On Tue, Sep 27, 2022 at 12:14:24AM +0530, Aravind Iddamsetty 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.
>
> v2:
> 1. dropped is_dsm_invalid, updated valid_stolen_size check from Lucas
> (Jani, Lucas)
> 2. drop lmembar_is_igpu_stolen
> 3. revert to referring GFXMEM_BAR as GEN12_LMEM_BAR (Lucas)
>
> v3:(Jani)
> 1. rename get_mtl_gms_size to mtl_get_gms_size
> 2. define register for MMIO address
>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Cc: Lucas De Marchi <lucas.demarchi@xxxxxxxxx>
> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
>
Since this stuff is somewhat hard to find documentation on, you might
want to include a bspec page number or two here.
Bspec: 63830
seems like a useful one for reference at least.
> 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 | 88 ++++++++++++++++++----
> drivers/gpu/drm/i915/gt/intel_ggtt.c | 2 +-
> drivers/gpu/drm/i915/i915_drv.h | 3 +
> drivers/gpu/drm/i915/i915_reg.h | 5 ++
> 4 files changed, 81 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> index c5a4035c99cd..0eb66c55bbf3 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_stolen.c
> @@ -77,9 +77,9 @@ void i915_gem_stolen_remove_node(struct drm_i915_private *i915,
> mutex_unlock(&i915->mm.stolen_lock);
> }
>
> -static bool valid_stolen_size(struct resource *dsm)
> +static bool valid_stolen_size(struct drm_i915_private *i915, struct resource *dsm)
> {
> - return dsm->start != 0 && dsm->end > dsm->start;
> + return (dsm->start != 0 || HAS_BAR2_SMEM_STOLEN(i915)) && dsm->end > dsm->start;
> }
>
> static int adjust_stolen(struct drm_i915_private *i915,
> @@ -88,7 +88,7 @@ static int adjust_stolen(struct drm_i915_private *i915,
> struct i915_ggtt *ggtt = to_gt(i915)->ggtt;
> struct intel_uncore *uncore = ggtt->vm.gt->uncore;
>
> - if (!valid_stolen_size(dsm))
> + if (!valid_stolen_size(i915, dsm))
> return -EINVAL;
>
> /*
> @@ -135,7 +135,7 @@ static int adjust_stolen(struct drm_i915_private *i915,
> }
> }
>
> - if (!valid_stolen_size(dsm))
> + if (!valid_stolen_size(i915, dsm))
> return -EINVAL;
>
> return 0;
> @@ -148,9 +148,10 @@ static int request_smem_stolen(struct drm_i915_private *i915,
>
> /*
> * With stolen lmem, we don't need to request system memory for the
> - * address range since it's local to the gpu.
> + * address range since it's local to the gpu and in some IGFX devices
> + * BAR2 is exposed as stolen
Minor nitpick: this sentence is a bit hard to read/understand. I'd
leave the original sentence as is and add a separate sentence explaining
the situation for igpu platforms with stolen memory exposed through
BAR2.
> */
> - if (HAS_LMEM(i915))
> + if (HAS_LMEM(i915) || HAS_BAR2_SMEM_STOLEN(i915))
> return 0;
>
> /*
> @@ -385,8 +386,6 @@ 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;
> @@ -404,6 +403,12 @@ 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 (HAS_BAR2_SMEM_STOLEN(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;
> }
>
> /*
> @@ -833,6 +838,34 @@ static const struct intel_memory_region_ops i915_region_stolen_lmem_ops = {
> .init_object = _i915_gem_object_stolen_init,
> };
>
> +static int mtl_get_gms_size(struct intel_uncore *uncore)
> +{
> + u16 ggc, gms;
> +
> + ggc = intel_uncore_read16(uncore, GGC);
> +
> + /* check GGMS, should be fixed 0x3 (8MB) */
> + if ((ggc & GGMS_MASK) != GGMS_MASK)
> + return -EIO;
> +
> + /* return valid GMS value, -EIO if invalid */
> + gms = (ggc & GMS_MASK) >> GMS_SHIFT;
It's better to write this as
gms = REG_FIELD_GET(GMS_MASK, ggc);
You can also eliminate the definition of GMS_SHIFT with that.
> + switch (gms) {
> + case 0x0 ... 0x10:
Shouldn't this just be 0x0 ... 0x4?
> + return gms * 32;
> + case 0x20:
> + return 1024;
> + case 0x30:
> + return 1536;
> + case 0x40:
> + return 2048;
I don't see 0x20, 0x30, or 0x40 listed as valid values in the bspec
anymore.
> + case 0xf0 ... 0xfe:
> + return (gms - 0xf0 + 1) * 4;
> + default:
You might want to add a MISSING_CASE(gms) since this isn't supposed to
be able to happen, but if it does, we'd like to see which invalid value
we actually received.
> + return -EIO;
> + }
> +}
> +
> struct intel_memory_region *
> i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
> u16 instance)
> @@ -843,6 +876,7 @@ 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);
> @@ -850,12 +884,8 @@ i915_gem_stolen_lmem_setup(struct drm_i915_private *i915, u16 type,
> if (!i915_pci_resource_valid(pdev, GEN12_LMEM_BAR))
> return ERR_PTR(-ENXIO);
>
> - /* Use DSM base address instead for stolen memory */
> - dsm_base = intel_uncore_read64(uncore, GEN12_DSMBASE) & GEN12_BDSM_MASK;
> - if (IS_DG1(uncore->i915)) {
> + if (HAS_BAR2_SMEM_STOLEN(i915) || IS_DG1(i915)) {
> lmem_size = pci_resource_len(pdev, GEN12_LMEM_BAR);
> - if (WARN_ON(lmem_size < dsm_base))
> - return ERR_PTR(-ENODEV);
> } else {
> resource_size_t lmem_range;
>
> @@ -864,13 +894,39 @@ 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 = mtl_get_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, GEN12_LMEM_BAR) != 256 * SZ_1M);
You could simplify to just SZ_256M here. Also SZ_8M for some of the
other spots below.
Matt
> + 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, GEN12_LMEM_BAR) < dsm_size) {
> io_start = 0;
> io_size = 0;
> + } else if (HAS_BAR2_SMEM_STOLEN(i915)) {
> + io_start = pci_resource_start(pdev, GEN12_LMEM_BAR) + 8 * SZ_1M;
> } else {
> io_start = pci_resource_start(pdev, GEN12_LMEM_BAR) + dsm_base;
> - io_size = dsm_size;
> }
>
> 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 d830d52ded5d..b33ba0d49bbd 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -975,6 +975,9 @@ 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)
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 5003a5ffbc6a..3ace2d6b4961 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7967,6 +7967,11 @@ enum skl_power_gate {
> _ICL_PIPE_DSS_CTL2_PB, \
> _ICL_PIPE_DSS_CTL2_PC)
>
> +#define GGC _MMIO(0x108040)
> +#define GMS_MASK REG_GENMASK(15, 8)
> +#define GMS_SHIFT 8
> +#define GGMS_MASK REG_GENMASK(7, 6)
> +
> #define GEN12_GSMBASE _MMIO(0x108100)
> #define GEN12_DSMBASE _MMIO(0x1080C0)
> #define GEN12_BDSM_MASK REG_GENMASK64(63, 20)
> --
> 2.25.1
>
--
Matt Roper
Graphics Software Engineer
VTT-OSGC Platform Enablement
Intel Corporation
