Re: [PATCH v3 2/2] drm/xe/vf: Fix up GGTT mappings on S4 resume across VFs.

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

On Tue, Nov 18, 2025 at 12:47:41PM +0000, Satyanarayana K V P wrote:
> When SR-IOV is enabled, a VM may suspend on one VF and resume on a
> different VF after S4 sleep cycle. Because GGTT space is not virtualized,
> this transition can lead to incorrect GGTT references. To address this,
> validate the GGTT space during resume and apply necessary fixups if the
> VF has changed.
> 
> Signed-off-by: Satyanarayana K V P <satyanarayana.k.v.p@intel.com>
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Michal Winiarski <michal.winiarski@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> Cc: Tomasz Lis <tomasz.lis@intel.com>
> 
> ---
> V2 -> V3:
> - Fixed review comments (Michal).
> - Added a new function xe_gt_sriov_vf_resume_fixups() which handshakes
> with GUC and does GGTT fixups.
> - Updated commit message.
> 
> V1 -> V2:
> - Rebased to latest drm-tip.
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_vf.c | 38 +++++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_gt_sriov_vf.h |  1 +
>  drivers/gpu/drm/xe/xe_pm.c          |  7 ++++++
>  drivers/gpu/drm/xe/xe_sriov_vf.c    | 30 +++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_sriov_vf.h    |  1 +
>  5 files changed, 77 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> index be7986537aad..87aa1d6576d6 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
> @@ -1335,6 +1335,44 @@ int xe_gt_sriov_vf_init(struct xe_gt *gt)
>  					vf_migration_fini, gt);
>  }
>  
> +/**
> + * xe_gt_sriov_vf_resume_early() - Resume from S4.
> + * @gt: the &xe_gt.
> + *
> + * This function shall be called only by VF.
> + *
> + * Returns: 0 if the operation completed successfully, or a negative
> + * error code otherwise.
> + */
> +int xe_gt_sriov_vf_resume_early(struct xe_gt *gt)
> +{
> +	u64 start, size;
> +	s64 shift;
> +	int err;
> +
> +	xe_gt_assert(gt, IS_SRIOV_VF(gt_to_xe(gt)));
> +
> +	err = xe_gt_sriov_vf_bootstrap(gt);
> +	if (unlikely(err))
> +		goto out;
> +
> +	err = vf_query_ggtt_info(gt, &start, &size, &shift);
> +	if (unlikely(err))
> +		goto out;
> +
> +	if (shift) {
> +		err = vf_post_migration_fixups(gt);
> +		if (unlikely(err))
> +			goto out;
> +	}
> +
> +out:
> +	if (unlikely(err))
> +		xe_gt_sriov_err(gt, "Fixups during resume failed (%d)\n", err);
> +
> +	return err;
> +}
> +
>  /**
>   * xe_gt_sriov_vf_recovery_pending() - VF post migration recovery pending
>   * @gt: the &xe_gt
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.h b/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
> index af40276790fa..68026b561d7d 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
> @@ -25,6 +25,7 @@ void xe_gt_sriov_vf_migrated_event_handler(struct xe_gt *gt);
>  
>  int xe_gt_sriov_vf_init_early(struct xe_gt *gt);
>  int xe_gt_sriov_vf_init(struct xe_gt *gt);
> +int xe_gt_sriov_vf_resume_early(struct xe_gt *gt);
>  bool xe_gt_sriov_vf_recovery_pending(struct xe_gt *gt);
>  
>  u32 xe_gt_sriov_vf_gmdid(struct xe_gt *gt);
> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> index 4f8688fd3f00..a6fcddc47d62 100644
> --- a/drivers/gpu/drm/xe/xe_pm.c
> +++ b/drivers/gpu/drm/xe/xe_pm.c
> @@ -24,6 +24,7 @@
>  #include "xe_late_bind_fw.h"
>  #include "xe_pcode.h"
>  #include "xe_pxp.h"
> +#include "xe_sriov_vf.h"
>  #include "xe_sriov_vf_ccs.h"
>  #include "xe_trace.h"
>  #include "xe_vm.h"
> @@ -248,6 +249,12 @@ int xe_pm_resume(struct xe_device *xe)
>  
>  	xe_display_pm_resume_early(xe);
>  
> +	if (IS_SRIOV_VF(xe)) {
> +		err = xe_sriov_vf_resume_early(xe);
> +		if (unlikely(err))
> +			goto err;
> +	}
> +
>  	/*
>  	 * This only restores pinned memory which is the memory required for the
>  	 * GT(s) to resume.
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.c b/drivers/gpu/drm/xe/xe_sriov_vf.c
> index 39c829daa97c..a33f86b7986d 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_vf.c
> @@ -191,6 +191,36 @@ int xe_sriov_vf_init_late(struct xe_device *xe)
>  	return xe_sriov_vf_ccs_init(xe);
>  }
>  
> +/**
> + * xe_sriov_vf_resume_early() - Early resume operations for SR-IOV Virtual
> + * Function.
> + * @xe: the &xe_device to resume
> + *
> + * This function shall be called only by VF.
> + *
> + * Return: 0 on success or a negative error code on failure.
> + */
> +int xe_sriov_vf_resume_early(struct xe_device *xe)
> +{
> +	struct xe_gt *gt;
> +	int err = 0;
> +	u8 id;
> +
> +	xe_assert(xe, IS_SRIOV_VF(xe));
> +
> +	for_each_gt(gt, xe, id) {
> +		err = xe_gt_sriov_vf_resume_early(gt);
> +		if (unlikely(err))
> +			goto out;
> +	}
> +
> +out:
> +	if (unlikely(err))
> +		xe_sriov_err(xe, "VF resume early failed with (%d)\n", err);
> +
> +	return err;
> +}
> +
>  static int sa_info_vf_ccs(struct seq_file *m, void *data)
>  {
>  	struct drm_info_node *node = m->private;
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.h b/drivers/gpu/drm/xe/xe_sriov_vf.h
> index e967d4166a43..54fe6eedeff6 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_vf.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_vf.h
> @@ -13,6 +13,7 @@ struct xe_device;
>  
>  void xe_sriov_vf_init_early(struct xe_device *xe);
>  int xe_sriov_vf_init_late(struct xe_device *xe);
> +int xe_sriov_vf_resume_early(struct xe_device *xe);
>  bool xe_sriov_vf_migration_supported(struct xe_device *xe);
>  void xe_sriov_vf_migration_disable(struct xe_device *xe, const char *fmt, ...);
>  void xe_sriov_vf_debugfs_register(struct xe_device *xe, struct dentry *root);
> -- 
> 2.51.0
>