Re: [PATCH v5] drm/msm: gpu: Enable zap shader for A5XX

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Wed 17 May 07:45 PDT 2017, Jordan Crouse wrote:

> The A5XX GPU powers on in "secure" mode. In secure mode the GPU can
> only render to buffers that are marked as secure and inaccessible
> to the kernel and user through a series of hardware protections. In
> practice secure mode is used to draw things like a UI on a secure
> video frame.
> 
> In order to switch out of secure mode the GPU executes a special
> shader that clears out the GMEM and other sensitve registers and
> then writes a register. Because the kernel can't be trusted the
> shader binary is signed and verified and programmed by the
> secure world. To do this we need to read the MDT header and the
> segments from the firmware location and put them in memory and
> present them for approval.
> 
> For targets without secure support there is an out: if the
> secure world doesn't support secure then there are no hardware
> protections and we can freely write the SECVID_TRUST register from
> the CPU. We don't have 100% confidence that we can query the
> secure capabilities at run time but we have enough calls that
> need to go right to give us some confidence that we're at least doing
> something useful.
> 
> Of course if we guess wrong you trigger a permissions violation
> which usually ends up in a system crash but thats a problem
> that shows up immediately.
> 
> [v2: use child device per Bjorn]
> [v3: use generic MDT loader per Bjorn]
> [v4: use managed dma functions and ifdefs for the MDT loader]
> [v5: Add depends for QCOM_MDT_LOADER]
> 
> Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
> ---
>  drivers/gpu/drm/msm/Kconfig                |   1 +
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c      | 180 ++++++++++++++++++++++++++++-
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.h      |   2 +
>  drivers/gpu/drm/msm/adreno/adreno_device.c |   1 +
>  drivers/gpu/drm/msm/adreno/adreno_gpu.h    |   1 +
>  5 files changed, 183 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/Kconfig b/drivers/gpu/drm/msm/Kconfig
> index 5b8e23d..b29bd30 100644
> --- a/drivers/gpu/drm/msm/Kconfig
> +++ b/drivers/gpu/drm/msm/Kconfig
> @@ -5,6 +5,7 @@ config DRM_MSM
>  	depends on ARCH_QCOM || (ARM && COMPILE_TEST)
>  	depends on OF && COMMON_CLK
>  	depends on MMU
> +	depends on QCOM_MDT_LOADER || QCOM_MDT_LOADER=n
>  	select REGULATOR
>  	select DRM_KMS_HELPER
>  	select DRM_PANEL
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index 31a9bce..058cb80 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -11,6 +11,12 @@
>   *
>   */
>  
> +#include <linux/types.h>
> +#include <linux/cpumask.h>
> +#include <linux/qcom_scm.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/of_reserved_mem.h>
> +#include <linux/soc/qcom/mdt_loader.h>
>  #include "msm_gem.h"
>  #include "msm_mmu.h"
>  #include "a5xx_gpu.h"
> @@ -18,6 +24,62 @@
>  extern bool hang_debug;
>  static void a5xx_dump(struct msm_gpu *gpu);
>  
> +#define GPU_PAS_ID 13
> +
> +#ifdef CONFIG_QCOM_MDT_LOADER

#if IS_ENABLED(CONFIG_QCOM_MDT_LOADER)


Apart from that

Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn