Re: [PATCH v1 2/2] drm/amdgpu: adding device coredump support

["Somalapuram, Amaranath" <asomalap@amd.com>]

On 5/24/2022 8:34 PM, Sharma, Shashank wrote:
>
>
> On 5/24/2022 3:18 PM, Somalapuram, Amaranath wrote:
>>
>> On 5/24/2022 6:20 PM, Sharma, Shashank wrote:
>>>
>>>
>>> On 5/24/2022 2:10 PM, Somalapuram, Amaranath wrote:
>>>>
>>>> On 5/24/2022 3:23 PM, Sharma, Shashank wrote:
>>>>>
>>>>>
>>>>> On 5/24/2022 8:42 AM, Somalapuram, Amaranath wrote:
>>>>>>
>>>>>> On 5/20/2022 7:52 PM, Sharma, Shashank wrote:
>>>>>>>
>>>>>>>
>>>>>>> On 5/20/2022 3:49 PM, Somalapuram Amaranath wrote:
>>>>>>>> Added device coredump information:
>>>>>>>> - Kernel version
>>>>>>>> - Module
>>>>>>>> - Time
>>>>>>>> - VRAM status
>>>>>>>> - Guilty process name and PID
>>>>>>>> - GPU register dumps
>>>>>>>>
>>>>>>>> Signed-off-by: Somalapuram Amaranath 
>>>>>>>> <Amaranath.Somalapuram@amd.com>
>>>>>>>> ---
>>>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu.h        |  3 ++
>>>>>>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 59 
>>>>>>>> ++++++++++++++++++++++
>>>>>>>>   2 files changed, 62 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h 
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>>>>>> index c79d9992b113..f28d9c563f74 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
>>>>>>>> @@ -1044,6 +1044,9 @@ struct amdgpu_device {
>>>>>>>>       uint32_t *reset_dump_reg_list;
>>>>>>>>       uint32_t            *reset_dump_reg_value;
>>>>>>>>       int                             num_regs;
>>>>>>>> +    struct amdgpu_task_info reset_context_task_info;
>>>>>>>> +    bool reset_context_vram_lost;
>>>>>>>
>>>>>>> How about drop the 'context' from name and just reset_task_info 
>>>>>>> and reset_vram_lost ?
>>>>>> OK.
>>>>>>>
>>>>>>>> +    struct timespec64 reset_time;
>>>>>>>>         struct amdgpu_reset_domain    *reset_domain;
>>>>>>>>   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c 
>>>>>>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>>> index 963c897a76e6..f9b710e741a7 100644
>>>>>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>>>>>>>> @@ -32,6 +32,8 @@
>>>>>>>>   #include <linux/slab.h>
>>>>>>>>   #include <linux/iommu.h>
>>>>>>>>   #include <linux/pci.h>
>>>>>>>> +#include <linux/devcoredump.h>
>>>>>>>> +#include <generated/utsrelease.h>
>>>>>>>>     #include <drm/drm_atomic_helper.h>
>>>>>>>>   #include <drm/drm_probe_helper.h>
>>>>>>>> @@ -4733,6 +4735,55 @@ static int amdgpu_reset_reg_dumps(struct 
>>>>>>>> amdgpu_device *adev)
>>>>>>>>       return 0;
>>>>>>>>   }
>>>>>>>>   +#ifdef CONFIG_DEV_COREDUMP
>>>>>>>> +static ssize_t amdgpu_devcoredump_read(char *buffer, loff_t 
>>>>>>>> offset,
>>>>>>>> +        size_t count, void *data, size_t datalen)
>>>>>>>> +{
>>>>>>>> +    struct drm_printer p;
>>>>>>>> +    struct amdgpu_device *adev = data;
>>>>>>>> +    struct drm_print_iterator iter;
>>>>>>>> +    int i;
>>>>>>>> +
>>>>>>>
>>>>>>> A NULL check for 'buffer' here could prevent a segfault later.
>>>>>>>
>>>>>> Agreed.
>>>>>>>> +    iter.data = buffer;
>>>>>>>> +    iter.offset = 0;
>>>>>>>> +    iter.start = offset;
>>>>>>>> +    iter.remain = count;
>>>>>>>> +
>>>>>>>> +    p = drm_coredump_printer(&iter);
>>>>>>>> +
>>>>>>>> +    drm_printf(&p, "**** AMDGPU Device Coredump ****\n");
>>>>>>>> +    drm_printf(&p, "kernel: " UTS_RELEASE "\n");
>>>>>>>> +    drm_printf(&p, "module: " KBUILD_MODNAME "\n");
>>>>>>>> +    drm_printf(&p, "time: %lld.%09ld\n", 
>>>>>>>> adev->reset_time.tv_sec, adev->reset_time.tv_nsec);
>>>>>>>> +    if (adev->reset_context_task_info.pid)
>>>>>>>> +        drm_printf(&p, "process_name: %s PID: %d\n",
>>>>>>>> + adev->reset_context_task_info.process_name,
>>>>>>>> + adev->reset_context_task_info.pid);
>>>>>>> Please fix the alignment of print variables.
>>>>>>>
>>>>>> I will cross check this.
>>>>>>>> +
>>>>>>>> +    if (adev->reset_context_vram_lost)
>>>>>>>> +        drm_printf(&p, "VRAM is lost due to GPU reset!\n");
>>>>>>>> +    if (adev->num_regs) {
>>>>>>>> +        drm_printf(&p, "AMDGPU register dumps:\nOffset: 
>>>>>>>> Value:\n");
>>>>>>>> +
>>>>>>>> +        for (i = 0; i < adev->num_regs; i++)
>>>>>>>> +            drm_printf(&p, "0x%08x: 0x%08x\n",
>>>>>>>> + adev->reset_dump_reg_list[i],
>>>>>>>> + adev->reset_dump_reg_value[i]);
>>>>>>>> +    }
>>>>>>>> +
>>>>>>>> +    return count - iter.remain;
>>>>>>>> +}
>>>>>>>> +
>>>>>>>> +static void amdgpu_reset_capture_coredumpm(struct 
>>>>>>>> amdgpu_device *adev)
>>>>>>>> +{
>>>>>>>> +    struct drm_device *dev = adev_to_drm(adev);
>>>>>>>> +
>>>>>>>> +    ktime_get_ts64(&adev->reset_time);
>>>>>>>> +    dev_coredumpm(dev->dev, THIS_MODULE, adev, 0, GFP_KERNEL,
>>>>>>>> +            amdgpu_devcoredump_read, NULL);
>>>>>>> instead of registering NULL as free function, I would prefer you 
>>>>>>> to have a dummy no_op free function registered, which we can 
>>>>>>> consume if something changes.
>>>>>> you mean something like this (function without any code):
>>>>>> staticvoidamdgpu_devcoredump_free(void*data)
>>>>>> {
>>>>>> }
>>>>>
>>>>> Yes, precisely.
>>>>>
>>>>>>>> +}
>>>>>>>> +#endif
>>>>>>>> +
>>>>>>>>   int amdgpu_do_asic_reset(struct list_head *device_list_handle,
>>>>>>>>                struct amdgpu_reset_context *reset_context)
>>>>>>>>   {
>>>>>>>> @@ -4817,6 +4868,14 @@ int amdgpu_do_asic_reset(struct 
>>>>>>>> list_head *device_list_handle,
>>>>>>>>                       goto out;
>>>>>>>>                     vram_lost = 
>>>>>>>> amdgpu_device_check_vram_lost(tmp_adev);
>>>>>>>> +#ifdef CONFIG_DEV_COREDUMP
>>>>>>>> + tmp_adev->reset_context_vram_lost = vram_lost;
>>>>>>>> + tmp_adev->reset_context_task_info.pid = 0;
>>>>>>> why is the PID hardcoded to 0 ?
>>>>>> in case of reset context reset_context->job->vm is null 
>>>>>> (possibility that reset can be non VM related).
>>>>>> If we don't set tmp_adev->reset_context_task_info.pid = 0, it 
>>>>>> will show previous reset valid PID.
>>>>>>
>>>>>
>>>>> But when the VM is not NULL, are we updating this PID somewhere ? 
>>>>> I did not see that happening in this series.
>>>> This is the only place where PID get updated.
>>>> For example sequence of operation like:
>>>> 1st reset:
>>>> -valid VM and tmp_adev->reset_context_task_info.pid is set to some 
>>>> valid PID
>>>> 2nd reset:
>>>> -invalid VM
>>>> -tmp_adev context will remain same (adev context will be same after 
>>>> successful  GPU reset sequence).
>>>> -tmp_adev->reset_context_task_info.pid will be holding 1st reset 
>>>> PID value
>>>>
>>>> if we don't set it 0, it can give wrong PID.
>>>>
>>>
>>> I get your point, and agree, that when the vm is invalid, PID is 
>>> invalid so we should send pid=0. But where are you handling the case 
>>> when VM is valid and pid is valid ?
>> valid VM check in the below condition:
>> -->if (reset_context->job && reset_context->job->vm)
>> reset_context->job->vm->task_info will have the required information.
>
> And how will that reflect on tmp_adev->reset_context_task_info.pid ? 
> The point is, if this parameter is being set to zero, means it is 
> being used somewhere, so when and how will this become non-zero ?
>
#ifdef CONFIG_DEV_COREDUMP
                                 tmp_adev->reset_context_vram_lost = 
vram_lost;
tmp_adev->reset_context_task_info.pid = 0;
                                 if (reset_context->job && 
reset_context->job->vm)
tmp_adev->reset_context_task_info =
reset_context->job->vm->task_info;
amdgpu_reset_capture_coredumpm(tmp_adev);
#endif
tmp_adev->reset_context_task_info refers to 
reset_context->job->vm->task_info,
i am not setting PID and process name separately, instead i am having 
the reference to the reset_context->job->vm->task_info on valid VM.

Regards,
S.Amarnath
> - Shashank
>
>>>
>>> - Shashank
>>>
>>>> Regards,
>>>> S.Amarnath
>>>>>
>>>>> - Shashank
>>>>>
>>>>>>
>>>>>> Regards,
>>>>>> S.Amarnath
>>>>>>>> +                if (reset_context->job && reset_context->job->vm)
>>>>>>>> + tmp_adev->reset_context_task_info =
>>>>>>>> + reset_context->job->vm->task_info;
>>>>>>>> + amdgpu_reset_capture_coredumpm(tmp_adev);
>>>>>>>> +#endif
>>>>>>>>                   if (vram_lost) {
>>>>>>>>                       DRM_INFO("VRAM is lost due to GPU 
>>>>>>>> reset!\n");
>>>>>>>>
>>>>>>> - Shashank
>>>>>>>                      amdgpu_inc_vram_lost(tmp_adev);