Re: [PATCH 3/3] drm/xe/oa: Allow preemption to be disabled on the stream exec queue

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

On Tue, Jun 25, 2024 at 01:15:18PM -0700, Ashutosh Dixit wrote:
>Mesa VK_KHR_performance_query use case requires preemption to be disabled
>for the stream exec queue. Implement this functionality here based on the
>new set_no_preempt and clear_no_preempt exec queue ops.
>
>Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

lgtm

Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

>---
> drivers/gpu/drm/xe/xe_oa.c       | 33 +++++++++++++++++++++++++++++++-
> drivers/gpu/drm/xe/xe_oa_types.h |  3 +++
> include/uapi/drm/xe_drm.h        |  6 ++++++
> 3 files changed, 41 insertions(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
>index a68659fd5386..6453c36c4539 100644
>--- a/drivers/gpu/drm/xe/xe_oa.c
>+++ b/drivers/gpu/drm/xe/xe_oa.c
>@@ -80,6 +80,7 @@ struct xe_oa_open_param {
> 	int engine_instance;
> 	struct xe_exec_queue *exec_q;
> 	struct xe_hw_engine *hwe;
>+	bool no_preempt;
> };
>
> struct xe_oa_config_bo {
>@@ -1018,6 +1019,13 @@ static int xe_oa_enable_locked(struct xe_oa_stream *stream)
> 	if (stream->enabled)
> 		return 0;
>
>+	if (stream->no_preempt) {
>+		int ret = stream->exec_q->ops->set_no_preempt(stream->exec_q);
>+
>+		if (ret)
>+			return ret;
>+	}
>+
> 	xe_oa_stream_enable(stream);
>
> 	stream->enabled = true;
>@@ -1026,13 +1034,18 @@ static int xe_oa_enable_locked(struct xe_oa_stream *stream)
>
> static int xe_oa_disable_locked(struct xe_oa_stream *stream)
> {
>+	int ret = 0;
>+
> 	if (!stream->enabled)
> 		return 0;
>
> 	xe_oa_stream_disable(stream);
>
>+	if (stream->no_preempt)
>+		ret = stream->exec_q->ops->clear_no_preempt(stream->exec_q);
>+
> 	stream->enabled = false;
>-	return 0;
>+	return ret;
> }
>
> static long xe_oa_config_locked(struct xe_oa_stream *stream, u64 arg)
>@@ -1307,6 +1320,7 @@ static int xe_oa_stream_init(struct xe_oa_stream *stream,
> 	stream->sample = param->sample;
> 	stream->periodic = param->period_exponent > 0;
> 	stream->period_exponent = param->period_exponent;
>+	stream->no_preempt = param->no_preempt;
>
> 	/*
> 	 * For Xe2+, when overrun mode is enabled, there are no partial reports at the end
>@@ -1651,6 +1665,13 @@ static int xe_oa_set_prop_engine_instance(struct xe_oa *oa, u64 value,
> 	return 0;
> }
>
>+static int xe_oa_set_no_preempt(struct xe_oa *oa, u64 value,
>+				struct xe_oa_open_param *param)
>+{
>+	param->no_preempt = value;
>+	return 0;
>+}
>+
> typedef int (*xe_oa_set_property_fn)(struct xe_oa *oa, u64 value,
> 				     struct xe_oa_open_param *param);
> static const xe_oa_set_property_fn xe_oa_set_property_funcs[] = {
>@@ -1662,6 +1683,7 @@ static const xe_oa_set_property_fn xe_oa_set_property_funcs[] = {
> 	[DRM_XE_OA_PROPERTY_OA_DISABLED] = xe_oa_set_prop_disabled,
> 	[DRM_XE_OA_PROPERTY_EXEC_QUEUE_ID] = xe_oa_set_prop_exec_queue_id,
> 	[DRM_XE_OA_PROPERTY_OA_ENGINE_INSTANCE] = xe_oa_set_prop_engine_instance,
>+	[DRM_XE_OA_PROPERTY_NO_PREEMPT] = xe_oa_set_no_preempt,
> };
>
> static int xe_oa_user_ext_set_property(struct xe_oa *oa, u64 extension,
>@@ -1766,6 +1788,15 @@ int xe_oa_stream_open_ioctl(struct drm_device *dev, u64 data, struct drm_file *f
> 	if (param.exec_q && !param.sample)
> 		privileged_op = false;
>
>+	if (param.no_preempt) {
>+		if (!param.exec_q) {
>+			drm_dbg(&oa->xe->drm, "Preemption disable without exec_q!\n");
>+			ret = -EINVAL;
>+			goto err_exec_q;
>+		}
>+		privileged_op = true;
>+	}
>+
> 	if (privileged_op && xe_perf_stream_paranoid && !perfmon_capable()) {
> 		drm_dbg(&oa->xe->drm, "Insufficient privileges to open xe perf stream\n");
> 		ret = -EACCES;
>diff --git a/drivers/gpu/drm/xe/xe_oa_types.h b/drivers/gpu/drm/xe/xe_oa_types.h
>index 706d45577dae..540c3ec53a6d 100644
>--- a/drivers/gpu/drm/xe/xe_oa_types.h
>+++ b/drivers/gpu/drm/xe/xe_oa_types.h
>@@ -235,5 +235,8 @@ struct xe_oa_stream {
>
> 	/** @oa_status: temporary storage for oa_status register value */
> 	u32 oa_status;
>+
>+	/** @no_preempt: Whether preemption and timeslicing is disabled for stream exec_q */
>+	u32 no_preempt;
> };
> #endif
>diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h
>index b410553faa9b..12eaa8532b5c 100644
>--- a/include/uapi/drm/xe_drm.h
>+++ b/include/uapi/drm/xe_drm.h
>@@ -1611,6 +1611,12 @@ enum drm_xe_oa_property_id {
> 	 * pass along with @DRM_XE_OA_PROPERTY_EXEC_QUEUE_ID or will default to 0.
> 	 */
> 	DRM_XE_OA_PROPERTY_OA_ENGINE_INSTANCE,
>+
>+	/**
>+	 * @DRM_XE_OA_PROPERTY_NO_PREEMPT: Allow preemption and timeslicing
>+	 * to be disabled for the stream exec queue.
>+	 */
>+	DRM_XE_OA_PROPERTY_NO_PREEMPT,
> };
>
> /**
>-- 
>2.41.0
>