Re: [PATCH 14/14] drm/amdgpu: introduce doorbell bo in kernel

[Shashank Sharma <shashank.sharma@amd.com>]

On 06/02/2023 17:57, Christian König wrote:
> Am 03.02.23 um 20:08 schrieb Shashank Sharma:
>> From: Alex Deucher <alexander.deucher@amd.com>
>>
>> This patch does the following:
>> - Removes doorbell ptr from adev.
>> - Moves doorbell.num_doorbells into mman.num_doorbells.
>> - Introduces a kernel bo for doorbell management in form of 
>> mman.doorbell_kernel_bo.
>>    This bo holds the doorbell space now.
>> - Introduces mman.doorbell_bo_size: to save total doorbell memory size.
>> - Also introduces mman.doorbell_va to save CPU address of doorbell BO
>>    mapping. This ptr will be used now for doorbell read/write from 
>> doorbell BAR.
>
> Please don't call any CPU address VA, this is a term we usually use 
> with GPUVM.
>
> Rather use doorbell_cpu_addr for this.
>
> Christian.

Noted,

- Shashank

>
>>
>> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
>> Signed-off-by: Shashank Sharma <shashank.sharma@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h          |  1 -
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c   |  5 ++--
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c   | 16 ++++++-------
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h |  4 ----
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c      | 24 ++++++++++++++++----
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h      |  6 +++++
>>   6 files changed, 35 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> index e1c1a360614e..dd3875ae1ad3 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>> @@ -834,7 +834,6 @@ struct amdgpu_device {
>>       spinlock_t audio_endpt_idx_lock;
>>       amdgpu_block_rreg_t        audio_endpt_rreg;
>>       amdgpu_block_wreg_t        audio_endpt_wreg;
>> -    struct amdgpu_doorbell        doorbell;
>>         /* clock/pll info */
>>       struct amdgpu_clock            clock;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>> index 28076da2258f..aea943e337df 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
>> @@ -109,11 +109,10 @@ static void amdgpu_doorbell_get_kfd_info(struct 
>> amdgpu_device *adev,
>>           *aperture_base = adev->gmc.doorbell_aper_base;
>>           *aperture_size = 0;
>>           *start_offset = 0;
>> -    } else if (adev->gmc.doorbell_aper_size > 
>> adev->doorbell.num_doorbells *
>> -                        sizeof(u32)) {
>> +    } else if (adev->gmc.doorbell_aper_size > 
>> adev->mman.doorbell_kernel_bo_size) {
>>           *aperture_base = adev->gmc.doorbell_aper_base;
>>           *aperture_size = adev->gmc.doorbell_aper_size;
>> -        *start_offset = adev->doorbell.num_doorbells * sizeof(u32);
>> +        *start_offset = adev->mman.doorbell_kernel_bo_size;
>>       } else {
>>           *aperture_base = 0;
>>           *aperture_size = 0;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> index 7c21ffe63ebc..9c3ce1ae66ea 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> @@ -593,8 +593,8 @@ u32 amdgpu_mm_rdoorbell(struct amdgpu_device 
>> *adev, u32 index)
>>       if (amdgpu_device_skip_hw_access(adev))
>>           return 0;
>>   -    if (index < adev->doorbell.num_doorbells) {
>> -        return readl(adev->mman.doorbell_aper_base_kaddr + index);
>> +    if (index < adev->mman.num_doorbells) {
>> +        return readl(adev->mman.doorbell_va + index);
>>       } else {
>>           DRM_ERROR("reading beyond doorbell aperture: 0x%08x!\n", 
>> index);
>>           return 0;
>> @@ -616,8 +616,8 @@ void amdgpu_mm_wdoorbell(struct amdgpu_device 
>> *adev, u32 index, u32 v)
>>       if (amdgpu_device_skip_hw_access(adev))
>>           return;
>>   -    if (index < adev->doorbell.num_doorbells) {
>> -        writel(v, adev->mman.doorbell_aper_base_kaddr + index);
>> +    if (index < adev->mman.num_doorbells) {
>> +        writel(v, adev->mman.doorbell_va + index);
>>       } else {
>>           DRM_ERROR("writing beyond doorbell aperture: 0x%08x!\n", 
>> index);
>>       }
>> @@ -637,8 +637,8 @@ u64 amdgpu_mm_rdoorbell64(struct amdgpu_device 
>> *adev, u32 index)
>>       if (amdgpu_device_skip_hw_access(adev))
>>           return 0;
>>   -    if (index < adev->doorbell.num_doorbells) {
>> -        return atomic64_read((atomic64_t 
>> *)(adev->mman.doorbell_aper_base_kaddr + index));
>> +    if (index < adev->mman.num_doorbells) {
>> +        return atomic64_read((atomic64_t *)(adev->mman.doorbell_va + 
>> index));
>>       } else {
>>           DRM_ERROR("reading beyond doorbell aperture: 0x%08x!\n", 
>> index);
>>           return 0;
>> @@ -660,8 +660,8 @@ void amdgpu_mm_wdoorbell64(struct amdgpu_device 
>> *adev, u32 index, u64 v)
>>       if (amdgpu_device_skip_hw_access(adev))
>>           return;
>>   -    if (index < adev->doorbell.num_doorbells) {
>> -        atomic64_set((atomic64_t 
>> *)(adev->mman.doorbell_aper_base_kaddr + index), v);
>> +    if (index < adev->mman.num_doorbells) {
>> +        atomic64_set((atomic64_t *)(adev->mman.doorbell_va + index), 
>> v);
>>       } else {
>>           DRM_ERROR("writing beyond doorbell aperture: 0x%08x!\n", 
>> index);
>>       }
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>> index 464be28da4fb..97298a98561f 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_doorbell.h
>> @@ -24,10 +24,6 @@
>>   /*
>>    * GPU doorbell structures, functions & helpers
>>    */
>> -struct amdgpu_doorbell {
>> -    u32            num_doorbells;    /* Number of doorbells actually 
>> reserved for amdgpu. */
>> -};
>> -
>>   /* Reserved doorbells for amdgpu (including multimedia).
>>    * KFD can use all the rest in the 2M doorbell bar.
>>    * For asic before vega10, doorbell is 32-bit, so the
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index e38720b91958..8f0537f16cc8 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -1742,7 +1742,7 @@ static int amdgpu_ttm_doorbell_init(struct 
>> amdgpu_device *adev)
>>       if (adev->asic_type < CHIP_BONAIRE) {
>>           adev->gmc.doorbell_aper_base = 0;
>>           adev->gmc.doorbell_aper_size = 0;
>> -        adev->doorbell.num_doorbells = 0;
>> +        adev->mman.num_doorbells = 0;
>>           adev->mman.doorbell_aper_base_kaddr = NULL;
>>           return 0;
>>       }
>> @@ -1759,13 +1759,13 @@ static int amdgpu_ttm_doorbell_init(struct 
>> amdgpu_device *adev)
>> adev->gmc.doorbell_aper_size);
>>         if (adev->enable_mes) {
>> -        adev->doorbell.num_doorbells =
>> +        adev->mman.num_doorbells =
>>               adev->gmc.doorbell_aper_size / sizeof(u32);
>>       } else {
>> -        adev->doorbell.num_doorbells =
>> +        adev->mman.num_doorbells =
>>               min_t(u32, adev->gmc.doorbell_aper_size / sizeof(u32),
>>                     adev->doorbell_index.max_assignment+1);
>> -        if (adev->doorbell.num_doorbells == 0)
>> +        if (adev->mman.num_doorbells == 0)
>>               return -EINVAL;
>>             /* For Vega, reserve and map two pages on doorbell BAR 
>> since SDMA
>> @@ -1775,7 +1775,7 @@ static int amdgpu_ttm_doorbell_init(struct 
>> amdgpu_device *adev)
>>            * the max num_doorbells should + 1 page (0x400 in dword)
>>            */
>>           if (adev->asic_type >= CHIP_VEGA10)
>> -            adev->doorbell.num_doorbells += 0x400;
>> +            adev->mman.num_doorbells += 0x400;
>>       }
>>         return 0;
>> @@ -1901,6 +1901,18 @@ int amdgpu_ttm_init(struct amdgpu_device *adev)
>>       if (r)
>>           return r;
>>   +    adev->mman.doorbell_kernel_bo_size = adev->mman.num_doorbells 
>> * sizeof(u32);
>> +    r = amdgpu_bo_create_kernel_at(adev,
>> +                      0,
>> +                      adev->mman.doorbell_kernel_bo_size,
>> +                      AMDGPU_GEM_DOMAIN_DOORBELL,
>> +                      &adev->mman.doorbell_kernel_bo,
>> +                      &adev->mman.doorbell_va);
>> +    if (r) {
>> +        DRM_ERROR("Failed to create doorbell BO\n");
>> +        return r;
>> +    }
>> +
>>       DRM_INFO("amdgpu: %uM of VRAM memory ready\n",
>>            (unsigned) (adev->gmc.real_vram_size / (1024 * 1024)));
>>   @@ -1992,6 +2004,8 @@ void amdgpu_ttm_fini(struct amdgpu_device *adev)
>>                         NULL, NULL);
>>       amdgpu_bo_free_kernel(&adev->mman.sdma_access_bo, NULL,
>>                       &adev->mman.sdma_access_ptr);
>> + amdgpu_bo_free_kernel(&adev->mman.doorbell_kernel_bo,
>> +                  NULL, &adev->mman.doorbell_va);
>>       amdgpu_ttm_fw_reserve_vram_fini(adev);
>>       amdgpu_ttm_drv_reserve_vram_fini(adev);
>>   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> index a492de079c2e..405294ca9834 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
>> @@ -98,6 +98,12 @@ struct amdgpu_mman {
>>       /* PAGE_SIZE'd BO for process memory r/w over SDMA. */
>>       struct amdgpu_bo    *sdma_access_bo;
>>       void            *sdma_access_ptr;
>> +
>> +    /* doorbells reserved for the kernel driver */
>> +    u32            num_doorbells;    /* Number of doorbells actually 
>> reserved for amdgpu. */
>> +    uint64_t        doorbell_kernel_bo_size;
>> +    struct amdgpu_bo    *doorbell_kernel_bo;
>> +    void            *doorbell_va;
>>   };
>>     struct amdgpu_copy_mem {
>