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@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_perf.c | 45 +++++++++++++++++++++++++++++++++++++++-
2 files changed, 45 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index dd88eb1..558cc0b 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2116,6 +2116,7 @@ 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 7e1fc6b..ac1f600 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -62,6 +62,8 @@
#define POLL_FREQUENCY 200
#define POLL_PERIOD (NSEC_PER_SEC / POLL_FREQUENCY)
+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.
@@ -1158,7 +1160,13 @@ int i915_perf_open_ioctl_locked(struct drm_device *dev,
}
}
- 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;
@@ -1399,6 +1407,37 @@ 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,
+ },
+ {}
+};
+
+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))
@@ -1431,6 +1470,8 @@ 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;
}
@@ -1439,6 +1480,8 @@ 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;
}
--
2.9.2
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