Re: [PATCH 1/3] drm/xe: Introduce a simple wedged state

[Aravind Iddamsetty <aravind.iddamsetty@linux.intel.com>]

On 15/03/24 00:23, Rodrigo Vivi wrote:
> On Thu, Mar 14, 2024 at 09:03:10AM +0530, Aravind Iddamsetty wrote:
>> On 14/03/24 07:10, Aravind Iddamsetty wrote:
>>> On 14/03/24 01:24, Rodrigo Vivi wrote:
>>>
>>> Hi Rodrigo,
>>>
>>>> Introduce a very simple 'wedged' state where any attempt
>>>> to access the GPU is entirely blocked.
>>>>
>>>> On some critical cases, like on gt_reset failure, we need to
>>>> block any other attempt to use the GPU. Otherwise we are at
>>>> a risk of reaching cases that would force us to reboot the machine.
>>>>
>>>> So, when this cases are identified we corner and block any GPU
>>>> access. No IOCTL and not even another GT reset should be attempted.
>>>>
>>>> The 'wedged' state in Xe is an end state with no way back.
>>>> Only a module reload can restore the GPU access.
>>> I believe we should also expose this wedged state to userspace so that
>>> any admin can take action, typically sysman is interested to know that.
>>>
>>> A sysfs at the pci device level?
>>>
>>> Thanks,
>>> Aravind.
>> Also, I feel at this point we can reintroduce the RESET_REQUIRED uevent
>> when GT reset fails, which we dropped for realignment purpose.
> Hi Aravind,
>
> Thanks for the feedback and ideas.
> Yes, I believe it is a good idea, but please let's have this as a follow-up
> so we don't have a risk of lingering the addition of this protection.
>
> Then we can also work together and prepare the sysfs and uevent user space
> usages at the same time so we don't face any blockages there.

Ya sure, agreeable to me.


Thanks,
Aravind.
>
> Thanks,
> Rodrigo.
>
>> Thanks,
>>
>> Aravind.
>>>> Cc: Anshuman Gupta <anshuman.gupta@intel.com>
>>>> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
>>>> ---
>>>>  drivers/gpu/drm/xe/xe_device.c       |  6 ++++++
>>>>  drivers/gpu/drm/xe/xe_device.h       | 11 +++++++++++
>>>>  drivers/gpu/drm/xe/xe_device_types.h |  6 ++++++
>>>>  drivers/gpu/drm/xe/xe_gt.c           |  4 ++++
>>>>  drivers/gpu/drm/xe/xe_migrate.c      |  6 ++++++
>>>>  5 files changed, 33 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
>>>> index 919ad88f0495..5f0a2bdb7c24 100644
>>>> --- a/drivers/gpu/drm/xe/xe_device.c
>>>> +++ b/drivers/gpu/drm/xe/xe_device.c
>>>> @@ -142,6 +142,9 @@ static long xe_drm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
>>>>  	struct xe_device *xe = to_xe_device(file_priv->minor->dev);
>>>>  	long ret;
>>>>  
>>>> +	if (xe_device_wedged(xe))
>>>> +		return -ECANCELED;
>>>> +
>>>>  	ret = xe_pm_runtime_get_ioctl(xe);
>>>>  	if (ret >= 0)
>>>>  		ret = drm_ioctl(file, cmd, arg);
>>>> @@ -157,6 +160,9 @@ static long xe_drm_compat_ioctl(struct file *file, unsigned int cmd, unsigned lo
>>>>  	struct xe_device *xe = to_xe_device(file_priv->minor->dev);
>>>>  	long ret;
>>>>  
>>>> +	if (xe_device_wedged(xe))
>>>> +		return -ECANCELED;
>>>> +
>>>>  	ret = xe_pm_runtime_get_ioctl(xe);
>>>>  	if (ret >= 0)
>>>>  		ret = drm_compat_ioctl(file, cmd, arg);
>>>> diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
>>>> index 14be34d9f543..d10664d32f7f 100644
>>>> --- a/drivers/gpu/drm/xe/xe_device.h
>>>> +++ b/drivers/gpu/drm/xe/xe_device.h
>>>> @@ -176,4 +176,15 @@ void xe_device_snapshot_print(struct xe_device *xe, struct drm_printer *p);
>>>>  u64 xe_device_canonicalize_addr(struct xe_device *xe, u64 address);
>>>>  u64 xe_device_uncanonicalize_addr(struct xe_device *xe, u64 address);
>>>>  
>>>> +static inline bool xe_device_wedged(struct xe_device *xe)
>>>> +{
>>>> +	return atomic_read(&xe->wedged);
>>>> +}
>>>> +
>>>> +static inline void xe_device_declare_wedged(struct xe_device *xe)
>>>> +{
>>>> +	atomic_set(&xe->wedged, 1);
>>>> +	drm_err(&xe->drm, "CRITICAL: Xe has been declared wedged. A module reload is required.\n");
>>>> +}
>>>> +
>>>>  #endif
>>>> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
>>>> index 9785eef2e5a4..13971eb2334f 100644
>>>> --- a/drivers/gpu/drm/xe/xe_device_types.h
>>>> +++ b/drivers/gpu/drm/xe/xe_device_types.h
>>>> @@ -455,6 +455,12 @@ struct xe_device {
>>>>  	/** @needs_flr_on_fini: requests function-reset on fini */
>>>>  	bool needs_flr_on_fini;
>>>>  
>>>> +	/**
>>>> +	 * @wedged: Xe device faced a critical error and is now blocked.
>>>> +	 * It cannot return to life without a module reload.
>>>> +	 */
>>>> +	atomic_t wedged;
>>>> +
>>>>  	/* private: */
>>>>  
>>>>  #if IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
>>>> diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
>>>> index 85408e7a932b..972c0c6d0608 100644
>>>> --- a/drivers/gpu/drm/xe/xe_gt.c
>>>> +++ b/drivers/gpu/drm/xe/xe_gt.c
>>>> @@ -633,6 +633,9 @@ static int gt_reset(struct xe_gt *gt)
>>>>  {
>>>>  	int err;
>>>>  
>>>> +	if (xe_device_wedged(gt_to_xe(gt)))
>>>> +	    return -ECANCELED;
>>>> +
>>>>  	/* We only support GT resets with GuC submission */
>>>>  	if (!xe_device_uc_enabled(gt_to_xe(gt)))
>>>>  		return -ENODEV;
>>>> @@ -686,6 +689,7 @@ static int gt_reset(struct xe_gt *gt)
>>>>  	xe_gt_err(gt, "reset failed (%pe)\n", ERR_PTR(err));
>>>>  
>>>>  	gt_to_xe(gt)->needs_flr_on_fini = true;
>>>> +	xe_device_declare_wedged(gt_to_xe(gt));
>>>>  
>>>>  	return err;
>>>>  }
>>>> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
>>>> index ee1bb938c493..5b2eeb2048b5 100644
>>>> --- a/drivers/gpu/drm/xe/xe_migrate.c
>>>> +++ b/drivers/gpu/drm/xe/xe_migrate.c
>>>> @@ -713,6 +713,9 @@ struct dma_fence *xe_migrate_copy(struct xe_migrate *m,
>>>>  		xe_bo_needs_ccs_pages(src_bo) && xe_bo_needs_ccs_pages(dst_bo);
>>>>  	bool copy_system_ccs = copy_ccs && (!src_is_vram || !dst_is_vram);
>>>>  
>>>> +	if (xe_device_wedged(xe))
>>>> +	    return ERR_PTR(-ECANCELED);
>>>> +
>>>>  	/* Copying CCS between two different BOs is not supported yet. */
>>>>  	if (XE_WARN_ON(copy_ccs && src_bo != dst_bo))
>>>>  		return ERR_PTR(-EINVAL);
>>>> @@ -986,6 +989,9 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
>>>>  	int err;
>>>>  	int pass = 0;
>>>>  
>>>> +	if (xe_device_wedged(xe))
>>>> +	    return ERR_PTR(-ECANCELED);
>>>> +
>>>>  	if (!clear_vram)
>>>>  		xe_res_first_sg(xe_bo_sg(bo), 0, bo->size, &src_it);
>>>>  	else