[PATCH] drm/amdgpu: fix modprobe failure of the secondary GPU when GDDR6 training enabled(V4)

[Alex Deucher]

On Fri, Jan 10, 2020 at 12:30 AM Tianci Yin <tianci.yin at amd.com> wrote:
>
> From: "Tianci.Yin" <tianci.yin at amd.com>
>
> [why]
> In dual GPUs scenario, stolen_size is assigned to zero on the secondary GPU,
> since there is no pre-OS console using that memory. Then the bottom region of
> VRAM was allocated as GTT, unfortunately a small region of bottom VRAM was
> encroached by UMC firmware during GDDR6 BIST training, this cause page fault.
>
> [how]
> Forcing stolen_size to 3MB, then the bottom region of VRAM was
> allocated as stolen memory, GTT corruption avoid.
>
> Change-Id: I310a72ba0402994defbe50839842a8edb025a868
> Signed-off-by: Tianci.Yin <tianci.yin at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h |  5 +++++
>  drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c  | 27 ++++++++++++++++++++++++-
>  2 files changed, 31 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> index c91dd602d5f1..e4b2f9bcaeb7 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gmc.h
> @@ -60,6 +60,11 @@
>   */
>  #define AMDGPU_GMC_FAULT_TIMEOUT       5000ULL
>
> +/*
> + * Default stolen memory size, 1024 * 768 * 4
> + */
> +#define AMDGPU_STOLEN_VGA_DEFAULT_SIZE 0x300000ULL

It would be better to call this
AMDGPU_STOLEN_BIST_TRAINING_DEFAULT_SIZE.  Also, I sounds like we are
probably going to have to assume that all of vram could be touched and
adjust our sequnce appropriately.  I think we are just getting lucky
with this size because most imporant kernel structures are in the
lower area of vram.

Alex

> +
>  struct firmware;
>
>  /*
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> index 5ad89bb6f3ba..14961f1ebfab 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v10_0.c
> @@ -566,7 +566,12 @@ static int gmc_v10_0_late_init(void *handle)
>         struct amdgpu_device *adev = (struct amdgpu_device *)handle;
>         int r;
>
> -       amdgpu_bo_late_init(adev);
> +       /*
> +        * Can't free the stolen VGA memory when it might be used for memory
> +        * training again.
> +        */
> +       if (!adev->fw_vram_usage.mem_train_support)
> +               amdgpu_bo_late_init(adev);
>
>         r = amdgpu_gmc_allocate_vm_inv_eng(adev);
>         if (r)
> @@ -750,6 +755,19 @@ static int gmc_v10_0_sw_init(void *handle)
>
>         adev->gmc.stolen_size = gmc_v10_0_get_vbios_fb_size(adev);
>
> +       /*
> +        * In dual GPUs scenario, stolen_size is assigned to zero on the
> +        * secondary GPU, since there is no pre-OS console using that memory.
> +        * Then the bottom region of VRAM was allocated as GTT, unfortunately a
> +        * small region of bottom VRAM was encroached by UMC firmware during
> +        * GDDR6 BIST training, this cause page fault.
> +        * The page fault can be fixed by forcing stolen_size to 3MB, then the
> +        * bottom region of VRAM was allocated as stolen memory, GTT corruption
> +        * avoid.
> +        */
> +       adev->gmc.stolen_size = max(adev->gmc.stolen_size,
> +                                   AMDGPU_STOLEN_VGA_DEFAULT_SIZE);
> +
>         /* Memory manager */
>         r = amdgpu_bo_init(adev);
>         if (r)
> @@ -789,6 +807,13 @@ static void gmc_v10_0_gart_fini(struct amdgpu_device *adev)
>  static int gmc_v10_0_sw_fini(void *handle)
>  {
>         struct amdgpu_device *adev = (struct amdgpu_device *)handle;
> +       void *stolen_vga_buf;
> +
> +       /*
> +        * Free the stolen memory if it wasn't already freed in late_init
> +        * because of memory training.
> +        */
> +       amdgpu_bo_free_kernel(&adev->stolen_vga_memory, NULL, &stolen_vga_buf);
>
>         amdgpu_vm_manager_fini(adev);
>         gmc_v10_0_gart_fini(adev);
> --
> 2.17.1
>
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