Re: [PATCH net-next v9 6/6] vhost/net: Support VIRTIO_NET_F_HASH_REPORT
From: Akihiko Odaki
Date: Tue Mar 11 2025 - 02:24:27 EST
On 2025/03/11 9:42, Jason Wang wrote:
On Mon, Mar 10, 2025 at 3:04 PM Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> wrote:
On 2025/03/10 13:43, Jason Wang wrote:
On Fri, Mar 7, 2025 at 7:02 PM Akihiko Odaki <akihiko.odaki@xxxxxxxxxx> wrote:
VIRTIO_NET_F_HASH_REPORT allows to report hash values calculated on the
host. When VHOST_NET_F_VIRTIO_NET_HDR is employed, it will report no
hash values (i.e., the hash_report member is always set to
VIRTIO_NET_HASH_REPORT_NONE). Otherwise, the values reported by the
underlying socket will be reported.
VIRTIO_NET_F_HASH_REPORT requires VIRTIO_F_VERSION_1.
Signed-off-by: Akihiko Odaki <akihiko.odaki@xxxxxxxxxx>
Tested-by: Lei Yang <leiyang@xxxxxxxxxx>
---
drivers/vhost/net.c | 49 +++++++++++++++++++++++++++++--------------------
1 file changed, 29 insertions(+), 20 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index b9b9e9d40951856d881d77ac74331d914473cd56..16b241b44f89820a42c302f3586ea6bb5e0d4289 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -73,6 +73,7 @@ enum {
VHOST_NET_FEATURES = VHOST_FEATURES |
(1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
(1ULL << VIRTIO_NET_F_MRG_RXBUF) |
+ (1ULL << VIRTIO_NET_F_HASH_REPORT) |
(1ULL << VIRTIO_F_ACCESS_PLATFORM) |
(1ULL << VIRTIO_F_RING_RESET)
};
@@ -1097,9 +1098,11 @@ static void handle_rx(struct vhost_net *net)
.msg_controllen = 0,
.msg_flags = MSG_DONTWAIT,
};
- struct virtio_net_hdr hdr = {
- .flags = 0,
- .gso_type = VIRTIO_NET_HDR_GSO_NONE
+ struct virtio_net_hdr_v1_hash hdr = {
+ .hdr = {
+ .flags = 0,
+ .gso_type = VIRTIO_NET_HDR_GSO_NONE
+ }
};
size_t total_len = 0;
int err, mergeable;
@@ -1110,7 +1113,6 @@ static void handle_rx(struct vhost_net *net)
bool set_num_buffers;
struct socket *sock;
struct iov_iter fixup;
- __virtio16 num_buffers;
int recv_pkts = 0;
mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
@@ -1191,30 +1193,30 @@ static void handle_rx(struct vhost_net *net)
vhost_discard_vq_desc(vq, headcount);
continue;
}
+ hdr.hdr.num_buffers = cpu_to_vhost16(vq, headcount);
/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
if (unlikely(vhost_hlen)) {
- if (copy_to_iter(&hdr, sizeof(hdr),
- &fixup) != sizeof(hdr)) {
+ if (copy_to_iter(&hdr, vhost_hlen,
+ &fixup) != vhost_hlen) {
vq_err(vq, "Unable to write vnet_hdr "
"at addr %p\n", vq->iov->iov_base);
goto out;
Is this an "issue" specific to RSS/HASH? If it's not, we need a separate patch.
Honestly, I'm not sure if it's too late to fix this.
There is nothing wrong with the current implementation.
Note that I meant the vhost_hlen part, and the current code is tricky.
The comment said:
"""
/* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
"""
So it tries to only offer virtio_net_hdr even if vhost_hlen is the set
to mrg_rxbuf len.
And this patch changes this behaviour.
mrg_rxbuf only adds the num_buffers field, which is always set for
mrg_rxbuf.
The num_buffers was not set for VIRTIO_F_VERSION_1 in the past, but this
was also fixed with commit a3b9c053d82a ("vhost/net: Set num_buffers for
virtio 1.0")
So there is no behavioral change for existing features with this patch.
Regards,
Akihiko Odaki
Thanks
The current
implementation fills the header with zero except num_buffers, which it
fills some real value. This functionality is working fine with
VIRTIO_NET_F_MRG_RXBUF and VIRTIO_F_VERSION_1, which change the header size.
Now I'm adding VIRTIO_NET_F_HASH_REPORT and it adds the hash_report
field, which also needs to be initialized with zero, so I'm making sure
vhost_net will also initialize it.
Regards,
Akihiko Odaki
Others look fine.
Thanks