From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?UTF-8?Q?Christian_K=c3=b6nig?= Subject: Re: [PATCH 7/8] drm/amdgpu: reserve vram for memory training Date: Wed, 9 Oct 2019 13:40:33 +0200 Message-ID: <045b7cfd-989f-7cff-310f-92d9780e73fe@gmail.com> References: <20191008192934.5481-1-alexander.deucher@amd.com> <20191008192934.5481-8-alexander.deucher@amd.com> Reply-To: christian.koenig-5C7GfCeVMHo@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1693187088==" Return-path: In-Reply-To: Content-Language: en-US List-Id: Discussion list for AMD gfx List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: amd-gfx-bounces-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org Sender: "amd-gfx" To: "Yin, Tianci (Rico)" , "Tuikov, Luben" , Alex Deucher , "amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org" Cc: "Deucher, Alexander" This is a multi-part message in MIME format. --===============1693187088== Content-Type: multipart/alternative; boundary="------------4B0E7261945FCFA47FAA3ADA" Content-Language: en-US This is a multi-part message in MIME format. --------------4B0E7261945FCFA47FAA3ADA Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Am 09.10.19 um 13:12 schrieb Yin, Tianci (Rico): > Here is where you definitively set "ret" so DO NOT preinitialize it to 0, > just to avoid "pesky compiler unininitialized variable warnings"--those > are helpful to make the code more secure: a variable should be > intentionally > initialized in all paths. > > Rico: Still in confusion, pre-initialization can avoid "uninitialized > variable", why should we can't pre-initialize? Because it avoids the uninitialized variable warning :) See we really want the warning because it means that we have a bug in the code somewhere. Regards, Christian. > ------------------------------------------------------------------------ > *From:* Tuikov, Luben > *Sent:* Wednesday, October 9, 2019 11:44 > *To:* Alex Deucher ; > amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org > *Cc:* Deucher, Alexander ; Yin, Tianci > (Rico) > *Subject:* Re: [PATCH 7/8] drm/amdgpu: reserve vram for memory training > On 2019-10-08 3:29 p.m., Alex Deucher wrote: > > From: "Tianci.Yin" > > > > memory training using specific fixed vram segment, reserve these > > segments before anyone may allocate it. > > > > Change-Id: I1436755813a565608a2857a683f535377620a637 > > Reviewed-by: Alex Deucher > > Signed-off-by: Tianci.Yin > > --- > >  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 96 +++++++++++++++++++++++++ > >  1 file changed, 96 insertions(+) > > > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > > index 74a9bd94f10c..0819721af16e 100644 > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c > > @@ -1667,6 +1667,93 @@ static int > amdgpu_ttm_fw_reserve_vram_init(struct amdgpu_device *adev) > > &adev->fw_vram_usage.va); > >  } > > > > +/* > > + * Memoy training reservation functions > > + */ > > Include an empty line between the two comments, just as you would > a paragraph in written text. > > > +/** > > + * amdgpu_ttm_training_reserve_vram_fini - free memory training > reserved vram > > + * > > + * @adev: amdgpu_device pointer > > + * > > + * free memory training reserved vram if it has been reserved. > > + */ > > +static int amdgpu_ttm_training_reserve_vram_fini(struct > amdgpu_device *adev) > > +{ > > +     int ret = 0; > > +     struct psp_memory_training_context *ctx = > &adev->psp.mem_train_ctx; > > + > > +     ctx->init = PSP_MEM_TRAIN_NOT_SUPPORT; > > +     if(ctx->c2p_bo) { > > Space after keywords, according to LKCS: > if (...) > > > + amdgpu_bo_free_kernel(&ctx->c2p_bo, NULL, NULL); > > +             ctx->c2p_bo = NULL; > > +     } > > +     if(ctx->p2c_bo) { > > Space after keywords, according to LKCS: > if (...) > > > + amdgpu_bo_free_kernel(&ctx->p2c_bo, NULL, NULL); > > +             ctx->p2c_bo = NULL; > > +     } > > + > > +     return ret; > > +} > > Get rid of "ret" variable altogether as it is not used in this function. > > > + > > +/** > > + * amdgpu_ttm_training_reserve_vram_init - create bo vram > reservation from memory training > > + * > > + * @adev: amdgpu_device pointer > > + * > > + * create bo vram reservation from memory training. > > + */ > > +static int amdgpu_ttm_training_reserve_vram_init(struct > amdgpu_device *adev) > > +{ > > +     int ret = 0; > > DO NOT preinitialize ret. > > > +     struct psp_memory_training_context *ctx = > &adev->psp.mem_train_ctx; > > + > > +     memset(ctx, 0, sizeof(*ctx)); > > +     if(!adev->fw_vram_usage.mem_train_support) { > > Space after keywords: "if (". > > > +             DRM_DEBUG("memory training does not support!\n"); > > +             return 0; > > +     } > > + > > +     ctx->c2p_train_data_offset = adev->fw_vram_usage.mem_train_fb_loc; > > +     ctx->p2c_train_data_offset = (adev->gmc.mc_vram_size - > GDDR6_MEM_TRAINING_OFFSET); > > +     ctx->train_data_size = GDDR6_MEM_TRAINING_DATA_SIZE_IN_BYTES; > > + > > + > DRM_DEBUG("train_data_size:%llx,p2c_train_data_offset:%llx,c2p_train_data_offset:%llx.\n", > > +               ctx->train_data_size, > > +               ctx->p2c_train_data_offset, > > +               ctx->c2p_train_data_offset); > > + > > +     ret = amdgpu_bo_create_kernel_at(adev, > > Here is where you definitively set "ret" so DO NOT preinitialize it to 0, > just to avoid "pesky compiler unininitialized variable warnings"--those > are helpful to make the code more secure: a variable should be > intentionally > initialized in all paths. > > > + ctx->p2c_train_data_offset, > > + ctx->train_data_size, > > + AMDGPU_GEM_DOMAIN_VRAM, > > + &ctx->p2c_bo, > > +                                      NULL); > > +     if(ret) { > > Space after keywords "if (". > > > +             DRM_ERROR("alloc p2c_bo failed(%d)!\n", ret); > > +             ret = -ENOMEM; > > +             goto err_out; > > +     } > > + > > +     ret = amdgpu_bo_create_kernel_at(adev, > > + ctx->c2p_train_data_offset, > > + ctx->train_data_size, > > + AMDGPU_GEM_DOMAIN_VRAM, > > + &ctx->c2p_bo, > > +                                      NULL); > > +     if(ret) { > > Space after keywords: "if (", according to LKCS. > > Regards, > Luben > > > +             DRM_ERROR("alloc c2p_bo failed(%d)!\n", ret); > > +             ret = -ENOMEM; > > +             goto err_out; > > +     } > > + > > +     ctx->init = PSP_MEM_TRAIN_RESERVE_SUCCESS; > > +     return 0; > > + > > +err_out: > > +     amdgpu_ttm_training_reserve_vram_fini(adev); > > +     return ret; > > +} > > + > >  /** > >   * amdgpu_ttm_init - Init the memory management (ttm) as well as > various > >   * gtt/vram related fields. > > @@ -1740,6 +1827,14 @@ int amdgpu_ttm_init(struct amdgpu_device *adev) > >                return r; > >        } > > > > +     /* > > +      *The reserved vram for memory training must be pinned to the > specified > > +      *place on the VRAM, so reserve it early. > > +      */ > > +     r = amdgpu_ttm_training_reserve_vram_init(adev); > > +     if (r) > > +             return r; > > + > >        /* allocate memory as required for VGA > >         * This is used for VGA emulation and pre-OS scanout buffers to > >         * avoid display artifacts while transitioning between pre-OS > > @@ -1825,6 +1920,7 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev) > >                return; > > > >        amdgpu_ttm_debugfs_fini(adev); > > +     amdgpu_ttm_training_reserve_vram_fini(adev); > >        amdgpu_ttm_fw_reserve_vram_fini(adev); > >        if (adev->mman.aper_base_kaddr) > > iounmap(adev->mman.aper_base_kaddr); > > > > > _______________________________________________ > amd-gfx mailing list > amd-gfx-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org > https://lists.freedesktop.org/mailman/listinfo/amd-gfx --------------4B0E7261945FCFA47FAA3ADA Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: 8bit
Am 09.10.19 um 13:12 schrieb Yin, Tianci (Rico):
Here is where you definitively set "ret" so DO NOT preinitialize it to 0,
just to avoid "pesky compiler unininitialized variable warnings"--those
are helpful to make the code more secure: a variable should be intentionally
initialized in all paths.

Rico: Still in confusion, pre-initialization can avoid "uninitialized variable", why should we can't pre-initialize?

Because it avoids the uninitialized variable warning :)

See we really want the warning because it means that we have a bug in the code somewhere.

Regards,
Christian.

On 2019-10-08 3:29 p.m., Alex Deucher wrote:
> From: "Tianci.Yin" <tianci.yin-5C7GfCeVMHo@public.gmane.org>
>
> memory training using specific fixed vram segment, reserve these
> segments before anyone may allocate it.
>
> Change-Id: I1436755813a565608a2857a683f535377620a637
> Reviewed-by: Alex Deucher <alexander.deucher-5C7GfCeVMHo@public.gmane.org>
> Signed-off-by: Tianci.Yin <tianci.yin-5C7GfCeVMHo@public.gmane.org>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 96 +++++++++++++++++++++++++
>  1 file changed, 96 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 74a9bd94f10c..0819721af16e 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1667,6 +1667,93 @@ static int amdgpu_ttm_fw_reserve_vram_init(struct amdgpu_device *adev)
>                                          &adev->fw_vram_usage.va);
>  }
> 
> +/*
> + * Memoy training reservation functions
> + */

Include an empty line between the two comments, just as you would
a paragraph in written text.

> +/**
> + * amdgpu_ttm_training_reserve_vram_fini - free memory training reserved vram
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * free memory training reserved vram if it has been reserved.
> + */
> +static int amdgpu_ttm_training_reserve_vram_fini(struct amdgpu_device *adev)
> +{
> +     int ret = 0;
> +     struct psp_memory_training_context *ctx = &adev->psp.mem_train_ctx;
> +
> +     ctx->init = PSP_MEM_TRAIN_NOT_SUPPORT;
> +     if(ctx->c2p_bo) {

Space after keywords, according to LKCS:
if (...)

> +             amdgpu_bo_free_kernel(&ctx->c2p_bo, NULL, NULL);
> +             ctx->c2p_bo = NULL;
> +     }
> +     if(ctx->p2c_bo) {

Space after keywords, according to LKCS:
if (...)

> +             amdgpu_bo_free_kernel(&ctx->p2c_bo, NULL, NULL);
> +             ctx->p2c_bo = NULL;
> +     }
> +
> +     return ret;
> +}

Get rid of "ret" variable altogether as it is not used in this function.

> +
> +/**
> + * amdgpu_ttm_training_reserve_vram_init - create bo vram reservation from memory training
> + *
> + * @adev: amdgpu_device pointer
> + *
> + * create bo vram reservation from memory training.
> + */
> +static int amdgpu_ttm_training_reserve_vram_init(struct amdgpu_device *adev)
> +{
> +     int ret = 0;

DO NOT preinitialize ret.

> +     struct psp_memory_training_context *ctx = &adev->psp.mem_train_ctx;
> +
> +     memset(ctx, 0, sizeof(*ctx));
> +     if(!adev->fw_vram_usage.mem_train_support) {

Space after keywords: "if (".

> +             DRM_DEBUG("memory training does not support!\n");
> +             return 0;
> +     }
> +
> +     ctx->c2p_train_data_offset = adev->fw_vram_usage.mem_train_fb_loc;
> +     ctx->p2c_train_data_offset = (adev->gmc.mc_vram_size - GDDR6_MEM_TRAINING_OFFSET);
> +     ctx->train_data_size = GDDR6_MEM_TRAINING_DATA_SIZE_IN_BYTES;
> +
> +     DRM_DEBUG("train_data_size:%llx,p2c_train_data_offset:%llx,c2p_train_data_offset:%llx.\n",
> +               ctx->train_data_size,
> +               ctx->p2c_train_data_offset,
> +               ctx->c2p_train_data_offset);
> +
> +     ret = amdgpu_bo_create_kernel_at(adev,

Here is where you definitively set "ret" so DO NOT preinitialize it to 0,
just to avoid "pesky compiler unininitialized variable warnings"--those
are helpful to make the code more secure: a variable should be intentionally
initialized in all paths.

> +                                      ctx->p2c_train_data_offset,
> +                                      ctx->train_data_size,
> +                                      AMDGPU_GEM_DOMAIN_VRAM,
> +                                      &ctx->p2c_bo,
> +                                      NULL);
> +     if(ret) {

Space after keywords "if (".

> +             DRM_ERROR("alloc p2c_bo failed(%d)!\n", ret);
> +             ret = -ENOMEM;
> +             goto err_out;
> +     }
> +
> +     ret = amdgpu_bo_create_kernel_at(adev,
> +                                      ctx->c2p_train_data_offset,
> +                                      ctx->train_data_size,
> +                                      AMDGPU_GEM_DOMAIN_VRAM,
> +                                      &ctx->c2p_bo,
> +                                      NULL);
> +     if(ret) {

Space after keywords: "if (", according to LKCS.

Regards,
Luben

> +             DRM_ERROR("alloc c2p_bo failed(%d)!\n", ret);
> +             ret = -ENOMEM;
> +             goto err_out;
> +     }
> +
> +     ctx->init = PSP_MEM_TRAIN_RESERVE_SUCCESS;
> +     return 0;
> +
> +err_out:
> +     amdgpu_ttm_training_reserve_vram_fini(adev);
> +     return ret;
> +}
> +
>  /**
>   * amdgpu_ttm_init - Init the memory management (ttm) as well as various
>   * gtt/vram related fields.
> @@ -1740,6 +1827,14 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>                return r;
>        }
> 
> +     /*
> +      *The reserved vram for memory training must be pinned to the specified
> +      *place on the VRAM, so reserve it early.
> +      */
> +     r = amdgpu_ttm_training_reserve_vram_init(adev);
> +     if (r)
> +             return r;
> +
>        /* allocate memory as required for VGA
>         * This is used for VGA emulation and pre-OS scanout buffers to
>         * avoid display artifacts while transitioning between pre-OS
> @@ -1825,6 +1920,7 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
>                return;
> 
>        amdgpu_ttm_debugfs_fini(adev);
> +     amdgpu_ttm_training_reserve_vram_fini(adev);
>        amdgpu_ttm_fw_reserve_vram_fini(adev);
>        if (adev->mman.aper_base_kaddr)
>                iounmap(adev->mman.aper_base_kaddr);
> 


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