Re: [PATCH v4 07/14] drm/amdgpu: Register IOMMU topology notifier per device.

From: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
To: christian.koenig@amd.com, amd-gfx@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch,
	robh@kernel.org, l.stach@pengutronix.de, yuq825@gmail.com,
	eric@anholt.net
Cc: Alexander.Deucher@amd.com, gregkh@linuxfoundation.org
Subject: Re: [PATCH v4 07/14] drm/amdgpu: Register IOMMU topology notifier per device.
Date: Wed, 20 Jan 2021 14:38:12 -0500	[thread overview]
Message-ID: <1a0f32ef-3700-83b7-1260-813f9048a41f@amd.com> (raw)
In-Reply-To: <2e6b1fd8-d20f-ce57-44f2-f679d1530ff9@amd.com>

Ping

Andrey

On 1/20/21 12:01 AM, Andrey Grodzovsky wrote:
>
> On 1/19/21 3:48 AM, Christian König wrote:
>> Am 18.01.21 um 22:01 schrieb Andrey Grodzovsky:
>>> Handle all DMA IOMMU gropup related dependencies before the
>>> group is removed.
>>>
>>> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  5 ++++
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 46 
>>> ++++++++++++++++++++++++++++++
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c   |  2 +-
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h   |  1 +
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 10 +++++++
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.h |  2 ++
>>>   6 files changed, 65 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> index 478a7d8..2953420 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>> @@ -51,6 +51,7 @@
>>>   #include <linux/dma-fence.h>
>>>   #include <linux/pci.h>
>>>   #include <linux/aer.h>
>>> +#include <linux/notifier.h>
>>>     #include <drm/ttm/ttm_bo_api.h>
>>>   #include <drm/ttm/ttm_bo_driver.h>
>>> @@ -1041,6 +1042,10 @@ struct amdgpu_device {
>>>         bool                            in_pci_err_recovery;
>>>       struct pci_saved_state          *pci_state;
>>> +
>>> +    struct notifier_block        nb;
>>> +    struct blocking_notifier_head    notifier;
>>> +    struct list_head        device_bo_list;
>>>   };
>>>     static inline struct amdgpu_device *drm_to_adev(struct drm_device *ddev)
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> index 45e23e3..e99f4f1 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>> @@ -70,6 +70,8 @@
>>>   #include <drm/task_barrier.h>
>>>   #include <linux/pm_runtime.h>
>>>   +#include <linux/iommu.h>
>>> +
>>>   MODULE_FIRMWARE("amdgpu/vega10_gpu_info.bin");
>>>   MODULE_FIRMWARE("amdgpu/vega12_gpu_info.bin");
>>>   MODULE_FIRMWARE("amdgpu/raven_gpu_info.bin");
>>> @@ -3200,6 +3202,39 @@ static const struct attribute 
>>> *amdgpu_dev_attributes[] = {
>>>   };
>>>     +static int amdgpu_iommu_group_notifier(struct notifier_block *nb,
>>> +                     unsigned long action, void *data)
>>> +{
>>> +    struct amdgpu_device *adev = container_of(nb, struct amdgpu_device, nb);
>>> +    struct amdgpu_bo *bo = NULL;
>>> +
>>> +    /*
>>> +     * Following is a set of IOMMU group dependencies taken care of before
>>> +     * device's IOMMU group is removed
>>> +     */
>>> +    if (action == IOMMU_GROUP_NOTIFY_DEL_DEVICE) {
>>> +
>>> +        spin_lock(&ttm_bo_glob.lru_lock);
>>> +        list_for_each_entry(bo, &adev->device_bo_list, bo) {
>>> +            if (bo->tbo.ttm)
>>> +                ttm_tt_unpopulate(bo->tbo.bdev, bo->tbo.ttm);
>>> +        }
>>> +        spin_unlock(&ttm_bo_glob.lru_lock);
>>
>> That approach won't work. ttm_tt_unpopulate() might sleep on an IOMMU lock.
>>
>> You need to use a mutex here or even better make sure you can access the 
>> device_bo_list without a lock in this moment.
>>
>> Christian.
>
>
> I can think of switching to RCU list ? Otherwise, elements are added
> on BO create and deleted on BO destroy, how can i prevent any of those from
> happening while in this section besides mutex ? Make a copy list and run over 
> it instead ?
>
> Andrey
>
>
>>
>>> +
>>> +        if (adev->irq.ih.use_bus_addr)
>>> +            amdgpu_ih_ring_fini(adev, &adev->irq.ih);
>>> +        if (adev->irq.ih1.use_bus_addr)
>>> +            amdgpu_ih_ring_fini(adev, &adev->irq.ih1);
>>> +        if (adev->irq.ih2.use_bus_addr)
>>> +            amdgpu_ih_ring_fini(adev, &adev->irq.ih2);
>>> +
>>> +        amdgpu_gart_dummy_page_fini(adev);
>>> +    }
>>> +
>>> +    return NOTIFY_OK;
>>> +}
>>> +
>>> +
>>>   /**
>>>    * amdgpu_device_init - initialize the driver
>>>    *
>>> @@ -3304,6 +3339,8 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>>>         INIT_WORK(&adev->xgmi_reset_work, amdgpu_device_xgmi_reset_func);
>>>   +    INIT_LIST_HEAD(&adev->device_bo_list);
>>> +
>>>       adev->gfx.gfx_off_req_count = 1;
>>>       adev->pm.ac_power = power_supply_is_system_supplied() > 0;
>>>   @@ -3575,6 +3612,15 @@ int amdgpu_device_init(struct amdgpu_device *adev,
>>>       if (amdgpu_device_cache_pci_state(adev->pdev))
>>>           pci_restore_state(pdev);
>>>   +    BLOCKING_INIT_NOTIFIER_HEAD(&adev->notifier);
>>> +    adev->nb.notifier_call = amdgpu_iommu_group_notifier;
>>> +
>>> +    if (adev->dev->iommu_group) {
>>> +        r = iommu_group_register_notifier(adev->dev->iommu_group, &adev->nb);
>>> +        if (r)
>>> +            goto failed;
>>> +    }
>>> +
>>>       return 0;
>>>     failed:
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c
>>> index 0db9330..486ad6d 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.c
>>> @@ -92,7 +92,7 @@ static int amdgpu_gart_dummy_page_init(struct 
>>> amdgpu_device *adev)
>>>    *
>>>    * Frees the dummy page used by the driver (all asics).
>>>    */
>>> -static void amdgpu_gart_dummy_page_fini(struct amdgpu_device *adev)
>>> +void amdgpu_gart_dummy_page_fini(struct amdgpu_device *adev)
>>>   {
>>>       if (!adev->dummy_page_addr)
>>>           return;
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h
>>> index afa2e28..5678d9c 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gart.h
>>> @@ -61,6 +61,7 @@ int amdgpu_gart_table_vram_pin(struct amdgpu_device *adev);
>>>   void amdgpu_gart_table_vram_unpin(struct amdgpu_device *adev);
>>>   int amdgpu_gart_init(struct amdgpu_device *adev);
>>>   void amdgpu_gart_fini(struct amdgpu_device *adev);
>>> +void amdgpu_gart_dummy_page_fini(struct amdgpu_device *adev);
>>>   int amdgpu_gart_unbind(struct amdgpu_device *adev, uint64_t offset,
>>>                  int pages);
>>>   int amdgpu_gart_map(struct amdgpu_device *adev, uint64_t offset,
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>>> index 6cc9919..4a1de69 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>>> @@ -94,6 +94,10 @@ static void amdgpu_bo_destroy(struct ttm_buffer_object *tbo)
>>>       }
>>>       amdgpu_bo_unref(&bo->parent);
>>>   +    spin_lock(&ttm_bo_glob.lru_lock);
>>> +    list_del(&bo->bo);
>>> +    spin_unlock(&ttm_bo_glob.lru_lock);
>>> +
>>>       kfree(bo->metadata);
>>>       kfree(bo);
>>>   }
>>> @@ -613,6 +617,12 @@ static int amdgpu_bo_do_create(struct amdgpu_device *adev,
>>>       if (bp->type == ttm_bo_type_device)
>>>           bo->flags &= ~AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
>>>   +    INIT_LIST_HEAD(&bo->bo);
>>> +
>>> +    spin_lock(&ttm_bo_glob.lru_lock);
>>> +    list_add_tail(&bo->bo, &adev->device_bo_list);
>>> +    spin_unlock(&ttm_bo_glob.lru_lock);
>>> +
>>>       return 0;
>>>     fail_unreserve:
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>> index 9ac3756..5ae8555 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.h
>>> @@ -110,6 +110,8 @@ struct amdgpu_bo {
>>>       struct list_head        shadow_list;
>>>         struct kgd_mem                  *kfd_bo;
>>> +
>>> +    struct list_head        bo;
>>>   };
>>>     static inline struct amdgpu_bo *ttm_to_amdgpu_bo(struct 
>>> ttm_buffer_object *tbo)
>>
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