Re: [PATCH 19/26] drm/xe/pf: Add helpers for VF MMIO migration data handling

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

On 10/11/2025 9:38 PM, Michał Winiarski wrote:
> In an upcoming change, the VF MMIO migration data will be handled as
> part of VF control state machine. Add the necessary helpers to allow the
> migration data transfer to/from the VF MMIO registers.
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf.c | 88 +++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_gt_sriov_pf.h | 19 +++++++
>  2 files changed, 107 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf.c
> index c4dda87b47cc8..6ceb9e024e41e 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf.c
> @@ -194,6 +194,94 @@ static void pf_clear_vf_scratch_regs(struct xe_gt *gt, unsigned int vfid)
>  	}
>  }
>  
> +/**
> + * xe_gt_sriov_pf_mmio_vf_size - Get the size of VF MMIO register data.
> + * @gt: the &struct xe_gt
> + * @vfid: VF identifier
> + *
> + * Return: size in bytes.
> + */
> +size_t xe_gt_sriov_pf_mmio_vf_size(struct xe_gt *gt, unsigned int vfid)
> +{
> +	if (xe_gt_is_media_type(gt))
> +		return MED_VF_SW_FLAG_COUNT * sizeof(u32);
> +	else
> +		return VF_SW_FLAG_COUNT * sizeof(u32);
> +}
> +
> +/**
> + * xe_gt_sriov_pf_mmio_vf_save - Save VF MMIO register values to a buffer.
> + * @gt: the &struct xe_gt
> + * @vfid: VF identifier
> + * @buf: destination buffer
> + * @size: destination buffer size in bytes
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_gt_sriov_pf_mmio_vf_save(struct xe_gt *gt, unsigned int vfid, void *buf, size_t size)
> +{
> +	u32 stride = pf_get_vf_regs_stride(gt_to_xe(gt));
> +	struct xe_reg scratch;
> +	u32 *regs = buf;
> +	int n, count;
> +
> +	if (size != xe_gt_sriov_pf_mmio_vf_size(gt, vfid))
> +		return -EINVAL;
> +
> +	if (xe_gt_is_media_type(gt)) {
> +		count = MED_VF_SW_FLAG_COUNT;
> +		for (n = 0; n < count; n++) {
> +			scratch = xe_reg_vf_to_pf(MED_VF_SW_FLAG(n), vfid, stride);
> +			regs[n] = xe_mmio_read32(&gt->mmio, scratch);
> +		}
> +	} else {
> +		count = VF_SW_FLAG_COUNT;
> +		for (n = 0; n < count; n++) {
> +			scratch = xe_reg_vf_to_pf(VF_SW_FLAG(n), vfid, stride);
> +			regs[n] = xe_mmio_read32(&gt->mmio, scratch);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * xe_gt_sriov_pf_mmio_vf_restore - Restore VF MMIO register values from a buffer.
> + * @gt: the &struct xe_gt
> + * @vfid: VF identifier
> + * @buf: source buffer
> + * @size: source buffer size in bytes
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_gt_sriov_pf_mmio_vf_restore(struct xe_gt *gt, unsigned int vfid,
> +				   const void *buf, size_t size)
> +{
> +	u32 stride = pf_get_vf_regs_stride(gt_to_xe(gt));
> +	const u32 *regs = buf;
> +	struct xe_reg scratch;
> +	int n, count;
> +
> +	if (size != xe_gt_sriov_pf_mmio_vf_size(gt, vfid))
> +		return -EINVAL;
> +
> +	if (xe_gt_is_media_type(gt)) {
> +		count = MED_VF_SW_FLAG_COUNT;
> +		for (n = 0; n < count; n++) {
> +			scratch = xe_reg_vf_to_pf(MED_VF_SW_FLAG(n), vfid, stride);
> +			xe_mmio_write32(&gt->mmio, scratch, regs[n]);
> +		}
> +	} else {
> +		count = VF_SW_FLAG_COUNT;
> +		for (n = 0; n < count; n++) {
> +			scratch = xe_reg_vf_to_pf(VF_SW_FLAG(n), vfid, stride);
> +			xe_mmio_write32(&gt->mmio, scratch, regs[n]);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
>  /**
>   * xe_gt_sriov_pf_sanitize_hw() - Reset hardware state related to a VF.
>   * @gt: the &xe_gt
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf.h
> index e7fde3f9937af..5e5f31d943d89 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf.h
> @@ -6,6 +6,8 @@
>  #ifndef _XE_GT_SRIOV_PF_H_
>  #define _XE_GT_SRIOV_PF_H_
>  
> +#include <linux/types.h>

likely also <linux/errno.h> if you want to keep stubs (but double check if those are really needed)

> +
>  struct xe_gt;
>  
>  #ifdef CONFIG_PCI_IOV
> @@ -16,6 +18,10 @@ void xe_gt_sriov_pf_init_hw(struct xe_gt *gt);
>  void xe_gt_sriov_pf_sanitize_hw(struct xe_gt *gt, unsigned int vfid);
>  void xe_gt_sriov_pf_stop_prepare(struct xe_gt *gt);
>  void xe_gt_sriov_pf_restart(struct xe_gt *gt);
> +size_t xe_gt_sriov_pf_mmio_vf_size(struct xe_gt *gt, unsigned int vfid);
> +int xe_gt_sriov_pf_mmio_vf_save(struct xe_gt *gt, unsigned int vfid, void *buf, size_t size);
> +int xe_gt_sriov_pf_mmio_vf_restore(struct xe_gt *gt, unsigned int vfid,
> +				   const void *buf, size_t size);
>  #else
>  static inline int xe_gt_sriov_pf_init_early(struct xe_gt *gt)
>  {
> @@ -38,6 +44,19 @@ static inline void xe_gt_sriov_pf_stop_prepare(struct xe_gt *gt)
>  static inline void xe_gt_sriov_pf_restart(struct xe_gt *gt)
>  {
>  }
> +size_t xe_gt_sriov_pf_mmio_vf_size(struct xe_gt *gt, unsigned int vfid)
> +{
> +	return 0;
> +}
> +int xe_gt_sriov_pf_mmio_vf_save(struct xe_gt *gt, unsigned int vfid, void *buf, size_t size)
> +{
> +	return -ENODEV;
> +}
> +int xe_gt_sriov_pf_mmio_vf_restore(struct xe_gt *gt, unsigned int vfid,
> +				   const void *buf, size_t size)
> +{
> +	return -ENODEV;
> +}
>  #endif
>  
>  #endif