Re: [PATCH 2/5] drm/xe/guc: use SZ_4K for alignment

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Wed, 2025-02-26 at 10:03 +0100, Francois Dugast wrote:
> Hi,
> 
> On Tue, Feb 25, 2025 at 09:00:49PM -0800, Matthew Brost wrote:
> > On Wed, Feb 26, 2025 at 10:00:19AM +0800, Mingcong Bai via B4 Relay
> > wrote:
> > > From: Mingcong Bai <jeffbai@aosc.io>
> > > 
> > > Per the "Firmware" chapter in "drm/xe Intel GFX Driver", as well
> > > as
> > > "Volume 8: Command Stream Programming" in "Intel® Arc™ A-Series
> > > Graphics
> > > and Intel Data Center GPU Flex Series Open-Source Programmer's
> > > Reference
> > > Manual For the discrete GPUs code named "Alchemist" and "Arctic
> > > Sound-M""
> > > and "Intel® Iris® Xe MAX Graphics Open Source Programmer's
> > > Reference
> > > Manual For the 2020 Discrete GPU formerly named "DG1"":
> > > 
> > >   "The RINGBUF register sets (defined in Memory Interface
> > > Registers) are
> > >   used to specify the ring buffer memory areas. The ring buffer
> > > must start
> > >   on a 4KB boundary and be allocated in linear memory. The length
> > > of any
> > >   one ring buffer is limited to 2MB."
> > > 
> > > The Graphics micro (μ) Controller (GuC) really expects command
> > > buffers
> > > aligned to 4K boundaries.
> > > 
> > > Current code uses `PAGE_SIZE' as an assumed alignment reference
> > > but 4K
> > > kernel page sizes is by no means a guarantee. On 16K-paged
> > > kernels, this
> > > causes driver failures after loading the GuC firmware:
> > > 
> > > [    7.398317] xe 0000:09:00.0: [drm] Found dg2/g10 (device ID
> > > 56a1) display version 13.00 stepping C0
> > > [    7.410429] xe 0000:09:00.0: [drm] Using GuC firmware from
> > > i915/dg2_guc_70.bin version 70.36.0
> > > [   10.719989] xe 0000:09:00.0: [drm] *ERROR* GT0: load failed:
> > > status = 0x800001EC, time = 3297ms, freq = 2400MHz (req 2400MHz),
> > > done = 0
> > > [   10.732106] xe 0000:09:00.0: [drm] *ERROR* GT0: load failed:
> > > status: Reset = 0, BootROM = 0x76, UKernel = 0x01, MIA = 0x00,
> > > Auth = 0x02
> > > [   10.744214] xe 0000:09:00.0: [drm] *ERROR* CRITICAL: Xe has
> > > declared device 0000:09:00.0 as wedged.
> > >                Please file a _new_ bug report at
> > > https://gitlab.freedesktop.org/drm/xe/kernel/issues/new
> > > [   10.828908] xe 0000:09:00.0: [drm] *ERROR* GT0: GuC mmio
> > > request 0x4100: no reply 0x4100
> > > 
> > > Correct this by revising all instances of `PAGE_SIZE' to `SZ_4K'
> > > and
> > > revise `PAGE_ALIGN()' calls to `ALIGN()' with `SZ_4K' as the
> > > second
> > > argument (overriding `PAGE_SIZE').
> > > 
> > > Cc: stable@vger.kernel.org
> > > Fixes: 84d15f426110 ("drm/xe/guc: Add capture size check in GuC
> > > log buffer")
> > > Fixes: 9c8c7a7e6f1f ("drm/xe/guc: Prepare GuC register list and
> > > update ADS size for error capture")
> > > Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for
> > > Intel GPUs")
> > > Tested-by: Mingcong Bai <jeffbai@aosc.io>
> > > Tested-by: Haien Liang <27873200@qq.com>
> > > Tested-by: Shirong Liu <lsr1024@qq.com>
> > > Tested-by: Haofeng Wu <s2600cw2@126.com>
> > > Link:
> > > https://github.com/FanFansfan/loongson-linux/commit/22c55ab3931c32410a077b3ddb6dca3f28223360
> > > Co-developed-by: Shang Yatsen <429839446@qq.com>
> > > Signed-off-by: Shang Yatsen <429839446@qq.com>
> > > Co-developed-by: Kexy Biscuit <kexybiscuit@aosc.io>
> > > Signed-off-by: Kexy Biscuit <kexybiscuit@aosc.io>
> > > Signed-off-by: Mingcong Bai <jeffbai@aosc.io>
> > 
> > Typo in last reply:
> > Reviewed-by: Matthew Brost <matthew.brost@intel.com>
> 
> Nit: in order to improve clarity and to limit potential mistakes in
> the future, you could add:
> 
>     /* GuC really expects command buffers aligned to 4K boundaries.
> */
>     #define GUC_ALIGN SZ_4K
> 
> Then use s/SZ_4K/GUC_ALIGN/ in your changes. It would make clear this
> value does not come from PAGE_SIZE or XE_PAGE_SIZE.

I was thinking the same.

But on another topic, From a quick read of the commit message it's not
clear why a 16K alignment would fail, since a 16K aligned bo would also
be 4K aligned?

/Thomas


> 
> Francois
> 
> > 
> > > ---
> > >  drivers/gpu/drm/xe/xe_guc.c         |  4 ++--
> > >  drivers/gpu/drm/xe/xe_guc_ads.c     | 32 ++++++++++++++++-------
> > > ---------
> > >  drivers/gpu/drm/xe/xe_guc_capture.c |  8 ++++----
> > >  drivers/gpu/drm/xe/xe_guc_ct.c      |  2 +-
> > >  drivers/gpu/drm/xe/xe_guc_log.c     |  4 ++--
> > >  drivers/gpu/drm/xe/xe_guc_pc.c      |  4 ++--
> > >  6 files changed, 27 insertions(+), 27 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/xe/xe_guc.c
> > > b/drivers/gpu/drm/xe/xe_guc.c
> > > index
> > > 408365dfe4eed02336bbd208b60491aea27a8a6e..595873780a5774501f04b2f
> > > 01ebdf8a45c7ac931 100644
> > > --- a/drivers/gpu/drm/xe/xe_guc.c
> > > +++ b/drivers/gpu/drm/xe/xe_guc.c
> > > @@ -88,7 +88,7 @@ static u32 guc_ctl_feature_flags(struct xe_guc
> > > *guc)
> > >  
> > >  static u32 guc_ctl_log_params_flags(struct xe_guc *guc)
> > >  {
> > > -	u32 offset = guc_bo_ggtt_addr(guc, guc->log.bo) >>
> > > PAGE_SHIFT;
> > > +	u32 offset = guc_bo_ggtt_addr(guc, guc->log.bo) >>
> > > XE_PTE_SHIFT;
> > >  	u32 flags;
> > >  
> > >  	#if (((CRASH_BUFFER_SIZE) % SZ_1M) == 0)
> > > @@ -141,7 +141,7 @@ static u32 guc_ctl_log_params_flags(struct
> > > xe_guc *guc)
> > >  
> > >  static u32 guc_ctl_ads_flags(struct xe_guc *guc)
> > >  {
> > > -	u32 ads = guc_bo_ggtt_addr(guc, guc->ads.bo) >>
> > > PAGE_SHIFT;
> > > +	u32 ads = guc_bo_ggtt_addr(guc, guc->ads.bo) >>
> > > XE_PTE_SHIFT;
> > >  	u32 flags = ads << GUC_ADS_ADDR_SHIFT;
> > >  
> > >  	return flags;
> > > diff --git a/drivers/gpu/drm/xe/xe_guc_ads.c
> > > b/drivers/gpu/drm/xe/xe_guc_ads.c
> > > index
> > > fab259adc380be28c79fae5946e123427359ec60..65e88ad43e8adef75288930
> > > 0abd0197a0ac4a1a3 100644
> > > --- a/drivers/gpu/drm/xe/xe_guc_ads.c
> > > +++ b/drivers/gpu/drm/xe/xe_guc_ads.c
> > > @@ -143,17 +143,17 @@ static size_t guc_ads_regset_size(struct
> > > xe_guc_ads *ads)
> > >  
> > >  static size_t guc_ads_golden_lrc_size(struct xe_guc_ads *ads)
> > >  {
> > > -	return PAGE_ALIGN(ads->golden_lrc_size);
> > > +	return ALIGN(ads->golden_lrc_size, SZ_4K);
> > >  }
> > >  
> > >  static u32 guc_ads_waklv_size(struct xe_guc_ads *ads)
> > >  {
> > > -	return PAGE_ALIGN(ads->ads_waklv_size);
> > > +	return ALIGN(ads->ads_waklv_size, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_capture_size(struct xe_guc_ads *ads)
> > >  {
> > > -	return PAGE_ALIGN(ads->capture_size);
> > > +	return ALIGN(ads->capture_size, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_um_queues_size(struct xe_guc_ads *ads)
> > > @@ -168,7 +168,7 @@ static size_t guc_ads_um_queues_size(struct
> > > xe_guc_ads *ads)
> > >  
> > >  static size_t guc_ads_private_data_size(struct xe_guc_ads *ads)
> > >  {
> > > -	return PAGE_ALIGN(ads_to_guc(ads)-
> > > >fw.private_data_size);
> > > +	return ALIGN(ads_to_guc(ads)->fw.private_data_size,
> > > SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_regset_offset(struct xe_guc_ads *ads)
> > > @@ -183,7 +183,7 @@ static size_t
> > > guc_ads_golden_lrc_offset(struct xe_guc_ads *ads)
> > >  	offset = guc_ads_regset_offset(ads) +
> > >  		guc_ads_regset_size(ads);
> > >  
> > > -	return PAGE_ALIGN(offset);
> > > +	return ALIGN(offset, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_waklv_offset(struct xe_guc_ads *ads)
> > > @@ -193,7 +193,7 @@ static size_t guc_ads_waklv_offset(struct
> > > xe_guc_ads *ads)
> > >  	offset = guc_ads_golden_lrc_offset(ads) +
> > >  		 guc_ads_golden_lrc_size(ads);
> > >  
> > > -	return PAGE_ALIGN(offset);
> > > +	return ALIGN(offset, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_capture_offset(struct xe_guc_ads *ads)
> > > @@ -203,7 +203,7 @@ static size_t guc_ads_capture_offset(struct
> > > xe_guc_ads *ads)
> > >  	offset = guc_ads_waklv_offset(ads) +
> > >  		 guc_ads_waklv_size(ads);
> > >  
> > > -	return PAGE_ALIGN(offset);
> > > +	return ALIGN(offset, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_um_queues_offset(struct xe_guc_ads *ads)
> > > @@ -213,7 +213,7 @@ static size_t guc_ads_um_queues_offset(struct
> > > xe_guc_ads *ads)
> > >  	offset = guc_ads_capture_offset(ads) +
> > >  		 guc_ads_capture_size(ads);
> > >  
> > > -	return PAGE_ALIGN(offset);
> > > +	return ALIGN(offset, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_private_data_offset(struct xe_guc_ads
> > > *ads)
> > > @@ -223,7 +223,7 @@ static size_t
> > > guc_ads_private_data_offset(struct xe_guc_ads *ads)
> > >  	offset = guc_ads_um_queues_offset(ads) +
> > >  		guc_ads_um_queues_size(ads);
> > >  
> > > -	return PAGE_ALIGN(offset);
> > > +	return ALIGN(offset, SZ_4K);
> > >  }
> > >  
> > >  static size_t guc_ads_size(struct xe_guc_ads *ads)
> > > @@ -276,7 +276,7 @@ static size_t
> > > calculate_golden_lrc_size(struct xe_guc_ads *ads)
> > >  			continue;
> > >  
> > >  		real_size = xe_gt_lrc_size(gt, class);
> > > -		alloc_size = PAGE_ALIGN(real_size);
> > > +		alloc_size = ALIGN(real_size, SZ_4K);
> > >  		total_size += alloc_size;
> > >  	}
> > >  
> > > @@ -612,12 +612,12 @@ static int guc_capture_prep_lists(struct
> > > xe_guc_ads *ads)
> > >  					 offsetof(struct
> > > __guc_ads_blob, system_info));
> > >  
> > >  	/* first, set aside the first page for a capture_list
> > > with zero descriptors */
> > > -	total_size = PAGE_SIZE;
> > > +	total_size = SZ_4K;
> > >  	if (!xe_guc_capture_getnullheader(guc, &ptr, &size))
> > >  		xe_map_memcpy_to(ads_to_xe(ads),
> > > ads_to_map(ads), capture_offset, ptr, size);
> > >  
> > >  	null_ggtt = ads_ggtt + capture_offset;
> > > -	capture_offset += PAGE_SIZE;
> > > +	capture_offset += SZ_4K;
> > >  
> > >  	/*
> > >  	 * Populate capture list : at this point adps is already
> > > allocated and
> > > @@ -681,10 +681,10 @@ static int guc_capture_prep_lists(struct
> > > xe_guc_ads *ads)
> > >  		}
> > >  	}
> > >  
> > > -	if (ads->capture_size != PAGE_ALIGN(total_size))
> > > +	if (ads->capture_size != ALIGN(total_size, SZ_4K))
> > >  		xe_gt_dbg(gt, "ADS capture alloc size changed
> > > from %d to %d\n",
> > > -			  ads->capture_size,
> > > PAGE_ALIGN(total_size));
> > > -	return PAGE_ALIGN(total_size);
> > > +			  ads->capture_size, ALIGN(total_size,
> > > SZ_4K));
> > > +	return ALIGN(total_size, SZ_4K);
> > >  }
> > >  
> > >  static void guc_mmio_regset_write_one(struct xe_guc_ads *ads,
> > > @@ -928,7 +928,7 @@ static void guc_populate_golden_lrc(struct
> > > xe_guc_ads *ads)
> > >  		xe_gt_assert(gt, gt->default_lrc[class]);
> > >  
> > >  		real_size = xe_gt_lrc_size(gt, class);
> > > -		alloc_size = PAGE_ALIGN(real_size);
> > > +		alloc_size = ALIGN(real_size, SZ_4K);
> > >  		total_size += alloc_size;
> > >  
> > >  		/*
> > > diff --git a/drivers/gpu/drm/xe/xe_guc_capture.c
> > > b/drivers/gpu/drm/xe/xe_guc_capture.c
> > > index
> > > f6d523e4c5feb7f07d695af90f4c44c7a9072c2d..dac51f8720fc6c7d27baa31
> > > a1b5c567f560e8c1f 100644
> > > --- a/drivers/gpu/drm/xe/xe_guc_capture.c
> > > +++ b/drivers/gpu/drm/xe/xe_guc_capture.c
> > > @@ -590,8 +590,8 @@ guc_capture_getlistsize(struct xe_guc *guc,
> > > u32 owner, u32 type,
> > >  		return -ENODATA;
> > >  
> > >  	if (size)
> > > -		*size = PAGE_ALIGN((sizeof(struct
> > > guc_debug_capture_list)) +
> > > -				   (num_regs * sizeof(struct
> > > guc_mmio_reg)));
> > > +		*size = ALIGN((sizeof(struct
> > > guc_debug_capture_list)) +
> > > +			      (num_regs * sizeof(struct
> > > guc_mmio_reg)), SZ_4K);
> > >  
> > >  	return 0;
> > >  }
> > > @@ -738,7 +738,7 @@ size_t
> > > xe_guc_capture_ads_input_worst_size(struct xe_guc *guc)
> > >  	 * sequence, that is, during the pre-hwconfig phase
> > > before we have
> > >  	 * the exact engine fusing info.
> > >  	 */
> > > -	total_size = PAGE_SIZE;	/* Pad a page in front
> > > for empty lists */
> > > +	total_size = SZ_4K;	/* Pad a page in front for empty
> > > lists */
> > >  	for (i = 0; i < GUC_CAPTURE_LIST_INDEX_MAX; i++) {
> > >  		for (j = 0; j < GUC_CAPTURE_LIST_CLASS_MAX; j++)
> > > {
> > >  			if (xe_guc_capture_getlistsize(guc, i,
> > > @@ -758,7 +758,7 @@ size_t
> > > xe_guc_capture_ads_input_worst_size(struct xe_guc *guc)
> > >  		total_size += global_size;
> > >  	}
> > >  
> > > -	return PAGE_ALIGN(total_size);
> > > +	return ALIGN(total_size, SZ_4K);
> > >  }
> > >  
> > >  static int guc_capture_output_size_est(struct xe_guc *guc)
> > > diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c
> > > b/drivers/gpu/drm/xe/xe_guc_ct.c
> > > index
> > > 72ad576fc18eb583110b44b118abeba4c6be936a..a58c58e599122f3e9ebd1e8
> > > 374c17c3b4663a5ed 100644
> > > --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> > > +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> > > @@ -212,7 +212,7 @@ int xe_guc_ct_init(struct xe_guc_ct *ct)
> > >  	struct xe_bo *bo;
> > >  	int err;
> > >  
> > > -	xe_gt_assert(gt, !(guc_ct_size() % PAGE_SIZE));
> > > +	xe_gt_assert(gt, !(guc_ct_size() % SZ_4K));
> > >  
> > >  	ct->g2h_wq = alloc_ordered_workqueue("xe-g2h-wq",
> > > WQ_MEM_RECLAIM);
> > >  	if (!ct->g2h_wq)
> > > diff --git a/drivers/gpu/drm/xe/xe_guc_log.c
> > > b/drivers/gpu/drm/xe/xe_guc_log.c
> > > index
> > > 0ca3056d8bd3fa37bdb79a7a71ef671270771657..9975005732f645b4735f95f
> > > bae8ebe431e793ebe 100644
> > > --- a/drivers/gpu/drm/xe/xe_guc_log.c
> > > +++ b/drivers/gpu/drm/xe/xe_guc_log.c
> > > @@ -58,7 +58,7 @@ static size_t guc_log_size(void)
> > >  	 *  |         Capture logs          |
> > >  	 *  +===============================+ + CAPTURE_SIZE
> > >  	 */
> > > -	return PAGE_SIZE + CRASH_BUFFER_SIZE + DEBUG_BUFFER_SIZE
> > > +
> > > +	return SZ_4K + CRASH_BUFFER_SIZE + DEBUG_BUFFER_SIZE +
> > >  		CAPTURE_BUFFER_SIZE;
> > >  }
> > >  
> > > @@ -331,7 +331,7 @@ u32 xe_guc_get_log_buffer_size(struct
> > > xe_guc_log *log, enum guc_log_buffer_type
> > >  u32 xe_guc_get_log_buffer_offset(struct xe_guc_log *log, enum
> > > guc_log_buffer_type type)
> > >  {
> > >  	enum guc_log_buffer_type i;
> > > -	u32 offset = PAGE_SIZE;/* for the log_buffer_states */
> > > +	u32 offset = SZ_4K;	/* for the log_buffer_states */
> > >  
> > >  	for (i = GUC_LOG_BUFFER_CRASH_DUMP; i <
> > > GUC_LOG_BUFFER_TYPE_MAX; ++i) {
> > >  		if (i == type)
> > > diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c
> > > b/drivers/gpu/drm/xe/xe_guc_pc.c
> > > index
> > > df7f130fb663fc2fd170a94cc1b835b4b4cca167..0f97c6310a3a5696490aaa4
> > > 827eb3aa0d45ea6d6 100644
> > > --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> > > +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> > > @@ -1000,7 +1000,7 @@ int xe_guc_pc_start(struct xe_guc_pc *pc)
> > >  {
> > >  	struct xe_device *xe = pc_to_xe(pc);
> > >  	struct xe_gt *gt = pc_to_gt(pc);
> > > -	u32 size = PAGE_ALIGN(sizeof(struct slpc_shared_data));
> > > +	u32 size = ALIGN(sizeof(struct slpc_shared_data),
> > > SZ_4K);
> > >  	unsigned int fw_ref;
> > >  	int ret;
> > >  
> > > @@ -1110,7 +1110,7 @@ int xe_guc_pc_init(struct xe_guc_pc *pc)
> > >  	struct xe_tile *tile = gt_to_tile(gt);
> > >  	struct xe_device *xe = gt_to_xe(gt);
> > >  	struct xe_bo *bo;
> > > -	u32 size = PAGE_ALIGN(sizeof(struct slpc_shared_data));
> > > +	u32 size = ALIGN(sizeof(struct slpc_shared_data),
> > > SZ_4K);
> > >  	int err;
> > >  
> > >  	if (xe->info.skip_guc_pc)
> > > 
> > > -- 
> > > 2.48.1
> > > 
> > >