hv_netvsc: Add support to set MTU reservation from guest side

When packet encapsulation is in use, the MTU needs to be reduced for
headroom reservation.
The existing code takes the updated MTU value only from the host side.
But vSwitch extensions, such as Open vSwitch, require the flexibility
to change the MTU to different values from within a guest during the
lifecycle of a vNIC, when the encapsulation protocol is changed. The
patch supports this kind of MTU changes.

Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Haiyang Zhang 2015-07-06 14:11:37 -07:00 committed by David S. Miller
parent 9e29e21a9b
commit f9cbce34c3
3 changed files with 3 additions and 3 deletions

View file

@ -589,6 +589,7 @@ struct nvsp_message {
#define NETVSC_MTU 65536
#define NETVSC_MTU_MIN 68
#define NETVSC_RECEIVE_BUFFER_SIZE (1024*1024*16) /* 16MB */
#define NETVSC_RECEIVE_BUFFER_SIZE_LEGACY (1024*1024*15) /* 15MB */

View file

@ -743,8 +743,7 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
if (nvdev->nvsp_version >= NVSP_PROTOCOL_VERSION_2)
limit = NETVSC_MTU - ETH_HLEN;
/* Hyper-V hosts don't support MTU < ETH_DATA_LEN (1500) */
if (mtu < ETH_DATA_LEN || mtu > limit)
if (mtu < NETVSC_MTU_MIN || mtu > limit)
return -EINVAL;
nvdev->start_remove = true;

View file

@ -1054,7 +1054,7 @@ int rndis_filter_device_add(struct hv_device *dev,
ret = rndis_filter_query_device(rndis_device,
RNDIS_OID_GEN_MAXIMUM_FRAME_SIZE,
&mtu, &size);
if (ret == 0 && size == sizeof(u32))
if (ret == 0 && size == sizeof(u32) && mtu < net_device->ndev->mtu)
net_device->ndev->mtu = mtu;
/* Get the mac address */