Re: [PATCH 05/26] drm/xe/pf: Add data structures and handlers for migration rings

[Michal Wajdeczko <michal.wajdeczko@intel.com>]

On 10/11/2025 9:38 PM, Michał Winiarski wrote:
> Migration data is queued in a per-GT ptr_ring to decouple the worker
> responsible for handling the data transfer from the .read()/.write()
> syscalls.

... from the .read() and .write() syscalls.

> Add the data structures and handlers that will be used in future
> commits.
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c   |   4 +
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c | 163 ++++++++++++++++++
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h |   9 +
>  .../drm/xe/xe_gt_sriov_pf_migration_types.h   |   5 +-
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_types.h     |   3 +
>  drivers/gpu/drm/xe/xe_sriov_pf_migration.c    | 147 ++++++++++++++++
>  drivers/gpu/drm/xe/xe_sriov_pf_migration.h    |  20 +++
>  .../gpu/drm/xe/xe_sriov_pf_migration_types.h  |  37 ++++
>  drivers/gpu/drm/xe/xe_sriov_pf_types.h        |   3 +
>  9 files changed, 390 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> index 44df984278548..16a88e7599f6d 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> @@ -19,6 +19,7 @@
>  #include "xe_guc_ct.h"
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf_control.h"
> +#include "xe_sriov_pf_migration.h"
>  #include "xe_sriov_pf_service.h"
>  #include "xe_tile.h"
>  
> @@ -388,6 +389,8 @@ static bool pf_enter_vf_wip(struct xe_gt *gt, unsigned int vfid)
>  
>  static void pf_exit_vf_wip(struct xe_gt *gt, unsigned int vfid)
>  {
> +	struct wait_queue_head *wq = xe_sriov_pf_migration_waitqueue(gt_to_xe(gt), vfid);
> +
>  	if (pf_exit_vf_state(gt, vfid, XE_GT_SRIOV_STATE_WIP)) {
>  		struct xe_gt_sriov_control_state *cs = pf_pick_vf_control(gt, vfid);

we can declare wq here

>  
> @@ -399,6 +402,7 @@ static void pf_exit_vf_wip(struct xe_gt *gt, unsigned int vfid)
>  		pf_exit_vf_resume_wip(gt, vfid);
>  
>  		complete_all(&cs->done);
> +		wake_up_all(wq);
>  	}
>  }
>  
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> index f8604b172963e..af5952f42fff1 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> @@ -7,6 +7,7 @@
>  
>  #include "abi/guc_actions_sriov_abi.h"
>  #include "xe_bo.h"
> +#include "xe_gt_sriov_pf_control.h"
>  #include "xe_gt_sriov_pf_helpers.h"
>  #include "xe_gt_sriov_pf_migration.h"
>  #include "xe_gt_sriov_printk.h"
> @@ -15,6 +16,17 @@
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf_migration.h"
>  
> +#define XE_GT_SRIOV_PF_MIGRATION_RING_TIMEOUT (HZ * 20)
> +#define XE_GT_SRIOV_PF_MIGRATION_RING_SIZE 5
> +
> +static struct xe_gt_sriov_pf_migration *pf_pick_gt_migration(struct xe_gt *gt, unsigned int vfid)
> +{
> +	xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
> +	xe_gt_assert(gt, vfid <= xe_sriov_pf_get_totalvfs(gt_to_xe(gt)));
> +
> +	return &gt->sriov.pf.vfs[vfid].migration;
> +}
> +
>  /* Return: number of dwords saved/restored/required or a negative error code on failure */
>  static int guc_action_vf_save_restore(struct xe_guc *guc, u32 vfid, u32 opcode,
>  				      u64 addr, u32 ndwords)
> @@ -382,6 +394,142 @@ ssize_t xe_gt_sriov_pf_migration_write_guc_state(struct xe_gt *gt, unsigned int
>  }
>  #endif /* CONFIG_DEBUG_FS */
>  
> +/**
> + * xe_gt_sriov_pf_migration_ring_empty() - Check if a migration ring is empty
> + * @gt: the &struct xe_gt
> + * @vfid: the VF identifier
> + *
> + * Return: true if the ring is empty, otherwise false.
> + */
> +bool xe_gt_sriov_pf_migration_ring_empty(struct xe_gt *gt, unsigned int vfid)
> +{
> +	return ptr_ring_empty(&pf_pick_gt_migration(gt, vfid)->ring);
> +}
> +
> +/**
> + * xe_gt_sriov_pf_migration_produce() - Add migration data packet to migration ring
> + * @gt: the &struct xe_gt
> + * @vfid: the VF identifier
> + * @data: &struct xe_sriov_pf_migration_data packet
> + *
> + * If the ring is full, wait until there is space in the ring.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_gt_sriov_pf_migration_ring_produce(struct xe_gt *gt, unsigned int vfid,
> +					  struct xe_sriov_pf_migration_data *data)
> +{
> +	struct xe_gt_sriov_pf_migration *migration = pf_pick_gt_migration(gt, vfid);
> +	struct wait_queue_head *wq = xe_sriov_pf_migration_waitqueue(gt_to_xe(gt), vfid);
> +	unsigned long timeout = XE_GT_SRIOV_PF_MIGRATION_RING_TIMEOUT;
> +	int ret;
> +
> +	xe_gt_assert(gt, data->tile == gt->tile->id);
> +	xe_gt_assert(gt, data->gt == gt->info.id);
> +
> +	while (1) {
> +		ret = ptr_ring_produce(&migration->ring, data);
> +		if (ret == 0) {

		if (!ret)
			break;
> +			wake_up_all(wq);
> +			break;
> +		}
> +
> +		if (!xe_gt_sriov_pf_control_check_vf_data_wip(gt, vfid))
> +			return -EINVAL;
> +
> +		ret = wait_event_interruptible_timeout(*wq,
> +						       !ptr_ring_full(&migration->ring),
> +						       timeout);
> +		if (ret == 0)
> +			return -ETIMEDOUT;
> +
> +		timeout = ret;
> +	}
> +

	wake_up_all(wq);
	return 0;

> +	return ret;
> +}
> +
> +/**
> + * xe_gt_sriov_pf_migration_consume() - Get migration data packet from migration ring
> + * @gt: the &struct xe_gt
> + * @vfid: the VF identifier
> + *
> + * If the ring is empty, wait until there are new migration data packets to process.
> + *
> + * Return: Pointer to &struct xe_sriov_pf_migration_data on success,
> + *	   ERR_PTR(-ENODATA) if ring is empty and no more migration data is expected,
> + *	   ERR_PTR value in case of error.
> + */
> +struct xe_sriov_pf_migration_data *
> +xe_gt_sriov_pf_migration_ring_consume(struct xe_gt *gt, unsigned int vfid)
> +{
> +	struct xe_gt_sriov_pf_migration *migration = pf_pick_gt_migration(gt, vfid);
> +	struct wait_queue_head *wq = xe_sriov_pf_migration_waitqueue(gt_to_xe(gt), vfid);
> +	unsigned long timeout = XE_GT_SRIOV_PF_MIGRATION_RING_TIMEOUT;
> +	struct xe_sriov_pf_migration_data *data;
> +	int ret;
> +
> +	while (1) {
> +		data = ptr_ring_consume(&migration->ring);
> +		if (data) {
> +			wake_up_all(wq);
> +			break;
> +		}
> +
> +		if (!xe_gt_sriov_pf_control_check_vf_data_wip(gt, vfid))
> +			return ERR_PTR(-ENODATA);
> +
> +		ret = wait_event_interruptible_timeout(*wq,
> +					 !ptr_ring_empty(&migration->ring) ||
> +					 !xe_gt_sriov_pf_control_check_vf_data_wip(gt, vfid),
> +					 timeout);
> +		if (ret == 0)
> +			return ERR_PTR(-ETIMEDOUT);
> +
> +		timeout = ret;
> +	}
> +
> +	return data;
> +}
> +
> +/**
> + * xe_gt_sriov_pf_migration_consume_nowait() - Get migration data packet from migration ring
> + * @gt: the &struct xe_gt
> + * @vfid: the VF identifier
> + *
> + * Similar to xe_gt_sriov_pf_migration_consume(), but doesn't wait until more data is available.
> + *
> + * Return: Pointer to &struct xe_sriov_pf_migration_data on success,
> + *	   ERR_PTR(-EAGAIN) if ring is empty but migration data is expected,
> + *	   ERR_PTR(-ENODATA) if ring is empty and no more migration data is expected,
> + *	   ERR_PTR value in case of error.
> + */
> +struct xe_sriov_pf_migration_data *
> +xe_gt_sriov_pf_migration_ring_consume_nowait(struct xe_gt *gt, unsigned int vfid)
> +{
> +	struct xe_gt_sriov_pf_migration *migration = pf_pick_gt_migration(gt, vfid);
> +	struct wait_queue_head *wq = xe_sriov_pf_migration_waitqueue(gt_to_xe(gt), vfid);
> +	struct xe_sriov_pf_migration_data *data;
> +
> +	data = ptr_ring_consume(&migration->ring);
> +	if (data) {
> +		wake_up_all(wq);
> +		return data;
> +	}
> +
> +	if (!xe_gt_sriov_pf_control_check_vf_data_wip(gt, vfid))
> +		return ERR_PTR(-ENODATA);
> +
> +	return ERR_PTR(-EAGAIN);
> +}
> +
> +static void pf_gt_migration_cleanup(struct drm_device *dev, void *arg)

no need for the "pf" prefix

and if this is only about ptr_ring, then it could be:

static void action_ring_cleanup(...)
{
	struct ptr_ring *r = arg;

	ptr_ring_cleanup(r, NULL);
}

> +{
> +	struct xe_gt_sriov_pf_migration *migration = arg;
> +
> +	ptr_ring_cleanup(&migration->ring, NULL);
> +}
> +
>  /**
>   * xe_gt_sriov_pf_migration_init() - Initialize support for VF migration.
>   * @gt: the &xe_gt
> @@ -393,6 +541,7 @@ ssize_t xe_gt_sriov_pf_migration_write_guc_state(struct xe_gt *gt, unsigned int
>  int xe_gt_sriov_pf_migration_init(struct xe_gt *gt)
>  {
>  	struct xe_device *xe = gt_to_xe(gt);
> +	unsigned int n, totalvfs;
>  	int err;
>  
>  	xe_gt_assert(gt, IS_SRIOV_PF(xe));
> @@ -404,5 +553,19 @@ int xe_gt_sriov_pf_migration_init(struct xe_gt *gt)
>  	if (err)
>  		return err;
>  
> +	totalvfs = xe_sriov_pf_get_totalvfs(xe);
> +	for (n = 0; n <= totalvfs; n++) {
> +		struct xe_gt_sriov_pf_migration *migration = pf_pick_gt_migration(gt, n);
> +
> +		err = ptr_ring_init(&migration->ring,
> +				    XE_GT_SRIOV_PF_MIGRATION_RING_SIZE, GFP_KERNEL);
> +		if (err)
> +			return err;
> +
> +		err = drmm_add_action_or_reset(&xe->drm, pf_gt_migration_cleanup, migration);
> +		if (err)
> +			return err;
> +	}
> +
>  	return 0;
>  }
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> index 09faeae00ddbb..1e4dc46413823 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> @@ -9,11 +9,20 @@
>  #include <linux/types.h>
>  
>  struct xe_gt;
> +struct xe_sriov_pf_migration_data;
>  
>  int xe_gt_sriov_pf_migration_init(struct xe_gt *gt);
>  int xe_gt_sriov_pf_migration_save_guc_state(struct xe_gt *gt, unsigned int vfid);
>  int xe_gt_sriov_pf_migration_restore_guc_state(struct xe_gt *gt, unsigned int vfid);
>  
> +bool xe_gt_sriov_pf_migration_ring_empty(struct xe_gt *gt, unsigned int vfid);
> +int xe_gt_sriov_pf_migration_ring_produce(struct xe_gt *gt, unsigned int vfid,
> +					  struct xe_sriov_pf_migration_data *data);
> +struct xe_sriov_pf_migration_data *
> +xe_gt_sriov_pf_migration_ring_consume(struct xe_gt *gt, unsigned int vfid);
> +struct xe_sriov_pf_migration_data *
> +xe_gt_sriov_pf_migration_ring_consume_nowait(struct xe_gt *gt, unsigned int vfid);
> +
>  #ifdef CONFIG_DEBUG_FS
>  ssize_t xe_gt_sriov_pf_migration_read_guc_state(struct xe_gt *gt, unsigned int vfid,
>  						char __user *buf, size_t count, loff_t *pos);
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h
> index fdc5a31dd8989..8434689372082 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration_types.h
> @@ -7,6 +7,7 @@
>  #define _XE_GT_SRIOV_PF_MIGRATION_TYPES_H_
>  
>  #include <linux/mutex.h>
> +#include <linux/ptr_ring.h>
>  #include <linux/types.h>
>  
>  /**
> @@ -27,9 +28,11 @@ struct xe_gt_sriov_state_snapshot {
>  /**
>   * struct xe_gt_sriov_pf_migration - GT-level data.
>   *
> - * Used by the PF driver to maintain non-VF specific per-GT data.
> + * Used by the PF driver to maintain per-VF migration data.

we try to match struct name with the sub-component name, not use it as per-VF name

if you want to have struct for the per-VF data, pick a different name, maybe:

	struct xe_gt_sriov_pf_migration_state

or just reuse one that you plan to remove later:

	struct xe_gt_sriov_state_snapshot

>   */
>  struct xe_gt_sriov_pf_migration {
> +	/** @ring: queue containing VF save / restore migration data */
> +	struct ptr_ring ring;
>  };
>  
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_types.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_types.h
> index 9a856da379d39..fbb08f8030f7f 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_types.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_types.h
> @@ -33,6 +33,9 @@ struct xe_gt_sriov_metadata {
>  
>  	/** @snapshot: snapshot of the VF state data */
>  	struct xe_gt_sriov_state_snapshot snapshot;
> +
> +	/** @migration: */

missing description

> +	struct xe_gt_sriov_pf_migration migration;
>  };
>  
>  /**
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration.c b/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> index cf6a210d5597a..347682f29a03c 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> @@ -4,7 +4,35 @@
>   */
>  
>  #include "xe_sriov.h"
> +#include <drm/drm_managed.h>
> +
> +#include "xe_device.h"
> +#include "xe_gt_sriov_pf_control.h"
> +#include "xe_gt_sriov_pf_migration.h"
> +#include "xe_pm.h"
> +#include "xe_sriov_pf_helpers.h"
>  #include "xe_sriov_pf_migration.h"
> +#include "xe_sriov_printk.h"
> +
> +static struct xe_sriov_pf_migration *pf_pick_migration(struct xe_device *xe, unsigned int vfid)
> +{
> +	xe_assert(xe, IS_SRIOV_PF(xe));
> +	xe_assert(xe, vfid <= xe_sriov_pf_get_totalvfs(xe));
> +
> +	return &xe->sriov.pf.vfs[vfid].migration;
> +}
> +
> +/**
> + * xe_sriov_pf_migration_waitqueue - Get waitqueue for migration
> + * @xe: the &struct xe_device
> + * @vfid: the VF identifier
> + *
> + * Return: pointer to the migration waitqueue.
> + */
> +wait_queue_head_t *xe_sriov_pf_migration_waitqueue(struct xe_device *xe, unsigned int vfid)
> +{
> +	return &pf_pick_migration(xe, vfid)->wq;
> +}
>  
>  /**
>   * xe_sriov_pf_migration_supported() - Check if SR-IOV VF migration is supported by the device
> @@ -35,9 +63,128 @@ static bool pf_check_migration_support(struct xe_device *xe)
>   */
>  int xe_sriov_pf_migration_init(struct xe_device *xe)
>  {
> +	unsigned int n, totalvfs;
> +
>  	xe_assert(xe, IS_SRIOV_PF(xe));
>  
>  	xe->sriov.pf.migration.supported = pf_check_migration_support(xe);
> +	if (!xe_sriov_pf_migration_supported(xe))
> +		return 0;
> +
> +	totalvfs = xe_sriov_pf_get_totalvfs(xe);
> +	for (n = 1; n <= totalvfs; n++) {
> +		struct xe_sriov_pf_migration *migration = pf_pick_migration(xe, n);
> +
> +		init_waitqueue_head(&migration->wq);
> +	}
>  
>  	return 0;
>  }
> +
> +static bool pf_migration_empty(struct xe_device *xe, unsigned int vfid)
> +{
> +	struct xe_gt *gt;
> +	u8 gt_id;
> +
> +	for_each_gt(gt, xe, gt_id) {
> +		if (!xe_gt_sriov_pf_migration_ring_empty(gt, vfid))
> +			return false;
> +	}
> +
> +	return true;
> +}
> +
> +static struct xe_sriov_pf_migration_data *
> +pf_migration_consume(struct xe_device *xe, unsigned int vfid)
> +{
> +	struct xe_sriov_pf_migration_data *data;
> +	struct xe_gt *gt;
> +	u8 gt_id;
> +	bool no_data = true;
> +
> +	for_each_gt(gt, xe, gt_id) {
> +		data = xe_gt_sriov_pf_migration_ring_consume_nowait(gt, vfid);
> +
> +		if (!IS_ERR(data))
> +			return data;
> +		else if (PTR_ERR(data) == -EAGAIN)
> +			no_data = false;
> +	}
> +
> +	if (no_data)
> +		return ERR_PTR(-ENODATA);
> +
> +	return ERR_PTR(-EAGAIN);
> +}
> +
> +/**
> + * xe_sriov_pf_migration_consume() - Consume a SR-IOV VF migration data packet from the device
> + * @xe: the &struct xe_device
> + * @vfid: the VF identifier
> + *
> + * If there is no migration data to process, wait until more data is available.
> + *
> + * Return: Pointer to &struct xe_sriov_pf_migration_data on success,
> + *	   ERR_PTR(-ENODATA) if ring is empty and no more migration data is expected,

can we use NULL as indication of no data ? then all ERR_PTR will be errors

> + *	   ERR_PTR value in case of error.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +struct xe_sriov_pf_migration_data *
> +xe_sriov_pf_migration_consume(struct xe_device *xe, unsigned int vfid)
> +{
> +	struct xe_sriov_pf_migration *migration = pf_pick_migration(xe, vfid);
> +	unsigned long timeout = HZ * 5;
> +	struct xe_sriov_pf_migration_data *data;
> +	int ret;
> +
> +	if (!IS_SRIOV_PF(xe))
> +		return ERR_PTR(-ENODEV);

this is "PF" function, we shouldn't get here if we are not a PF

use assert here, and make sure the caller verifies the PF mode

> +
> +	while (1) {
> +		data = pf_migration_consume(xe, vfid);
> +		if (!IS_ERR(data) || PTR_ERR(data) != -EAGAIN)
> +			goto out;
> +
> +		ret = wait_event_interruptible_timeout(migration->wq,
> +						       !pf_migration_empty(xe, vfid),
> +						       timeout);
> +		if (ret == 0) {
> +			xe_sriov_warn(xe, "VF%d Timed out waiting for migration data\n", vfid);
> +			return ERR_PTR(-ETIMEDOUT);
> +		}
> +
> +		timeout = ret;
> +	}
> +
> +out:
> +	return data;
> +}
> +
> +/**
> + * xe_sriov_pf_migration_produce() - Produce a SR-IOV VF migration data packet for device to process
> + * @xe: the &struct xe_device
> + * @vfid: the VF identifier
> + * @data: VF migration data
> + *
> + * If the underlying data structure is full, wait until there is space.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_sriov_pf_migration_produce(struct xe_device *xe, unsigned int vfid,
> +				  struct xe_sriov_pf_migration_data *data)
> +{
> +	struct xe_gt *gt;
> +
> +	if (!IS_SRIOV_PF(xe))
> +		return -ENODEV;
> +
> +	gt = xe_device_get_gt(xe, data->gt);
> +	if (!gt || data->tile != gt->tile->id) {
> +		xe_sriov_err_ratelimited(xe, "VF%d Unknown GT - tile_id:%d, gt_id:%d\n",
> +					 vfid, data->tile, data->gt);
> +		return -EINVAL;
> +	}
> +
> +	return xe_gt_sriov_pf_migration_ring_produce(gt, vfid, data);
> +}
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration.h b/drivers/gpu/drm/xe/xe_sriov_pf_migration.h
> index d3058b6682192..f2020ba19c2da 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_migration.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration.h
> @@ -7,12 +7,18 @@
>  #define _XE_SRIOV_PF_MIGRATION_H_
>  
>  #include <linux/types.h>
> +#include <linux/wait.h>
>  
>  struct xe_device;
>  
>  #ifdef CONFIG_PCI_IOV
>  int xe_sriov_pf_migration_init(struct xe_device *xe);
>  bool xe_sriov_pf_migration_supported(struct xe_device *xe);
> +struct xe_sriov_pf_migration_data *
> +xe_sriov_pf_migration_consume(struct xe_device *xe, unsigned int vfid);
> +int xe_sriov_pf_migration_produce(struct xe_device *xe, unsigned int vfid,
> +				  struct xe_sriov_pf_migration_data *data);
> +wait_queue_head_t *xe_sriov_pf_migration_waitqueue(struct xe_device *xe, unsigned int vfid);
>  #else
>  static inline int xe_sriov_pf_migration_init(struct xe_device *xe)
>  {
> @@ -22,6 +28,20 @@ static inline bool xe_sriov_pf_migration_supported(struct xe_device *xe)
>  {
>  	return false;
>  }
> +static inline struct xe_sriov_pf_migration_data *
> +xe_sriov_pf_migration_consume(struct xe_device *xe, unsigned int vfid)
> +{
> +	return ERR_PTR(-ENODEV);
> +}
> +static inline int xe_sriov_pf_migration_produce(struct xe_device *xe, unsigned int vfid,
> +						struct xe_sriov_pf_migration_data *data)
> +{
> +	return -ENODEV;
> +}
> +wait_queue_head_t *xe_sriov_pf_migration_waitqueue(struct xe_device *xe, unsigned int vfid)
> +{
> +	return ERR_PTR(-ENODEV);
> +}

didn't fully check, but do we really need all these stubs?
likely those functions will be called from other real PF-only functions

>  #endif
>  
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration_types.h b/drivers/gpu/drm/xe/xe_sriov_pf_migration_types.h
> index e69de29bb2d1d..80fdea32b884a 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_migration_types.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration_types.h
> @@ -0,0 +1,37 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +#ifndef _XE_SRIOV_PF_MIGRATION_TYPES_H_
> +#define _XE_SRIOV_PF_MIGRATION_TYPES_H_
> +
> +#include <linux/types.h>
> +#include <linux/wait.h>
> +

add kernel-doc

> +struct xe_sriov_pf_migration_data {
> +	struct xe_device *xe;
> +	void *vaddr;
> +	size_t remaining;
> +	size_t hdr_remaining;
> +	union {
> +		struct xe_bo *bo;
> +		void *buff;
> +	};
> +	__struct_group(xe_sriov_pf_migration_hdr, hdr, __packed,
> +		u8 version;
> +		u8 type;
> +		u8 tile;
> +		u8 gt;
> +		u32 flags;
> +		u64 offset;
> +		u64 size;
> +	);
> +};
> +
> +struct xe_sriov_pf_migration {
> +	/** @wq: waitqueue used to avoid busy-waiting for snapshot production/consumption */
> +	wait_queue_head_t wq;
> +};
> +
> +#endif
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_types.h b/drivers/gpu/drm/xe/xe_sriov_pf_types.h
> index 2d2fcc0a2f258..b3ae21a5a0490 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_types.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_types.h
> @@ -9,6 +9,7 @@
>  #include <linux/mutex.h>
>  #include <linux/types.h>
>  
> +#include "xe_sriov_pf_migration_types.h"
>  #include "xe_sriov_pf_service_types.h"
>  
>  /**
> @@ -17,6 +18,8 @@
>  struct xe_sriov_metadata {
>  	/** @version: negotiated VF/PF ABI version */
>  	struct xe_sriov_pf_service_version version;
> +	/** @migration: migration data */
> +	struct xe_sriov_pf_migration migration;
>  };
>  
>  /**