Re: [PATCH 06/26] drm/xe/pf: Add helpers for migration data allocation / free

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

On 10/11/2025 9:38 PM, Michał Winiarski wrote:
> Now that it's possible to free the packets - connect the restore
> handling logic with the ring.
> The helpers will also be used in upcoming changes that will start producing
> migration data packets.
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/xe/Makefile                   |   1 +
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c   |  48 ++++++-
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c |  10 +-
>  drivers/gpu/drm/xe/xe_sriov_pf_migration.c    |   1 +
>  .../gpu/drm/xe/xe_sriov_pf_migration_data.c   | 135 ++++++++++++++++++
>  .../gpu/drm/xe/xe_sriov_pf_migration_data.h   |  32 +++++

while this is used by the PF only, maybe those files don't have to include _pf_ tag (like xe_pci_sriov.c or xe_sriov_vfio.c ?)

 .../gpu/drm/xe/xe_sriov_migration_data.c   | 135 ++++++++++++++++++
 .../gpu/drm/xe/xe_sriov_migration_data.h   |  32 +++++

or

 .../gpu/drm/xe/xe_sriov_vfio_data.c   | 135 ++++++++++++++++++
 .../gpu/drm/xe/xe_sriov_vfio_data.h   |  32 +++++

>  6 files changed, 224 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/gpu/drm/xe/xe_sriov_pf_migration_data.c
>  create mode 100644 drivers/gpu/drm/xe/xe_sriov_pf_migration_data.h
> 
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 71f685a315dca..e253d65366de4 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -177,6 +177,7 @@ xe-$(CONFIG_PCI_IOV) += \
>  	xe_sriov_pf_control.o \
>  	xe_sriov_pf_debugfs.o \
>  	xe_sriov_pf_migration.o \
> +	xe_sriov_pf_migration_data.o \
>  	xe_sriov_pf_service.o \
>  	xe_tile_sriov_pf_debugfs.o
>  
> 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 16a88e7599f6d..04a4e92133c2e 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> @@ -20,6 +20,7 @@
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf_control.h"
>  #include "xe_sriov_pf_migration.h"
> +#include "xe_sriov_pf_migration_data.h"
>  #include "xe_sriov_pf_service.h"
>  #include "xe_tile.h"
>  
> @@ -949,14 +950,57 @@ static void pf_exit_vf_restored(struct xe_gt *gt, unsigned int vfid)
>  	pf_exit_vf_state(gt, vfid, XE_GT_SRIOV_STATE_RESTORED);
>  }
>  
> +static void pf_enter_vf_restore_failed(struct xe_gt *gt, unsigned int vfid)
> +{
> +	pf_enter_vf_state(gt, vfid, XE_GT_SRIOV_STATE_RESTORE_FAILED);
> +	pf_exit_vf_wip(gt, vfid);
> +}
> +
> +static int pf_handle_vf_restore_data(struct xe_gt *gt, unsigned int vfid,
> +				     struct xe_sriov_pf_migration_data *data)
> +{
> +	switch (data->type) {
> +	default:
> +		xe_gt_sriov_notice(gt, "Skipping VF%u invalid data type: %d\n", vfid, data->type);
> +		pf_enter_vf_restore_failed(gt, vfid);

shouldn't this be done in pf_handle_vf_restore_wip() where all other state transitions are done?

> +	}
> +
> +	return -EINVAL;
> +}
> +
>  static bool pf_handle_vf_restore_wip(struct xe_gt *gt, unsigned int vfid)
>  {
> +	struct xe_sriov_pf_migration_data *data;
> +	int ret;
> +
>  	if (!pf_check_vf_state(gt, vfid, XE_GT_SRIOV_STATE_RESTORE_WIP))

in other places in VF control state machine we use slightly different pattern:

	// can we exit state AAA?
	if (!pf_exit_vf_state(AAA))
		return false;	// no, we are not in this state
				// try to process other state

	// yes, we _were_ in AAA, process this state
	ret = handle_state_aaa();

	// now decide where to go next
	if (ret == -EAGAIN)
		pf_enter_vf_state(AAA);		// back
	else if (ret < 0)
		pf_enter_vf_state(AAA_FAILED)	// failed
	else
		pf_enter_vf_state(AAA_DONE)	// next

	// state was processed, start next iteration
	return true;

>  		return false;
>  
> -	pf_exit_vf_restore_wip(gt, vfid);
> -	pf_enter_vf_restored(gt, vfid);
> +	data = xe_gt_sriov_pf_migration_ring_consume(gt, vfid);
> +	if (IS_ERR(data)) {
> +		if (PTR_ERR(data) == -ENODATA &&
> +		    !xe_gt_sriov_pf_control_check_vf_data_wip(gt, vfid)) {
> +			pf_exit_vf_restore_wip(gt, vfid);
> +			pf_enter_vf_restored(gt, vfid);
> +		} else {
> +			pf_enter_vf_restore_failed(gt, vfid);
> +		}
> +		return false;

this should be 'true' as we completed this state processing
> +	}
> +
> +	xe_gt_assert(gt, gt->info.id == data->gt);
> +	xe_gt_assert(gt, gt->tile->id == data->tile);
> +
> +	ret = pf_handle_vf_restore_data(gt, vfid, data);
> +	if (ret) {
> +		xe_gt_sriov_err(gt, "VF%u failed to restore data type: %d (%d)\n",

use %pe for error

> +				vfid, data->type, ret);

maybe for debug try to dump here more details about failing data packet

> +		xe_sriov_pf_migration_data_free(data);
> +		pf_enter_vf_restore_failed(gt, vfid);
> +		return false;
> +	}
>  
> +	xe_sriov_pf_migration_data_free(data);
>  	return true;
>  }
>  
> 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 af5952f42fff1..582aaf062cbd4 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> @@ -15,6 +15,7 @@
>  #include "xe_guc_ct.h"
>  #include "xe_sriov.h"
>  #include "xe_sriov_pf_migration.h"
> +#include "xe_sriov_pf_migration_data.h"
>  
>  #define XE_GT_SRIOV_PF_MIGRATION_RING_TIMEOUT (HZ * 20)
>  #define XE_GT_SRIOV_PF_MIGRATION_RING_SIZE 5
> @@ -523,11 +524,18 @@ xe_gt_sriov_pf_migration_ring_consume_nowait(struct xe_gt *gt, unsigned int vfid
>  	return ERR_PTR(-EAGAIN);
>  }
>  
> +static void pf_mig_data_destroy(void *ptr)
> +{
> +	struct xe_sriov_pf_migration_data *data = ptr;
> +
> +	xe_sriov_pf_migration_data_free(data);
> +}
> +
>  static void pf_gt_migration_cleanup(struct drm_device *dev, void *arg)
>  {
>  	struct xe_gt_sriov_pf_migration *migration = arg;
>  
> -	ptr_ring_cleanup(&migration->ring, NULL);
> +	ptr_ring_cleanup(&migration->ring, pf_mig_data_destroy);
>  }
>  
>  /**
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration.c b/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> index 347682f29a03c..d39cee66589b5 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration.c
> @@ -12,6 +12,7 @@
>  #include "xe_pm.h"
>  #include "xe_sriov_pf_helpers.h"
>  #include "xe_sriov_pf_migration.h"
> +#include "xe_sriov_pf_migration_data.h"
>  #include "xe_sriov_printk.h"
>  
>  static struct xe_sriov_pf_migration *pf_pick_migration(struct xe_device *xe, unsigned int vfid)
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration_data.c b/drivers/gpu/drm/xe/xe_sriov_pf_migration_data.c
> new file mode 100644
> index 0000000000000..cfc6b512c6674
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration_data.c
> @@ -0,0 +1,135 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +#include "xe_bo.h"
> +#include "xe_device.h"
> +#include "xe_sriov_pf_migration_data.h"
> +
> +static bool data_needs_bo(struct xe_sriov_pf_migration_data *data)
> +{
> +	unsigned int type = data->type;
> +
> +	return type == XE_SRIOV_MIG_DATA_CCS ||
> +	       type == XE_SRIOV_MIG_DATA_VRAM;
> +}
> +
> +/**
> + * xe_sriov_pf_migration_data_alloc() - Allocate migration data packet
> + * @xe: the &struct xe_device
> + *
> + * Only allocates the "outer" structure, without initializing the migration
> + * data backing storage.
> + *
> + * Return: Pointer to &struct xe_sriov_pf_migration_data on success,
> + *         NULL in case of error.
> + */
> +struct xe_sriov_pf_migration_data *
> +xe_sriov_pf_migration_data_alloc(struct xe_device *xe)
> +{
> +	struct xe_sriov_pf_migration_data *data;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return NULL;
> +
> +	data->xe = xe;
> +	data->hdr_remaining = sizeof(data->hdr);
> +
> +	return data;
> +}
> +
> +/**
> + * xe_sriov_pf_migration_data_free() - Free migration data packet
> + * @data: the &struct xe_sriov_pf_migration_data packet
> + */
> +void xe_sriov_pf_migration_data_free(struct xe_sriov_pf_migration_data *data)
> +{
> +	if (data_needs_bo(data)) {
> +		if (data->bo)

not needed, xe_bo_unpin_map_no_vm() checks for NULL

> +			xe_bo_unpin_map_no_vm(data->bo);
> +	} else {
> +		if (data->buff)

not needed, kvfree() also checks for NULL

> +			kvfree(data->buff);
> +	}
> +
> +	kfree(data);
> +}
> +
> +static int mig_data_init(struct xe_sriov_pf_migration_data *data)
> +{
> +	struct xe_gt *gt = xe_device_get_gt(data->xe, data->gt);
> +
> +	if (!gt || data->tile != gt->tile->id)
> +		return -EINVAL;

didn't we check that already in xe_sriov_pf_migration_produce() ?

in other places we call xe_sriov_pf_migration_data_init() using ids from real tile and gt

> +
> +	if (data->size == 0)
> +		return 0;
> +
> +	if (data_needs_bo(data)) {
> +		struct xe_bo *bo = xe_bo_create_pin_map_novm(data->xe, gt->tile,
> +							     PAGE_ALIGN(data->size),
> +							     ttm_bo_type_kernel,
> +							     XE_BO_FLAG_SYSTEM | XE_BO_FLAG_PINNED,
> +							     false);
> +		if (IS_ERR(bo))
> +			return PTR_ERR(bo);
> +
> +		data->bo = bo;
> +		data->vaddr = bo->vmap.vaddr;
> +	} else {
> +		void *buff = kvzalloc(data->size, GFP_KERNEL);
> +		if (!buff)
> +			return -ENOMEM;
> +
> +		data->buff = buff;
> +		data->vaddr = buff;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * xe_sriov_pf_migration_data_init() - Initialize the migration data header and backing storage
> + * @data: the &struct xe_sriov_pf_migration_data packet
> + * @tile_id: tile identifier
> + * @gt_id: GT identifier
> + * @type: &enum xe_sriov_pf_migration_data_type

here type is enum

> + * @offset: offset of data packet payload (within wider resource)
> + * @size: size of data packet payload
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_sriov_pf_migration_data_init(struct xe_sriov_pf_migration_data *data, u8 tile_id, u8 gt_id,
> +				    unsigned int type, loff_t offset, size_t size)

but here is plain int ?

> +{
> +	xe_assert(data->xe, type < XE_SRIOV_MIG_DATA_MAX);

if it's "enum" - no need to check

if it's "int" and type is coming from outside of our code, then assert is not sufficient anyway

nit: if assert stays, add sep line here

> +	data->version = 1;

magic "1" needs its own #define

> +	data->type = type;
> +	data->tile = tile_id;
> +	data->gt = gt_id;
> +	data->offset = offset;
> +	data->size = size;
> +	data->remaining = size;
> +
> +	return mig_data_init(data);
> +}
> +
> +/**
> + * xe_sriov_pf_migration_data_init() - Initialize the migration data backing storage based on header
> + * @data: the &struct xe_sriov_pf_migration_data packet
> + *
> + * Header data is expected to be filled prior to calling this function
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_sriov_pf_migration_data_init_from_hdr(struct xe_sriov_pf_migration_data *data)
> +{
> +	if (WARN_ON(data->hdr_remaining))

better: xe_WARN_ON(xe, ....)

but does it really deserves any WARN here?
we rather know who is the caller 

> +		return -EINVAL;
> +
> +	data->remaining = data->size;
> +
> +	return mig_data_init(data);
> +}
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_migration_data.h b/drivers/gpu/drm/xe/xe_sriov_pf_migration_data.h
> new file mode 100644
> index 0000000000000..1dde4cfcdbc47
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_migration_data.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +#ifndef _XE_SRIOV_PF_MIGRATION_DATA_H_
> +#define _XE_SRIOV_PF_MIGRATION_DATA_H_
> +
> +#include <linux/types.h>
> +
> +struct xe_device;
> +
> +enum xe_sriov_pf_migration_data_type {

maybe add a note that default 0 was skipped on purpose to catch uninitialized/invalid data

> +	XE_SRIOV_MIG_DATA_DESCRIPTOR = 1,

shouldn't we try to match enumerator names with enum name?

	XE_SRIOV_PF_MIGRATION_DATA_TYPE_DESCRIPTOR = 1,
	XE_SRIOV_PF_MIGRATION_DATA_TYPE_TRAILER,
	XE_SRIOV_PF_MIGRATION_DATA_TYPE_...,

or change the enum (and file) name:

	xe_sriov_migration_data.c

	XE_SRIOV_MIGRATION_DATA_TYPE_DESCRIPTOR = 1,
	XE_SRIOV_MIGRATION_DATA_TYPE_TRAILER,
	XE_SRIOV_MIGRATION_DATA_TYPE_...,
> +	XE_SRIOV_MIG_DATA_TRAILER,
> +	XE_SRIOV_MIG_DATA_GGTT,
> +	XE_SRIOV_MIG_DATA_MMIO,
> +	XE_SRIOV_MIG_DATA_GUC,
> +	XE_SRIOV_MIG_DATA_CCS,
> +	XE_SRIOV_MIG_DATA_VRAM,
> +	XE_SRIOV_MIG_DATA_MAX,

please drop it
> +};
> +
> +struct xe_sriov_pf_migration_data *
> +xe_sriov_pf_migration_data_alloc(struct xe_device *xe);
> +void xe_sriov_pf_migration_data_free(struct xe_sriov_pf_migration_data *snapshot);
> +
> +int xe_sriov_pf_migration_data_init(struct xe_sriov_pf_migration_data *data, u8 tile_id, u8 gt_id,
> +				    unsigned int type, loff_t offset, size_t size);
> +int xe_sriov_pf_migration_data_init_from_hdr(struct xe_sriov_pf_migration_data *snapshot);
> +
> +#endif