[PATCH 6/6] vp_vdpa: introduce legacy virtio pci driver

[Wu Zongyong <wuzongyong@linux.alibaba.com>]

This patch implements a vdpa driver for legacy virtio-pci device. And
this has been tested with the ENI(Elastic Network Interface) which is a
hardware virtio network device in Alibaba ECS baremetal instance.

Note that legacy device doesn't support to change the virtqueue size, so
users should use get_vq_num_unchangeable callback to check if the
virqueue size can be changed. If not, users should get the virqueue size
first by the get_vq_num_max callback first then allocate same size
memory for the virtqueue otherwise the device won't work correctly.

Signed-off-by: Wu Zongyong <wuzongyong@linux.alibaba.com>
---
 drivers/vdpa/Kconfig                     |   7 +
 drivers/vdpa/virtio_pci/Makefile         |   1 +
 drivers/vdpa/virtio_pci/vp_vdpa_common.c |   5 +
 drivers/vdpa/virtio_pci/vp_vdpa_common.h |  11 +
 drivers/vdpa/virtio_pci/vp_vdpa_legacy.c | 346 +++++++++++++++++++++++
 5 files changed, 370 insertions(+)
 create mode 100644 drivers/vdpa/virtio_pci/vp_vdpa_legacy.c

diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
index a503c1b2bfd9..ccb4fdb11f0f 100644
--- a/drivers/vdpa/Kconfig
+++ b/drivers/vdpa/Kconfig
@@ -67,4 +67,11 @@ config VP_VDPA
 	help
 	  This kernel module bridges virtio PCI device to vDPA bus.
 
+config VP_VDPA_LEGACY
+	bool "Support legacy virtio pci device"
+	depends on VP_VDPA
+	select VIRTIO_PCI_LIB_LEGACY
+	help
+	  This option enables bridges legacy virito PCI device to vDPA bus.
+
 endif # VDPA
diff --git a/drivers/vdpa/virtio_pci/Makefile b/drivers/vdpa/virtio_pci/Makefile
index a772d86952b1..77c52dfb8b56 100644
--- a/drivers/vdpa/virtio_pci/Makefile
+++ b/drivers/vdpa/virtio_pci/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
 
 vp_vdpa-y += vp_vdpa_common.o vp_vdpa_modern.o
+vp_vdpa-$(CONFIG_VP_VDPA_LEGACY) += vp_vdpa_legacy.o
 obj-$(CONFIG_VP_VDPA) += vp_vdpa.o
diff --git a/drivers/vdpa/virtio_pci/vp_vdpa_common.c b/drivers/vdpa/virtio_pci/vp_vdpa_common.c
index 3ff24c9ad6e4..fa91dc153244 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa_common.c
+++ b/drivers/vdpa/virtio_pci/vp_vdpa_common.c
@@ -8,6 +8,7 @@
  * Based on virtio_pci_modern.c.
  */
 
+#include "linux/err.h"
 #include <linux/irqreturn.h>
 #include <linux/interrupt.h>
 #include "vp_vdpa_common.h"
@@ -172,6 +173,10 @@ static int vp_vdpa_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		return ret;
 
 	vp_vdpa = vp_vdpa_modern_probe(pdev);
+	if (PTR_ERR(vp_vdpa) == -ENODEV) {
+		dev_info(&pdev->dev, "Tring legacy driver");
+		vp_vdpa = vp_vdpa_legacy_probe(pdev);
+	}
 	if (IS_ERR(vp_vdpa))
 		return PTR_ERR(vp_vdpa);
 
diff --git a/drivers/vdpa/virtio_pci/vp_vdpa_common.h b/drivers/vdpa/virtio_pci/vp_vdpa_common.h
index 57886b55a2e9..39f241d8321b 100644
--- a/drivers/vdpa/virtio_pci/vp_vdpa_common.h
+++ b/drivers/vdpa/virtio_pci/vp_vdpa_common.h
@@ -10,6 +10,7 @@
 #include <linux/virtio_ring.h>
 #include <linux/virtio_pci.h>
 #include <linux/virtio_pci_modern.h>
+#include <linux/virtio_pci_legacy.h>
 
 #define VP_VDPA_DRIVER_NAME "vp_vdpa"
 #define VP_VDPA_NAME_SIZE 256
@@ -26,6 +27,7 @@ struct vp_vdpa {
 	struct vdpa_device vdpa;
 	struct pci_dev *pci_dev;
 	struct virtio_pci_modern_device mdev;
+	struct virtio_pci_legacy_device ldev;
 	struct vp_vring *vring;
 	struct vdpa_callback config_cb;
 	char msix_name[VP_VDPA_NAME_SIZE];
@@ -53,4 +55,13 @@ void vp_vdpa_free_irq_vectors(void *data);
 
 struct vp_vdpa *vp_vdpa_modern_probe(struct pci_dev *pdev);
 
+#if IS_ENABLED(CONFIG_VP_VDPA_LEGACY)
+struct vp_vdpa *vp_vdpa_legacy_probe(struct pci_dev *pdev);
+#else
+static inline struct vp_vdpa *vp_vdpa_legacy_probe(struct pci_dev *pdev)
+{
+	return ERR_PTR(-ENODEV);
+}
+#endif
+
 #endif
diff --git a/drivers/vdpa/virtio_pci/vp_vdpa_legacy.c b/drivers/vdpa/virtio_pci/vp_vdpa_legacy.c
new file mode 100644
index 000000000000..75a6879a27ca
--- /dev/null
+++ b/drivers/vdpa/virtio_pci/vp_vdpa_legacy.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vDPA bridge driver for legacy virtio-pci device
+ *
+ * Copyright (c) 2021, Alibaba Inc. All rights reserved.
+ * Author: Wu Zongyong <wuzongyong@linux.alibaba.com>
+ */
+
+#include "linux/pci.h"
+#include "linux/virtio_byteorder.h"
+#include "linux/virtio_pci_legacy.h"
+#include <uapi/linux/virtio_net.h>
+#include <uapi/linux/virtio_blk.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_pci.h>
+#include "vp_vdpa_common.h"
+
+static struct virtio_pci_legacy_device *vdpa_to_ldev(struct vdpa_device *vdpa)
+{
+	struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
+
+	return &vp_vdpa->ldev;
+}
+
+static u64 vp_vdpa_get_features(struct vdpa_device *vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	return vp_legacy_get_features(ldev);
+}
+
+static int vp_vdpa_set_features(struct vdpa_device *vdpa, u64 features)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	vp_legacy_set_features(ldev, features);
+
+	return 0;
+}
+
+static u8 vp_vdpa_get_status(struct vdpa_device *vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	return vp_legacy_get_status(ldev);
+}
+
+static int vp_vdpa_set_vq_state_split(struct vdpa_device *vdpa,
+				      const struct vdpa_vq_state *state)
+{
+	const struct vdpa_vq_state_split *split = &state->split;
+
+	if (split->avail_index == 0)
+		return 0;
+
+	return -EOPNOTSUPP;
+}
+
+static int vp_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 qid,
+				const struct vdpa_vq_state *state)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	/* Note that this is not supported by virtio specification.
+	 * But if the state is by chance equal to the device initial
+	 * state, we can let it go.
+	 */
+	if (!vp_legacy_get_queue_enable(ldev, qid))
+		return vp_vdpa_set_vq_state_split(vdpa,	state);
+
+	return -EOPNOTSUPP;
+}
+
+static void vp_vdpa_set_vq_ready(struct vdpa_device *vdpa,
+				 u16 qid, bool ready)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	/* Legacy devices can only be activated by setting vq address,
+	 * and queue_enable is not supported by specification. So for
+	 * legacy devices, we use @vp_vdpa_set_vq_address to set vq
+	 * ready instead.
+	 */
+	if (!ready)
+		vp_legacy_set_queue_address(ldev, qid, 0);
+}
+
+static bool vp_vdpa_get_vq_ready(struct vdpa_device *vdpa, u16 qid)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	return vp_legacy_get_queue_enable(ldev, qid);
+}
+
+/* Legacy devices don't support set vq num by specification,
+ * just report an error if someone try to set it.
+ */
+static void vp_vdpa_set_vq_num(struct vdpa_device *vdpa, u16 qid,
+			       u32 num)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	dev_err(&ldev->pci_dev->dev, "legacy device don't support set vq num\n");
+}
+
+static u16 vp_vdpa_get_vq_num_max(struct vdpa_device *vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	/* assume all virtqueues have the same size */
+	return vp_legacy_get_queue_size(ldev, 0);
+}
+
+static int vp_vdpa_set_vq_address(struct vdpa_device *vdpa, u16 qid,
+				  u64 desc_area, u64 driver_area,
+				  u64 device_area)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	vp_legacy_set_queue_address(ldev, qid, desc_area >> VIRTIO_PCI_QUEUE_ADDR_SHIFT);
+
+	return 0;
+}
+
+static u32 vp_vdpa_get_device_id(struct vdpa_device *vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	return ldev->id.device;
+}
+
+static u32 vp_vdpa_get_vendor_id(struct vdpa_device *vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+
+	return ldev->id.vendor;
+}
+
+static size_t vp_vdpa_get_config_size(struct vdpa_device *vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = vdpa_to_ldev(vdpa);
+	size_t size;
+
+	switch (ldev->id.device) {
+	case VIRTIO_ID_NET:
+		size = sizeof(struct virtio_net_config);
+		break;
+	case VIRTIO_ID_BLOCK:
+		size = sizeof(struct virtio_blk_config);
+		break;
+	default:
+		size = 0;
+		dev_err(&ldev->pci_dev->dev, "VIRTIO ID %u not support\n", ldev->id.device);
+	}
+
+	return size;
+}
+
+static void vp_vdpa_get_config(struct vdpa_device *vdpa,
+			       unsigned int offset,
+			       void *buf, unsigned int len)
+{
+	struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
+	struct virtio_pci_legacy_device *ldev = &vp_vdpa->ldev;
+	void __iomem *ioaddr = ldev->ioaddr +
+		VIRTIO_PCI_CONFIG_OFF(vp_vdpa->vectors) +
+		offset;
+	u8 *p = buf;
+	int i;
+
+	/* legacy devices don't have a configuration generation field,
+	 * so we just read it once.
+	 */
+	for (i = 0; i < len; i++)
+		*p++ = ioread8(ioaddr + i);
+}
+
+static void vp_vdpa_set_config(struct vdpa_device *vdpa,
+			       unsigned int offset, const void *buf,
+			       unsigned int len)
+{
+	struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
+	struct virtio_pci_legacy_device *ldev = &vp_vdpa->ldev;
+	void __iomem *ioaddr = ldev->ioaddr +
+		VIRTIO_PCI_CONFIG_OFF(vp_vdpa->vectors) +
+		offset;
+	const u8 *p = buf;
+	int i;
+
+	for (i = 0; i < len; i++)
+		iowrite8(*p++, ioaddr + i);
+}
+
+static void vp_vdpa_set_status(struct vdpa_device *vdpa, u8 status)
+{
+	struct vp_vdpa *vp_vdpa = vdpa_to_vp(vdpa);
+	struct virtio_pci_legacy_device *ldev = &vp_vdpa->ldev;
+	u8 s = vp_vdpa_get_status(vdpa);
+
+	if (status & VIRTIO_CONFIG_S_DRIVER_OK &&
+	    !(s & VIRTIO_CONFIG_S_DRIVER_OK)) {
+		vp_vdpa_request_irq(vp_vdpa);
+	}
+
+	vp_legacy_set_status(ldev, status);
+
+	if (!(status & VIRTIO_CONFIG_S_DRIVER_OK) &&
+	    (s & VIRTIO_CONFIG_S_DRIVER_OK)) {
+		vp_vdpa_free_irq(vp_vdpa);
+	}
+}
+
+static bool vp_vdpa_get_vq_num_unchangeable(struct vdpa_device *vdpa)
+{
+	return true;
+}
+
+static const struct vdpa_config_ops vp_vdpa_ops = {
+	.get_features	= vp_vdpa_get_features,
+	.set_features	= vp_vdpa_set_features,
+	.get_status	= vp_vdpa_get_status,
+	.set_status	= vp_vdpa_set_status,
+	.get_vq_num_max	= vp_vdpa_get_vq_num_max,
+	.get_vq_state	= vp_vdpa_get_vq_state,
+	.set_vq_state	= vp_vdpa_set_vq_state,
+	.set_vq_cb	= vp_vdpa_set_vq_cb,
+	.set_vq_ready	= vp_vdpa_set_vq_ready,
+	.get_vq_ready	= vp_vdpa_get_vq_ready,
+	.set_vq_num	= vp_vdpa_set_vq_num,
+	.set_vq_address	= vp_vdpa_set_vq_address,
+	.kick_vq	= vp_vdpa_kick_vq,
+	.get_device_id	= vp_vdpa_get_device_id,
+	.get_vendor_id	= vp_vdpa_get_vendor_id,
+	.get_vq_align	= vp_vdpa_get_vq_align,
+	.get_config_size = vp_vdpa_get_config_size,
+	.get_config	= vp_vdpa_get_config,
+	.set_config	= vp_vdpa_set_config,
+	.set_config_cb  = vp_vdpa_set_config_cb,
+	.get_vq_irq	= vp_vdpa_get_vq_irq,
+	.get_vq_num_unchangeable = vp_vdpa_get_vq_num_unchangeable,
+};
+
+static u16 vp_vdpa_get_num_queues(struct vp_vdpa *vp_vdpa)
+{
+	struct virtio_pci_legacy_device *ldev = &vp_vdpa->ldev;
+	u32 features = vp_legacy_get_features(ldev);
+	u16 num;
+
+	switch (ldev->id.device) {
+	case VIRTIO_ID_NET:
+		num = 2;
+		if (features & VIRTIO_NET_F_MQ) {
+			__virtio16 max_virtqueue_pairs;
+
+			vp_vdpa_get_config(&vp_vdpa->vdpa,
+				offsetof(struct virtio_net_config, max_virtqueue_pairs),
+				&max_virtqueue_pairs,
+				sizeof(max_virtqueue_pairs));
+			num = 2 * __virtio16_to_cpu(virtio_legacy_is_little_endian(),
+						max_virtqueue_pairs);
+		}
+
+		if (features & VIRTIO_NET_F_CTRL_VQ)
+			num += 1;
+		break;
+	case VIRTIO_ID_BLOCK:
+		num = 1;
+		break;
+	default:
+		num = 0;
+		dev_err(&ldev->pci_dev->dev, "VIRTIO ID %u not support\n", ldev->id.device);
+	}
+
+	return num;
+}
+
+static u16 vp_vdpa_queue_vector(struct vp_vdpa *vp_vdpa, u16 idx, u16 vector)
+{
+	return vp_legacy_queue_vector(&vp_vdpa->ldev, idx, vector);
+}
+
+static u16 vp_vdpa_config_vector(struct vp_vdpa *vp_vdpa, u16 vector)
+{
+	return vp_legacy_config_vector(&vp_vdpa->ldev, vector);
+}
+
+struct vp_vdpa *vp_vdpa_legacy_probe(struct pci_dev *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct vp_vdpa *vp_vdpa;
+	struct virtio_pci_legacy_device *ldev;
+	int ret, i;
+
+	vp_vdpa = vdpa_alloc_device(struct vp_vdpa, vdpa, dev, &vp_vdpa_ops, NULL);
+	if (vp_vdpa == NULL) {
+		dev_err(dev, "vp_vdpa: Failed to allocate vDPA structure\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	ldev = &vp_vdpa->ldev;
+	ldev->pci_dev = pdev;
+
+	ret = vp_legacy_probe(ldev);
+	if (ret) {
+		dev_err(dev, "Failed to probe legacy PCI device\n");
+		goto err;
+	}
+
+	pci_set_master(pdev);
+	pci_set_drvdata(pdev, vp_vdpa);
+
+	vp_vdpa->vdpa.dma_dev = &pdev->dev;
+	vp_vdpa->queues = vp_vdpa_get_num_queues(vp_vdpa);
+
+	ret = devm_add_action_or_reset(dev, vp_vdpa_free_irq_vectors, pdev);
+	if (ret) {
+		dev_err(dev,
+			"Failed for adding devres for freeing irq vectors\n");
+		goto err;
+	}
+
+	vp_vdpa->vring = devm_kcalloc(dev, vp_vdpa->queues,
+				      sizeof(*vp_vdpa->vring),
+				      GFP_KERNEL);
+	if (!vp_vdpa->vring) {
+		ret = -ENOMEM;
+		dev_err(dev, "Fail to allocate virtqueues\n");
+		goto err;
+	}
+
+	for (i = 0; i < vp_vdpa->queues; i++) {
+		vp_vdpa->vring[i].irq = VIRTIO_MSI_NO_VECTOR;
+		vp_vdpa->vring[i].notify = ldev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
+		vp_vdpa->vring[i].notify_pa = pci_resource_start(pdev, 0) + VIRTIO_PCI_QUEUE_NOTIFY;
+	}
+	vp_vdpa->config_irq = VIRTIO_MSI_NO_VECTOR;
+
+	vp_vdpa->queue_vector = vp_vdpa_queue_vector;
+	vp_vdpa->config_vector = vp_vdpa_config_vector;
+
+	return vp_vdpa;
+
+err:
+	put_device(&vp_vdpa->vdpa.dev);
+	return ERR_PTR(ret);
+}
-- 
2.31.1