Re: [PATCH V1 vfio 6/9] virtio-pci: Introduce APIs to execute legacy IO admin commands

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

On Wed, Oct 25, 2023 at 04:00:43PM +0300, Yishai Hadas wrote:
> On 25/10/2023 13:17, Michael S. Tsirkin wrote:
> > On Wed, Oct 25, 2023 at 12:18:32PM +0300, Yishai Hadas wrote:
> > > On 25/10/2023 0:01, Michael S. Tsirkin wrote:
> > > 
> > >      On Tue, Oct 17, 2023 at 04:42:14PM +0300, Yishai Hadas wrote:
> > > 
> > >          Introduce APIs to execute legacy IO admin commands.
> > > 
> > >          It includes: list_query/use, io_legacy_read/write,
> > >          io_legacy_notify_info.
> > > 
> > >          Those APIs will be used by the next patches from this series.
> > > 
> > >          Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
> > >          ---
> > >           drivers/virtio/virtio_pci_common.c |  11 ++
> > >           drivers/virtio/virtio_pci_common.h |   2 +
> > >           drivers/virtio/virtio_pci_modern.c | 206 +++++++++++++++++++++++++++++
> > >           include/linux/virtio_pci_admin.h   |  18 +++
> > >           4 files changed, 237 insertions(+)
> > >           create mode 100644 include/linux/virtio_pci_admin.h
> > > 
> > >          diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > >          index 6b4766d5abe6..212d68401d2c 100644
> > >          --- a/drivers/virtio/virtio_pci_common.c
> > >          +++ b/drivers/virtio/virtio_pci_common.c
> > >          @@ -645,6 +645,17 @@ static struct pci_driver virtio_pci_driver = {
> > >                  .sriov_configure = virtio_pci_sriov_configure,
> > >           };
> > > 
> > >          +struct virtio_device *virtio_pci_vf_get_pf_dev(struct pci_dev *pdev)
> > >          +{
> > >          +       struct virtio_pci_device *pf_vp_dev;
> > >          +
> > >          +       pf_vp_dev = pci_iov_get_pf_drvdata(pdev, &virtio_pci_driver);
> > >          +       if (IS_ERR(pf_vp_dev))
> > >          +               return NULL;
> > >          +
> > >          +       return &pf_vp_dev->vdev;
> > >          +}
> > >          +
> > >           module_pci_driver(virtio_pci_driver);
> > > 
> > >           MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
> > >          diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
> > >          index a21b9ba01a60..2785e61ed668 100644
> > >          --- a/drivers/virtio/virtio_pci_common.h
> > >          +++ b/drivers/virtio/virtio_pci_common.h
> > >          @@ -155,4 +155,6 @@ static inline void virtio_pci_legacy_remove(struct virtio_pci_device *vp_dev)
> > >           int virtio_pci_modern_probe(struct virtio_pci_device *);
> > >           void virtio_pci_modern_remove(struct virtio_pci_device *);
> > > 
> > >          +struct virtio_device *virtio_pci_vf_get_pf_dev(struct pci_dev *pdev);
> > >          +
> > >           #endif
> > >          diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > >          index cc159a8e6c70..00b65e20b2f5 100644
> > >          --- a/drivers/virtio/virtio_pci_modern.c
> > >          +++ b/drivers/virtio/virtio_pci_modern.c
> > >          @@ -719,6 +719,212 @@ static void vp_modern_destroy_avq(struct virtio_device *vdev)
> > >                  vp_dev->del_vq(&vp_dev->admin_vq.info);
> > >           }
> > > 
> > >          +/*
> > >          + * virtio_pci_admin_list_query - Provides to driver list of commands
> > >          + * supported for the PCI VF.
> > >          + * @dev: VF pci_dev
> > >          + * @buf: buffer to hold the returned list
> > >          + * @buf_size: size of the given buffer
> > >          + *
> > >          + * Returns 0 on success, or negative on failure.
> > >          + */
> > >          +int virtio_pci_admin_list_query(struct pci_dev *pdev, u8 *buf, int buf_size)
> > >          +{
> > >          +       struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> > >          +       struct virtio_admin_cmd cmd = {};
> > >          +       struct scatterlist result_sg;
> > >          +
> > >          +       if (!virtio_dev)
> > >          +               return -ENODEV;
> > >          +
> > >          +       sg_init_one(&result_sg, buf, buf_size);
> > >          +       cmd.opcode = cpu_to_le16(VIRTIO_ADMIN_CMD_LIST_QUERY);
> > >          +       cmd.group_type = cpu_to_le16(VIRTIO_ADMIN_GROUP_TYPE_SRIOV);
> > >          +       cmd.result_sg = &result_sg;
> > >          +
> > >          +       return vp_modern_admin_cmd_exec(virtio_dev, &cmd);
> > >          +}
> > >          +EXPORT_SYMBOL_GPL(virtio_pci_admin_list_query);
> > >          +
> > >          +/*
> > >          + * virtio_pci_admin_list_use - Provides to device list of commands
> > >          + * used for the PCI VF.
> > >          + * @dev: VF pci_dev
> > >          + * @buf: buffer which holds the list
> > >          + * @buf_size: size of the given buffer
> > >          + *
> > >          + * Returns 0 on success, or negative on failure.
> > >          + */
> > >          +int virtio_pci_admin_list_use(struct pci_dev *pdev, u8 *buf, int buf_size)
> > >          +{
> > >          +       struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> > >          +       struct virtio_admin_cmd cmd = {};
> > >          +       struct scatterlist data_sg;
> > >          +
> > >          +       if (!virtio_dev)
> > >          +               return -ENODEV;
> > >          +
> > >          +       sg_init_one(&data_sg, buf, buf_size);
> > >          +       cmd.opcode = cpu_to_le16(VIRTIO_ADMIN_CMD_LIST_USE);
> > >          +       cmd.group_type = cpu_to_le16(VIRTIO_ADMIN_GROUP_TYPE_SRIOV);
> > >          +       cmd.data_sg = &data_sg;
> > >          +
> > >          +       return vp_modern_admin_cmd_exec(virtio_dev, &cmd);
> > >          +}
> > >          +EXPORT_SYMBOL_GPL(virtio_pci_admin_list_use);
> > > 
> > >      list commands are actually for a group, not for the VF.
> > > 
> > > The VF was given to let the function gets the PF from it.
> > > 
> > > For now, the only existing 'group_type' in the spec is SRIOV, this is why we
> > > hard-coded it internally to match the VF PCI.
> > > 
> > > Alternatively,
> > > We can change the API to get the PF and 'group_type' from the caller to better
> > > match future usage.
> > > However, this will require to export the virtio_pci_vf_get_pf_dev() API outside
> > > virtio-pci.
> > > 
> > > Do you prefer to change to the latter option ?
> > No, there are several points I wanted to make but this
> > was not one of them.
> > 
> > First, for query, I was trying to suggest changing the comment.
> > Something like:
> >           + * virtio_pci_admin_list_query - Provides to driver list of commands
> >           + * supported for the group including the given member device.
> >           + * @dev: member pci device.
> 
> Following your suggestion below, to issue inside virtio the query/use and
> keep its data internally (i.e. on the 'admin_queue' context).
> 
> We may suggest the below API for the upper-layers (e.g. vfio) to be
> exported.
> 
> bool virtio_pci_admin_supported_cmds(struct pci_dev *pdev, u64 cmds)
> 
> It will find the PF from the VF and internally will check on the
> 'admin_queue' context whether the given 'cmds' input is supported.
> 
> Its output will be true/false.
> 
> Makes sense ?
> 
> > 	
> > 
> > 
> > Second, I don't think using buf/size  like this is necessary.
> > For now we have a small number of commands just work with u64.
> OK, just keep in mind that upon issuing the command towards the controller
> this still needs to be an allocated u64 data on the heap to work properly.
> > 
> > 
> > Third, while list could be an OK API, the use API does not
> > really work. If you call use with one set of parameters for
> > one VF and another for another then they conflict do they not?
> > 
> > So you need virtio core to do the list/use dance for you,
> > save the list of commands on the PF (which again is just u64 for now)
> > and vfio or vdpa or whatnot will just query that.
> > I hope I'm being clear.
> 
> In that case the virtio_pci_admin_list_query() and
> virtio_pci_admin_list_use() won't be exported any more and will be static in
> virtio-pci.
> 
> They will be called internally as part of activating the admin_queue and
> will simply get struct virtio_device* (the PF) instead of struct pci_dev
> *pdev.


Yes - I think some kind of API will be needed to setup/cleanup.
Then 1st call to setup would do the list/use dance? some ref counting?

And maybe the API should just be
bool virtio_pci_admin_has_legacy_io()



> > 
> > 
> > > 
> > > 
> > >          +
> > >          +/*
> > >          + * virtio_pci_admin_legacy_io_write - Write legacy registers of a member device
> > >          + * @dev: VF pci_dev
> > >          + * @opcode: op code of the io write command
> > > 
> > >      opcode is actually either VIRTIO_ADMIN_CMD_LEGACY_COMMON_CFG_WRITE
> > >      or VIRTIO_ADMIN_CMD_LEGACY_DEV_CFG_WRITE correct?
> > > 
> > >      So please just add 2 APIs for this so users don't need to care.
> > >      Could be wrappers around these two things.
> > > 
> > > 
> > > OK.
> > > 
> > > We'll export the below 2 APIs [1] which internally will call
> > > virtio_pci_admin_legacy_io_write() with the proper op code hard-coded.
> > > 
> > > [1]virtio_pci_admin_legacy_device_io_write()
> > >       virtio_pci_admin_legacy_common_io_write()
> > > 
> > > Yishai
> > > 
> > Makes sense.
> 
> OK, we may do the same split for the 'legacy_io_read' commands to be
> symmetric with the 'legacy_io_write', right ?
> 
> Yishai

makes sense.

> > > 
> > >          + * @offset: starting byte offset within the registers to write to
> > >          + * @size: size of the data to write
> > >          + * @buf: buffer which holds the data
> > >          + *
> > >          + * Returns 0 on success, or negative on failure.
> > >          + */
> > >          +int virtio_pci_admin_legacy_io_write(struct pci_dev *pdev, u16 opcode,
> > >          +                                    u8 offset, u8 size, u8 *buf)
> > >          +{
> > >          +       struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> > >          +       struct virtio_admin_cmd_legacy_wr_data *data;
> > >          +       struct virtio_admin_cmd cmd = {};
> > >          +       struct scatterlist data_sg;
> > >          +       int vf_id;
> > >          +       int ret;
> > >          +
> > >          +       if (!virtio_dev)
> > >          +               return -ENODEV;
> > >          +
> > >          +       vf_id = pci_iov_vf_id(pdev);
> > >          +       if (vf_id < 0)
> > >          +               return vf_id;
> > >          +
> > >          +       data = kzalloc(sizeof(*data) + size, GFP_KERNEL);
> > >          +       if (!data)
> > >          +               return -ENOMEM;
> > >          +
> > >          +       data->offset = offset;
> > >          +       memcpy(data->registers, buf, size);
> > >          +       sg_init_one(&data_sg, data, sizeof(*data) + size);
> > >          +       cmd.opcode = cpu_to_le16(opcode);
> > >          +       cmd.group_type = cpu_to_le16(VIRTIO_ADMIN_GROUP_TYPE_SRIOV);
> > >          +       cmd.group_member_id = cpu_to_le64(vf_id + 1);
> > >          +       cmd.data_sg = &data_sg;
> > >          +       ret = vp_modern_admin_cmd_exec(virtio_dev, &cmd);
> > >          +
> > >          +       kfree(data);
> > >          +       return ret;
> > >          +}
> > >          +EXPORT_SYMBOL_GPL(virtio_pci_admin_legacy_io_write);
> > >          +
> > >          +/*
> > >          + * virtio_pci_admin_legacy_io_read - Read legacy registers of a member device
> > >          + * @dev: VF pci_dev
> > >          + * @opcode: op code of the io read command
> > >          + * @offset: starting byte offset within the registers to read from
> > >          + * @size: size of the data to be read
> > >          + * @buf: buffer to hold the returned data
> > >          + *
> > >          + * Returns 0 on success, or negative on failure.
> > >          + */
> > >          +int virtio_pci_admin_legacy_io_read(struct pci_dev *pdev, u16 opcode,
> > >          +                                   u8 offset, u8 size, u8 *buf)
> > >          +{
> > >          +       struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> > >          +       struct virtio_admin_cmd_legacy_rd_data *data;
> > >          +       struct scatterlist data_sg, result_sg;
> > >          +       struct virtio_admin_cmd cmd = {};
> > >          +       int vf_id;
> > >          +       int ret;
> > >          +
> > >          +       if (!virtio_dev)
> > >          +               return -ENODEV;
> > >          +
> > >          +       vf_id = pci_iov_vf_id(pdev);
> > >          +       if (vf_id < 0)
> > >          +               return vf_id;
> > >          +
> > >          +       data = kzalloc(sizeof(*data), GFP_KERNEL);
> > >          +       if (!data)
> > >          +               return -ENOMEM;
> > >          +
> > >          +       data->offset = offset;
> > >          +       sg_init_one(&data_sg, data, sizeof(*data));
> > >          +       sg_init_one(&result_sg, buf, size);
> > >          +       cmd.opcode = cpu_to_le16(opcode);
> > >          +       cmd.group_type = cpu_to_le16(VIRTIO_ADMIN_GROUP_TYPE_SRIOV);
> > >          +       cmd.group_member_id = cpu_to_le64(vf_id + 1);
> > >          +       cmd.data_sg = &data_sg;
> > >          +       cmd.result_sg = &result_sg;
> > >          +       ret = vp_modern_admin_cmd_exec(virtio_dev, &cmd);
> > >          +
> > >          +       kfree(data);
> > >          +       return ret;
> > >          +}
> > >          +EXPORT_SYMBOL_GPL(virtio_pci_admin_legacy_io_read);
> > >          +
> > >          +/*
> > >          + * virtio_pci_admin_legacy_io_notify_info - Read the queue notification
> > >          + * information for legacy interface
> > >          + * @dev: VF pci_dev
> > >          + * @req_bar_flags: requested bar flags
> > >          + * @bar: on output the BAR number of the member device
> > >          + * @bar_offset: on output the offset within bar
> > >          + *
> > >          + * Returns 0 on success, or negative on failure.
> > >          + */
> > >          +int virtio_pci_admin_legacy_io_notify_info(struct pci_dev *pdev,
> > >          +                                          u8 req_bar_flags, u8 *bar,
> > >          +                                          u64 *bar_offset)
> > >          +{
> > >          +       struct virtio_device *virtio_dev = virtio_pci_vf_get_pf_dev(pdev);
> > >          +       struct virtio_admin_cmd_notify_info_result *result;
> > >          +       struct virtio_admin_cmd cmd = {};
> > >          +       struct scatterlist result_sg;
> > >          +       int vf_id;
> > >          +       int ret;
> > >          +
> > >          +       if (!virtio_dev)
> > >          +               return -ENODEV;
> > >          +
> > >          +       vf_id = pci_iov_vf_id(pdev);
> > >          +       if (vf_id < 0)
> > >          +               return vf_id;
> > >          +
> > >          +       result = kzalloc(sizeof(*result), GFP_KERNEL);
> > >          +       if (!result)
> > >          +               return -ENOMEM;
> > >          +
> > >          +       sg_init_one(&result_sg, result, sizeof(*result));
> > >          +       cmd.opcode = cpu_to_le16(VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO);
> > >          +       cmd.group_type = cpu_to_le16(VIRTIO_ADMIN_GROUP_TYPE_SRIOV);
> > >          +       cmd.group_member_id = cpu_to_le64(vf_id + 1);
> > >          +       cmd.result_sg = &result_sg;
> > >          +       ret = vp_modern_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 = &result->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(result);
> > >          +       return ret;
> > >          +}
> > >          +EXPORT_SYMBOL_GPL(virtio_pci_admin_legacy_io_notify_info);
> > >          +
> > >           static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
> > >                  .get            = NULL,
> > >                  .set            = NULL,
> > >          diff --git a/include/linux/virtio_pci_admin.h b/include/linux/virtio_pci_admin.h
> > >          new file mode 100644
> > >          index 000000000000..cb916a4bc1b1
> > >          --- /dev/null
> > >          +++ b/include/linux/virtio_pci_admin.h
> > >          @@ -0,0 +1,18 @@
> > >          +/* SPDX-License-Identifier: GPL-2.0 */
> > >          +#ifndef _LINUX_VIRTIO_PCI_ADMIN_H
> > >          +#define _LINUX_VIRTIO_PCI_ADMIN_H
> > >          +
> > >          +#include <linux/types.h>
> > >          +#include <linux/pci.h>
> > >          +
> > >          +int virtio_pci_admin_list_use(struct pci_dev *pdev, u8 *buf, int buf_size);
> > >          +int virtio_pci_admin_list_query(struct pci_dev *pdev, u8 *buf, int buf_size);
> > >          +int virtio_pci_admin_legacy_io_write(struct pci_dev *pdev, u16 opcode,
> > >          +                                    u8 offset, u8 size, u8 *buf);
> > >          +int virtio_pci_admin_legacy_io_read(struct pci_dev *pdev, u16 opcode,
> > >          +                                   u8 offset, u8 size, u8 *buf);
> > >          +int virtio_pci_admin_legacy_io_notify_info(struct pci_dev *pdev,
> > >          +                                          u8 req_bar_flags, u8 *bar,
> > >          +                                          u64 *bar_offset);
> > >          +
> > >          +#endif /* _LINUX_VIRTIO_PCI_ADMIN_H */
> > >          --
> > >          2.27.0
> > > 
> > > 

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