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

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On 22/09/2023 12:54, Michael S. Tsirkin wrote:
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@xxxxxxxxxx>

This stuff is pure virtio spec. I think it should live under
drivers/virtio, too.

The motivation to put it in the vfio layer was from the below main reasons:

1) Having it inside virtio may require to export a symbol/function per command.

   This will end up today by 5 and in the future (e.g. live migration) with much more exported symbols.

   With current code we export only 2 generic symbols virtio_pci_vf_get_pf_dev(), virtio_admin_cmd_exec() which may fit for any further extension.

2) For now there is no logic in this vfio layer, however, in the future we may have some DMA/other logic that should better fit to the caller/client layer (i.e. vfio).

By the way, this follows what was done already between vfio/mlx5 to mlx5_core modules where mlx5_core exposes generic APIs to execute a command and to get the a PF from a given mlx5 VF.

This way, we can enable further commands to be added/extended easily/cleanly.

See for example here [1, 2].

[1] https://elixir.bootlin.com/linux/v6.6-rc3/source/drivers/vfio/pci/mlx5/cmd.c#L210

[2] https://elixir.bootlin.com/linux/v6.6-rc3/source/drivers/vfio/pci/mlx5/cmd.c#L683

Yishai


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