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

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

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 ?

> +	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.

> +	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.

> +
> +	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.
> +}
> +#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 ?
> +				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);