Re: [Intel-gfx] [RFC-v23 13/13] drm/i915/pxp: Add plane decryption support

["Gupta, Anshuman" <anshuman.gupta@intel.com>]

Jani/Ville
I had received an offline comment form Gaurav on this patch,
See below,
> -----Original Message-----
> From: Huang, Sean Z <sean.z.huang@intel.com>
> Sent: Tuesday, January 19, 2021 1:13 PM
> To: Intel-gfx@lists.freedesktop.org
> Cc: Gaurav, Kumar <kumar.gaurav@intel.com>; Gupta, Anshuman
> <anshuman.gupta@intel.com>; Bommu, Krishnaiah
> <krishnaiah.bommu@intel.com>; Huang, Sean Z <sean.z.huang@intel.com>
> Subject: [RFC-v23 13/13] drm/i915/pxp: Add plane decryption support
> 
> From: Anshuman Gupta <anshuman.gupta@intel.com>
> 
> Add support to enable/disable PLANE_SURF Decryption Request bit.
> It requires only to enable plane decryption support when following
> condition met.
> 1. PXP session is enabled.
> 2. Buffer object is protected.
> 
> v2:
> - Rebased to libva_cp-drm-tip_tgl_cp tree.
> - Used gen fb obj user_flags instead gem_object_metadata. [Krishna]
> 
> v3:
> - intel_pxp_gem_object_status() API changes.
> 
> Cc: Bommu Krishnaiah <krishnaiah.bommu@intel.com>
> Cc: Huang Sean Z <sean.z.huang@intel.com>
> Cc: Gaurav Kumar <kumar.gaurav@intel.com>
> Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_sprite.c | 21 ++++++++++++++++++---
>  drivers/gpu/drm/i915/i915_reg.h             |  1 +
>  2 files changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c
> b/drivers/gpu/drm/i915/display/intel_sprite.c
> index cf3589fd0ddb..39f8c922ce66 100644
> --- a/drivers/gpu/drm/i915/display/intel_sprite.c
> +++ b/drivers/gpu/drm/i915/display/intel_sprite.c
> @@ -39,6 +39,8 @@
>  #include <drm/drm_plane_helper.h>
>  #include <drm/drm_rect.h>
> 
> +#include "pxp/intel_pxp.h"
> +
>  #include "i915_drv.h"
>  #include "i915_trace.h"
>  #include "i915_vgpu.h"
> @@ -768,6 +770,11 @@ icl_program_input_csc(struct intel_plane *plane,
>  			  PLANE_INPUT_CSC_POSTOFF(pipe, plane_id, 2),
> 0x0);  }
> 
> +static bool intel_fb_obj_protected(const struct drm_i915_gem_object
> +*obj) {
> +	return obj->user_flags & I915_BO_PROTECTED ? true : false; }
> +
>  static void
>  skl_plane_async_flip(struct intel_plane *plane,
>  		     const struct intel_crtc_state *crtc_state, @@ -804,6
> +811,7 @@ skl_program_plane(struct intel_plane *plane,
>  	u32 surf_addr = plane_state->color_plane[color_plane].offset;
>  	u32 stride = skl_plane_stride(plane_state, color_plane);
>  	const struct drm_framebuffer *fb = plane_state->hw.fb;
> +	const struct drm_i915_gem_object *obj = intel_fb_obj(fb);
>  	int aux_plane = intel_main_to_aux_plane(fb, color_plane);
>  	int crtc_x = plane_state->uapi.dst.x1;
>  	int crtc_y = plane_state->uapi.dst.y1; @@ -814,7 +822,7 @@
> skl_program_plane(struct intel_plane *plane,
>  	u8 alpha = plane_state->hw.alpha >> 8;
>  	u32 plane_color_ctl = 0, aux_dist = 0;
>  	unsigned long irqflags;
> -	u32 keymsk, keymax;
> +	u32 keymsk, keymax, plane_surf;
>  	u32 plane_ctl = plane_state->ctl;
> 
>  	plane_ctl |= skl_plane_ctl_crtc(crtc_state); @@ -890,8 +898,15
> @@ skl_program_plane(struct intel_plane *plane,
>  	 * the control register just before the surface register.
>  	 */
>  	intel_de_write_fw(dev_priv, PLANE_CTL(pipe, plane_id), plane_ctl);
> -	intel_de_write_fw(dev_priv, PLANE_SURF(pipe, plane_id),
> -			  intel_plane_ggtt_offset(plane_state) + surf_addr);
> +	plane_surf = intel_plane_ggtt_offset(plane_state) + surf_addr;
> +
> +	if (intel_pxp_gem_object_status(dev_priv) &&
> +	    intel_fb_obj_protected(obj))
> +		plane_surf |= PLANE_SURF_DECRYPTION_ENABLED;
Here in case of if fb obj is protected but pxp session is not enabled i.e intel_pxp_gem_object_status() returns false, request to show the black frame buffer on display instead of corrupted data.
                            plane_surf = 0xXXX; //Pointer to black framebuffer
But above approach would be a hack. 
@Jani and @Ville could you please guide with the general way of handling this as pxp session keys can be invalidated at any time.

Thanks,
Anshuman Gupta.
> +	else
> +		plane_surf &= ~PLANE_SURF_DECRYPTION_ENABLED;
> +
> +	intel_de_write_fw(dev_priv, PLANE_SURF(pipe, plane_id),
> plane_surf);
> 
>  	if (plane_state->scaler_id >= 0)
>  		skl_program_scaler(plane, crtc_state, plane_state); diff --git
> a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 97bcecada87f..7a4817054bc8 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -7208,6 +7208,7 @@ enum {
>  #define _PLANE_SURF_3(pipe)	_PIPE(pipe, _PLANE_SURF_3_A,
> _PLANE_SURF_3_B)
>  #define PLANE_SURF(pipe, plane)	\
>  	_MMIO_PLANE(plane, _PLANE_SURF_1(pipe),
> _PLANE_SURF_2(pipe))
> +#define   PLANE_SURF_DECRYPTION_ENABLED		REG_BIT(2)
> 
>  #define _PLANE_OFFSET_1_B			0x711a4
>  #define _PLANE_OFFSET_2_B			0x712a4
> --
> 2.17.1

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