Consistent with the kernel.perf_event_paranoid sysctl option that can allow non-root users to access system wide cpu metrics, this can optionally allow non-root users to access system wide OA counter metrics from Gen graphics hardware.
Signed-off-by: Robert Bragg robert@sixbynine.org Reviewed-by: Matthew Auld matthew.auld@intel.com --- drivers/gpu/drm/i915/i915_drv.h | 1 + drivers/gpu/drm/i915/i915_perf.c | 50 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index 3b86427..66629bc 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2162,6 +2162,7 @@ struct drm_i915_private { bool initialized;
struct kobject *metrics_kobj; + struct ctl_table_header *sysctl_header;
struct mutex lock; struct list_head streams; diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c index c45bba5..1d61731 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -64,6 +64,11 @@ #define POLL_FREQUENCY 200 #define POLL_PERIOD (NSEC_PER_SEC / POLL_FREQUENCY)
+/* for sysctl proc_dointvec_minmax of dev.i915.perf_stream_paranoid */ +static int zero; +static int one = 1; +static u32 i915_perf_stream_paranoid = true; + /* The maximum exponent the hardware accepts is 63 (essentially it selects one * of the 64bit timestamp bits to trigger reports from) but there's currently * no known use case for sampling as infrequently as once per 47 thousand years. @@ -1206,7 +1211,13 @@ i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv, } }
- if (!specific_ctx && !capable(CAP_SYS_ADMIN)) { + /* Similar to perf's kernel.perf_paranoid_cpu sysctl option + * we check a dev.i915.perf_stream_paranoid sysctl option + * to determine if it's ok to access system wide OA counters + * without CAP_SYS_ADMIN privileges. + */ + if (!specific_ctx && + i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) { DRM_ERROR("Insufficient privileges to open system-wide i915 perf stream\n"); ret = -EACCES; goto err_ctx; @@ -1450,6 +1461,39 @@ void i915_perf_unregister(struct drm_i915_private *dev_priv) dev_priv->perf.metrics_kobj = NULL; }
+static struct ctl_table oa_table[] = { + { + .procname = "perf_stream_paranoid", + .data = &i915_perf_stream_paranoid, + .maxlen = sizeof(i915_perf_stream_paranoid), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &one, + }, + {} +}; + +static struct ctl_table i915_root[] = { + { + .procname = "i915", + .maxlen = 0, + .mode = 0555, + .child = oa_table, + }, + {} +}; + +static struct ctl_table dev_root[] = { + { + .procname = "dev", + .maxlen = 0, + .mode = 0555, + .child = i915_root, + }, + {} +}; + void i915_perf_init(struct drm_i915_private *dev_priv) { if (!IS_HASWELL(dev_priv)) @@ -1482,6 +1526,8 @@ void i915_perf_init(struct drm_i915_private *dev_priv) dev_priv->perf.oa.n_builtin_sets = i915_oa_n_builtin_metric_sets_hsw;
+ dev_priv->perf.sysctl_header = register_sysctl_table(dev_root); + dev_priv->perf.initialized = true; }
@@ -1490,6 +1536,8 @@ void i915_perf_fini(struct drm_i915_private *dev_priv) if (!dev_priv->perf.initialized) return;
+ unregister_sysctl_table(dev_priv->perf.sysctl_header); + memset(&dev_priv->perf.oa.ops, 0, sizeof(dev_priv->perf.oa.ops)); dev_priv->perf.initialized = false; }