[RFC 5/6] drm/i915: Add dev.i915.perf_event_paranoid sysctl option
From: Robert Bragg <hidden>
Date: 2015-09-29 14:41:21
Also in:
dri-devel, intel-gfx, lkml
Subsystem:
drm drivers, intel drm i915 driver (meteor lake, dg2 and older excluding poulsbo, moorestown and derivative), the rest · Maintainers:
David Airlie, Simona Vetter, Jani Nikula, Joonas Lahtinen, Rodrigo Vivi, Tvrtko Ursulin, Linus Torvalds
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 <redacted> --- drivers/gpu/drm/i915/i915_perf.c | 46 +++++++++++++++++++++++++++++++++++++++- 1 file changed, 45 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index bc1c4d1..ab82857 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c@@ -38,6 +38,8 @@ #define POLL_FREQUENCY 200 #define POLL_PERIOD max_t(u64, 10000, NSEC_PER_SEC / POLL_FREQUENCY) +static u32 i915_perf_event_paranoid = true; + #define OA_EXPONENT_MAX 0x3f static struct i915_oa_format hsw_oa_formats[I915_OA_FORMAT_MAX] = {
@@ -1016,7 +1018,13 @@ int i915_perf_open_ioctl_locked(struct drm_device *dev, void *data, } } - if (!specific_ctx && !capable(CAP_SYS_ADMIN)) { + /* Similar to perf's kernel.perf_paranoid_cpu sysctl option + * we check a dev.i915.perf_event_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_event_paranoid && !capable(CAP_SYS_ADMIN)) { DRM_ERROR("Insufficient privileges to open perf event\n"); ret = -EACCES; goto err_ctx;
@@ -1096,6 +1104,38 @@ int i915_perf_open_ioctl(struct drm_device *dev, void *data, return ret; } + +static struct ctl_table oa_table[] = { + { + .procname = "perf_event_paranoid", + .data = &i915_perf_event_paranoid, + .maxlen = sizeof(i915_perf_event_paranoid), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + {} +}; + +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_device *dev) { struct drm_i915_private *dev_priv = to_i915(dev);
@@ -1103,6 +1143,8 @@ void i915_perf_init(struct drm_device *dev) if (!IS_HASWELL(dev)) return; + dev_priv->perf.sysctl_header = register_sysctl_table(dev_root); + hrtimer_init(&dev_priv->perf.oa.poll_check_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); dev_priv->perf.oa.poll_check_timer.function = poll_check_timer_cb;
@@ -1132,6 +1174,8 @@ void i915_perf_fini(struct drm_device *dev) if (!dev_priv->perf.initialized) return; + unregister_sysctl_table(dev_priv->perf.sysctl_header); + dev_priv->perf.oa.ops.init_oa_buffer = NULL; dev_priv->perf.initialized = false;
--
2.5.2