Jiri Pirko
2023-Feb-17 12:15 UTC
[patch net-next] net: virtio_net: implement exact header length guest feature
From: Jiri Pirko <jiri at nvidia.com>
virtio_net_hdr_from_skb() fills up hdr_len to skb_headlen(skb).
Virtio spec introduced a feature VIRTIO_NET_F_GUEST_HDRLEN which when
set implicates that the driver provides the exact size of the header.
The driver already complies to fill the correct value. Introduce the
feature and advertise it.
Signed-off-by: Jiri Pirko <jiri at nvidia.com>
---
drivers/net/virtio_net.c | 6 ++++--
include/uapi/linux/virtio_net.h | 1 +
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index fb5e68ed3ec2..e85b03988733 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -62,7 +62,8 @@ static const unsigned long guest_offloads[] = {
VIRTIO_NET_F_GUEST_UFO,
VIRTIO_NET_F_GUEST_CSUM,
VIRTIO_NET_F_GUEST_USO4,
- VIRTIO_NET_F_GUEST_USO6
+ VIRTIO_NET_F_GUEST_USO6,
+ VIRTIO_NET_F_GUEST_HDRLEN
};
#define GUEST_OFFLOAD_GRO_HW_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
@@ -4213,7 +4214,8 @@ static struct virtio_device_id id_table[] = {
VIRTIO_NET_F_CTRL_MAC_ADDR, \
VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \
- VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL
+ VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL, \
+ VIRTIO_NET_F_GUEST_HDRLEN
static unsigned int features[] = {
VIRTNET_FEATURES,
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index b4062bed186a..12c1c9699935 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -61,6 +61,7 @@
#define VIRTIO_NET_F_GUEST_USO6 55 /* Guest can handle USOv6 in. */
#define VIRTIO_NET_F_HOST_USO 56 /* Host can handle USO in. */
#define VIRTIO_NET_F_HASH_REPORT 57 /* Supports hash report */
+#define VIRTIO_NET_F_GUEST_HDRLEN 59 /* Guest provides the exact hdr_len
value. */
#define VIRTIO_NET_F_RSS 60 /* Supports RSS RX steering */
#define VIRTIO_NET_F_RSC_EXT 61 /* extended coalescing info */
#define VIRTIO_NET_F_STANDBY 62 /* Act as standby for another device
--
2.39.0
Michael S. Tsirkin
2023-Feb-17 12:22 UTC
[patch net-next] net: virtio_net: implement exact header length guest feature
On Fri, Feb 17, 2023 at 01:15:47PM +0100, Jiri Pirko wrote:> From: Jiri Pirko <jiri at nvidia.com> > > virtio_net_hdr_from_skb() fills up hdr_len to skb_headlen(skb). > > Virtio spec introduced a feature VIRTIO_NET_F_GUEST_HDRLEN which when > set implicates that the driver provides the exact size of the header. > > The driver already complies to fill the correct value. Introduce the > feature and advertise it. > > Signed-off-by: Jiri Pirko <jiri at nvidia.com>Could you add a bit of motivation just for the record? Does this improve performance for some card? By how much? Expected to help some future card? thanks!> --- > drivers/net/virtio_net.c | 6 ++++-- > include/uapi/linux/virtio_net.h | 1 + > 2 files changed, 5 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index fb5e68ed3ec2..e85b03988733 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -62,7 +62,8 @@ static const unsigned long guest_offloads[] = { > VIRTIO_NET_F_GUEST_UFO, > VIRTIO_NET_F_GUEST_CSUM, > VIRTIO_NET_F_GUEST_USO4, > - VIRTIO_NET_F_GUEST_USO6 > + VIRTIO_NET_F_GUEST_USO6, > + VIRTIO_NET_F_GUEST_HDRLEN > }; > > #define GUEST_OFFLOAD_GRO_HW_MASK ((1ULL << VIRTIO_NET_F_GUEST_TSO4) | \ > @@ -4213,7 +4214,8 @@ static struct virtio_device_id id_table[] = { > VIRTIO_NET_F_CTRL_MAC_ADDR, \ > VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \ > VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \ > - VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL > + VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_NOTF_COAL, \ > + VIRTIO_NET_F_GUEST_HDRLEN > > static unsigned int features[] = { > VIRTNET_FEATURES, > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > index b4062bed186a..12c1c9699935 100644 > --- a/include/uapi/linux/virtio_net.h > +++ b/include/uapi/linux/virtio_net.h > @@ -61,6 +61,7 @@ > #define VIRTIO_NET_F_GUEST_USO6 55 /* Guest can handle USOv6 in. */ > #define VIRTIO_NET_F_HOST_USO 56 /* Host can handle USO in. */ > #define VIRTIO_NET_F_HASH_REPORT 57 /* Supports hash report */ > +#define VIRTIO_NET_F_GUEST_HDRLEN 59 /* Guest provides the exact hdr_len value. */ > #define VIRTIO_NET_F_RSS 60 /* Supports RSS RX steering */ > #define VIRTIO_NET_F_RSC_EXT 61 /* extended coalescing info */ > #define VIRTIO_NET_F_STANDBY 62 /* Act as standby for another device > -- > 2.39.0