Re: [PATCH 1/1] drm/i915/mtl: enable local stolen memory

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On 20-09-2022 13:05, Jani Nikula wrote:
> On Tue, 20 Sep 2022, Aravind Iddamsetty <aravind.iddamsetty@xxxxxxxxx> wrote:
>> As an integrated GPU, MTL does not have local memory and
>> HAS_LMEM() returns false.  However the platform's stolen memory
>> is presented via BAR2 (i.e., the BAR we traditionally consider
>> to be the LMEM BAR) and should be managed by the driver the same
>> way that local memory is on dgpu platforms (which includes
>> setting the "lmem" bit on page table entries).  We use the term
>> "local stolen memory" to refer to this model.
>>
>> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
>> Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
>>
>> Signed-off-by: CQ Tang <cq.tang@xxxxxxxxx>
>> Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@xxxxxxxxx>
>> Original-author: CQ Tang
>> ---
>>  drivers/gpu/drm/i915/gem/i915_gem_stolen.c | 113 +++++++++++++++++----
>>  drivers/gpu/drm/i915/gt/intel_ggtt.c       |   2 +-
>>  drivers/gpu/drm/i915/i915_drv.h            |   3 +
>>  3 files changed, 100 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
>> index acc561c0f0aa..bad5250fb764 100644
>> --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
>> +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
>> @@ -77,6 +77,19 @@ void i915_gem_stolen_remove_node(struct drm_i915_private *i915,
>>  	mutex_unlock(&i915->mm.stolen_lock);
>>  }
>>  
>> +static bool is_dsm_invalid(struct drm_i915_private *i915, struct resource *dsm)
> 
> Abstracting this as a separate function looks like a separate patch.
> 
> I generally recommend using positive naming, "is dsm valid", to avoid
> any double negatives that might pop up, now or in the
> future. !is_dsm_invalid() gets slower for human brains to parse.
sure will change it.

Thanks,
Aravind.
> 
> BR,
> Jani.
> 
> 
>> +{
>> +	if (!HAS_BAR2_SMEM_STOLEN(i915)) {
>> +		if (dsm->start == 0)
>> +			return true;
>> +	}
>> +
>> +	if (dsm->end <= dsm->start)
>> +		return true;
>> +
>> +	return false;
>> +}
>> +
>>  static int i915_adjust_stolen(struct drm_i915_private *i915,
>>  			      struct resource *dsm)
>>  {
>> @@ -84,7 +97,7 @@ static int i915_adjust_stolen(struct drm_i915_private *i915,
>>  	struct intel_uncore *uncore = ggtt->vm.gt->uncore;
>>  	struct resource *r;
>>  
>> -	if (dsm->start == 0 || dsm->end <= dsm->start)
>> +	if (is_dsm_invalid(i915, dsm))
>>  		return -EINVAL;
>>  
>>  	/*
>> @@ -136,7 +149,7 @@ static int i915_adjust_stolen(struct drm_i915_private *i915,
>>  	 * overlaps with the non-stolen system memory range, since lmem is local
>>  	 * to the gpu.
>>  	 */
>> -	if (HAS_LMEM(i915))
>> +	if (HAS_LMEM(i915) || HAS_BAR2_SMEM_STOLEN(i915))
>>  		return 0;
>>  
>>  	/*
>> @@ -371,8 +384,6 @@ static void icl_get_stolen_reserved(struct drm_i915_private *i915,
>>  
>>  	drm_dbg(&i915->drm, "GEN6_STOLEN_RESERVED = 0x%016llx\n", reg_val);
>>  
>> -	*base = reg_val & GEN11_STOLEN_RESERVED_ADDR_MASK;
>> -
>>  	switch (reg_val & GEN8_STOLEN_RESERVED_SIZE_MASK) {
>>  	case GEN8_STOLEN_RESERVED_1M:
>>  		*size = 1024 * 1024;
>> @@ -390,6 +401,12 @@ static void icl_get_stolen_reserved(struct drm_i915_private *i915,
>>  		*size = 8 * 1024 * 1024;
>>  		MISSING_CASE(reg_val & GEN8_STOLEN_RESERVED_SIZE_MASK);
>>  	}
>> +
>> +	if ((GRAPHICS_VER_FULL(i915) >= IP_VER(12, 70)) && !IS_DGFX(i915))
>> +		/* the base is initialized to stolen top so subtract size to get base */
>> +		*base -= *size;
>> +	else
>> +		*base = reg_val & GEN11_STOLEN_RESERVED_ADDR_MASK;
>>  }
>>  
>>  static int i915_gem_init_stolen(struct intel_memory_region *mem)
>> @@ -423,8 +440,7 @@ static int i915_gem_init_stolen(struct intel_memory_region *mem)
>>  	if (i915_adjust_stolen(i915, &i915->dsm))
>>  		return 0;
>>  
>> -	GEM_BUG_ON(i915->dsm.start == 0);
>> -	GEM_BUG_ON(i915->dsm.end <= i915->dsm.start);
>> +	GEM_BUG_ON(is_dsm_invalid(i915, &i915->dsm));
>>  
>>  	stolen_top = i915->dsm.end + 1;
>>  	reserved_base = stolen_top;
>> @@ -796,6 +812,46 @@ static const struct intel_memory_region_ops i915_region_stolen_lmem_ops = {
>>  	.init_object = _i915_gem_object_stolen_init,
>>  };
>>  
>> +static int get_mtl_gms_size(struct intel_uncore *uncore)
>> +{
>> +	u16 ggc, gms;
>> +
>> +	ggc = intel_uncore_read16(uncore, _MMIO(0x108040));
>> +
>> +	/* check GGMS, should be fixed 0x3 (8MB) */
>> +	if ((ggc & 0xc0) != 0xc0)
>> +		return -EIO;
>> +
>> +	/* return valid GMS value, -EIO if invalid */
>> +	gms = ggc >> 8;
>> +	switch (gms) {
>> +	case 0x0 ... 0x10:
>> +		return gms * 32;
>> +	case 0x20:
>> +		return 1024;
>> +	case 0x30:
>> +		return 1536;
>> +	case 0x40:
>> +		return 2048;
>> +	case 0xf0 ... 0xfe:
>> +		return (gms - 0xf0 + 1) * 4;
>> +	default:
>> +		return -EIO;
>> +	}
>> +}
>> +
>> +static inline bool lmembar_is_igpu_stolen(struct drm_i915_private *i915)
>> +{
>> +	u32 regions = RUNTIME_INFO(i915)->memory_regions;
>> +
>> +	if (regions & REGION_LMEM)
>> +		return false;
>> +
>> +	drm_WARN_ON(&i915->drm, (regions & REGION_STOLEN_LMEM) == 0);
>> +
>> +	return true;
>> +}
>> +
>>  struct intel_memory_region *
>>  i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
>>  			   u16 instance)
>> @@ -806,19 +862,16 @@ i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
>>  	struct intel_memory_region *mem;
>>  	resource_size_t io_start, io_size;
>>  	resource_size_t min_page_size;
>> +	int ret;
>>  
>>  	if (WARN_ON_ONCE(instance))
>>  		return ERR_PTR(-ENODEV);
>>  
>> -	if (!i915_pci_resource_valid(pdev, GEN12_LMEM_BAR))
>> +	if (!i915_pci_resource_valid(pdev, GFXMEM_BAR))
>>  		return ERR_PTR(-ENXIO);
>>  
>> -	/* Use DSM base address instead for stolen memory */
>> -	dsm_base = intel_uncore_read64(uncore, GEN12_DSMBASE);
>> -	if (IS_DG1(uncore->i915)) {
>> -		lmem_size = pci_resource_len(pdev, GEN12_LMEM_BAR);
>> -		if (WARN_ON(lmem_size < dsm_base))
>> -			return ERR_PTR(-ENODEV);
>> +	if (lmembar_is_igpu_stolen(i915) || IS_DG1(i915)) {
>> +		lmem_size = pci_resource_len(pdev, GFXMEM_BAR);
>>  	} else {
>>  		resource_size_t lmem_range;
>>  
>> @@ -827,13 +880,39 @@ i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
>>  		lmem_size *= SZ_1G;
>>  	}
>>  
>> -	dsm_size = lmem_size - dsm_base;
>> -	if (pci_resource_len(pdev, GEN12_LMEM_BAR) < lmem_size) {
>> +	if (HAS_BAR2_SMEM_STOLEN(i915)) {
>> +		/*
>> +		 * MTL dsm size is in GGC register, not the bar size.
>> +		 * also MTL uses offset to DSMBASE in ptes, so i915
>> +		 * uses dsm_base = 0 to setup stolen region.
>> +		 */
>> +		ret = get_mtl_gms_size(uncore);
>> +		if (ret < 0) {
>> +			drm_err(&i915->drm, "invalid MTL GGC register setting\n");
>> +			return ERR_PTR(ret);
>> +		}
>> +
>> +		dsm_base = 0;
>> +		dsm_size = (resource_size_t)(ret * SZ_1M);
>> +
>> +		GEM_BUG_ON(pci_resource_len(pdev, GFXMEM_BAR) != 256 * SZ_1M);
>> +		GEM_BUG_ON((dsm_size + 8 * SZ_1M) > lmem_size);
>> +	} else {
>> +		/* Use DSM base address instead for stolen memory */
>> +		dsm_base = intel_uncore_read64(uncore, GEN12_DSMBASE);
>> +		if (WARN_ON(lmem_size < dsm_base))
>> +			return ERR_PTR(-ENODEV);
>> +		dsm_size = lmem_size - dsm_base;
>> +	}
>> +
>> +	io_size = dsm_size;
>> +	if (pci_resource_len(pdev, GFXMEM_BAR) < dsm_size) {
>>  		io_start = 0;
>>  		io_size = 0;
>> +	} else if (HAS_BAR2_SMEM_STOLEN(i915)) {
>> +		io_start = pci_resource_start(pdev, GFXMEM_BAR) + 8 * SZ_1M;
>>  	} else {
>> -		io_start = pci_resource_start(pdev, GEN12_LMEM_BAR) + dsm_base;
>> -		io_size = dsm_size;
>> +		io_start = pci_resource_start(pdev, GFXMEM_BAR) + dsm_base;
>>  	}
>>  
>>  	min_page_size = HAS_64K_PAGES(i915) ? I915_GTT_PAGE_SIZE_64K :
>> diff --git a/drivers/gpu/drm/i915/gt/intel_ggtt.c b/drivers/gpu/drm/i915/gt/intel_ggtt.c
>> index 30cf5c3369d9..b31fe0fb013f 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_ggtt.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_ggtt.c
>> @@ -931,7 +931,7 @@ static int gen8_gmch_probe(struct i915_ggtt *ggtt)
>>  	unsigned int size;
>>  	u16 snb_gmch_ctl;
>>  
>> -	if (!HAS_LMEM(i915)) {
>> +	if (!HAS_LMEM(i915) && !HAS_BAR2_SMEM_STOLEN(i915)) {
>>  		if (!i915_pci_resource_valid(pdev, GTT_APERTURE_BAR))
>>  			return -ENXIO;
>>  
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index 134fc1621821..ef3120322077 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -973,6 +973,9 @@ IS_SUBPLATFORM(const struct drm_i915_private *i915,
>>  
>>  #define HAS_ONE_EU_PER_FUSE_BIT(i915)	(INTEL_INFO(i915)->has_one_eu_per_fuse_bit)
>>  
>> +#define HAS_BAR2_SMEM_STOLEN(i915) (!HAS_LMEM(i915) && \
>> +				    GRAPHICS_VER_FULL(i915) >= IP_VER(12, 70))
>> +
>>  /* intel_device_info.c */
>>  static inline struct intel_device_info *
>>  mkwrite_device_info(struct drm_i915_private *dev_priv)
> 



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