Re: [PATCH v3 22/28] drm/xe/pf: Handle VRAM migration data as part of PF control

[Matthew Brost <matthew.brost@intel.com>]

On Thu, Oct 30, 2025 at 09:31:29PM +0100, Michał Winiarski wrote:
> Connect the helpers to allow save and restore of VRAM migration data in
> stop_copy / resume device state.
> 
> Co-developed-by: Lukasz Laguna <lukasz.laguna@intel.com>
> Signed-off-by: Lukasz Laguna <lukasz.laguna@intel.com>
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c   |  15 ++
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c | 213 ++++++++++++++++++
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h |   5 +
>  .../drm/xe/xe_gt_sriov_pf_migration_types.h   |   2 +
>  drivers/gpu/drm/xe/xe_sriov_pf_control.c      |   3 +
>  5 files changed, 238 insertions(+)
> 
> 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 7cd7cae950bc7..de0f63610e780 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> @@ -880,6 +880,18 @@ static int pf_handle_vf_save_data(struct xe_gt *gt, unsigned int vfid)
>  		return -EAGAIN;
>  	}
>  
> +	if (xe_gt_sriov_pf_migration_save_test(gt, vfid, XE_SRIOV_MIGRATION_DATA_TYPE_VRAM)) {
> +		ret = xe_gt_sriov_pf_migration_vram_save(gt, vfid);
> +		if (ret == -EAGAIN)
> +			return -EAGAIN;
> +		else if (ret)
> +			return ret;
> +
> +		xe_gt_sriov_pf_migration_save_clear(gt, vfid, XE_SRIOV_MIGRATION_DATA_TYPE_VRAM);
> +
> +		return -EAGAIN;
> +	}
> +
>  	return 0;
>  }
>  
> @@ -1095,6 +1107,9 @@ static int pf_handle_vf_restore_data(struct xe_gt *gt, unsigned int vfid)
>  	case XE_SRIOV_MIGRATION_DATA_TYPE_GUC:
>  		ret = xe_gt_sriov_pf_migration_guc_restore(gt, vfid, data);
>  		break;
> +	case XE_SRIOV_MIGRATION_DATA_TYPE_VRAM:
> +		ret = xe_gt_sriov_pf_migration_vram_restore(gt, vfid, data);
> +		break;
>  	default:
>  		xe_gt_sriov_notice(gt, "Skipping VF%u unknown data type: %d\n", vfid, data->type);
>  		break;
> 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 5e90aeafeeb41..7ccd43545fdac 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.c
> @@ -19,6 +19,7 @@
>  #include "xe_gt_sriov_printk.h"
>  #include "xe_guc_buf.h"
>  #include "xe_guc_ct.h"
> +#include "xe_migrate.h"
>  #include "xe_mmio.h"
>  #include "xe_sriov.h"
>  #include "xe_sriov_migration_data.h"
> @@ -505,6 +506,207 @@ int xe_gt_sriov_pf_migration_mmio_restore(struct xe_gt *gt, unsigned int vfid,
>  	return pf_restore_vf_mmio_mig_data(gt, vfid, data);
>  }
>  
> +static ssize_t pf_migration_vram_size(struct xe_gt *gt, unsigned int vfid)
> +{
> +	if (!xe_gt_is_main_type(gt))
> +		return 0;
> +
> +	return xe_gt_sriov_pf_config_get_lmem(gt, vfid);
> +}
> +
> +static struct dma_fence *__pf_save_restore_vram(struct xe_gt *gt, unsigned int vfid,
> +						struct xe_bo *vram, u64 vram_offset,
> +						struct xe_bo *sysmem, u64 sysmem_offset,
> +						size_t size, bool save)
> +{
> +	struct dma_fence *ret = NULL;
> +	struct drm_exec exec;
> +	int err;
> +
> +	drm_exec_init(&exec, DRM_EXEC_INTERRUPTIBLE_WAIT, 0);

It is a bit incongruent that the dma-resv lock is interruptible here.

> +	drm_exec_until_all_locked(&exec) {
> +		err = drm_exec_lock_obj(&exec, &vram->ttm.base);
> +		drm_exec_retry_on_contention(&exec);
> +		if (err) {
> +			ret = ERR_PTR(err);
> +			goto err;
> +		}
> +
> +		err = drm_exec_lock_obj(&exec, &sysmem->ttm.base);
> +		drm_exec_retry_on_contention(&exec);
> +		if (err) {
> +			ret = ERR_PTR(err);
> +			goto err;
> +		}
> +	}
> +
> +	ret = xe_migrate_vram_copy_chunk(vram, vram_offset, sysmem, sysmem_offset, size,
> +					 save ? XE_MIGRATE_COPY_TO_SRAM : XE_MIGRATE_COPY_TO_VRAM);
> +
> +err:
> +	drm_exec_fini(&exec);
> +
> +	return ret;
> +}
> +
> +#define PF_VRAM_SAVE_RESTORE_TIMEOUT (5 * HZ)
> +static int pf_save_vram_chunk(struct xe_gt *gt, unsigned int vfid,
> +			      struct xe_bo *src_vram, u64 src_vram_offset,
> +			      size_t size)
> +{
> +	struct xe_sriov_migration_data *data;
> +	struct dma_fence *fence;
> +	int ret;
> +
> +	data = xe_sriov_migration_data_alloc(gt_to_xe(gt));
> +	if (!data)
> +		return -ENOMEM;
> +
> +	ret = xe_sriov_migration_data_init(data, gt->tile->id, gt->info.id,
> +					   XE_SRIOV_MIGRATION_DATA_TYPE_VRAM,
> +					   src_vram_offset, size);
> +	if (ret)
> +		goto fail;
> +
> +	fence = __pf_save_restore_vram(gt, vfid,
> +				       src_vram, src_vram_offset,
> +				       data->bo, 0, size, true);
> +
> +	ret = dma_fence_wait_timeout(fence, false, PF_VRAM_SAVE_RESTORE_TIMEOUT);

Then here the dma-fence wait is non-interruptible.

> +	dma_fence_put(fence);
> +	if (!ret) {
> +		ret = -ETIME;
> +		goto fail;
> +	}
> +
> +	xe_gt_sriov_dbg_verbose(gt, "VF%u VRAM data save (%zu bytes)\n", vfid, size);
> +	pf_dump_mig_data(gt, vfid, data);
> +
> +	ret = xe_gt_sriov_pf_migration_save_produce(gt, vfid, data);
> +	if (ret)
> +		goto fail;
> +
> +	return 0;
> +
> +fail:
> +	xe_sriov_migration_data_free(data);
> +	return ret;
> +}
> +
> +#define VF_VRAM_STATE_CHUNK_MAX_SIZE SZ_512M
> +static int pf_save_vf_vram_mig_data(struct xe_gt *gt, unsigned int vfid)
> +{
> +	struct xe_gt_sriov_migration_data *migration = pf_pick_gt_migration(gt, vfid);
> +	loff_t *offset = &migration->save.vram_offset;
> +	struct xe_bo *vram;
> +	size_t vram_size, chunk_size;
> +	int ret;
> +
> +	vram = xe_gt_sriov_pf_config_get_lmem_obj(gt, vfid);
> +	if (!vram)
> +		return -ENXIO;
> +
> +	vram_size = xe_bo_size(vram);
> +
> +	xe_gt_assert(gt, *offset < vram_size);
> +
> +	chunk_size = min(vram_size - *offset, VF_VRAM_STATE_CHUNK_MAX_SIZE);
> +
> +	ret = pf_save_vram_chunk(gt, vfid, vram, *offset, chunk_size);
> +	if (ret)
> +		goto fail;
> +
> +	*offset += chunk_size;
> +
> +	xe_bo_put(vram);
> +
> +	if (*offset < vram_size)
> +		return -EAGAIN;
> +
> +	return 0;
> +
> +fail:
> +	xe_bo_put(vram);
> +	xe_gt_sriov_err(gt, "Failed to save VF%u VRAM data (%pe)\n", vfid, ERR_PTR(ret));
> +	return ret;
> +}
> +
> +static int pf_restore_vf_vram_mig_data(struct xe_gt *gt, unsigned int vfid,
> +				       struct xe_sriov_migration_data *data)
> +{
> +	u64 end = data->hdr.offset + data->hdr.size;
> +	struct dma_fence *fence;
> +	struct xe_bo *vram;
> +	size_t size;
> +	int ret = 0;
> +
> +	vram = xe_gt_sriov_pf_config_get_lmem_obj(gt, vfid);
> +	if (!vram)
> +		return -ENXIO;
> +
> +	size = xe_bo_size(vram);
> +
> +	if (end > size || end < data->hdr.size) {
> +		ret = -EINVAL;
> +		goto err;
> +	}
> +
> +	xe_gt_sriov_dbg_verbose(gt, "VF%u VRAM data restore (%llu bytes)\n", vfid, data->size);
> +	pf_dump_mig_data(gt, vfid, data);
> +
> +	fence = __pf_save_restore_vram(gt, vfid, vram, data->hdr.offset,
> +				       data->bo, 0, data->hdr.size, false);
> +	ret = dma_fence_wait_timeout(fence, false, PF_VRAM_SAVE_RESTORE_TIMEOUT);

And also here the dma-fence wait is non-interruptible.

Aside from the incongruence, the usage of drm-exec, dma-fences looks correct.

Matt

> +	dma_fence_put(fence);
> +	if (!ret) {
> +		ret = -ETIME;
> +		goto err;
> +	}
> +
> +	return 0;
> +err:
> +	xe_bo_put(vram);
> +	xe_gt_sriov_err(gt, "Failed to restore VF%u VRAM data (%pe)\n", vfid, ERR_PTR(ret));
> +	return ret;
> +}
> +
> +/**
> + * xe_gt_sriov_pf_migration_vram_save() - Save VF VRAM migration data.
> + * @gt: the &xe_gt
> + * @vfid: the VF identifier (can't be 0)
> + *
> + * This function is for PF only.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_gt_sriov_pf_migration_vram_save(struct xe_gt *gt, unsigned int vfid)
> +{
> +	xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
> +	xe_gt_assert(gt, vfid != PFID);
> +	xe_gt_assert(gt, vfid <= xe_sriov_pf_get_totalvfs(gt_to_xe(gt)));
> +
> +	return pf_save_vf_vram_mig_data(gt, vfid);
> +}
> +
> +/**
> + * xe_gt_sriov_pf_migration_vram_restore() - Restore VF VRAM migration data.
> + * @gt: the &xe_gt
> + * @vfid: the VF identifier (can't be 0)
> + *
> + * This function is for PF only.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_gt_sriov_pf_migration_vram_restore(struct xe_gt *gt, unsigned int vfid,
> +					  struct xe_sriov_migration_data *data)
> +{
> +	xe_gt_assert(gt, IS_SRIOV_PF(gt_to_xe(gt)));
> +	xe_gt_assert(gt, vfid != PFID);
> +	xe_gt_assert(gt, vfid <= xe_sriov_pf_get_totalvfs(gt_to_xe(gt)));
> +
> +	return pf_restore_vf_vram_mig_data(gt, vfid, data);
> +}
> +
>  /**
>   * xe_gt_sriov_pf_migration_size() - Total size of migration data from all components within a GT.
>   * @gt: the &xe_gt
> @@ -544,6 +746,13 @@ ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid)
>  		size += sizeof(struct xe_sriov_pf_migration_hdr);
>  	total += size;
>  
> +	size = pf_migration_vram_size(gt, vfid);
> +	if (size < 0)
> +		return size;
> +	if (size > 0)
> +		size += sizeof(struct xe_sriov_pf_migration_hdr);
> +	total += size;
> +
>  	return total;
>  }
>  
> @@ -602,6 +811,7 @@ void xe_gt_sriov_pf_migration_save_init(struct xe_gt *gt, unsigned int vfid)
>  	struct xe_gt_sriov_migration_data *migration = pf_pick_gt_migration(gt, vfid);
>  
>  	migration->save.data_remaining = 0;
> +	migration->save.vram_offset = 0;
>  
>  	xe_gt_assert(gt, pf_migration_guc_size(gt, vfid) > 0);
>  	set_bit(XE_SRIOV_MIGRATION_DATA_TYPE_GUC, &migration->save.data_remaining);
> @@ -611,6 +821,9 @@ void xe_gt_sriov_pf_migration_save_init(struct xe_gt *gt, unsigned int vfid)
>  
>  	xe_gt_assert(gt, pf_migration_mmio_size(gt, vfid) > 0);
>  	set_bit(XE_SRIOV_MIGRATION_DATA_TYPE_MMIO, &migration->save.data_remaining);
> +
> +	if (pf_migration_vram_size(gt, vfid) > 0)
> +		set_bit(XE_SRIOV_MIGRATION_DATA_TYPE_VRAM, &migration->save.data_remaining);
>  }
>  
>  /**
> 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 b0eec94fea3a6..85b43b2cceb73 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_migration.h
> @@ -25,6 +25,11 @@ int xe_gt_sriov_pf_migration_ggtt_restore(struct xe_gt *gt, unsigned int vfid,
>  int xe_gt_sriov_pf_migration_mmio_save(struct xe_gt *gt, unsigned int vfid);
>  int xe_gt_sriov_pf_migration_mmio_restore(struct xe_gt *gt, unsigned int vfid,
>  					  struct xe_sriov_migration_data *data);
> +int xe_gt_sriov_pf_migration_vram_save(struct xe_gt *gt, unsigned int vfid);
> +int xe_gt_sriov_pf_migration_vram_restore(struct xe_gt *gt, unsigned int vfid,
> +					  struct xe_sriov_migration_data *data);
> +
> +void xe_gt_sriov_pf_migration_save_init(struct xe_gt *gt, unsigned int vfid);
>  
>  ssize_t xe_gt_sriov_pf_migration_size(struct xe_gt *gt, unsigned int vfid);
>  
> 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 9f24878690d9c..f50c64241e9c0 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
> @@ -20,6 +20,8 @@ struct xe_gt_sriov_migration_data {
>  	struct {
>  		/** @save.data_remaining: bitmap of migration types that need to be saved */
>  		unsigned long data_remaining;
> +		/** @save.vram_offset: last saved offset within VRAM, used for chunked VRAM save */
> +		loff_t vram_offset;
>  	} save;
>  };
>  
> diff --git a/drivers/gpu/drm/xe/xe_sriov_pf_control.c b/drivers/gpu/drm/xe/xe_sriov_pf_control.c
> index c2768848daba1..aac8ecb861545 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_pf_control.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_pf_control.c
> @@ -5,6 +5,7 @@
>  
>  #include "xe_device.h"
>  #include "xe_gt_sriov_pf_control.h"
> +#include "xe_gt_sriov_pf_migration.h"
>  #include "xe_sriov_migration_data.h"
>  #include "xe_sriov_pf_control.h"
>  #include "xe_sriov_printk.h"
> @@ -171,6 +172,8 @@ int xe_sriov_pf_control_trigger_save_vf(struct xe_device *xe, unsigned int vfid)
>  		return ret;
>  
>  	for_each_gt(gt, xe, id) {
> +		xe_gt_sriov_pf_migration_save_init(gt, vfid);
> +
>  		ret = xe_gt_sriov_pf_control_trigger_save_vf(gt, vfid);
>  		if (ret)
>  			return ret;
> -- 
> 2.50.1
>