Re: [PATCH vfio 10/11] vfio/virtio: Expose admin commands over virtio device

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Sep 21, 2023 at 03:40:39PM +0300, Yishai Hadas wrote:
> Expose admin commands over the virtio device, to be used by the
> vfio-virtio driver in the next patches.
> 
> It includes: list query/use, legacy write/read, read notify_info.
> 
> Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
> ---
>  drivers/vfio/pci/virtio/cmd.c | 146 ++++++++++++++++++++++++++++++++++
>  drivers/vfio/pci/virtio/cmd.h |  27 +++++++
>  2 files changed, 173 insertions(+)
>  create mode 100644 drivers/vfio/pci/virtio/cmd.c
>  create mode 100644 drivers/vfio/pci/virtio/cmd.h
> 
> diff --git a/drivers/vfio/pci/virtio/cmd.c b/drivers/vfio/pci/virtio/cmd.c
> new file mode 100644
> index 000000000000..f068239cdbb0
> --- /dev/null
> +++ b/drivers/vfio/pci/virtio/cmd.c
> @@ -0,0 +1,146 @@
> +// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
> +/*
> + * Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved
> + */
> +
> +#include "cmd.h"
> +
> +int virtiovf_cmd_list_query(struct pci_dev *pdev, u8 *buf, int buf_size)
> +{
> +	struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> +	struct scatterlist out_sg;
> +	struct virtio_admin_cmd cmd = {};
> +
> +	if (!virtio_dev)
> +		return -ENOTCONN;
> +
> +	sg_init_one(&out_sg, buf, buf_size);
> +	cmd.opcode = VIRTIO_ADMIN_CMD_LIST_QUERY;
> +	cmd.group_type = VIRTIO_ADMIN_GROUP_TYPE_SRIOV;
> +	cmd.result_sg = &out_sg;
> +
> +	return virtio_admin_cmd_exec(virtio_dev, &cmd);
> +}
> +

in/out seem all wrong here. In virtio terminology, in means from
device to driver, out means from driver to device.

> +int virtiovf_cmd_list_use(struct pci_dev *pdev, u8 *buf, int buf_size)
> +{
> +	struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> +	struct scatterlist in_sg;
> +	struct virtio_admin_cmd cmd = {};
> +
> +	if (!virtio_dev)
> +		return -ENOTCONN;
> +
> +	sg_init_one(&in_sg, buf, buf_size);
> +	cmd.opcode = VIRTIO_ADMIN_CMD_LIST_USE;
> +	cmd.group_type = VIRTIO_ADMIN_GROUP_TYPE_SRIOV;
> +	cmd.data_sg = &in_sg;
> +
> +	return virtio_admin_cmd_exec(virtio_dev, &cmd);
> +}
> +
> +int virtiovf_cmd_lr_write(struct virtiovf_pci_core_device *virtvdev, u16 opcode,


what is _lr short for?

> +			  u8 offset, u8 size, u8 *buf)
> +{
> +	struct virtio_device *virtio_dev =
> +		virtio_pci_vf_get_pf_dev(virtvdev->core_device.pdev);
> +	struct virtio_admin_cmd_data_lr_write *in;
> +	struct scatterlist in_sg;
> +	struct virtio_admin_cmd cmd = {};
> +	int ret;
> +
> +	if (!virtio_dev)
> +		return -ENOTCONN;
> +
> +	in = kzalloc(sizeof(*in) + size, GFP_KERNEL);
> +	if (!in)
> +		return -ENOMEM;
> +
> +	in->offset = offset;
> +	memcpy(in->registers, buf, size);
> +	sg_init_one(&in_sg, in, sizeof(*in) + size);
> +	cmd.opcode = opcode;
> +	cmd.group_type = VIRTIO_ADMIN_GROUP_TYPE_SRIOV;
> +	cmd.group_member_id = virtvdev->vf_id + 1;

weird. why + 1?

> +	cmd.data_sg = &in_sg;
> +	ret = virtio_admin_cmd_exec(virtio_dev, &cmd);
> +
> +	kfree(in);
> +	return ret;
> +}

How do you know it's safe to send this command, in particular at
this time? This seems to be doing zero checks, and zero synchronization
with the PF driver.


> +
> +int virtiovf_cmd_lr_read(struct virtiovf_pci_core_device *virtvdev, u16 opcode,
> +			 u8 offset, u8 size, u8 *buf)
> +{
> +	struct virtio_device *virtio_dev =
> +		virtio_pci_vf_get_pf_dev(virtvdev->core_device.pdev);
> +	struct virtio_admin_cmd_data_lr_read *in;
> +	struct scatterlist in_sg, out_sg;
> +	struct virtio_admin_cmd cmd = {};
> +	int ret;
> +
> +	if (!virtio_dev)
> +		return -ENOTCONN;
> +
> +	in = kzalloc(sizeof(*in), GFP_KERNEL);
> +	if (!in)
> +		return -ENOMEM;
> +
> +	in->offset = offset;
> +	sg_init_one(&in_sg, in, sizeof(*in));
> +	sg_init_one(&out_sg, buf, size);
> +	cmd.opcode = opcode;
> +	cmd.group_type = VIRTIO_ADMIN_GROUP_TYPE_SRIOV;
> +	cmd.data_sg = &in_sg;
> +	cmd.result_sg = &out_sg;
> +	cmd.group_member_id = virtvdev->vf_id + 1;
> +	ret = virtio_admin_cmd_exec(virtio_dev, &cmd);
> +
> +	kfree(in);
> +	return ret;
> +}
> +
> +int virtiovf_cmd_lq_read_notify(struct virtiovf_pci_core_device *virtvdev,

and what is lq short for?

> +				u8 req_bar_flags, u8 *bar, u64 *bar_offset)
> +{
> +	struct virtio_device *virtio_dev =
> +		virtio_pci_vf_get_pf_dev(virtvdev->core_device.pdev);
> +	struct virtio_admin_cmd_notify_info_result *out;
> +	struct scatterlist out_sg;
> +	struct virtio_admin_cmd cmd = {};
> +	int ret;
> +
> +	if (!virtio_dev)
> +		return -ENOTCONN;
> +
> +	out = kzalloc(sizeof(*out), GFP_KERNEL);
> +	if (!out)
> +		return -ENOMEM;
> +
> +	sg_init_one(&out_sg, out, sizeof(*out));
> +	cmd.opcode = VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO;
> +	cmd.group_type = VIRTIO_ADMIN_GROUP_TYPE_SRIOV;
> +	cmd.result_sg = &out_sg;
> +	cmd.group_member_id = virtvdev->vf_id + 1;
> +	ret = virtio_admin_cmd_exec(virtio_dev, &cmd);
> +	if (!ret) {
> +		struct virtio_admin_cmd_notify_info_data *entry;
> +		int i;
> +
> +		ret = -ENOENT;
> +		for (i = 0; i < VIRTIO_ADMIN_CMD_MAX_NOTIFY_INFO; i++) {
> +			entry = &out->entries[i];
> +			if (entry->flags == VIRTIO_ADMIN_CMD_NOTIFY_INFO_FLAGS_END)
> +				break;
> +			if (entry->flags != req_bar_flags)
> +				continue;
> +			*bar = entry->bar;
> +			*bar_offset = le64_to_cpu(entry->offset);
> +			ret = 0;
> +			break;
> +		}
> +	}
> +
> +	kfree(out);
> +	return ret;
> +}
> diff --git a/drivers/vfio/pci/virtio/cmd.h b/drivers/vfio/pci/virtio/cmd.h
> new file mode 100644
> index 000000000000..c2a3645f4b90
> --- /dev/null
> +++ b/drivers/vfio/pci/virtio/cmd.h
> @@ -0,0 +1,27 @@
> +// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
> +/*
> + * Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
> + */
> +
> +#ifndef VIRTIO_VFIO_CMD_H
> +#define VIRTIO_VFIO_CMD_H
> +
> +#include <linux/kernel.h>
> +#include <linux/virtio.h>
> +#include <linux/vfio_pci_core.h>
> +#include <linux/virtio_pci.h>
> +
> +struct virtiovf_pci_core_device {
> +	struct vfio_pci_core_device core_device;
> +	int vf_id;
> +};
> +
> +int virtiovf_cmd_list_query(struct pci_dev *pdev, u8 *buf, int buf_size);
> +int virtiovf_cmd_list_use(struct pci_dev *pdev, u8 *buf, int buf_size);
> +int virtiovf_cmd_lr_write(struct virtiovf_pci_core_device *virtvdev, u16 opcode,
> +			  u8 offset, u8 size, u8 *buf);
> +int virtiovf_cmd_lr_read(struct virtiovf_pci_core_device *virtvdev, u16 opcode,
> +			 u8 offset, u8 size, u8 *buf);
> +int virtiovf_cmd_lq_read_notify(struct virtiovf_pci_core_device *virtvdev,
> +				u8 req_bar_flags, u8 *bar, u64 *bar_offset);
> +#endif /* VIRTIO_VFIO_CMD_H */
> -- 
> 2.27.0

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