linux-kernel - Re: [PATCH 10/26] drm/xe: Add sa/guc_buf

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Message-ID: <h2verfdsvi4xd7bnjw6xdwir6dpdjk6urykg2dp6uysu6td2tw@bpjfylz2gl7m>
Date: Tue, 21 Oct 2025 02:44:51 +0200
From: Michał Winiarski <michal.winiarski@...el.com>
To: Michal Wajdeczko <michal.wajdeczko@...el.com>
CC: Alex Williamson <alex.williamson@...hat.com>, Lucas De Marchi
	<lucas.demarchi@...el.com>, Thomas Hellström
	<thomas.hellstrom@...ux.intel.com>, Rodrigo Vivi <rodrigo.vivi@...el.com>,
	Jason Gunthorpe <jgg@...pe.ca>, Yishai Hadas <yishaih@...dia.com>, Kevin Tian
	<kevin.tian@...el.com>, Shameer Kolothum
	<shameerali.kolothum.thodi@...wei.com>, <intel-xe@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
	<dri-devel@...ts.freedesktop.org>, Matthew Brost <matthew.brost@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, "Lukasz
 Laguna" <lukasz.laguna@...el.com>
Subject: Re: [PATCH 10/26] drm/xe: Add sa/guc_buf_cache sync interface

On Mon, Oct 13, 2025 at 01:20:53PM +0200, Michal Wajdeczko wrote:
> 
> 
> On 10/11/2025 9:38 PM, Michał Winiarski wrote:
> > In upcoming changes the cached buffers are going to be used to read data
> > produced by the GuC. Add a counterpart to flush, which synchronizes the
> > CPU-side of suballocation with the GPU data and propagate the interface
> > to GuC Buffer Cache.
> > 
> > Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> > ---
> >  drivers/gpu/drm/xe/xe_guc_buf.c |  9 +++++++++
> >  drivers/gpu/drm/xe/xe_guc_buf.h |  1 +
> >  drivers/gpu/drm/xe/xe_sa.c      | 21 +++++++++++++++++++++
> >  drivers/gpu/drm/xe/xe_sa.h      |  1 +
> >  4 files changed, 32 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_guc_buf.c b/drivers/gpu/drm/xe/xe_guc_buf.c
> > index 502ca3a4ee606..1be26145f0b98 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_buf.c
> > +++ b/drivers/gpu/drm/xe/xe_guc_buf.c
> > @@ -127,6 +127,15 @@ u64 xe_guc_buf_flush(const struct xe_guc_buf buf)
> >  	return xe_sa_bo_gpu_addr(buf.sa);
> >  }
> >  
> > +/**
> > + * xe_guc_buf_sync() - Copy the data from the GPU memory to the sub-allocation.
> > + * @buf: the &xe_guc_buf to sync
> 
> for convenience, can we return the buf CPU pointer here?
> 
> something that I already had in my initial impl [1]
> 
> [1] https://patchwork.freedesktop.org/patch/619024/?series=139801&rev=1

Will do.

Thanks,
-Michał

> 
> 
> > + */
> > +void xe_guc_buf_sync(const struct xe_guc_buf buf)
> > +{
> > +	xe_sa_bo_sync(buf.sa);
> > +}
> > +
> >  /**
> >   * xe_guc_buf_cpu_ptr() - Obtain a CPU pointer to the sub-allocation.
> >   * @buf: the &xe_guc_buf to query
> > diff --git a/drivers/gpu/drm/xe/xe_guc_buf.h b/drivers/gpu/drm/xe/xe_guc_buf.h
> > index 0d67604d96bdd..fe6b5ffe0d6eb 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_buf.h
> > +++ b/drivers/gpu/drm/xe/xe_guc_buf.h
> > @@ -31,6 +31,7 @@ static inline bool xe_guc_buf_is_valid(const struct xe_guc_buf buf)
> >  
> >  void *xe_guc_buf_cpu_ptr(const struct xe_guc_buf buf);
> >  u64 xe_guc_buf_flush(const struct xe_guc_buf buf);
> > +void xe_guc_buf_sync(const struct xe_guc_buf buf);
> >  u64 xe_guc_buf_gpu_addr(const struct xe_guc_buf buf);
> >  u64 xe_guc_cache_gpu_addr_from_ptr(struct xe_guc_buf_cache *cache, const void *ptr, u32 size);
> >  
> > diff --git a/drivers/gpu/drm/xe/xe_sa.c b/drivers/gpu/drm/xe/xe_sa.c
> > index fedd017d6dd36..2115789c2bfb7 100644
> > --- a/drivers/gpu/drm/xe/xe_sa.c
> > +++ b/drivers/gpu/drm/xe/xe_sa.c
> > @@ -110,6 +110,10 @@ struct drm_suballoc *__xe_sa_bo_new(struct xe_sa_manager *sa_manager, u32 size,
> >  	return drm_suballoc_new(&sa_manager->base, size, gfp, true, 0);
> >  }
> >  
> > +/**
> > + * xe_sa_bo_flush_write() - Copy the data from the sub-allocation to the GPU memory.
> > + * @sa_bo: the &drm_suballoc to flush
> > + */
> >  void xe_sa_bo_flush_write(struct drm_suballoc *sa_bo)
> >  {
> >  	struct xe_sa_manager *sa_manager = to_xe_sa_manager(sa_bo->manager);
> > @@ -123,6 +127,23 @@ void xe_sa_bo_flush_write(struct drm_suballoc *sa_bo)
> >  			 drm_suballoc_size(sa_bo));
> >  }
> >  
> > +/**
> > + * xe_sa_bo_sync() - Copy the data from GPU memory to the sub-allocation.
> > + * @sa_bo: the &drm_suballoc to sync
> > + */
> > +void xe_sa_bo_sync(struct drm_suballoc *sa_bo)
> > +{
> > +	struct xe_sa_manager *sa_manager = to_xe_sa_manager(sa_bo->manager);
> > +	struct xe_device *xe = tile_to_xe(sa_manager->bo->tile);
> > +
> > +	if (!sa_manager->bo->vmap.is_iomem)
> > +		return;
> > +
> > +	xe_map_memcpy_from(xe, xe_sa_bo_cpu_addr(sa_bo), &sa_manager->bo->vmap,
> > +			   drm_suballoc_soffset(sa_bo),
> > +			   drm_suballoc_size(sa_bo));
> > +}
> > +
> >  void xe_sa_bo_free(struct drm_suballoc *sa_bo,
> >  		   struct dma_fence *fence)
> >  {
> > diff --git a/drivers/gpu/drm/xe/xe_sa.h b/drivers/gpu/drm/xe/xe_sa.h
> > index 99dbf0eea5402..28fd8bb6450c2 100644
> > --- a/drivers/gpu/drm/xe/xe_sa.h
> > +++ b/drivers/gpu/drm/xe/xe_sa.h
> > @@ -37,6 +37,7 @@ static inline struct drm_suballoc *xe_sa_bo_new(struct xe_sa_manager *sa_manager
> >  }
> >  
> >  void xe_sa_bo_flush_write(struct drm_suballoc *sa_bo);
> > +void xe_sa_bo_sync(struct drm_suballoc *sa_bo);
> >  void xe_sa_bo_free(struct drm_suballoc *sa_bo, struct dma_fence *fence);
> >  
> >  static inline struct xe_sa_manager *
>