Re: [PATCH v6 2/4] drm/xe/vf: Fix GuC FW check for VF migration support

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

On 10/21/2025 8:12 PM, Tomasz Lis wrote:
> The check whether GuC ABI version meets requirements shall be
> performed after said version is received from GuC.
> 
> Doing it in wrong order was triggering a warning:
> xe 0000:00:02.1: [drm] Assertion `gt->sriov.vf.guc_version.major` failed!
> 
> With this change, dislodge part of the VF migration support check
> and moved it to after GuC handshake.
> 
> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
> Tested-by: Matthew Brost <matthew.brost@intel.com> #v1
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6349
> Fixes: ff1d2b5e3d28 ("drm/xe: Read VF GMD_ID with a specifically-allocated dummy GT")
> Signed-off-by: Tomasz Lis <tomasz.lis@intel.com>
> ---
> v2: Use xe_sriov_vf_ccs_migration_bb_needed()
> 
> v3: Update commit message, move check funct to ccs module (Michal),
>  rename xe_sriov_vf_migration_disable(), remove its duplicate
> 
> v4: Limit scope of some functions to xe_sriov_vf_ccs file,
>  switched 'Fixes:' tag to a different commit (Michal)
> 
> v5: Squashed with "Helper for telling whether CCS migration BBs are
>  needed", added kerneldoc, moved location of some checks (Michal)
> 
>  drivers/gpu/drm/xe/xe_sriov_vf.c     | 33 +++++++------------
>  drivers/gpu/drm/xe/xe_sriov_vf.h     |  1 +
>  drivers/gpu/drm/xe/xe_sriov_vf_ccs.c | 48 ++++++++++++++++++++++++++--
>  3 files changed, 59 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.c b/drivers/gpu/drm/xe/xe_sriov_vf.c
> index 0d8135f3927c..13d6c094ae8f 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_vf.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_vf.c
> @@ -133,7 +133,12 @@ bool xe_sriov_vf_migration_supported(struct xe_device *xe)
>  	return !xe->sriov.vf.migration.disabled;
>  }
>  
> -static void vf_disable_migration(struct xe_device *xe, const char *fmt, ...)
> +/**
> + * xe_sriov_vf_migration_disable - Turn off VF migration with given log message.
> + * @xe: the &xe_device instance.
> + * @fmt: format string for the log message, to be combined with following VAs.
> + */
> +void xe_sriov_vf_migration_disable(struct xe_device *xe, const char *fmt, ...)
>  {
>  	struct va_format vaf;
>  	va_list va_args;
> @@ -156,22 +161,13 @@ static void vf_migration_init_early(struct xe_device *xe)
>  	 * supported at production quality.
>  	 */
>  	if (!IS_ENABLED(CONFIG_DRM_XE_DEBUG))
> -		return vf_disable_migration(xe,
> -					    "experimental feature not available on production builds");
> +		return xe_sriov_vf_migration_disable(xe,
> +				"experimental feature not available on production builds");

indent ?

>  
>  	if (GRAPHICS_VER(xe) < 20)
> -		return vf_disable_migration(xe, "requires gfx version >= 20, but only %u found",
> -					    GRAPHICS_VER(xe));
> -
> -	if (!IS_DGFX(xe)) {
> -		struct xe_uc_fw_version guc_version;
> -
> -		xe_gt_sriov_vf_guc_versions(xe_device_get_gt(xe, 0), NULL, &guc_version);
> -		if (MAKE_GUC_VER_STRUCT(guc_version) < MAKE_GUC_VER(1, 23, 0))
> -			return vf_disable_migration(xe,
> -						    "CCS migration requires GuC ABI >= 1.23 but only %u.%u found",
> -						    guc_version.major, guc_version.minor);
> -	}
> +		return xe_sriov_vf_migration_disable(xe,
> +				"requires gfx version >= 20, but only %u found",
> +				GRAPHICS_VER(xe));
>  }
>  
>  /**
> @@ -193,12 +189,7 @@ void xe_sriov_vf_init_early(struct xe_device *xe)
>   */
>  int xe_sriov_vf_init_late(struct xe_device *xe)
>  {
> -	int err = 0;
> -
> -	if (xe_sriov_vf_migration_supported(xe))
> -		err = xe_sriov_vf_ccs_init(xe);
> -
> -	return err;
> +	return xe_sriov_vf_ccs_init(xe);
>  }
>  
>  static int sa_info_vf_ccs(struct seq_file *m, void *data)
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.h b/drivers/gpu/drm/xe/xe_sriov_vf.h
> index 4df95266b261..e967d4166a43 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_vf.h
> +++ b/drivers/gpu/drm/xe/xe_sriov_vf.h
> @@ -14,6 +14,7 @@ struct xe_device;
>  void xe_sriov_vf_init_early(struct xe_device *xe);
>  int xe_sriov_vf_init_late(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);
>  
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c b/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c
> index 790249801364..842e2a4e4774 100644
> --- a/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c
> +++ b/drivers/gpu/drm/xe/xe_sriov_vf_ccs.c
> @@ -10,6 +10,8 @@
>  #include "xe_device.h"
>  #include "xe_exec_queue.h"
>  #include "xe_exec_queue_types.h"
> +#include "xe_gt_sriov_vf.h"
> +#include "xe_guc.h"
>  #include "xe_guc_submit.h"
>  #include "xe_lrc.h"
>  #include "xe_migrate.h"
> @@ -260,6 +262,49 @@ int xe_sriov_vf_ccs_register_context(struct xe_device *xe)
>  	return err;
>  }
>  
> +/*
> + * Whether GuC requires CCS copy BBs for VF migration.
> + * @xe: the &xe_device instance.
> + *
> + * Only selected platforms require VF KMD to maintain CCS copy BBs and linked LRCAs.
> + *
> + * Return: true if VF driver must participate in the CCS migration, false otherwise.
> + */
> +static bool vf_migration_ccs_bb_needed(struct xe_device *xe)
> +{
> +	xe_assert(xe, IS_SRIOV_VF(xe));
> +
> +	return !IS_DGFX(xe) && xe_device_has_flat_ccs(xe);
> +}
> +
> +/*
> + * Check for disable migration due to no CCS BBs support in GuC FW.
> + * @xe: the &xe_device instance.
> + *
> + * Performs late disable of VF migration feature in case GuC FW cannot support it.
> + *
> + * Returns: True if VF migration with CCS BBs is supported, false othherwise.

typo

> + */
> +static bool vf_migration_ccs_bb_support_check(struct xe_device *xe)
> +{
> +	struct xe_gt *gt = xe_device_get_gt(xe, 0);

this will make static code analyzer unhappy

likely xe_root_mmio_gt(xe) can be used instead to avoid that

> +	struct xe_uc_fw_version guc_version;
> +
> +	if (!xe_sriov_vf_migration_supported(xe) ||
> +	    !vf_migration_ccs_bb_needed(xe))
> +		return false;

nit: IMO it would be cleaner if moved to the caller side ... 

> +
> +	xe_gt_sriov_vf_guc_versions(gt, NULL, &guc_version);
> +	if (MAKE_GUC_VER_STRUCT(guc_version) < MAKE_GUC_VER(1, 23, 0)) {
> +		xe_sriov_vf_migration_disable(xe,
> +					      "CCS migration requires GuC ABI >= 1.23 but only %u.%u found",
> +					      guc_version.major, guc_version.minor);
> +		return false;
> +	}
> +
> +	return true;
> +}
> +
>  static void xe_sriov_vf_ccs_fini(void *arg)
>  {
>  	struct xe_sriov_vf_ccs_ctx *ctx = arg;
> @@ -292,9 +337,8 @@ int xe_sriov_vf_ccs_init(struct xe_device *xe)
>  	int err;
>  
>  	xe_assert(xe, IS_SRIOV_VF(xe));
> -	xe_assert(xe, xe_sriov_vf_migration_supported(xe));
>  
> -	if (IS_DGFX(xe) || !xe_device_has_flat_ccs(xe))
> +	if (!vf_migration_ccs_bb_support_check(xe))

... here

>  		return 0;
>  
>  	for_each_ccs_rw_ctx(ctx_id) {

but otherwise LGTM, so if CI is happy, then

Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>