On Fri, Oct 9, 2020 at 9:49 PM Willem de Bruijn
[off-list ref] wrote:

On Thu, Oct 8, 2020 at 9:19 PM Tonghao Zhang [off-list ref] wrote:

quoted

On Wed, Sep 30, 2020 at 6:05 PM Willem de Bruijn
[off-list ref] wrote:

quoted

On Wed, Sep 30, 2020 at 4:05 AM [off-list ref] wrote:

quoted

From: Tonghao Zhang <redacted>

Allow user configuring RXCSUM separately with ethtool -K,
reusing the existing virtnet_set_guest_offloads helper
that configures RXCSUM for XDP. This is conditional on
VIRTIO_NET_F_CTRL_GUEST_OFFLOADS.

If Rx checksum is disabled, LRO should also be disabled.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Tonghao Zhang <redacted>

The first patch was merged into net.

Please wait until that is merged into net-next, as this depends on the
other patch.

quoted

---
v2:
* LRO depends the rx csum
* remove the unnecessary check
---
 drivers/net/virtio_net.c | 49 ++++++++++++++++++++++++++++++----------
 1 file changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 21b71148c532..5407a0106771 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -68,6 +68,8 @@ static const unsigned long guest_offloads[] = {
                                (1ULL << VIRTIO_NET_F_GUEST_ECN)  | \
                                (1ULL << VIRTIO_NET_F_GUEST_UFO))

+#define GUEST_OFFLOAD_CSUM_MASK (1ULL << VIRTIO_NET_F_GUEST_CSUM)
+
 struct virtnet_stat_desc {
        char desc[ETH_GSTRING_LEN];
        size_t offset;

@@ -2522,29 +2524,49 @@ static int virtnet_get_phys_port_name(struct net_device *dev, char *buf,
        return 0;
 }

+static netdev_features_t virtnet_fix_features(struct net_device *netdev,
+                                             netdev_features_t features)
+{
+       /* If Rx checksum is disabled, LRO should also be disabled.
+        * That is life. :)

Please remove this second line.

OK

quoted

quoted

+        */
+       if (!(features & NETIF_F_RXCSUM))
+               features &= ~NETIF_F_LRO;
+
+       return features;
+}
+
 static int virtnet_set_features(struct net_device *dev,
                                netdev_features_t features)
 {
        struct virtnet_info *vi = netdev_priv(dev);
-       u64 offloads;
+       u64 offloads = vi->guest_offloads &
+                      vi->guest_offloads_capable;

When can vi->guest_offloads have bits set outside the mask of
vi->guest_offloads_capable?

In this case, we can use only vi->guest_offloads. and
guest_offloads_capable will not be used any more.
so should we remove guest_offloads_capable ?

That bitmap stores the capabilities of the device as learned at
initial device probe. I don't see how it can be removed.

Hi Willem
guest_offloads_capable was introduced by
a02e8964eaf9 ("virtio-net: ethtool configurable LRO")
and used only for LRO. Now we don't use it anymore, right ?
because this patch (virtio-net: ethtool configurable RXCSUM)
doesn't use it.


-- 
Best regards, Tonghao