vp_vdpa: support feature provisioning

This patch allows the device features to be provisioned via
netlink. This is done by:

1) validating the provisioned features to be a subset of the parent
   features.
2) clearing the features that is not wanted by the userspace

For example:

# vdpa mgmtdev show
pci/0000:02:00.0:
  supported_classes net
  max_supported_vqs 3
  dev_features CSUM GUEST_CSUM CTRL_GUEST_OFFLOADS MAC GUEST_TSO4
  GUEST_TSO6 GUEST_ECN GUEST_UFO HOST_TSO4 HOST_TSO6 HOST_ECN HOST_UFO
  MRG_RXBUF STATUS CTRL_VQ CTRL_RX CTRL_VLAN CTRL_RX_EXTRA
  GUEST_ANNOUNCE CTRL_MAC_ADDR RING_INDIRECT_DESC RING_EVENT_IDX
  VERSION_1 ACCESS_PLATFORM

1) provision vDPA device with all features that are supported by the virtio-pci

# vdpa dev add name dev1 mgmtdev pci/0000:02:00.0
# vdpa dev config show
dev1: mac 52:54:00:12:34:56 link up link_announce false mtu 65535
  negotiated_features CSUM GUEST_CSUM CTRL_GUEST_OFFLOADS MAC
  GUEST_TSO4 GUEST_TSO6 GUEST_ECN GUEST_UFO HOST_TSO4 HOST_TSO6
  HOST_ECN HOST_UFO MRG_RXBUF STATUS CTRL_VQ CTRL_RX CTRL_VLAN
  GUEST_ANNOUNCE CTRL_MAC_ADDR RING_INDIRECT_DESC RING_EVENT_IDX
  VERSION_1 ACCESS_PLATFORM

2) provision vDPA device with a subset of the features

# vdpa dev add name dev1 mgmtdev pci/0000:02:00.0 device_features 0x300020000
# dev1: mac 52:54:00:12:34:56 link up link_announce false mtu 65535
  negotiated_features CTRL_VQ VERSION_1 ACCESS_PLATFORM
Reviewed-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220927074810.28627-4-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/virtio_pci/vp_vdpa.c

@@ -17,6 +17,7 @@
 #include <linux/virtio_ring.h>
 #include <linux/virtio_pci.h>
 #include <linux/virtio_pci_modern.h>
+#include <uapi/linux/vdpa.h>
 
 #define VP_VDPA_QUEUE_MAX 256
 #define VP_VDPA_DRIVER_NAME "vp_vdpa"
@@ -35,6 +36,7 @@ struct vp_vdpa {
 	struct virtio_pci_modern_device *mdev;
 	struct vp_vring *vring;
 	struct vdpa_callback config_cb;
+	u64 device_features;
 	char msix_name[VP_VDPA_NAME_SIZE];
 	int config_irq;
 	int queues;
@@ -66,9 +68,9 @@ static struct virtio_pci_modern_device *vp_vdpa_to_mdev(struct vp_vdpa *vp_vdpa)
 
 static u64 vp_vdpa_get_device_features(struct vdpa_device *vdpa)
 {
-	struct virtio_pci_modern_device *mdev = vdpa_to_mdev(vdpa);
+	struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
 
-	return vp_modern_get_features(mdev);
+	return vp_vdpa->device_features;
 }
 
 static int vp_vdpa_set_driver_features(struct vdpa_device *vdpa, u64 features)
@@ -475,6 +477,7 @@ static int vp_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
 	struct pci_dev *pdev = mdev->pci_dev;
 	struct device *dev = &pdev->dev;
 	struct vp_vdpa *vp_vdpa = NULL;
+	u64 device_features;
 	int ret, i;
 
 	vp_vdpa = vdpa_alloc_device(struct vp_vdpa, vdpa,
@@ -491,6 +494,20 @@ static int vp_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
 	vp_vdpa->queues = vp_modern_get_num_queues(mdev);
 	vp_vdpa->mdev = mdev;
 
+	device_features = vp_modern_get_features(mdev);
+	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_FEATURES)) {
+		if (add_config->device_features & ~device_features) {
+			ret = -EINVAL;
+			dev_err(&pdev->dev, "Try to provision features "
+				"that are not supported by the device: "
+				"device_features 0x%llx provisioned 0x%llx\n",
+				device_features, add_config->device_features);
+			goto err;
+		}
+		device_features = add_config->device_features;
+	}
+	vp_vdpa->device_features = device_features;
+
 	ret = devm_add_action_or_reset(dev, vp_vdpa_free_irq_vectors, pdev);
 	if (ret) {
 		dev_err(&pdev->dev,
@@ -599,6 +616,7 @@ static int vp_vdpa_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	mgtdev->id_table = mdev_id;
 	mgtdev->max_supported_vqs = vp_modern_get_num_queues(mdev);
 	mgtdev->supported_features = vp_modern_get_features(mdev);
+	mgtdev->config_attr_mask = (1 << VDPA_ATTR_DEV_FEATURES);
 	pci_set_master(pdev);
 	pci_set_drvdata(pdev, vp_vdpa_mgtdev);