Re: [PATCH v3 11/11] drm/xe/multi_queue: Whitelist QUEUE_TIMESTAMP register

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

On Tue, May 05, 2026 at 04:44:20PM -0700, Umesh Nerlige Ramappa wrote:
>In a multi-queue use case, when a job is running on the secondary queue,
>the CTX_TIMESTAMP does not reflect the queues run ticks. Instead, we use
>the QUEUE TIMESTAMP to check how long the job ran. For user space to see
>the run ticks for a secondary queue, whitelist the QUEUE_TIMESTAMP
>register.
>
>Compute PR: https://github.com/intel/compute-runtime/pull/923
>
>Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

LGTM.
Reviewed-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>

>---
>v2: Whitelist QUEUE_TIMESTAMP only for copy and compute engines (Niranjana)
>v3: (Niranjana)
>- s/multiq/multi_queue/
>- Base the condition on multi_queue_engine_class_mask
>---
> drivers/gpu/drm/xe/xe_reg_whitelist.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
>diff --git a/drivers/gpu/drm/xe/xe_reg_whitelist.c b/drivers/gpu/drm/xe/xe_reg_whitelist.c
>index 8cc313182968..6f96bf84df66 100644
>--- a/drivers/gpu/drm/xe/xe_reg_whitelist.c
>+++ b/drivers/gpu/drm/xe/xe_reg_whitelist.c
>@@ -9,6 +9,7 @@
> #include "regs/xe_gt_regs.h"
> #include "regs/xe_oa_regs.h"
> #include "xe_device.h"
>+#include "xe_gt.h"
> #include "xe_gt_types.h"
> #include "xe_gt_printk.h"
> #include "xe_platform_types.h"
>@@ -33,6 +34,13 @@ static bool match_has_mert(const struct xe_device *xe,
> 	return xe_device_has_mert((struct xe_device *)xe);
> }
>
>+static bool match_multi_queue_class(const struct xe_device *xe,
>+				    const struct xe_gt *gt,
>+				    const struct xe_hw_engine *hwe)
>+{
>+	return xe_gt_hwe_class_supports_multi_queue(gt, hwe->class);
>+}
>+
> static const struct xe_rtp_entry_sr register_whitelist[] = {
> 	{ XE_RTP_NAME("WaAllowPMDepthAndInvocationCountAccessFromUMD, 1408556865"),
> 	  XE_RTP_RULES(GRAPHICS_VERSION_RANGE(1200, 1210), ENGINE_CLASS(RENDER)),
>@@ -54,6 +62,12 @@ static const struct xe_rtp_entry_sr register_whitelist[] = {
> 				RING_FORCE_TO_NONPRIV_ACCESS_RD,
> 				XE_RTP_ACTION_FLAG(ENGINE_BASE)))
> 	},
>+	{ XE_RTP_NAME("allow_read_queue_timestamp"),
>+	  XE_RTP_RULES(GRAPHICS_VERSION_RANGE(3500, 3511), FUNC(match_multi_queue_class)),
>+	  XE_RTP_ACTIONS(WHITELIST(RING_QUEUE_TIMESTAMP(0),
>+				   RING_FORCE_TO_NONPRIV_ACCESS_RD,
>+				   XE_RTP_ACTION_FLAG(ENGINE_BASE)))
>+	},
> 	{ XE_RTP_NAME("16014440446"),
> 	  XE_RTP_RULES(PLATFORM(PVC)),
> 	  XE_RTP_ACTIONS(WHITELIST(XE_REG(0x4400),
>-- 
>2.51.0
>