Re: [PATCH v2 2/3] drm/i915: Allow userspace to request no-error-capture upon GPU hangs

[Dave Gordon <david.s.gordon@intel.com>]

On 11/12/15 22:59, Chris Wilson wrote:
> igt likes to inject GPU hangs into its command streams. However, as we
> expect these hangs, we don't actually want them recorded in the dmesg
> output or stored in the i915_error_state (usually). To accomodate this
> allow userspace to set a flag on the context that any hang emanating
> from that context will not be recorded. We still do the error capture
> (otherwise how do we find the guilty context and know its intent?) as
> part of the reason for random GPU hang injection is to exercise the race
> conditions between the error capture and normal execution.
>
> v2: Split out the request->ringbuf error capture changes.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_drv.h         |  8 ++++++--
>   drivers/gpu/drm/i915/i915_gem_context.c | 13 +++++++++++++
>   drivers/gpu/drm/i915/i915_gpu_error.c   | 13 ++++++++-----
>   include/uapi/drm/i915_drm.h             |  1 +
>   4 files changed, 28 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index b33091c2c39e..c511b3cbf9b2 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -493,6 +493,7 @@ struct drm_i915_error_state {
>   	struct timeval time;
>
>   	char error_msg[128];
> +	bool simulated;
>   	int iommu;
>   	u32 reset_count;
>   	u32 suspend_count;
> @@ -845,7 +846,9 @@ struct i915_ctx_hang_stats {
>   /* This must match up with the value previously used for execbuf2.rsvd1. */
>   #define DEFAULT_CONTEXT_HANDLE 0

The #defines below need a comment, at the very least:

/* Bits in struct intel_context::flags below */

otherwise we can't tell where they are appropriate.

With that fixed, then

Reviewed-by: Dave Gordon <david.s.gordon@intel.com>

> -#define CONTEXT_NO_ZEROMAP (1<<0)
> +#define CONTEXT_NO_ZEROMAP		(1<<0)
> +#define CONTEXT_NO_ERROR_CAPTURE	(1<<1)
> +
>   /**
>    * struct intel_context - as the name implies, represents a context.
>    * @ref: reference count.
> @@ -870,11 +873,12 @@ struct intel_context {
>   	int user_handle;
>   	uint8_t remap_slice;
>   	struct drm_i915_private *i915;
> -	int flags;
>   	struct drm_i915_file_private *file_priv;
>   	struct i915_ctx_hang_stats hang_stats;
>   	struct i915_hw_ppgtt *ppgtt;
>
> +	unsigned flags;
> +
>   	/* Legacy ring buffer submission */
>   	struct {
>   		struct drm_i915_gem_object *rcs_state;
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 900ffd044db8..d9998ab9d94d 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -938,6 +938,9 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
>   		else
>   			args->value = to_i915(dev)->gtt.base.total;
>   		break;
> +	case I915_CONTEXT_PARAM_NO_ERROR_CAPTURE:
> +		args->value = !!(ctx->flags & CONTEXT_NO_ERROR_CAPTURE);
> +		break;
>   	default:
>   		ret = -EINVAL;
>   		break;
> @@ -983,6 +986,16 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
>   			ctx->flags |= args->value ? CONTEXT_NO_ZEROMAP : 0;
>   		}
>   		break;
> +	case I915_CONTEXT_PARAM_NO_ERROR_CAPTURE:
> +		if (args->size) {
> +			ret = -EINVAL;
> +		} else {
> +			if (args->value)
> +				ctx->flags |= CONTEXT_NO_ERROR_CAPTURE;
> +			else
> +				ctx->flags &= ~CONTEXT_NO_ERROR_CAPTURE;
> +		}
> +		break;
>   	default:
>   		ret = -EINVAL;
>   		break;
> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
> index 6eefe9c36931..6db6d7e02aea 100644
> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
> @@ -1040,6 +1040,7 @@ static void i915_gem_record_rings(struct drm_device *dev,
>   				rcu_read_unlock();
>   			}
>
> +			error->simulated |= request->ctx->flags & CONTEXT_NO_ERROR_CAPTURE;
>   			rbuf = request->ringbuf;
>   		}
>
> @@ -1336,12 +1337,14 @@ void i915_capture_error_state(struct drm_device *dev, bool wedged,
>   	i915_error_capture_msg(dev, error, wedged, error_msg);
>   	DRM_INFO("%s\n", error->error_msg);
>
> -	spin_lock_irqsave(&dev_priv->gpu_error.lock, flags);
> -	if (dev_priv->gpu_error.first_error == NULL) {
> -		dev_priv->gpu_error.first_error = error;
> -		error = NULL;
> +	if (!error->simulated) {
> +		spin_lock_irqsave(&dev_priv->gpu_error.lock, flags);
> +		if (dev_priv->gpu_error.first_error == NULL) {
> +			dev_priv->gpu_error.first_error = error;
> +			error = NULL;
> +		}
> +		spin_unlock_irqrestore(&dev_priv->gpu_error.lock, flags);
>   	}
> -	spin_unlock_irqrestore(&dev_priv->gpu_error.lock, flags);
>
>   	if (error) {
>   		i915_error_state_free(&error->ref);
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index acf21026c78a..7fee4416dcc7 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -1140,6 +1140,7 @@ struct drm_i915_gem_context_param {
>   #define I915_CONTEXT_PARAM_BAN_PERIOD	0x1
>   #define I915_CONTEXT_PARAM_NO_ZEROMAP	0x2
>   #define I915_CONTEXT_PARAM_GTT_SIZE	0x3
> +#define I915_CONTEXT_PARAM_NO_ERROR_CAPTURE	0x4
>   	__u64 value;
>   };
>
>

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