vsock_loopback. For all transports the unsent bytes counter is incremented in virtio_transport_get_credit. In virtio_transport (G2H) and in vhost-vsock (H2G) the counter is decremented when the skbuff is consumed. In vsock_loopback the same skbuff is passed from the transmitter to the receiver, so the counter is decremented before queuing the skbuff to the receiver. Signed-off-by: Luigi Leonardi Reviewed-by: Stefano Garzarella Signed-off-by: David S. Miller