pds_vdpa: always allow offering VIRTIO_NET_F_MAC

Our driver sets a mac if the HW is 00:..:00 so we need to be sure to
advertise VIRTIO_NET_F_MAC even if the HW doesn't.  We also need to be
sure that virtio_net sees the VIRTIO_NET_F_MAC and doesn't rewrite the
mac address that a user may have set with the vdpa utility.

After reading the hw_feature bits, add the VIRTIO_NET_F_MAC to the driver's
supported_features and use that for reporting what is available.  If the
HW is not advertising it, be sure to strip the VIRTIO_NET_F_MAC before
finishing the feature negotiation.  If the user specifies a device_features
bitpattern in the vdpa utility without the VIRTIO_NET_F_MAC set, then
don't set the mac.

Fixes: 151cc834 ("pds_vdpa: add support for vdpa and vdpamgmt interfaces")
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Message-Id: <20230711042437.69381-3-shannon.nelson@amd.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

drivers/vdpa/pds/debugfs.c

@@ -224,8 +224,6 @@ static int config_show(struct seq_file *seq, void *v)
 	seq_printf(seq, "dev_status:           %#x\n", status);
 	print_status_bits(seq, status);
 
-	seq_printf(seq, "req_features:         %#llx\n", pdsv->req_features);
-	print_feature_bits_all(seq, pdsv->req_features);
 	driver_features = vp_modern_get_driver_features(&pdsv->vdpa_aux->vd_mdev);
 	seq_printf(seq, "driver_features:      %#llx\n", driver_features);
 	print_feature_bits_all(seq, driver_features);

drivers/vdpa/pds/vdpa_dev.c

@@ -318,6 +318,7 @@ static int pds_vdpa_set_driver_features(struct vdpa_device *vdpa_dev, u64 featur
 	struct device *dev = &pdsv->vdpa_dev.dev;
 	u64 driver_features;
 	u64 nego_features;
+	u64 hw_features;
 	u64 missing;
 
 	if (!(features & BIT_ULL(VIRTIO_F_ACCESS_PLATFORM)) && features) {
@@ -325,21 +326,26 @@ static int pds_vdpa_set_driver_features(struct vdpa_device *vdpa_dev, u64 featur
 		return -EOPNOTSUPP;
 	}
 
-	pdsv->req_features = features;
-
 	/* Check for valid feature bits */
-	nego_features = features & le64_to_cpu(pdsv->vdpa_aux->ident.hw_features);
-	missing = pdsv->req_features & ~nego_features;
+	nego_features = features & pdsv->supported_features;
+	missing = features & ~nego_features;
 	if (missing) {
 		dev_err(dev, "Can't support all requested features in %#llx, missing %#llx features\n",
-			pdsv->req_features, missing);
+			features, missing);
 		return -EOPNOTSUPP;
 	}
 
+	pdsv->negotiated_features = nego_features;
+
 	driver_features = pds_vdpa_get_driver_features(vdpa_dev);
 	dev_dbg(dev, "%s: %#llx => %#llx\n",
 		__func__, driver_features, nego_features);
 
+	/* if we're faking the F_MAC, strip it before writing to device */
+	hw_features = le64_to_cpu(pdsv->vdpa_aux->ident.hw_features);
+	if (!(hw_features & BIT_ULL(VIRTIO_NET_F_MAC)))
+		nego_features &= ~BIT_ULL(VIRTIO_NET_F_MAC);
+
 	if (driver_features == nego_features)
 		return 0;
 
@@ -352,7 +358,7 @@ static u64 pds_vdpa_get_driver_features(struct vdpa_device *vdpa_dev)
 {
 	struct pds_vdpa_device *pdsv = vdpa_to_pdsv(vdpa_dev);
 
-	return vp_modern_get_driver_features(&pdsv->vdpa_aux->vd_mdev);
+	return pdsv->negotiated_features;
 }
 
 static void pds_vdpa_set_config_cb(struct vdpa_device *vdpa_dev,
@@ -564,7 +570,7 @@ static int pds_vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 
 	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES)) {
 		u64 unsupp_features =
-			add_config->device_features & ~mgmt->supported_features;
+			add_config->device_features & ~pdsv->supported_features;
 
 		if (unsupp_features) {
 			dev_err(dev, "Unsupported features: %#llx\n", unsupp_features);
@@ -615,7 +621,8 @@ static int pds_vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 	}
 
 	/* Set a mac, either from the user config if provided
-	 * or set a random mac if default is 00:..:00
+	 * or use the device's mac if not 00:..:00
+	 * or set a random mac
 	 */
 	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR)) {
 		ether_addr_copy(pdsv->mac, add_config->net.mac);
@@ -624,7 +631,8 @@ static int pds_vdpa_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 
 		vc = pdsv->vdpa_aux->vd_mdev.device;
 		memcpy_fromio(pdsv->mac, vc->mac, sizeof(pdsv->mac));
-		if (is_zero_ether_addr(pdsv->mac)) {
+		if (is_zero_ether_addr(pdsv->mac) &&
+		    (pdsv->supported_features & BIT_ULL(VIRTIO_NET_F_MAC))) {
 			eth_random_addr(pdsv->mac);
 			dev_info(dev, "setting random mac %pM\n", pdsv->mac);
 		}
@@ -752,6 +760,10 @@ int pds_vdpa_get_mgmt_info(struct pds_vdpa_aux *vdpa_aux)
 	mgmt->id_table = pds_vdpa_id_table;
 	mgmt->device = dev;
 	mgmt->supported_features = le64_to_cpu(vdpa_aux->ident.hw_features);
+
+	/* advertise F_MAC even if the device doesn't */
+	mgmt->supported_features |= BIT_ULL(VIRTIO_NET_F_MAC);
+
 	mgmt->config_attr_mask = BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR);
 	mgmt->config_attr_mask |= BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP);
 	mgmt->config_attr_mask |= BIT_ULL(VDPA_ATTR_DEV_FEATURES);

drivers/vdpa/pds/vdpa_dev.h

@@ -35,8 +35,8 @@ struct pds_vdpa_device {
 	struct pds_vdpa_aux *vdpa_aux;
 
 	struct pds_vdpa_vq_info vqs[PDS_VDPA_MAX_QUEUES];
-	u64 supported_features;		/* specified device features */
-	u64 req_features;		/* features requested by vdpa */
+	u64 supported_features;		/* supported device features */
+	u64 negotiated_features;	/* negotiated features */
 	u8 vdpa_index;			/* rsvd for future subdevice use */
 	u8 num_vqs;			/* num vqs in use */
 	u8 mac[ETH_ALEN];		/* mac selected when the device was added */