Re: [PATCH v2 10/26] drm/xe: Allow the caller to pass guc_buf_cache size

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

On 10/22/2025 12:41 AM, Michał Winiarski wrote:
> An upcoming change will use GuC buffer cache as a place where GuC
> migration data will be stored, and the memory requirement for that is
> larger than indirect data.
> Allow the caller to pass the size based on the intended usecase.
> 
> Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
> ---
>  drivers/gpu/drm/xe/tests/xe_guc_buf_kunit.c | 2 +-
>  drivers/gpu/drm/xe/xe_guc.c                 | 4 ++--
>  drivers/gpu/drm/xe/xe_guc_buf.c             | 6 +++---
>  drivers/gpu/drm/xe/xe_guc_buf.h             | 4 +++-
>  4 files changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/tests/xe_guc_buf_kunit.c b/drivers/gpu/drm/xe/tests/xe_guc_buf_kunit.c
> index d266882adc0e0..485e7a70e6bb7 100644
> --- a/drivers/gpu/drm/xe/tests/xe_guc_buf_kunit.c
> +++ b/drivers/gpu/drm/xe/tests/xe_guc_buf_kunit.c
> @@ -72,7 +72,7 @@ static int guc_buf_test_init(struct kunit *test)
>  	kunit_activate_static_stub(test, xe_managed_bo_create_pin_map,
>  				   replacement_xe_managed_bo_create_pin_map);
>  
> -	KUNIT_ASSERT_EQ(test, 0, xe_guc_buf_cache_init(&guc->buf));
> +	KUNIT_ASSERT_EQ(test, 0, xe_guc_buf_cache_init(&guc->buf, XE_GUC_BUF_CACHE_DEFAULT_SIZE));
>  
>  	test->priv = &guc->buf;
>  	return 0;
> diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
> index ecc3e091b89e6..7c65528859ecb 100644
> --- a/drivers/gpu/drm/xe/xe_guc.c
> +++ b/drivers/gpu/drm/xe/xe_guc.c
> @@ -812,7 +812,7 @@ static int vf_guc_init_post_hwconfig(struct xe_guc *guc)
>  	if (err)
>  		return err;
>  
> -	err = xe_guc_buf_cache_init(&guc->buf);
> +	err = xe_guc_buf_cache_init(&guc->buf, XE_GUC_BUF_CACHE_DEFAULT_SIZE);
>  	if (err)
>  		return err;
>  
> @@ -860,7 +860,7 @@ int xe_guc_init_post_hwconfig(struct xe_guc *guc)
>  	if (ret)
>  		return ret;
>  
> -	ret = xe_guc_buf_cache_init(&guc->buf);
> +	ret = xe_guc_buf_cache_init(&guc->buf, XE_GUC_BUF_CACHE_DEFAULT_SIZE);
>  	if (ret)
>  		return ret;
>  
> diff --git a/drivers/gpu/drm/xe/xe_guc_buf.c b/drivers/gpu/drm/xe/xe_guc_buf.c
> index 4d8a4712309f4..ed096a0331244 100644
> --- a/drivers/gpu/drm/xe/xe_guc_buf.c
> +++ b/drivers/gpu/drm/xe/xe_guc_buf.c
> @@ -28,16 +28,16 @@ static struct xe_gt *cache_to_gt(struct xe_guc_buf_cache *cache)
>   * @cache: the &xe_guc_buf_cache to initialize
>   *
>   * The Buffer Cache allows to obtain a reusable buffer that can be used to pass
> - * indirect H2G data to GuC without a need to create a ad-hoc allocation.
> + * data to GuC or read data from GuC without a need to create a ad-hoc allocation.
>   *
>   * Return: 0 on success or a negative error code on failure.
>   */
> -int xe_guc_buf_cache_init(struct xe_guc_buf_cache *cache)
> +int xe_guc_buf_cache_init(struct xe_guc_buf_cache *cache, u32 size)
>  {
>  	struct xe_gt *gt = cache_to_gt(cache);
>  	struct xe_sa_manager *sam;
>  
> -	sam = __xe_sa_bo_manager_init(gt_to_tile(gt), SZ_8K, 0, sizeof(u32));
> +	sam = __xe_sa_bo_manager_init(gt_to_tile(gt), size, 0, sizeof(u32));
>  	if (IS_ERR(sam))
>  		return PTR_ERR(sam);
>  	cache->sam = sam;
> diff --git a/drivers/gpu/drm/xe/xe_guc_buf.h b/drivers/gpu/drm/xe/xe_guc_buf.h
> index c5e0f1fd24d74..5210703309e81 100644
> --- a/drivers/gpu/drm/xe/xe_guc_buf.h
> +++ b/drivers/gpu/drm/xe/xe_guc_buf.h
> @@ -11,7 +11,9 @@
>  
>  #include "xe_guc_buf_types.h"
>  
> -int xe_guc_buf_cache_init(struct xe_guc_buf_cache *cache);
> +#define XE_GUC_BUF_CACHE_DEFAULT_SIZE SZ_8K
> +
> +int xe_guc_buf_cache_init(struct xe_guc_buf_cache *cache, u32 size);

alternatively, to minimize code changes, we can have:

int xe_guc_buf_cache_init_size(struct xe_guc_buf_cache *cache, u32 size);

static inline int xe_guc_buf_cache_init(struct xe_guc_buf_cache *cache)
{
	return xe_guc_buf_cache_init_size(cache, XE_GUC_BUF_CACHE_DEFAULT_SIZE);
}

but up to you,

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

>  u32 xe_guc_buf_cache_dwords(struct xe_guc_buf_cache *cache);
>  struct xe_guc_buf xe_guc_buf_reserve(struct xe_guc_buf_cache *cache, u32 dwords);
>  struct xe_guc_buf xe_guc_buf_from_data(struct xe_guc_buf_cache *cache,