[PATCH net-next 05/11] sfc: implement vdpa device config operations

[Gautam Dawar]

vDPA config operations can be broadly categorized in to either
virtqueue operations, device operations or DMA operations.
This patch implements most of the device level config operations.

SN1022 supports VIRTIO_F_IN_ORDER which is supported by the DPDK
virtio driver but not the kernel virtio driver. Due to a bug in
QEMU (https://gitlab.com/qemu-project/qemu/-/issues/331#), with
vhost-vdpa, this feature bit is returned with guest kernel virtio
driver in set_features config operation. The fix for this bug
(qemu_commit c33f23a419f95da16ab4faaf08be635c89b96ff0) is available
in QEMU versions 6.1.0 and later. Hence, that's the oldest QEMU
version required for testing with the vhost-vdpa driver.

With older QEMU releases, VIRTIO_F_IN_ORDER is negotiated but
not honored causing Firmware exception.

Signed-off-by: Gautam Dawar <gautam.dawar@xxxxxxx>
---
 drivers/net/ethernet/sfc/ef100_vdpa.h     |  14 ++
 drivers/net/ethernet/sfc/ef100_vdpa_ops.c | 148 ++++++++++++++++++++++
 2 files changed, 162 insertions(+)

diff --git a/drivers/net/ethernet/sfc/ef100_vdpa.h b/drivers/net/ethernet/sfc/ef100_vdpa.h
index 83f6d819f6a5..be7650c3166a 100644
--- a/drivers/net/ethernet/sfc/ef100_vdpa.h
+++ b/drivers/net/ethernet/sfc/ef100_vdpa.h
@@ -21,6 +21,18 @@
 /* Max queue pairs currently supported */
 #define EF100_VDPA_MAX_QUEUES_PAIRS 1
 
+/* Device ID of a virtio net device */
+#define EF100_VDPA_VIRTIO_NET_DEVICE_ID VIRTIO_ID_NET
+
+/* Vendor ID of Xilinx vDPA NIC */
+#define EF100_VDPA_VENDOR_ID  PCI_VENDOR_ID_XILINX
+
+/* Max number of Buffers supported in the virtqueue */
+#define EF100_VDPA_VQ_NUM_MAX_SIZE 512
+
+/* Alignment requirement of the Virtqueue */
+#define EF100_VDPA_VQ_ALIGN 4096
+
 /**
  * enum ef100_vdpa_nic_state - possible states for a vDPA NIC
  *
@@ -61,6 +73,7 @@ enum ef100_vdpa_vq_type {
  * @net_config: virtio_net_config data
  * @mac_address: mac address of interface associated with this vdpa device
  * @mac_configured: true after MAC address is configured
+ * @cfg_cb: callback for config change
  */
 struct ef100_vdpa_nic {
 	struct vdpa_device vdpa_dev;
@@ -76,6 +89,7 @@ struct ef100_vdpa_nic {
 	struct virtio_net_config net_config;
 	u8 *mac_address;
 	bool mac_configured;
+	struct vdpa_callback cfg_cb;
 };
 
 int ef100_vdpa_init(struct efx_probe_data *probe_data);
diff --git a/drivers/net/ethernet/sfc/ef100_vdpa_ops.c b/drivers/net/ethernet/sfc/ef100_vdpa_ops.c
index 31952931c198..87899baa1c52 100644
--- a/drivers/net/ethernet/sfc/ef100_vdpa_ops.c
+++ b/drivers/net/ethernet/sfc/ef100_vdpa_ops.c
@@ -10,12 +10,148 @@
 
 #include <linux/vdpa.h>
 #include "ef100_vdpa.h"
+#include "mcdi_vdpa.h"
 
 static struct ef100_vdpa_nic *get_vdpa_nic(struct vdpa_device *vdev)
 {
 	return container_of(vdev, struct ef100_vdpa_nic, vdpa_dev);
 }
 
+static u32 ef100_vdpa_get_vq_align(struct vdpa_device *vdev)
+{
+	return EF100_VDPA_VQ_ALIGN;
+}
+
+static u64 ef100_vdpa_get_device_features(struct vdpa_device *vdev)
+{
+	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
+	u64 features;
+	int rc;
+
+	rc = efx_vdpa_get_features(vdpa_nic->efx,
+				   EF100_VDPA_DEVICE_TYPE_NET, &features);
+	if (rc) {
+		dev_err(&vdev->dev, "%s: MCDI get features error:%d\n",
+			__func__, rc);
+		/* Returning 0 as value of features will lead to failure
+		 * of feature negotiation.
+		 */
+		return 0;
+	}
+
+	/* SN1022 supports VIRTIO_F_IN_ORDER which is supported by the DPDK
+	 * virtio driver but not the kernel virtio driver. Due to a bug in
+	 * QEMU (https://gitlab.com/qemu-project/qemu/-/issues/331#), with
+	 * vhost-vdpa, this feature bit is returned with guest kernel virtio
+	 * driver in set_features config operation. The fix for this bug
+	 * (commit c33f23a419f95da16ab4faaf08be635c89b96ff0) is available
+	 * in QEMU versions 6.1.0 and later. Hence, that's the oldest QEMU
+	 * version required for testing with the vhost-vdpa driver.
+	 */
+	features |= BIT_ULL(VIRTIO_NET_F_MAC);
+
+	return features;
+}
+
+static int ef100_vdpa_set_driver_features(struct vdpa_device *vdev,
+					  u64 features)
+{
+	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
+	u64 verify_features;
+	int rc;
+
+	mutex_lock(&vdpa_nic->lock);
+	if (vdpa_nic->vdpa_state != EF100_VDPA_STATE_INITIALIZED) {
+		dev_err(&vdev->dev, "%s: Invalid state %u\n",
+			__func__, vdpa_nic->vdpa_state);
+		rc = -EINVAL;
+		goto err;
+	}
+	verify_features = features & ~BIT_ULL(VIRTIO_NET_F_MAC);
+	rc = efx_vdpa_verify_features(vdpa_nic->efx,
+				      EF100_VDPA_DEVICE_TYPE_NET,
+				      verify_features);
+
+	if (rc) {
+		dev_err(&vdev->dev, "%s: MCDI verify features error:%d\n",
+			__func__, rc);
+		goto err;
+	}
+
+	vdpa_nic->features = features;
+err:
+	mutex_unlock(&vdpa_nic->lock);
+	return rc;
+}
+
+static u64 ef100_vdpa_get_driver_features(struct vdpa_device *vdev)
+{
+	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
+
+	return vdpa_nic->features;
+}
+
+static void ef100_vdpa_set_config_cb(struct vdpa_device *vdev,
+				     struct vdpa_callback *cb)
+{
+	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
+
+	if (cb)
+		vdpa_nic->cfg_cb = *cb;
+}
+
+static u16 ef100_vdpa_get_vq_num_max(struct vdpa_device *vdev)
+{
+	return EF100_VDPA_VQ_NUM_MAX_SIZE;
+}
+
+static u32 ef100_vdpa_get_device_id(struct vdpa_device *vdev)
+{
+	return EF100_VDPA_VIRTIO_NET_DEVICE_ID;
+}
+
+static u32 ef100_vdpa_get_vendor_id(struct vdpa_device *vdev)
+{
+	return EF100_VDPA_VENDOR_ID;
+}
+
+static size_t ef100_vdpa_get_config_size(struct vdpa_device *vdev)
+{
+	return sizeof(struct virtio_net_config);
+}
+
+static void ef100_vdpa_get_config(struct vdpa_device *vdev,
+				  unsigned int offset,
+				  void *buf, unsigned int len)
+{
+	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
+
+	/* Avoid the possibility of wrap-up after the sum exceeds U32_MAX */
+	if (WARN_ON(((u64)offset + len) > sizeof(struct virtio_net_config))) {
+		dev_err(&vdev->dev,
+			"%s: Offset + len exceeds config size\n", __func__);
+		return;
+	}
+	memcpy(buf, (u8 *)&vdpa_nic->net_config + offset, len);
+}
+
+static void ef100_vdpa_set_config(struct vdpa_device *vdev, unsigned int offset,
+				  const void *buf, unsigned int len)
+{
+	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
+
+	/* Avoid the possibility of wrap-up after the sum exceeds U32_MAX */
+	if (WARN_ON(((u64)offset + len) > sizeof(vdpa_nic->net_config))) {
+		dev_err(&vdev->dev,
+			"%s: Offset + len exceeds config size\n", __func__);
+		return;
+	}
+
+	memcpy((u8 *)&vdpa_nic->net_config + offset, buf, len);
+	if (is_valid_ether_addr(vdpa_nic->mac_address))
+		vdpa_nic->mac_configured = true;
+}
+
 static void ef100_vdpa_free(struct vdpa_device *vdev)
 {
 	struct ef100_vdpa_nic *vdpa_nic = get_vdpa_nic(vdev);
@@ -24,5 +160,17 @@ static void ef100_vdpa_free(struct vdpa_device *vdev)
 }
 
 const struct vdpa_config_ops ef100_vdpa_config_ops = {
+	.get_vq_align	     = ef100_vdpa_get_vq_align,
+	.get_device_features = ef100_vdpa_get_device_features,
+	.set_driver_features = ef100_vdpa_set_driver_features,
+	.get_driver_features = ef100_vdpa_get_driver_features,
+	.set_config_cb	     = ef100_vdpa_set_config_cb,
+	.get_vq_num_max      = ef100_vdpa_get_vq_num_max,
+	.get_device_id	     = ef100_vdpa_get_device_id,
+	.get_vendor_id	     = ef100_vdpa_get_vendor_id,
+	.get_config_size     = ef100_vdpa_get_config_size,
+	.get_config	     = ef100_vdpa_get_config,
+	.set_config	     = ef100_vdpa_set_config,
+	.get_generation      = NULL,
 	.free	             = ef100_vdpa_free,
 };
-- 
2.30.1