[Intel-xe] [PATCH v2 09/10] drm/xe: Carve out top of DSM as reserved

[Matt Roper]

On Wed, Jul 26, 2023 at 09:07:07AM -0700, Lucas De Marchi wrote:
> Top of DSM contains the WOPCM where kernel driver shouldn't access as
> it contains data from other HW agents. Carve it out from the stolen
> memory. On a MTL system, the output now matches the expected values:
> 
> Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>

Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

> ---
>  drivers/gpu/drm/xe/regs/xe_regs.h      | 3 +++
>  drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c | 8 +++++++-
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/regs/xe_regs.h b/drivers/gpu/drm/xe/regs/xe_regs.h
> index dbf572d11af0..315f6f8dadf3 100644
> --- a/drivers/gpu/drm/xe/regs/xe_regs.h
> +++ b/drivers/gpu/drm/xe/regs/xe_regs.h
> @@ -84,4 +84,7 @@
>  #define DSMBASE					XE_REG(0x1080C0)
>  #define   BDSM_MASK				REG_GENMASK64(63, 20)
>  
> +#define STOLEN_RESERVED				XE_REG(0x1082c0)
> +#define   WOPCM_SIZE_MASK			REG_GENMASK64(8, 7)
> +
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c b/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
> index 271b3fba4129..7bba8fff5a5d 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_stolen_mgr.c
> @@ -89,7 +89,7 @@ static s64 detect_bar2_dgfx(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
>  static u32 detect_bar2_integrated(struct xe_device *xe, struct xe_ttm_stolen_mgr *mgr)
>  {
>  	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
> -	u32 stolen_size;
> +	u32 stolen_size, wopcm_size;
>  	u32 ggc, gms;
>  
>  	ggc = xe_mmio_read32(xe_root_mmio_gt(xe), GGC);
> @@ -124,6 +124,12 @@ static u32 detect_bar2_integrated(struct xe_device *xe, struct xe_ttm_stolen_mgr
>  		return 0;
>  	}
>  
> +	/* Carve out the top of DSM as it contains the reserved WOPCM region */
> +	wopcm_size = REG_FIELD_GET64(WOPCM_SIZE_MASK,
> +				     xe_mmio_read64(xe_root_mmio_gt(xe),
> +						    STOLEN_RESERVED));
> +	stolen_size -= (1U << wopcm_size) * SZ_1M;
> +
>  	if (drm_WARN_ON(&xe->drm, stolen_size + SZ_8M > pci_resource_len(pdev, 2)))
>  		return 0;
>  
> -- 
> 2.40.1
> 

-- 
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation