Date:   Thu, 9 Sep 2021 09:57:50 -0400
From:   "Michael S. Tsirkin" <mst@...hat.com>
To:     Wu Zongyong <wuzongyong@...ux.alibaba.com>
Cc:     jasowang@...hat.com, virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, wei.yang1@...ux.alibaba.com
Subject: Re: [PATCH 6/6] vp_vdpa: introduce legacy virtio pci driver

On Wed, Sep 08, 2021 at 08:20:37PM +0800, Wu Zongyong wrote:
> 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.

Hmm isn't this implicit in this being a legacy device?

> 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@...ux.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@...ux.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

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