[Qemu-devel] [PATCH v2 0/3] virtio_net: allow hypervisor to indicate linkspeed and duplex setting

[Qemu-devel] [PATCH v2 0/3] virtio_net: allow hypervisor to indicate linkspeed and duplex setting

[Jason Baron]

We have found it useful to be able to set the linkspeed and duplex
settings from the host-side for virtio_net. This obviates the need
for guest changes and settings for these fields, and does not require
custom ethtool commands for virtio_net.
                                                                                                                          
The ability to set linkspeed and duplex is useful in various cases
as described here:                                                                                                        
                                                                                                                          
16032be virtio_net: add ethtool support for set and get of settings                                                       
                                                                                                                          
Using 'ethtool -s' continues to over-write the linkspeed/duplex                                                           
settings with this patch.                                                                                          
                                                                                                                          
The 1/3 patch is against net-next, while the 2-3/3 patch are the associated
qemu changes that would go in after as update-linux-headers.sh should
be run first. So the qemu patches are a demonstration of how I intend this
to work.
                                                                                                                          
Thanks,                                                                                                                   
                                                                                                                          
-Jason                                                                                                                    
                                                                                                                          
 linux changes:                                                                                                           

Jason Baron (1):
  virtio_net: propagate linkspeed/duplex settings from the hypervisor

 drivers/net/virtio_net.c        | 17 ++++++++++++++++-
 include/uapi/linux/virtio_net.h |  5 +++++
 2 files changed, 21 insertions(+), 1 deletion(-)
                                                                                                                          
                                                                                                                          
 qemu changes:                                                                                                            

Jason Baron (2):
  qemu: virtio-net: use 64-bit values for feature flags
  qemu: add linkspeed and duplex settings to virtio-net

 hw/net/virtio-net.c                         | 83 +++++++++++++++++++----------
 include/hw/virtio/virtio-net.h              |  5 +-
 include/standard-headers/linux/virtio_net.h |  4 ++
 3 files changed, 64 insertions(+), 28 deletions(-)

[Qemu-devel] [PATCH 2/3] qemu: use 64-bit values for feature flags in virtio-net

[Jason Baron]

In prepartion for using some of the high order feature bits, make sure that
virtio-net uses 64-bit values everywhere.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c            | 54 +++++++++++++++++++++---------------------
 include/hw/virtio/virtio-net.h |  2 +-
 2 files changed, 28 insertions(+), 28 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 38674b0..adc20df 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -48,18 +48,18 @@
     (offsetof(container, field) + sizeof(((container *)0)->field))
 
 typedef struct VirtIOFeature {
-    uint32_t flags;
+    uint64_t flags;
     size_t end;
 } VirtIOFeature;
 
 static VirtIOFeature feature_sizes[] = {
-    {.flags = 1 << VIRTIO_NET_F_MAC,
+    {.flags = 1ULL << VIRTIO_NET_F_MAC,
      .end = endof(struct virtio_net_config, mac)},
-    {.flags = 1 << VIRTIO_NET_F_STATUS,
+    {.flags = 1ULL << VIRTIO_NET_F_STATUS,
      .end = endof(struct virtio_net_config, status)},
-    {.flags = 1 << VIRTIO_NET_F_MQ,
+    {.flags = 1ULL << VIRTIO_NET_F_MQ,
      .end = endof(struct virtio_net_config, max_virtqueue_pairs)},
-    {.flags = 1 << VIRTIO_NET_F_MTU,
+    {.flags = 1ULL << VIRTIO_NET_F_MTU,
      .end = endof(struct virtio_net_config, mtu)},
     {}
 };
@@ -1938,7 +1938,7 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
     int i;
 
     if (n->net_conf.mtu) {
-        n->host_features |= (0x1 << VIRTIO_NET_F_MTU);
+        n->host_features |= (1ULL << VIRTIO_NET_F_MTU);
     }
 
     virtio_net_set_config_size(n, n->host_features);
@@ -2109,45 +2109,45 @@ static const VMStateDescription vmstate_virtio_net = {
 };
 
 static Property virtio_net_properties[] = {
-    DEFINE_PROP_BIT("csum", VirtIONet, host_features, VIRTIO_NET_F_CSUM, true),
-    DEFINE_PROP_BIT("guest_csum", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("csum", VirtIONet, host_features, VIRTIO_NET_F_CSUM, true),
+    DEFINE_PROP_BIT64("guest_csum", VirtIONet, host_features,
                     VIRTIO_NET_F_GUEST_CSUM, true),
-    DEFINE_PROP_BIT("gso", VirtIONet, host_features, VIRTIO_NET_F_GSO, true),
-    DEFINE_PROP_BIT("guest_tso4", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("gso", VirtIONet, host_features, VIRTIO_NET_F_GSO, true),
+    DEFINE_PROP_BIT64("guest_tso4", VirtIONet, host_features,
                     VIRTIO_NET_F_GUEST_TSO4, true),
-    DEFINE_PROP_BIT("guest_tso6", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("guest_tso6", VirtIONet, host_features,
                     VIRTIO_NET_F_GUEST_TSO6, true),
-    DEFINE_PROP_BIT("guest_ecn", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("guest_ecn", VirtIONet, host_features,
                     VIRTIO_NET_F_GUEST_ECN, true),
-    DEFINE_PROP_BIT("guest_ufo", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("guest_ufo", VirtIONet, host_features,
                     VIRTIO_NET_F_GUEST_UFO, true),
-    DEFINE_PROP_BIT("guest_announce", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("guest_announce", VirtIONet, host_features,
                     VIRTIO_NET_F_GUEST_ANNOUNCE, true),
-    DEFINE_PROP_BIT("host_tso4", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("host_tso4", VirtIONet, host_features,
                     VIRTIO_NET_F_HOST_TSO4, true),
-    DEFINE_PROP_BIT("host_tso6", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("host_tso6", VirtIONet, host_features,
                     VIRTIO_NET_F_HOST_TSO6, true),
-    DEFINE_PROP_BIT("host_ecn", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("host_ecn", VirtIONet, host_features,
                     VIRTIO_NET_F_HOST_ECN, true),
-    DEFINE_PROP_BIT("host_ufo", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("host_ufo", VirtIONet, host_features,
                     VIRTIO_NET_F_HOST_UFO, true),
-    DEFINE_PROP_BIT("mrg_rxbuf", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("mrg_rxbuf", VirtIONet, host_features,
                     VIRTIO_NET_F_MRG_RXBUF, true),
-    DEFINE_PROP_BIT("status", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("status", VirtIONet, host_features,
                     VIRTIO_NET_F_STATUS, true),
-    DEFINE_PROP_BIT("ctrl_vq", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("ctrl_vq", VirtIONet, host_features,
                     VIRTIO_NET_F_CTRL_VQ, true),
-    DEFINE_PROP_BIT("ctrl_rx", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("ctrl_rx", VirtIONet, host_features,
                     VIRTIO_NET_F_CTRL_RX, true),
-    DEFINE_PROP_BIT("ctrl_vlan", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("ctrl_vlan", VirtIONet, host_features,
                     VIRTIO_NET_F_CTRL_VLAN, true),
-    DEFINE_PROP_BIT("ctrl_rx_extra", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("ctrl_rx_extra", VirtIONet, host_features,
                     VIRTIO_NET_F_CTRL_RX_EXTRA, true),
-    DEFINE_PROP_BIT("ctrl_mac_addr", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("ctrl_mac_addr", VirtIONet, host_features,
                     VIRTIO_NET_F_CTRL_MAC_ADDR, true),
-    DEFINE_PROP_BIT("ctrl_guest_offloads", VirtIONet, host_features,
+    DEFINE_PROP_BIT64("ctrl_guest_offloads", VirtIONet, host_features,
                     VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, true),
-    DEFINE_PROP_BIT("mq", VirtIONet, host_features, VIRTIO_NET_F_MQ, false),
+    DEFINE_PROP_BIT64("mq", VirtIONet, host_features, VIRTIO_NET_F_MQ, false),
     DEFINE_NIC_PROPERTIES(VirtIONet, nic_conf),
     DEFINE_PROP_UINT32("x-txtimer", VirtIONet, net_conf.txtimer,
                        TX_TIMER_INTERVAL),
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index b81b6a4..e7634c9 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -67,7 +67,7 @@ typedef struct VirtIONet {
     uint32_t has_vnet_hdr;
     size_t host_hdr_len;
     size_t guest_hdr_len;
-    uint32_t host_features;
+    uint64_t host_features;
     uint8_t has_ufo;
     uint32_t mergeable_rx_bufs;
     uint8_t promisc;
-- 
2.6.1

[Qemu-devel] [PATCH 3/3] qemu: add linkspeed and duplex settings to virtio-net

[Jason Baron]

Although linkspeed and duplex can be set in a linux guest via 'ethtool -s',
this requires custom ethtool commands for virtio-net by default.

Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
the hypervisor to export a linkspeed and duplex setting. The user can
subsequently overwrite it later if desired via: 'ethtool -s'.

Linkspeed and duplex settings can be set as:
'-device virtio-net,speed=10000,duplex=full'

where speed is [-1...INT_MAX], and duplex is ["half"|"full"].

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c                         | 29 +++++++++++++++++++++++++++++
 include/hw/virtio/virtio-net.h              |  3 +++
 include/standard-headers/linux/virtio_net.h |  4 ++++
 3 files changed, 36 insertions(+)
 create mode 160000 pixman

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index adc20df..7fafe6e 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -40,6 +40,12 @@
 #define VIRTIO_NET_RX_QUEUE_MIN_SIZE VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE
 #define VIRTIO_NET_TX_QUEUE_MIN_SIZE VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE
 
+/* duplex and speed defines */
+#define DUPLEX_UNKNOWN          0xff
+#define DUPLEX_HALF             0x00
+#define DUPLEX_FULL             0x01
+#define SPEED_UNKNOWN           -1
+
 /*
  * Calculate the number of bytes up to and including the given 'field' of
  * 'container'.
@@ -61,6 +67,8 @@ static VirtIOFeature feature_sizes[] = {
      .end = endof(struct virtio_net_config, max_virtqueue_pairs)},
     {.flags = 1ULL << VIRTIO_NET_F_MTU,
      .end = endof(struct virtio_net_config, mtu)},
+    {.flags = 1ULL << VIRTIO_NET_F_SPEED_DUPLEX,
+     .end = endof(struct virtio_net_config, duplex)},
     {}
 };
 
@@ -88,6 +96,8 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
     virtio_stw_p(vdev, &netcfg.status, n->status);
     virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues);
     virtio_stw_p(vdev, &netcfg.mtu, n->net_conf.mtu);
+    virtio_stl_p(vdev, &netcfg.speed, n->net_conf.speed);
+    netcfg.duplex = n->net_conf.duplex;
     memcpy(netcfg.mac, n->mac, ETH_ALEN);
     memcpy(config, &netcfg, n->config_size);
 }
@@ -1941,6 +1951,23 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
         n->host_features |= (1ULL << VIRTIO_NET_F_MTU);
     }
 
+    n->host_features |= (1ULL << VIRTIO_NET_F_SPEED_DUPLEX);
+    if (n->net_conf.duplex_str) {
+        if (strncmp(n->net_conf.duplex_str, "half", 5) == 0) {
+            n->net_conf.duplex = DUPLEX_HALF;
+        } else if (strncmp(n->net_conf.duplex_str, "full", 5) == 0) {
+            n->net_conf.duplex = DUPLEX_FULL;
+        } else {
+            error_setg(errp, "'duplex' must be 'half' or 'full'");
+        }
+    } else {
+        n->net_conf.duplex = DUPLEX_UNKNOWN;
+    }
+    if (n->net_conf.speed < SPEED_UNKNOWN) {
+            error_setg(errp, "'speed' must be between -1 (SPEED_UNKOWN) and "
+                       "INT_MAX");
+    }
+
     virtio_net_set_config_size(n, n->host_features);
     virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
 
@@ -2160,6 +2187,8 @@ static Property virtio_net_properties[] = {
     DEFINE_PROP_UINT16("host_mtu", VirtIONet, net_conf.mtu, 0),
     DEFINE_PROP_BOOL("x-mtu-bypass-backend", VirtIONet, mtu_bypass_backend,
                      true),
+    DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN),
+    DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index e7634c9..02484dc 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -38,6 +38,9 @@ typedef struct virtio_net_conf
     uint16_t rx_queue_size;
     uint16_t tx_queue_size;
     uint16_t mtu;
+    int32_t speed;
+    char *duplex_str;
+    uint8_t duplex;
 } virtio_net_conf;
 
 /* Maximum packet size we can receive from tap device: header + 64k */
diff --git a/include/standard-headers/linux/virtio_net.h b/include/standard-headers/linux/virtio_net.h
index 30ff249..0ff1447 100644
--- a/include/standard-headers/linux/virtio_net.h
+++ b/include/standard-headers/linux/virtio_net.h
@@ -36,6 +36,7 @@
 #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
 #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload configuration. */
 #define VIRTIO_NET_F_MTU	3	/* Initial MTU advice */
+#define VIRTIO_NET_F_SPEED_DUPLEX 4	/* Host set linkspeed and duplex */
 #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
 #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
 #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
@@ -76,6 +77,9 @@ struct virtio_net_config {
 	uint16_t max_virtqueue_pairs;
 	/* Default maximum transmit unit advice */
 	uint16_t mtu;
+	/* Host exported linkspeed and duplex */
+	uint32_t speed;
+	uint8_t duplex;
 } QEMU_PACKED;
 
 /*

[Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[Jason Baron]

The ability to set speed and duplex for virtio_net in useful in various
scenarios as described here:

16032be virtio_net: add ethtool support for set and get of settings

However, it would be nice to be able to set this from the hypervisor,
such that virtio_net doesn't require custom guest ethtool commands.

Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
the hypervisor to export a linkspeed and duplex setting. The user can
subsequently overwrite it later if desired via: 'ethtool -s'.

Signed-off-by: Jason Baron <jbaron@akamai.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
---
 drivers/net/virtio_net.c        | 17 ++++++++++++++++-
 include/uapi/linux/virtio_net.h |  5 +++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 511f833..4168d82 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2621,6 +2621,20 @@ static int virtnet_probe(struct virtio_device *vdev)
 	netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
 
 	virtnet_init_settings(dev);
+	if (virtio_has_feature(vdev, VIRTIO_NET_F_SPEED_DUPLEX)) {
+		u32 speed;
+		u8 duplex;
+
+		speed = virtio_cread32(vdev, offsetof(struct virtio_net_config,
+				       speed));
+		if (ethtool_validate_speed(speed))
+			vi->speed = speed;
+		duplex = virtio_cread8(vdev,
+				       offsetof(struct virtio_net_config,
+				       duplex));
+		if (ethtool_validate_duplex(duplex))
+			vi->duplex = duplex;
+	}
 
 	err = register_netdev(dev);
 	if (err) {
@@ -2746,7 +2760,8 @@ static struct virtio_device_id id_table[] = {
 	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
 	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
 	VIRTIO_NET_F_CTRL_MAC_ADDR, \
-	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
+	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
+	VIRTIO_NET_F_SPEED_DUPLEX
 
 static unsigned int features[] = {
 	VIRTNET_FEATURES,
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index fc353b5..0f1548e 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -57,6 +57,8 @@
 					 * Steering */
 #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
 
+#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
+
 #ifndef VIRTIO_NET_NO_LEGACY
 #define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
 #endif /* VIRTIO_NET_NO_LEGACY */
@@ -76,6 +78,9 @@ struct virtio_net_config {
 	__u16 max_virtqueue_pairs;
 	/* Default maximum transmit unit advice */
 	__u16 mtu;
+	/* Host exported linkspeed and duplex */
+	__u32 speed;
+	__u8 duplex;
 } __attribute__((packed));
 
 /*
-- 
2.6.1

Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[David Miller]

From: Jason Baron <jbaron@akamai.com>
Date: Fri, 22 Dec 2017 16:54:01 -0500

> The ability to set speed and duplex for virtio_net in useful in various
> scenarios as described here:
> 
> 16032be virtio_net: add ethtool support for set and get of settings
> 
> However, it would be nice to be able to set this from the hypervisor,
> such that virtio_net doesn't require custom guest ethtool commands.
> 
> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
> the hypervisor to export a linkspeed and duplex setting. The user can
> subsequently overwrite it later if desired via: 'ethtool -s'.
> 
> Signed-off-by: Jason Baron <jbaron@akamai.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>

Looks mostly fine to me but need some virtio_net reviewers on this one.

> @@ -57,6 +57,8 @@
>  					 * Steering */
>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>  
> +#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
> +

Why use a value so far away from the largest existing one?

Just curious.

Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[Jason Baron]

On 12/27/2017 04:43 PM, David Miller wrote:
> From: Jason Baron <jbaron@akamai.com>
> Date: Fri, 22 Dec 2017 16:54:01 -0500
> 
>> The ability to set speed and duplex for virtio_net in useful in various
>> scenarios as described here:
>>
>> 16032be virtio_net: add ethtool support for set and get of settings
>>
>> However, it would be nice to be able to set this from the hypervisor,
>> such that virtio_net doesn't require custom guest ethtool commands.
>>
>> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
>> the hypervisor to export a linkspeed and duplex setting. The user can
>> subsequently overwrite it later if desired via: 'ethtool -s'.
>>
>> Signed-off-by: Jason Baron <jbaron@akamai.com>
>> Cc: "Michael S. Tsirkin" <mst@redhat.com>
>> Cc: Jason Wang <jasowang@redhat.com>
> 
> Looks mostly fine to me but need some virtio_net reviewers on this one.
> 
>> @@ -57,6 +57,8 @@
>>  					 * Steering */
>>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>>  
>> +#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
>> +
> 
> Why use a value so far away from the largest existing one?
> 
> Just curious.
> 

So that came from a discussion with Michael about which bit to use for
this, and he suggested using 63:

"
Transports started from bit 24 and are growing up.
So I would say devices should start from bit 63 and grow down.
"

https://patchwork.ozlabs.org/patch/848814/#1826669

I will add a comment to explain it.

Thanks,

-Jason

Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[Michael S. Tsirkin]

On Thu, Dec 28, 2017 at 10:53:54AM -0500, Jason Baron wrote:
> 
> 
> On 12/27/2017 04:43 PM, David Miller wrote:
> > From: Jason Baron <jbaron@akamai.com>
> > Date: Fri, 22 Dec 2017 16:54:01 -0500
> > 
> >> The ability to set speed and duplex for virtio_net in useful in various
> >> scenarios as described here:
> >>
> >> 16032be virtio_net: add ethtool support for set and get of settings
> >>
> >> However, it would be nice to be able to set this from the hypervisor,
> >> such that virtio_net doesn't require custom guest ethtool commands.
> >>
> >> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
> >> the hypervisor to export a linkspeed and duplex setting. The user can
> >> subsequently overwrite it later if desired via: 'ethtool -s'.
> >>
> >> Signed-off-by: Jason Baron <jbaron@akamai.com>
> >> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> >> Cc: Jason Wang <jasowang@redhat.com>
> > 
> > Looks mostly fine to me but need some virtio_net reviewers on this one.
> > 
> >> @@ -57,6 +57,8 @@
> >>  					 * Steering */
> >>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
> >>  
> >> +#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
> >> +
> > 
> > Why use a value so far away from the largest existing one?
> > 
> > Just curious.
> > 
> 
> So that came from a discussion with Michael about which bit to use for
> this, and he suggested using 63:
> 
> "
> Transports started from bit 24 and are growing up.
> So I would say devices should start from bit 63 and grow down.
> "
> 
> https://patchwork.ozlabs.org/patch/848814/#1826669
> 
> I will add a comment to explain it.

Maybe in the commit log. I don't think we need it in the header.

> Thanks,
> 
> -Jason

Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[Michael S. Tsirkin]

On Fri, Dec 22, 2017 at 04:54:01PM -0500, Jason Baron wrote:
> The ability to set speed and duplex for virtio_net in useful in various
> scenarios as described here:
> 
> 16032be virtio_net: add ethtool support for set and get of settings
> 
> However, it would be nice to be able to set this from the hypervisor,
> such that virtio_net doesn't require custom guest ethtool commands.
> 
> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
> the hypervisor to export a linkspeed and duplex setting. The user can
> subsequently overwrite it later if desired via: 'ethtool -s'.
> 
> Signed-off-by: Jason Baron <jbaron@akamai.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>
> ---
>  drivers/net/virtio_net.c        | 17 ++++++++++++++++-
>  include/uapi/linux/virtio_net.h |  5 +++++
>  2 files changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 511f833..4168d82 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2621,6 +2621,20 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
>  
>  	virtnet_init_settings(dev);
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_SPEED_DUPLEX)) {
> +		u32 speed;
> +		u8 duplex;
> +
> +		speed = virtio_cread32(vdev, offsetof(struct virtio_net_config,
> +				       speed));
> +		if (ethtool_validate_speed(speed))
> +			vi->speed = speed;
> +		duplex = virtio_cread8(vdev,
> +				       offsetof(struct virtio_net_config,
> +				       duplex));
> +		if (ethtool_validate_duplex(duplex))
> +			vi->duplex = duplex;
> +	}
>  
>  	err = register_netdev(dev);
>  	if (err) {

It would seem that speed/duplex can change at link up time.
Update it from virtnet_config_changed_work please.

> @@ -2746,7 +2760,8 @@ static struct virtio_device_id id_table[] = {
>  	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
>  	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
>  	VIRTIO_NET_F_CTRL_MAC_ADDR, \
> -	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
> +	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
> +	VIRTIO_NET_F_SPEED_DUPLEX
>  
>  static unsigned int features[] = {
>  	VIRTNET_FEATURES,
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index fc353b5..0f1548e 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -57,6 +57,8 @@
>  					 * Steering */
>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>  
> +#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
> +

Host -> device, to match virtio spec terminology.

>  #ifndef VIRTIO_NET_NO_LEGACY
>  #define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
>  #endif /* VIRTIO_NET_NO_LEGACY */
> @@ -76,6 +78,9 @@ struct virtio_net_config {
>  	__u16 max_virtqueue_pairs;
>  	/* Default maximum transmit unit advice */
>  	__u16 mtu;
> +	/* Host exported linkspeed and duplex */

I would rather drop this and document each field.

/*
speed, in units of 1Mb. All values 0 to INT_MAX are legal.
Any other value stands for unknown.
*/

> +	__u32 speed;

/*
0x00 - half duplex
0x01 - full duplex
Any other value stands for unknown.
*/

> +	__u8 duplex;


>  } __attribute__((packed));
>  
>  /*
> -- 
> 2.6.1

Re: [Qemu-devel] [PATCH net-next v2 1/3] virtio_net: propagate linkspeed/duplex settings from the hypervisor

[Michael S. Tsirkin]

On Fri, Dec 22, 2017 at 04:54:01PM -0500, Jason Baron wrote:
> The ability to set speed and duplex for virtio_net in useful in various
> scenarios as described here:
> 
> 16032be virtio_net: add ethtool support for set and get of settings
> 
> However, it would be nice to be able to set this from the hypervisor,
> such that virtio_net doesn't require custom guest ethtool commands.
> 
> Introduce a new feature flag, VIRTIO_NET_F_SPEED_DUPLEX, which allows
> the hypervisor to export a linkspeed and duplex setting. The user can
> subsequently overwrite it later if desired via: 'ethtool -s'.
> 
> Signed-off-by: Jason Baron <jbaron@akamai.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Jason Wang <jasowang@redhat.com>

Same as any host/guest API change, please send a copy to the virtio TC
to make sure we avoid conflicts.

> ---
>  drivers/net/virtio_net.c        | 17 ++++++++++++++++-
>  include/uapi/linux/virtio_net.h |  5 +++++
>  2 files changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 511f833..4168d82 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2621,6 +2621,20 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
>  
>  	virtnet_init_settings(dev);
> +	if (virtio_has_feature(vdev, VIRTIO_NET_F_SPEED_DUPLEX)) {
> +		u32 speed;
> +		u8 duplex;
> +
> +		speed = virtio_cread32(vdev, offsetof(struct virtio_net_config,
> +				       speed));
> +		if (ethtool_validate_speed(speed))
> +			vi->speed = speed;
> +		duplex = virtio_cread8(vdev,
> +				       offsetof(struct virtio_net_config,
> +				       duplex));
> +		if (ethtool_validate_duplex(duplex))
> +			vi->duplex = duplex;
> +	}
>  
>  	err = register_netdev(dev);
>  	if (err) {
> @@ -2746,7 +2760,8 @@ static struct virtio_device_id id_table[] = {
>  	VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, \
>  	VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, \
>  	VIRTIO_NET_F_CTRL_MAC_ADDR, \
> -	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS
> +	VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
> +	VIRTIO_NET_F_SPEED_DUPLEX
>  
>  static unsigned int features[] = {
>  	VIRTNET_FEATURES,
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index fc353b5..0f1548e 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -57,6 +57,8 @@
>  					 * Steering */
>  #define VIRTIO_NET_F_CTRL_MAC_ADDR 23	/* Set MAC address */
>  
> +#define VIRTIO_NET_F_SPEED_DUPLEX 63	/* Host set linkspeed and duplex */
> +
>  #ifndef VIRTIO_NET_NO_LEGACY
>  #define VIRTIO_NET_F_GSO	6	/* Host handles pkts w/ any GSO type */
>  #endif /* VIRTIO_NET_NO_LEGACY */
> @@ -76,6 +78,9 @@ struct virtio_net_config {
>  	__u16 max_virtqueue_pairs;
>  	/* Default maximum transmit unit advice */
>  	__u16 mtu;
> +	/* Host exported linkspeed and duplex */
> +	__u32 speed;
> +	__u8 duplex;
>  } __attribute__((packed));
>  
>  /*
> -- 
> 2.6.1