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24 * Robert Bragg <robert@sixbynine.org>
29 * DOC: i915 Perf Overview
31 * Gen graphics supports a large number of performance counters that can help
32 * driver and application developers understand and optimize their use of the
35 * This i915 perf interface enables userspace to configure and open a file
36 * descriptor representing a stream of GPU metrics which can then be read() as
37 * a stream of sample records.
39 * The interface is particularly suited to exposing buffered metrics that are
40 * captured by DMA from the GPU, unsynchronized with and unrelated to the CPU.
42 * Streams representing a single context are accessible to applications with a
43 * corresponding drm file descriptor, such that OpenGL can use the interface
44 * without special privileges. Access to system-wide metrics requires root
45 * privileges by default, unless changed via the dev.i915.perf_event_paranoid
51 * DOC: i915 Perf History and Comparison with Core Perf
53 * The interface was initially inspired by the core Perf infrastructure but
54 * some notable differences are:
56 * i915 perf file descriptors represent a "stream" instead of an "event"; where
57 * a perf event primarily corresponds to a single 64bit value, while a stream
58 * might sample sets of tightly-coupled counters, depending on the
59 * configuration. For example the Gen OA unit isn't designed to support
60 * orthogonal configurations of individual counters; it's configured for a set
61 * of related counters. Samples for an i915 perf stream capturing OA metrics
62 * will include a set of counter values packed in a compact HW specific format.
63 * The OA unit supports a number of different packing formats which can be
64 * selected by the user opening the stream. Perf has support for grouping
65 * events, but each event in the group is configured, validated and
66 * authenticated individually with separate system calls.
68 * i915 perf stream configurations are provided as an array of u64 (key,value)
69 * pairs, instead of a fixed struct with multiple miscellaneous config members,
70 * interleaved with event-type specific members.
72 * i915 perf doesn't support exposing metrics via an mmap'd circular buffer.
73 * The supported metrics are being written to memory by the GPU unsynchronized
74 * with the CPU, using HW specific packing formats for counter sets. Sometimes
75 * the constraints on HW configuration require reports to be filtered before it
76 * would be acceptable to expose them to unprivileged applications - to hide
77 * the metrics of other processes/contexts. For these use cases a read() based
78 * interface is a good fit, and provides an opportunity to filter data as it
79 * gets copied from the GPU mapped buffers to userspace buffers.
82 * Issues hit with first prototype based on Core Perf
83 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
85 * The first prototype of this driver was based on the core perf
86 * infrastructure, and while we did make that mostly work, with some changes to
87 * perf, we found we were breaking or working around too many assumptions baked
88 * into perf's currently cpu centric design.
90 * In the end we didn't see a clear benefit to making perf's implementation and
91 * interface more complex by changing design assumptions while we knew we still
92 * wouldn't be able to use any existing perf based userspace tools.
94 * Also considering the Gen specific nature of the Observability hardware and
95 * how userspace will sometimes need to combine i915 perf OA metrics with
96 * side-band OA data captured via MI_REPORT_PERF_COUNT commands; we're
97 * expecting the interface to be used by a platform specific userspace such as
98 * OpenGL or tools. This is to say; we aren't inherently missing out on having
99 * a standard vendor/architecture agnostic interface by not using perf.
102 * For posterity, in case we might re-visit trying to adapt core perf to be
103 * better suited to exposing i915 metrics these were the main pain points we
106 * - The perf based OA PMU driver broke some significant design assumptions:
108 * Existing perf pmus are used for profiling work on a cpu and we were
109 * introducing the idea of _IS_DEVICE pmus with different security
110 * implications, the need to fake cpu-related data (such as user/kernel
111 * registers) to fit with perf's current design, and adding _DEVICE records
112 * as a way to forward device-specific status records.
114 * The OA unit writes reports of counters into a circular buffer, without
115 * involvement from the CPU, making our PMU driver the first of a kind.
117 * Given the way we were periodically forward data from the GPU-mapped, OA
118 * buffer to perf's buffer, those bursts of sample writes looked to perf like
119 * we were sampling too fast and so we had to subvert its throttling checks.
121 * Perf supports groups of counters and allows those to be read via
122 * transactions internally but transactions currently seem designed to be
123 * explicitly initiated from the cpu (say in response to a userspace read())
124 * and while we could pull a report out of the OA buffer we can't
125 * trigger a report from the cpu on demand.
127 * Related to being report based; the OA counters are configured in HW as a
128 * set while perf generally expects counter configurations to be orthogonal.
129 * Although counters can be associated with a group leader as they are
130 * opened, there's no clear precedent for being able to provide group-wide
131 * configuration attributes (for example we want to let userspace choose the
132 * OA unit report format used to capture all counters in a set, or specify a
133 * GPU context to filter metrics on). We avoided using perf's grouping
134 * feature and forwarded OA reports to userspace via perf's 'raw' sample
135 * field. This suited our userspace well considering how coupled the counters
136 * are when dealing with normalizing. It would be inconvenient to split
137 * counters up into separate events, only to require userspace to recombine
138 * them. For Mesa it's also convenient to be forwarded raw, periodic reports
139 * for combining with the side-band raw reports it captures using
140 * MI_REPORT_PERF_COUNT commands.
142 * - As a side note on perf's grouping feature; there was also some concern
143 * that using PERF_FORMAT_GROUP as a way to pack together counter values
144 * would quite drastically inflate our sample sizes, which would likely
145 * lower the effective sampling resolutions we could use when the available
146 * memory bandwidth is limited.
148 * With the OA unit's report formats, counters are packed together as 32
149 * or 40bit values, with the largest report size being 256 bytes.
151 * PERF_FORMAT_GROUP values are 64bit, but there doesn't appear to be a
152 * documented ordering to the values, implying PERF_FORMAT_ID must also be
153 * used to add a 64bit ID before each value; giving 16 bytes per counter.
155 * Related to counter orthogonality; we can't time share the OA unit, while
156 * event scheduling is a central design idea within perf for allowing
157 * userspace to open + enable more events than can be configured in HW at any
158 * one time. The OA unit is not designed to allow re-configuration while in
159 * use. We can't reconfigure the OA unit without losing internal OA unit
160 * state which we can't access explicitly to save and restore. Reconfiguring
161 * the OA unit is also relatively slow, involving ~100 register writes. From
162 * userspace Mesa also depends on a stable OA configuration when emitting
163 * MI_REPORT_PERF_COUNT commands and importantly the OA unit can't be
164 * disabled while there are outstanding MI_RPC commands lest we hang the
167 * The contents of sample records aren't extensible by device drivers (i.e.
168 * the sample_type bits). As an example; Sourab Gupta had been looking to
169 * attach GPU timestamps to our OA samples. We were shoehorning OA reports
170 * into sample records by using the 'raw' field, but it's tricky to pack more
171 * than one thing into this field because events/core.c currently only lets a
172 * pmu give a single raw data pointer plus len which will be copied into the
173 * ring buffer. To include more than the OA report we'd have to copy the
174 * report into an intermediate larger buffer. I'd been considering allowing a
175 * vector of data+len values to be specified for copying the raw data, but
176 * it felt like a kludge to being using the raw field for this purpose.
178 * - It felt like our perf based PMU was making some technical compromises
179 * just for the sake of using perf:
181 * perf_event_open() requires events to either relate to a pid or a specific
182 * cpu core, while our device pmu related to neither. Events opened with a
183 * pid will be automatically enabled/disabled according to the scheduling of
184 * that process - so not appropriate for us. When an event is related to a
185 * cpu id, perf ensures pmu methods will be invoked via an inter process
186 * interrupt on that core. To avoid invasive changes our userspace opened OA
187 * perf events for a specific cpu. This was workable but it meant the
188 * majority of the OA driver ran in atomic context, including all OA report
189 * forwarding, which wasn't really necessary in our case and seems to make
190 * our locking requirements somewhat complex as we handled the interaction
191 * with the rest of the i915 driver.
194 #include <linux/anon_inodes.h>
195 #include <linux/sizes.h>
197 #include "i915_drv.h"
198 #include "i915_oa_hsw.h"
200 /* HW requires this to be a power of two, between 128k and 16M, though driver
201 * is currently generally designed assuming the largest 16M size is used such
202 * that the overflow cases are unlikely in normal operation.
204 #define OA_BUFFER_SIZE SZ_16M
206 #define OA_TAKEN(tail, head) ((tail - head) & (OA_BUFFER_SIZE - 1))
208 /* There's a HW race condition between OA unit tail pointer register updates and
209 * writes to memory whereby the tail pointer can sometimes get ahead of what's
210 * been written out to the OA buffer so far.
212 * Although this can be observed explicitly by checking for a zeroed report-id
213 * field in tail reports, it seems preferable to account for this earlier e.g.
214 * as part of the _oa_buffer_is_empty checks to minimize -EAGAIN polling cycles
217 * To give time for the most recent reports to land before they may be copied to
218 * userspace, the driver operates as if the tail pointer effectively lags behind
219 * the HW tail pointer by 'tail_margin' bytes. The margin in bytes is calculated
220 * based on this constant in nanoseconds, the current OA sampling exponent
221 * and current report size.
223 * There is also a fallback check while reading to simply skip over reports with
224 * a zeroed report-id.
226 #define OA_TAIL_MARGIN_NSEC 100000ULL
228 /* frequency for checking whether the OA unit has written new reports to the
229 * circular OA buffer...
231 #define POLL_FREQUENCY 200
232 #define POLL_PERIOD (NSEC_PER_SEC / POLL_FREQUENCY)
234 /* for sysctl proc_dointvec_minmax of dev.i915.perf_stream_paranoid */
237 static u32 i915_perf_stream_paranoid = true;
239 /* The maximum exponent the hardware accepts is 63 (essentially it selects one
240 * of the 64bit timestamp bits to trigger reports from) but there's currently
241 * no known use case for sampling as infrequently as once per 47 thousand years.
243 * Since the timestamps included in OA reports are only 32bits it seems
244 * reasonable to limit the OA exponent where it's still possible to account for
245 * overflow in OA report timestamps.
247 #define OA_EXPONENT_MAX 31
249 #define INVALID_CTX_ID 0xffffffff
252 /* For sysctl proc_dointvec_minmax of i915_oa_max_sample_rate
254 * 160ns is the smallest sampling period we can theoretically program the OA
255 * unit with on Haswell, corresponding to 6.25MHz.
257 static int oa_sample_rate_hard_limit = 6250000;
259 /* Theoretically we can program the OA unit to sample every 160ns but don't
260 * allow that by default unless root...
262 * The default threshold of 100000Hz is based on perf's similar
263 * kernel.perf_event_max_sample_rate sysctl parameter.
265 static u32 i915_oa_max_sample_rate = 100000;
267 /* XXX: beware if future OA HW adds new report formats that the current
268 * code assumes all reports have a power-of-two size and ~(size - 1) can
269 * be used as a mask to align the OA tail pointer.
271 static struct i915_oa_format hsw_oa_formats[I915_OA_FORMAT_MAX] = {
272 [I915_OA_FORMAT_A13] = { 0, 64 },
273 [I915_OA_FORMAT_A29] = { 1, 128 },
274 [I915_OA_FORMAT_A13_B8_C8] = { 2, 128 },
275 /* A29_B8_C8 Disallowed as 192 bytes doesn't factor into buffer size */
276 [I915_OA_FORMAT_B4_C8] = { 4, 64 },
277 [I915_OA_FORMAT_A45_B8_C8] = { 5, 256 },
278 [I915_OA_FORMAT_B4_C8_A16] = { 6, 128 },
279 [I915_OA_FORMAT_C4_B8] = { 7, 64 },
282 #define SAMPLE_OA_REPORT (1<<0)
285 * struct perf_open_properties - for validated properties given to open a stream
286 * @sample_flags: `DRM_I915_PERF_PROP_SAMPLE_*` properties are tracked as flags
287 * @single_context: Whether a single or all gpu contexts should be monitored
288 * @ctx_handle: A gem ctx handle for use with @single_context
289 * @metrics_set: An ID for an OA unit metric set advertised via sysfs
290 * @oa_format: An OA unit HW report format
291 * @oa_periodic: Whether to enable periodic OA unit sampling
292 * @oa_period_exponent: The OA unit sampling period is derived from this
294 * As read_properties_unlocked() enumerates and validates the properties given
295 * to open a stream of metrics the configuration is built up in the structure
296 * which starts out zero initialized.
298 struct perf_open_properties {
301 u64 single_context:1;
304 /* OA sampling state */
308 int oa_period_exponent;
311 /* NB: This is either called via fops or the poll check hrtimer (atomic ctx)
313 * It's safe to read OA config state here unlocked, assuming that this is only
314 * called while the stream is enabled, while the global OA configuration can't
317 * Note: we don't lock around the head/tail reads even though there's the slim
318 * possibility of read() fop errors forcing a re-init of the OA buffer
319 * pointers. A race here could result in a false positive !empty status which
322 static bool gen7_oa_buffer_is_empty_fop_unlocked(struct drm_i915_private *dev_priv)
324 int report_size = dev_priv->perf.oa.oa_buffer.format_size;
325 u32 oastatus2 = I915_READ(GEN7_OASTATUS2);
326 u32 oastatus1 = I915_READ(GEN7_OASTATUS1);
327 u32 head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
328 u32 tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
330 return OA_TAKEN(tail, head) <
331 dev_priv->perf.oa.tail_margin + report_size;
335 * append_oa_status - Appends a status record to a userspace read() buffer.
336 * @stream: An i915-perf stream opened for OA metrics
337 * @buf: destination buffer given by userspace
338 * @count: the number of bytes userspace wants to read
339 * @offset: (inout): the current position for writing into @buf
340 * @type: The kind of status to report to userspace
342 * Writes a status record (such as `DRM_I915_PERF_RECORD_OA_REPORT_LOST`)
343 * into the userspace read() buffer.
345 * The @buf @offset will only be updated on success.
347 * Returns: 0 on success, negative error code on failure.
349 static int append_oa_status(struct i915_perf_stream *stream,
353 enum drm_i915_perf_record_type type)
355 struct drm_i915_perf_record_header header = { type, 0, sizeof(header) };
357 if ((count - *offset) < header.size)
360 if (copy_to_user(buf + *offset, &header, sizeof(header)))
363 (*offset) += header.size;
369 * append_oa_sample - Copies single OA report into userspace read() buffer.
370 * @stream: An i915-perf stream opened for OA metrics
371 * @buf: destination buffer given by userspace
372 * @count: the number of bytes userspace wants to read
373 * @offset: (inout): the current position for writing into @buf
374 * @report: A single OA report to (optionally) include as part of the sample
376 * The contents of a sample are configured through `DRM_I915_PERF_PROP_SAMPLE_*`
377 * properties when opening a stream, tracked as `stream->sample_flags`. This
378 * function copies the requested components of a single sample to the given
381 * The @buf @offset will only be updated on success.
383 * Returns: 0 on success, negative error code on failure.
385 static int append_oa_sample(struct i915_perf_stream *stream,
391 struct drm_i915_private *dev_priv = stream->dev_priv;
392 int report_size = dev_priv->perf.oa.oa_buffer.format_size;
393 struct drm_i915_perf_record_header header;
394 u32 sample_flags = stream->sample_flags;
396 header.type = DRM_I915_PERF_RECORD_SAMPLE;
398 header.size = stream->sample_size;
400 if ((count - *offset) < header.size)
404 if (copy_to_user(buf, &header, sizeof(header)))
406 buf += sizeof(header);
408 if (sample_flags & SAMPLE_OA_REPORT) {
409 if (copy_to_user(buf, report, report_size))
413 (*offset) += header.size;
419 * Copies all buffered OA reports into userspace read() buffer.
420 * @stream: An i915-perf stream opened for OA metrics
421 * @buf: destination buffer given by userspace
422 * @count: the number of bytes userspace wants to read
423 * @offset: (inout): the current position for writing into @buf
424 * @head_ptr: (inout): the current oa buffer cpu read position
425 * @tail: the current oa buffer gpu write position
427 * Notably any error condition resulting in a short read (-%ENOSPC or
428 * -%EFAULT) will be returned even though one or more records may
429 * have been successfully copied. In this case it's up to the caller
430 * to decide if the error should be squashed before returning to
433 * Note: reports are consumed from the head, and appended to the
434 * tail, so the head chases the tail?... If you think that's mad
435 * and back-to-front you're not alone, but this follows the
436 * Gen PRM naming convention.
438 * Returns: 0 on success, negative error code on failure.
440 static int gen7_append_oa_reports(struct i915_perf_stream *stream,
447 struct drm_i915_private *dev_priv = stream->dev_priv;
448 int report_size = dev_priv->perf.oa.oa_buffer.format_size;
449 u8 *oa_buf_base = dev_priv->perf.oa.oa_buffer.vaddr;
450 int tail_margin = dev_priv->perf.oa.tail_margin;
451 u32 gtt_offset = i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma);
452 u32 mask = (OA_BUFFER_SIZE - 1);
457 if (WARN_ON(!stream->enabled))
460 head = *head_ptr - gtt_offset;
463 /* The OA unit is expected to wrap the tail pointer according to the OA
464 * buffer size and since we should never write a misaligned head
465 * pointer we don't expect to read one back either...
467 if (tail > OA_BUFFER_SIZE || head > OA_BUFFER_SIZE ||
468 head % report_size) {
469 DRM_ERROR("Inconsistent OA buffer pointer (head = %u, tail = %u): force restart\n",
471 dev_priv->perf.oa.ops.oa_disable(dev_priv);
472 dev_priv->perf.oa.ops.oa_enable(dev_priv);
473 *head_ptr = I915_READ(GEN7_OASTATUS2) &
474 GEN7_OASTATUS2_HEAD_MASK;
479 /* The tail pointer increases in 64 byte increments, not in report_size
482 tail &= ~(report_size - 1);
484 /* Move the tail pointer back by the current tail_margin to account for
485 * the possibility that the latest reports may not have really landed
489 if (OA_TAKEN(tail, head) < report_size + tail_margin)
496 (taken = OA_TAKEN(tail, head));
497 head = (head + report_size) & mask) {
498 u8 *report = oa_buf_base + head;
499 u32 *report32 = (void *)report;
501 /* All the report sizes factor neatly into the buffer
502 * size so we never expect to see a report split
503 * between the beginning and end of the buffer.
505 * Given the initial alignment check a misalignment
506 * here would imply a driver bug that would result
509 if (WARN_ON((OA_BUFFER_SIZE - head) < report_size)) {
510 DRM_ERROR("Spurious OA head ptr: non-integral report offset\n");
514 /* The report-ID field for periodic samples includes
515 * some undocumented flags related to what triggered
516 * the report and is never expected to be zero so we
517 * can check that the report isn't invalid before
518 * copying it to userspace...
520 if (report32[0] == 0) {
521 DRM_NOTE("Skipping spurious, invalid OA report\n");
525 ret = append_oa_sample(stream, buf, count, offset, report);
529 /* The above report-id field sanity check is based on
530 * the assumption that the OA buffer is initially
531 * zeroed and we reset the field after copying so the
532 * check is still meaningful once old reports start
538 *head_ptr = gtt_offset + head;
544 * gen7_oa_read - copy status records then buffered OA reports
545 * @stream: An i915-perf stream opened for OA metrics
546 * @buf: destination buffer given by userspace
547 * @count: the number of bytes userspace wants to read
548 * @offset: (inout): the current position for writing into @buf
550 * Checks Gen 7 specific OA unit status registers and if necessary appends
551 * corresponding status records for userspace (such as for a buffer full
552 * condition) and then initiate appending any buffered OA reports.
554 * Updates @offset according to the number of bytes successfully copied into
555 * the userspace buffer.
557 * Returns: zero on success or a negative error code
559 static int gen7_oa_read(struct i915_perf_stream *stream,
564 struct drm_i915_private *dev_priv = stream->dev_priv;
565 int report_size = dev_priv->perf.oa.oa_buffer.format_size;
572 if (WARN_ON(!dev_priv->perf.oa.oa_buffer.vaddr))
575 oastatus2 = I915_READ(GEN7_OASTATUS2);
576 oastatus1 = I915_READ(GEN7_OASTATUS1);
578 head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
579 tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
581 /* XXX: On Haswell we don't have a safe way to clear oastatus1
582 * bits while the OA unit is enabled (while the tail pointer
583 * may be updated asynchronously) so we ignore status bits
584 * that have already been reported to userspace.
586 oastatus1 &= ~dev_priv->perf.oa.gen7_latched_oastatus1;
588 /* We treat OABUFFER_OVERFLOW as a significant error:
590 * - The status can be interpreted to mean that the buffer is
591 * currently full (with a higher precedence than OA_TAKEN()
592 * which will start to report a near-empty buffer after an
593 * overflow) but it's awkward that we can't clear the status
594 * on Haswell, so without a reset we won't be able to catch
597 * - Since it also implies the HW has started overwriting old
598 * reports it may also affect our sanity checks for invalid
599 * reports when copying to userspace that assume new reports
600 * are being written to cleared memory.
602 * - In the future we may want to introduce a flight recorder
603 * mode where the driver will automatically maintain a safe
604 * guard band between head/tail, avoiding this overflow
605 * condition, but we avoid the added driver complexity for
608 if (unlikely(oastatus1 & GEN7_OASTATUS1_OABUFFER_OVERFLOW)) {
609 ret = append_oa_status(stream, buf, count, offset,
610 DRM_I915_PERF_RECORD_OA_BUFFER_LOST);
614 DRM_DEBUG("OA buffer overflow: force restart\n");
616 dev_priv->perf.oa.ops.oa_disable(dev_priv);
617 dev_priv->perf.oa.ops.oa_enable(dev_priv);
619 oastatus2 = I915_READ(GEN7_OASTATUS2);
620 oastatus1 = I915_READ(GEN7_OASTATUS1);
622 head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
623 tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
626 if (unlikely(oastatus1 & GEN7_OASTATUS1_REPORT_LOST)) {
627 ret = append_oa_status(stream, buf, count, offset,
628 DRM_I915_PERF_RECORD_OA_REPORT_LOST);
631 dev_priv->perf.oa.gen7_latched_oastatus1 |=
632 GEN7_OASTATUS1_REPORT_LOST;
635 ret = gen7_append_oa_reports(stream, buf, count, offset,
638 /* All the report sizes are a power of two and the
639 * head should always be incremented by some multiple
640 * of the report size.
642 * A warning here, but notably if we later read back a
643 * misaligned pointer we will treat that as a bug since
644 * it could lead to a buffer overrun.
646 WARN_ONCE(head & (report_size - 1),
647 "i915: Writing misaligned OA head pointer");
649 /* Note: we update the head pointer here even if an error
650 * was returned since the error may represent a short read
651 * where some some reports were successfully copied.
653 I915_WRITE(GEN7_OASTATUS2,
654 ((head & GEN7_OASTATUS2_HEAD_MASK) |
655 OA_MEM_SELECT_GGTT));
661 * i915_oa_wait_unlocked - handles blocking IO until OA data available
662 * @stream: An i915-perf stream opened for OA metrics
664 * Called when userspace tries to read() from a blocking stream FD opened
665 * for OA metrics. It waits until the hrtimer callback finds a non-empty
666 * OA buffer and wakes us.
668 * Note: it's acceptable to have this return with some false positives
669 * since any subsequent read handling will return -EAGAIN if there isn't
670 * really data ready for userspace yet.
672 * Returns: zero on success or a negative error code
674 static int i915_oa_wait_unlocked(struct i915_perf_stream *stream)
676 struct drm_i915_private *dev_priv = stream->dev_priv;
678 /* We would wait indefinitely if periodic sampling is not enabled */
679 if (!dev_priv->perf.oa.periodic)
682 /* Note: the oa_buffer_is_empty() condition is ok to run unlocked as it
683 * just performs mmio reads of the OA buffer head + tail pointers and
684 * it's assumed we're handling some operation that implies the stream
685 * can't be destroyed until completion (such as a read()) that ensures
686 * the device + OA buffer can't disappear
688 return wait_event_interruptible(dev_priv->perf.oa.poll_wq,
689 !dev_priv->perf.oa.ops.oa_buffer_is_empty(dev_priv));
693 * i915_oa_poll_wait - call poll_wait() for an OA stream poll()
694 * @stream: An i915-perf stream opened for OA metrics
695 * @file: An i915 perf stream file
696 * @wait: poll() state table
698 * For handling userspace polling on an i915 perf stream opened for OA metrics,
699 * this starts a poll_wait with the wait queue that our hrtimer callback wakes
700 * when it sees data ready to read in the circular OA buffer.
702 static void i915_oa_poll_wait(struct i915_perf_stream *stream,
706 struct drm_i915_private *dev_priv = stream->dev_priv;
708 poll_wait(file, &dev_priv->perf.oa.poll_wq, wait);
712 * i915_oa_read - just calls through to &i915_oa_ops->read
713 * @stream: An i915-perf stream opened for OA metrics
714 * @buf: destination buffer given by userspace
715 * @count: the number of bytes userspace wants to read
716 * @offset: (inout): the current position for writing into @buf
718 * Updates @offset according to the number of bytes successfully copied into
719 * the userspace buffer.
721 * Returns: zero on success or a negative error code
723 static int i915_oa_read(struct i915_perf_stream *stream,
728 struct drm_i915_private *dev_priv = stream->dev_priv;
730 return dev_priv->perf.oa.ops.read(stream, buf, count, offset);
734 * oa_get_render_ctx_id - determine and hold ctx hw id
735 * @stream: An i915-perf stream opened for OA metrics
737 * Determine the render context hw id, and ensure it remains fixed for the
738 * lifetime of the stream. This ensures that we don't have to worry about
739 * updating the context ID in OACONTROL on the fly.
741 * Returns: zero on success or a negative error code
743 static int oa_get_render_ctx_id(struct i915_perf_stream *stream)
745 struct drm_i915_private *dev_priv = stream->dev_priv;
746 struct intel_engine_cs *engine = dev_priv->engine[RCS];
749 ret = i915_mutex_lock_interruptible(&dev_priv->drm);
753 /* As the ID is the gtt offset of the context's vma we pin
754 * the vma to ensure the ID remains fixed.
756 * NB: implied RCS engine...
758 ret = engine->context_pin(engine, stream->ctx);
762 /* Explicitly track the ID (instead of calling i915_ggtt_offset()
763 * on the fly) considering the difference with gen8+ and
766 dev_priv->perf.oa.specific_ctx_id =
767 i915_ggtt_offset(stream->ctx->engine[engine->id].state);
770 mutex_unlock(&dev_priv->drm.struct_mutex);
776 * oa_put_render_ctx_id - counterpart to oa_get_render_ctx_id releases hold
777 * @stream: An i915-perf stream opened for OA metrics
779 * In case anything needed doing to ensure the context HW ID would remain valid
780 * for the lifetime of the stream, then that can be undone here.
782 static void oa_put_render_ctx_id(struct i915_perf_stream *stream)
784 struct drm_i915_private *dev_priv = stream->dev_priv;
785 struct intel_engine_cs *engine = dev_priv->engine[RCS];
787 mutex_lock(&dev_priv->drm.struct_mutex);
789 dev_priv->perf.oa.specific_ctx_id = INVALID_CTX_ID;
790 engine->context_unpin(engine, stream->ctx);
792 mutex_unlock(&dev_priv->drm.struct_mutex);
796 free_oa_buffer(struct drm_i915_private *i915)
798 mutex_lock(&i915->drm.struct_mutex);
800 i915_gem_object_unpin_map(i915->perf.oa.oa_buffer.vma->obj);
801 i915_vma_unpin(i915->perf.oa.oa_buffer.vma);
802 i915_gem_object_put(i915->perf.oa.oa_buffer.vma->obj);
804 i915->perf.oa.oa_buffer.vma = NULL;
805 i915->perf.oa.oa_buffer.vaddr = NULL;
807 mutex_unlock(&i915->drm.struct_mutex);
810 static void i915_oa_stream_destroy(struct i915_perf_stream *stream)
812 struct drm_i915_private *dev_priv = stream->dev_priv;
814 BUG_ON(stream != dev_priv->perf.oa.exclusive_stream);
816 dev_priv->perf.oa.ops.disable_metric_set(dev_priv);
818 free_oa_buffer(dev_priv);
820 intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
821 intel_runtime_pm_put(dev_priv);
824 oa_put_render_ctx_id(stream);
826 dev_priv->perf.oa.exclusive_stream = NULL;
829 static void gen7_init_oa_buffer(struct drm_i915_private *dev_priv)
831 u32 gtt_offset = i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma);
833 /* Pre-DevBDW: OABUFFER must be set with counters off,
834 * before OASTATUS1, but after OASTATUS2
836 I915_WRITE(GEN7_OASTATUS2, gtt_offset | OA_MEM_SELECT_GGTT); /* head */
837 I915_WRITE(GEN7_OABUFFER, gtt_offset);
838 I915_WRITE(GEN7_OASTATUS1, gtt_offset | OABUFFER_SIZE_16M); /* tail */
840 /* On Haswell we have to track which OASTATUS1 flags we've
841 * already seen since they can't be cleared while periodic
842 * sampling is enabled.
844 dev_priv->perf.oa.gen7_latched_oastatus1 = 0;
846 /* NB: although the OA buffer will initially be allocated
847 * zeroed via shmfs (and so this memset is redundant when
848 * first allocating), we may re-init the OA buffer, either
849 * when re-enabling a stream or in error/reset paths.
851 * The reason we clear the buffer for each re-init is for the
852 * sanity check in gen7_append_oa_reports() that looks at the
853 * report-id field to make sure it's non-zero which relies on
854 * the assumption that new reports are being written to zeroed
857 memset(dev_priv->perf.oa.oa_buffer.vaddr, 0, OA_BUFFER_SIZE);
859 /* Maybe make ->pollin per-stream state if we support multiple
860 * concurrent streams in the future.
862 dev_priv->perf.oa.pollin = false;
865 static int alloc_oa_buffer(struct drm_i915_private *dev_priv)
867 struct drm_i915_gem_object *bo;
868 struct i915_vma *vma;
871 if (WARN_ON(dev_priv->perf.oa.oa_buffer.vma))
874 ret = i915_mutex_lock_interruptible(&dev_priv->drm);
878 BUILD_BUG_ON_NOT_POWER_OF_2(OA_BUFFER_SIZE);
879 BUILD_BUG_ON(OA_BUFFER_SIZE < SZ_128K || OA_BUFFER_SIZE > SZ_16M);
881 bo = i915_gem_object_create(dev_priv, OA_BUFFER_SIZE);
883 DRM_ERROR("Failed to allocate OA buffer\n");
888 ret = i915_gem_object_set_cache_level(bo, I915_CACHE_LLC);
892 /* PreHSW required 512K alignment, HSW requires 16M */
893 vma = i915_gem_object_ggtt_pin(bo, NULL, 0, SZ_16M, 0);
898 dev_priv->perf.oa.oa_buffer.vma = vma;
900 dev_priv->perf.oa.oa_buffer.vaddr =
901 i915_gem_object_pin_map(bo, I915_MAP_WB);
902 if (IS_ERR(dev_priv->perf.oa.oa_buffer.vaddr)) {
903 ret = PTR_ERR(dev_priv->perf.oa.oa_buffer.vaddr);
907 dev_priv->perf.oa.ops.init_oa_buffer(dev_priv);
909 DRM_DEBUG_DRIVER("OA Buffer initialized, gtt offset = 0x%x, vaddr = %p\n",
910 i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma),
911 dev_priv->perf.oa.oa_buffer.vaddr);
916 __i915_vma_unpin(vma);
919 i915_gem_object_put(bo);
921 dev_priv->perf.oa.oa_buffer.vaddr = NULL;
922 dev_priv->perf.oa.oa_buffer.vma = NULL;
925 mutex_unlock(&dev_priv->drm.struct_mutex);
929 static void config_oa_regs(struct drm_i915_private *dev_priv,
930 const struct i915_oa_reg *regs,
935 for (i = 0; i < n_regs; i++) {
936 const struct i915_oa_reg *reg = regs + i;
938 I915_WRITE(reg->addr, reg->value);
942 static int hsw_enable_metric_set(struct drm_i915_private *dev_priv)
944 int ret = i915_oa_select_metric_set_hsw(dev_priv);
949 I915_WRITE(GDT_CHICKEN_BITS, (I915_READ(GDT_CHICKEN_BITS) |
954 * OA unit is using “crclk” for its functionality. When trunk
955 * level clock gating takes place, OA clock would be gated,
956 * unable to count the events from non-render clock domain.
957 * Render clock gating must be disabled when OA is enabled to
958 * count the events from non-render domain. Unit level clock
959 * gating for RCS should also be disabled.
961 I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) &
962 ~GEN7_DOP_CLOCK_GATE_ENABLE));
963 I915_WRITE(GEN6_UCGCTL1, (I915_READ(GEN6_UCGCTL1) |
964 GEN6_CSUNIT_CLOCK_GATE_DISABLE));
966 config_oa_regs(dev_priv, dev_priv->perf.oa.mux_regs,
967 dev_priv->perf.oa.mux_regs_len);
969 /* It apparently takes a fairly long time for a new MUX
970 * configuration to be be applied after these register writes.
971 * This delay duration was derived empirically based on the
972 * render_basic config but hopefully it covers the maximum
973 * configuration latency.
975 * As a fallback, the checks in _append_oa_reports() to skip
976 * invalid OA reports do also seem to work to discard reports
977 * generated before this config has completed - albeit not
980 * Unfortunately this is essentially a magic number, since we
981 * don't currently know of a reliable mechanism for predicting
982 * how long the MUX config will take to apply and besides
983 * seeing invalid reports we don't know of a reliable way to
984 * explicitly check that the MUX config has landed.
986 * It's even possible we've miss characterized the underlying
987 * problem - it just seems like the simplest explanation why
988 * a delay at this location would mitigate any invalid reports.
990 usleep_range(15000, 20000);
992 config_oa_regs(dev_priv, dev_priv->perf.oa.b_counter_regs,
993 dev_priv->perf.oa.b_counter_regs_len);
998 static void hsw_disable_metric_set(struct drm_i915_private *dev_priv)
1000 I915_WRITE(GEN6_UCGCTL1, (I915_READ(GEN6_UCGCTL1) &
1001 ~GEN6_CSUNIT_CLOCK_GATE_DISABLE));
1002 I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) |
1003 GEN7_DOP_CLOCK_GATE_ENABLE));
1005 I915_WRITE(GDT_CHICKEN_BITS, (I915_READ(GDT_CHICKEN_BITS) &
1009 static void gen7_update_oacontrol_locked(struct drm_i915_private *dev_priv)
1011 assert_spin_locked(&dev_priv->perf.hook_lock);
1013 if (dev_priv->perf.oa.exclusive_stream->enabled) {
1014 struct i915_gem_context *ctx =
1015 dev_priv->perf.oa.exclusive_stream->ctx;
1016 u32 ctx_id = dev_priv->perf.oa.specific_ctx_id;
1018 bool periodic = dev_priv->perf.oa.periodic;
1019 u32 period_exponent = dev_priv->perf.oa.period_exponent;
1020 u32 report_format = dev_priv->perf.oa.oa_buffer.format;
1022 I915_WRITE(GEN7_OACONTROL,
1023 (ctx_id & GEN7_OACONTROL_CTX_MASK) |
1025 GEN7_OACONTROL_TIMER_PERIOD_SHIFT) |
1026 (periodic ? GEN7_OACONTROL_TIMER_ENABLE : 0) |
1027 (report_format << GEN7_OACONTROL_FORMAT_SHIFT) |
1028 (ctx ? GEN7_OACONTROL_PER_CTX_ENABLE : 0) |
1029 GEN7_OACONTROL_ENABLE);
1031 I915_WRITE(GEN7_OACONTROL, 0);
1034 static void gen7_oa_enable(struct drm_i915_private *dev_priv)
1036 unsigned long flags;
1038 /* Reset buf pointers so we don't forward reports from before now.
1040 * Think carefully if considering trying to avoid this, since it
1041 * also ensures status flags and the buffer itself are cleared
1042 * in error paths, and we have checks for invalid reports based
1043 * on the assumption that certain fields are written to zeroed
1044 * memory which this helps maintains.
1046 gen7_init_oa_buffer(dev_priv);
1048 spin_lock_irqsave(&dev_priv->perf.hook_lock, flags);
1049 gen7_update_oacontrol_locked(dev_priv);
1050 spin_unlock_irqrestore(&dev_priv->perf.hook_lock, flags);
1054 * i915_oa_stream_enable - handle `I915_PERF_IOCTL_ENABLE` for OA stream
1055 * @stream: An i915 perf stream opened for OA metrics
1057 * [Re]enables hardware periodic sampling according to the period configured
1058 * when opening the stream. This also starts a hrtimer that will periodically
1059 * check for data in the circular OA buffer for notifying userspace (e.g.
1060 * during a read() or poll()).
1062 static void i915_oa_stream_enable(struct i915_perf_stream *stream)
1064 struct drm_i915_private *dev_priv = stream->dev_priv;
1066 dev_priv->perf.oa.ops.oa_enable(dev_priv);
1068 if (dev_priv->perf.oa.periodic)
1069 hrtimer_start(&dev_priv->perf.oa.poll_check_timer,
1070 ns_to_ktime(POLL_PERIOD),
1071 HRTIMER_MODE_REL_PINNED);
1074 static void gen7_oa_disable(struct drm_i915_private *dev_priv)
1076 I915_WRITE(GEN7_OACONTROL, 0);
1080 * i915_oa_stream_disable - handle `I915_PERF_IOCTL_DISABLE` for OA stream
1081 * @stream: An i915 perf stream opened for OA metrics
1083 * Stops the OA unit from periodically writing counter reports into the
1084 * circular OA buffer. This also stops the hrtimer that periodically checks for
1085 * data in the circular OA buffer, for notifying userspace.
1087 static void i915_oa_stream_disable(struct i915_perf_stream *stream)
1089 struct drm_i915_private *dev_priv = stream->dev_priv;
1091 dev_priv->perf.oa.ops.oa_disable(dev_priv);
1093 if (dev_priv->perf.oa.periodic)
1094 hrtimer_cancel(&dev_priv->perf.oa.poll_check_timer);
1097 static u64 oa_exponent_to_ns(struct drm_i915_private *dev_priv, int exponent)
1099 return div_u64(1000000000ULL * (2ULL << exponent),
1100 dev_priv->perf.oa.timestamp_frequency);
1103 static const struct i915_perf_stream_ops i915_oa_stream_ops = {
1104 .destroy = i915_oa_stream_destroy,
1105 .enable = i915_oa_stream_enable,
1106 .disable = i915_oa_stream_disable,
1107 .wait_unlocked = i915_oa_wait_unlocked,
1108 .poll_wait = i915_oa_poll_wait,
1109 .read = i915_oa_read,
1113 * i915_oa_stream_init - validate combined props for OA stream and init
1114 * @stream: An i915 perf stream
1115 * @param: The open parameters passed to `DRM_I915_PERF_OPEN`
1116 * @props: The property state that configures stream (individually validated)
1118 * While read_properties_unlocked() validates properties in isolation it
1119 * doesn't ensure that the combination necessarily makes sense.
1121 * At this point it has been determined that userspace wants a stream of
1122 * OA metrics, but still we need to further validate the combined
1123 * properties are OK.
1125 * If the configuration makes sense then we can allocate memory for
1126 * a circular OA buffer and apply the requested metric set configuration.
1128 * Returns: zero on success or a negative error code.
1130 static int i915_oa_stream_init(struct i915_perf_stream *stream,
1131 struct drm_i915_perf_open_param *param,
1132 struct perf_open_properties *props)
1134 struct drm_i915_private *dev_priv = stream->dev_priv;
1138 /* If the sysfs metrics/ directory wasn't registered for some
1139 * reason then don't let userspace try their luck with config
1142 if (!dev_priv->perf.metrics_kobj) {
1143 DRM_DEBUG("OA metrics weren't advertised via sysfs\n");
1147 if (!(props->sample_flags & SAMPLE_OA_REPORT)) {
1148 DRM_DEBUG("Only OA report sampling supported\n");
1152 if (!dev_priv->perf.oa.ops.init_oa_buffer) {
1153 DRM_DEBUG("OA unit not supported\n");
1157 /* To avoid the complexity of having to accurately filter
1158 * counter reports and marshal to the appropriate client
1159 * we currently only allow exclusive access
1161 if (dev_priv->perf.oa.exclusive_stream) {
1162 DRM_DEBUG("OA unit already in use\n");
1166 if (!props->metrics_set) {
1167 DRM_DEBUG("OA metric set not specified\n");
1171 if (!props->oa_format) {
1172 DRM_DEBUG("OA report format not specified\n");
1176 stream->sample_size = sizeof(struct drm_i915_perf_record_header);
1178 format_size = dev_priv->perf.oa.oa_formats[props->oa_format].size;
1180 stream->sample_flags |= SAMPLE_OA_REPORT;
1181 stream->sample_size += format_size;
1183 dev_priv->perf.oa.oa_buffer.format_size = format_size;
1184 if (WARN_ON(dev_priv->perf.oa.oa_buffer.format_size == 0))
1187 dev_priv->perf.oa.oa_buffer.format =
1188 dev_priv->perf.oa.oa_formats[props->oa_format].format;
1190 dev_priv->perf.oa.metrics_set = props->metrics_set;
1192 dev_priv->perf.oa.periodic = props->oa_periodic;
1193 if (dev_priv->perf.oa.periodic) {
1196 dev_priv->perf.oa.period_exponent = props->oa_period_exponent;
1198 /* See comment for OA_TAIL_MARGIN_NSEC for details
1199 * about this tail_margin...
1201 tail = div64_u64(OA_TAIL_MARGIN_NSEC,
1202 oa_exponent_to_ns(dev_priv,
1203 props->oa_period_exponent));
1204 dev_priv->perf.oa.tail_margin = (tail + 1) * format_size;
1208 ret = oa_get_render_ctx_id(stream);
1213 ret = alloc_oa_buffer(dev_priv);
1215 goto err_oa_buf_alloc;
1217 /* PRM - observability performance counters:
1219 * OACONTROL, performance counter enable, note:
1221 * "When this bit is set, in order to have coherent counts,
1222 * RC6 power state and trunk clock gating must be disabled.
1223 * This can be achieved by programming MMIO registers as
1224 * 0xA094=0 and 0xA090[31]=1"
1226 * In our case we are expecting that taking pm + FORCEWAKE
1227 * references will effectively disable RC6.
1229 intel_runtime_pm_get(dev_priv);
1230 intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
1232 ret = dev_priv->perf.oa.ops.enable_metric_set(dev_priv);
1236 stream->ops = &i915_oa_stream_ops;
1238 dev_priv->perf.oa.exclusive_stream = stream;
1243 intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
1244 intel_runtime_pm_put(dev_priv);
1245 free_oa_buffer(dev_priv);
1249 oa_put_render_ctx_id(stream);
1255 * i915_perf_read_locked - &i915_perf_stream_ops->read with error normalisation
1256 * @stream: An i915 perf stream
1257 * @file: An i915 perf stream file
1258 * @buf: destination buffer given by userspace
1259 * @count: the number of bytes userspace wants to read
1260 * @ppos: (inout) file seek position (unused)
1262 * Besides wrapping &i915_perf_stream_ops->read this provides a common place to
1263 * ensure that if we've successfully copied any data then reporting that takes
1264 * precedence over any internal error status, so the data isn't lost.
1266 * For example ret will be -ENOSPC whenever there is more buffered data than
1267 * can be copied to userspace, but that's only interesting if we weren't able
1268 * to copy some data because it implies the userspace buffer is too small to
1269 * receive a single record (and we never split records).
1271 * Another case with ret == -EFAULT is more of a grey area since it would seem
1272 * like bad form for userspace to ask us to overrun its buffer, but the user
1275 * http://yarchive.net/comp/linux/partial_reads_writes.html
1277 * Returns: The number of bytes copied or a negative error code on failure.
1279 static ssize_t i915_perf_read_locked(struct i915_perf_stream *stream,
1285 /* Note we keep the offset (aka bytes read) separate from any
1286 * error status so that the final check for whether we return
1287 * the bytes read with a higher precedence than any error (see
1288 * comment below) doesn't need to be handled/duplicated in
1289 * stream->ops->read() implementations.
1292 int ret = stream->ops->read(stream, buf, count, &offset);
1294 return offset ?: (ret ?: -EAGAIN);
1298 * i915_perf_read - handles read() FOP for i915 perf stream FDs
1299 * @file: An i915 perf stream file
1300 * @buf: destination buffer given by userspace
1301 * @count: the number of bytes userspace wants to read
1302 * @ppos: (inout) file seek position (unused)
1304 * The entry point for handling a read() on a stream file descriptor from
1305 * userspace. Most of the work is left to the i915_perf_read_locked() and
1306 * &i915_perf_stream_ops->read but to save having stream implementations (of
1307 * which we might have multiple later) we handle blocking read here.
1309 * We can also consistently treat trying to read from a disabled stream
1310 * as an IO error so implementations can assume the stream is enabled
1313 * Returns: The number of bytes copied or a negative error code on failure.
1315 static ssize_t i915_perf_read(struct file *file,
1320 struct i915_perf_stream *stream = file->private_data;
1321 struct drm_i915_private *dev_priv = stream->dev_priv;
1324 /* To ensure it's handled consistently we simply treat all reads of a
1325 * disabled stream as an error. In particular it might otherwise lead
1326 * to a deadlock for blocking file descriptors...
1328 if (!stream->enabled)
1331 if (!(file->f_flags & O_NONBLOCK)) {
1332 /* There's the small chance of false positives from
1333 * stream->ops->wait_unlocked.
1335 * E.g. with single context filtering since we only wait until
1336 * oabuffer has >= 1 report we don't immediately know whether
1337 * any reports really belong to the current context
1340 ret = stream->ops->wait_unlocked(stream);
1344 mutex_lock(&dev_priv->perf.lock);
1345 ret = i915_perf_read_locked(stream, file,
1347 mutex_unlock(&dev_priv->perf.lock);
1348 } while (ret == -EAGAIN);
1350 mutex_lock(&dev_priv->perf.lock);
1351 ret = i915_perf_read_locked(stream, file, buf, count, ppos);
1352 mutex_unlock(&dev_priv->perf.lock);
1356 /* Maybe make ->pollin per-stream state if we support multiple
1357 * concurrent streams in the future.
1359 dev_priv->perf.oa.pollin = false;
1365 static enum hrtimer_restart oa_poll_check_timer_cb(struct hrtimer *hrtimer)
1367 struct drm_i915_private *dev_priv =
1368 container_of(hrtimer, typeof(*dev_priv),
1369 perf.oa.poll_check_timer);
1371 if (!dev_priv->perf.oa.ops.oa_buffer_is_empty(dev_priv)) {
1372 dev_priv->perf.oa.pollin = true;
1373 wake_up(&dev_priv->perf.oa.poll_wq);
1376 hrtimer_forward_now(hrtimer, ns_to_ktime(POLL_PERIOD));
1378 return HRTIMER_RESTART;
1382 * i915_perf_poll_locked - poll_wait() with a suitable wait queue for stream
1383 * @dev_priv: i915 device instance
1384 * @stream: An i915 perf stream
1385 * @file: An i915 perf stream file
1386 * @wait: poll() state table
1388 * For handling userspace polling on an i915 perf stream, this calls through to
1389 * &i915_perf_stream_ops->poll_wait to call poll_wait() with a wait queue that
1390 * will be woken for new stream data.
1392 * Note: The &drm_i915_private->perf.lock mutex has been taken to serialize
1393 * with any non-file-operation driver hooks.
1395 * Returns: any poll events that are ready without sleeping
1397 static unsigned int i915_perf_poll_locked(struct drm_i915_private *dev_priv,
1398 struct i915_perf_stream *stream,
1402 unsigned int events = 0;
1404 stream->ops->poll_wait(stream, file, wait);
1406 /* Note: we don't explicitly check whether there's something to read
1407 * here since this path may be very hot depending on what else
1408 * userspace is polling, or on the timeout in use. We rely solely on
1409 * the hrtimer/oa_poll_check_timer_cb to notify us when there are
1412 if (dev_priv->perf.oa.pollin)
1419 * i915_perf_poll - call poll_wait() with a suitable wait queue for stream
1420 * @file: An i915 perf stream file
1421 * @wait: poll() state table
1423 * For handling userspace polling on an i915 perf stream, this ensures
1424 * poll_wait() gets called with a wait queue that will be woken for new stream
1427 * Note: Implementation deferred to i915_perf_poll_locked()
1429 * Returns: any poll events that are ready without sleeping
1431 static unsigned int i915_perf_poll(struct file *file, poll_table *wait)
1433 struct i915_perf_stream *stream = file->private_data;
1434 struct drm_i915_private *dev_priv = stream->dev_priv;
1437 mutex_lock(&dev_priv->perf.lock);
1438 ret = i915_perf_poll_locked(dev_priv, stream, file, wait);
1439 mutex_unlock(&dev_priv->perf.lock);
1445 * i915_perf_enable_locked - handle `I915_PERF_IOCTL_ENABLE` ioctl
1446 * @stream: A disabled i915 perf stream
1448 * [Re]enables the associated capture of data for this stream.
1450 * If a stream was previously enabled then there's currently no intention
1451 * to provide userspace any guarantee about the preservation of previously
1454 static void i915_perf_enable_locked(struct i915_perf_stream *stream)
1456 if (stream->enabled)
1459 /* Allow stream->ops->enable() to refer to this */
1460 stream->enabled = true;
1462 if (stream->ops->enable)
1463 stream->ops->enable(stream);
1467 * i915_perf_disable_locked - handle `I915_PERF_IOCTL_DISABLE` ioctl
1468 * @stream: An enabled i915 perf stream
1470 * Disables the associated capture of data for this stream.
1472 * The intention is that disabling an re-enabling a stream will ideally be
1473 * cheaper than destroying and re-opening a stream with the same configuration,
1474 * though there are no formal guarantees about what state or buffered data
1475 * must be retained between disabling and re-enabling a stream.
1477 * Note: while a stream is disabled it's considered an error for userspace
1478 * to attempt to read from the stream (-EIO).
1480 static void i915_perf_disable_locked(struct i915_perf_stream *stream)
1482 if (!stream->enabled)
1485 /* Allow stream->ops->disable() to refer to this */
1486 stream->enabled = false;
1488 if (stream->ops->disable)
1489 stream->ops->disable(stream);
1493 * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
1494 * @stream: An i915 perf stream
1495 * @cmd: the ioctl request
1496 * @arg: the ioctl data
1498 * Note: The &drm_i915_private->perf.lock mutex has been taken to serialize
1499 * with any non-file-operation driver hooks.
1501 * Returns: zero on success or a negative error code. Returns -EINVAL for
1502 * an unknown ioctl request.
1504 static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
1509 case I915_PERF_IOCTL_ENABLE:
1510 i915_perf_enable_locked(stream);
1512 case I915_PERF_IOCTL_DISABLE:
1513 i915_perf_disable_locked(stream);
1521 * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
1522 * @file: An i915 perf stream file
1523 * @cmd: the ioctl request
1524 * @arg: the ioctl data
1526 * Implementation deferred to i915_perf_ioctl_locked().
1528 * Returns: zero on success or a negative error code. Returns -EINVAL for
1529 * an unknown ioctl request.
1531 static long i915_perf_ioctl(struct file *file,
1535 struct i915_perf_stream *stream = file->private_data;
1536 struct drm_i915_private *dev_priv = stream->dev_priv;
1539 mutex_lock(&dev_priv->perf.lock);
1540 ret = i915_perf_ioctl_locked(stream, cmd, arg);
1541 mutex_unlock(&dev_priv->perf.lock);
1547 * i915_perf_destroy_locked - destroy an i915 perf stream
1548 * @stream: An i915 perf stream
1550 * Frees all resources associated with the given i915 perf @stream, disabling
1551 * any associated data capture in the process.
1553 * Note: The &drm_i915_private->perf.lock mutex has been taken to serialize
1554 * with any non-file-operation driver hooks.
1556 static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
1558 struct drm_i915_private *dev_priv = stream->dev_priv;
1560 if (stream->enabled)
1561 i915_perf_disable_locked(stream);
1563 if (stream->ops->destroy)
1564 stream->ops->destroy(stream);
1566 list_del(&stream->link);
1569 mutex_lock(&dev_priv->drm.struct_mutex);
1570 i915_gem_context_put(stream->ctx);
1571 mutex_unlock(&dev_priv->drm.struct_mutex);
1578 * i915_perf_release - handles userspace close() of a stream file
1579 * @inode: anonymous inode associated with file
1580 * @file: An i915 perf stream file
1582 * Cleans up any resources associated with an open i915 perf stream file.
1584 * NB: close() can't really fail from the userspace point of view.
1586 * Returns: zero on success or a negative error code.
1588 static int i915_perf_release(struct inode *inode, struct file *file)
1590 struct i915_perf_stream *stream = file->private_data;
1591 struct drm_i915_private *dev_priv = stream->dev_priv;
1593 mutex_lock(&dev_priv->perf.lock);
1594 i915_perf_destroy_locked(stream);
1595 mutex_unlock(&dev_priv->perf.lock);
1601 static const struct file_operations fops = {
1602 .owner = THIS_MODULE,
1603 .llseek = no_llseek,
1604 .release = i915_perf_release,
1605 .poll = i915_perf_poll,
1606 .read = i915_perf_read,
1607 .unlocked_ioctl = i915_perf_ioctl,
1611 static struct i915_gem_context *
1612 lookup_context(struct drm_i915_private *dev_priv,
1613 struct drm_i915_file_private *file_priv,
1614 u32 ctx_user_handle)
1616 struct i915_gem_context *ctx;
1619 ret = i915_mutex_lock_interruptible(&dev_priv->drm);
1621 return ERR_PTR(ret);
1623 ctx = i915_gem_context_lookup(file_priv, ctx_user_handle);
1625 i915_gem_context_get(ctx);
1627 mutex_unlock(&dev_priv->drm.struct_mutex);
1633 * i915_perf_open_ioctl_locked - DRM ioctl() for userspace to open a stream FD
1634 * @dev_priv: i915 device instance
1635 * @param: The open parameters passed to 'DRM_I915_PERF_OPEN`
1636 * @props: individually validated u64 property value pairs
1639 * See i915_perf_ioctl_open() for interface details.
1641 * Implements further stream config validation and stream initialization on
1642 * behalf of i915_perf_open_ioctl() with the &drm_i915_private->perf.lock mutex
1643 * taken to serialize with any non-file-operation driver hooks.
1645 * Note: at this point the @props have only been validated in isolation and
1646 * it's still necessary to validate that the combination of properties makes
1649 * In the case where userspace is interested in OA unit metrics then further
1650 * config validation and stream initialization details will be handled by
1651 * i915_oa_stream_init(). The code here should only validate config state that
1652 * will be relevant to all stream types / backends.
1654 * Returns: zero on success or a negative error code.
1657 i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
1658 struct drm_i915_perf_open_param *param,
1659 struct perf_open_properties *props,
1660 struct drm_file *file)
1662 struct i915_gem_context *specific_ctx = NULL;
1663 struct i915_perf_stream *stream = NULL;
1664 unsigned long f_flags = 0;
1668 if (props->single_context) {
1669 u32 ctx_handle = props->ctx_handle;
1670 struct drm_i915_file_private *file_priv = file->driver_priv;
1672 specific_ctx = lookup_context(dev_priv, file_priv, ctx_handle);
1673 if (IS_ERR(specific_ctx)) {
1674 ret = PTR_ERR(specific_ctx);
1676 DRM_DEBUG("Failed to look up context with ID %u for opening perf stream\n",
1682 /* Similar to perf's kernel.perf_paranoid_cpu sysctl option
1683 * we check a dev.i915.perf_stream_paranoid sysctl option
1684 * to determine if it's ok to access system wide OA counters
1685 * without CAP_SYS_ADMIN privileges.
1687 if (!specific_ctx &&
1688 i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
1689 DRM_DEBUG("Insufficient privileges to open system-wide i915 perf stream\n");
1694 stream = kzalloc(sizeof(*stream), GFP_KERNEL);
1700 stream->dev_priv = dev_priv;
1701 stream->ctx = specific_ctx;
1703 ret = i915_oa_stream_init(stream, param, props);
1707 /* we avoid simply assigning stream->sample_flags = props->sample_flags
1708 * to have _stream_init check the combination of sample flags more
1709 * thoroughly, but still this is the expected result at this point.
1711 if (WARN_ON(stream->sample_flags != props->sample_flags)) {
1716 list_add(&stream->link, &dev_priv->perf.streams);
1718 if (param->flags & I915_PERF_FLAG_FD_CLOEXEC)
1719 f_flags |= O_CLOEXEC;
1720 if (param->flags & I915_PERF_FLAG_FD_NONBLOCK)
1721 f_flags |= O_NONBLOCK;
1723 stream_fd = anon_inode_getfd("[i915_perf]", &fops, stream, f_flags);
1724 if (stream_fd < 0) {
1729 if (!(param->flags & I915_PERF_FLAG_DISABLED))
1730 i915_perf_enable_locked(stream);
1735 list_del(&stream->link);
1736 if (stream->ops->destroy)
1737 stream->ops->destroy(stream);
1742 mutex_lock(&dev_priv->drm.struct_mutex);
1743 i915_gem_context_put(specific_ctx);
1744 mutex_unlock(&dev_priv->drm.struct_mutex);
1751 * read_properties_unlocked - validate + copy userspace stream open properties
1752 * @dev_priv: i915 device instance
1753 * @uprops: The array of u64 key value pairs given by userspace
1754 * @n_props: The number of key value pairs expected in @uprops
1755 * @props: The stream configuration built up while validating properties
1757 * Note this function only validates properties in isolation it doesn't
1758 * validate that the combination of properties makes sense or that all
1759 * properties necessary for a particular kind of stream have been set.
1761 * Note that there currently aren't any ordering requirements for properties so
1762 * we shouldn't validate or assume anything about ordering here. This doesn't
1763 * rule out defining new properties with ordering requirements in the future.
1765 static int read_properties_unlocked(struct drm_i915_private *dev_priv,
1768 struct perf_open_properties *props)
1770 u64 __user *uprop = uprops;
1773 memset(props, 0, sizeof(struct perf_open_properties));
1776 DRM_DEBUG("No i915 perf properties given\n");
1780 /* Considering that ID = 0 is reserved and assuming that we don't
1781 * (currently) expect any configurations to ever specify duplicate
1782 * values for a particular property ID then the last _PROP_MAX value is
1783 * one greater than the maximum number of properties we expect to get
1786 if (n_props >= DRM_I915_PERF_PROP_MAX) {
1787 DRM_DEBUG("More i915 perf properties specified than exist\n");
1791 for (i = 0; i < n_props; i++) {
1792 u64 oa_period, oa_freq_hz;
1796 ret = get_user(id, uprop);
1800 ret = get_user(value, uprop + 1);
1804 switch ((enum drm_i915_perf_property_id)id) {
1805 case DRM_I915_PERF_PROP_CTX_HANDLE:
1806 props->single_context = 1;
1807 props->ctx_handle = value;
1809 case DRM_I915_PERF_PROP_SAMPLE_OA:
1810 props->sample_flags |= SAMPLE_OA_REPORT;
1812 case DRM_I915_PERF_PROP_OA_METRICS_SET:
1814 value > dev_priv->perf.oa.n_builtin_sets) {
1815 DRM_DEBUG("Unknown OA metric set ID\n");
1818 props->metrics_set = value;
1820 case DRM_I915_PERF_PROP_OA_FORMAT:
1821 if (value == 0 || value >= I915_OA_FORMAT_MAX) {
1822 DRM_DEBUG("Invalid OA report format\n");
1825 if (!dev_priv->perf.oa.oa_formats[value].size) {
1826 DRM_DEBUG("Invalid OA report format\n");
1829 props->oa_format = value;
1831 case DRM_I915_PERF_PROP_OA_EXPONENT:
1832 if (value > OA_EXPONENT_MAX) {
1833 DRM_DEBUG("OA timer exponent too high (> %u)\n",
1838 /* Theoretically we can program the OA unit to sample
1839 * every 160ns but don't allow that by default unless
1842 * On Haswell the period is derived from the exponent
1845 * period = 80ns * 2^(exponent + 1)
1847 BUILD_BUG_ON(sizeof(oa_period) != 8);
1848 oa_period = 80ull * (2ull << value);
1850 /* This check is primarily to ensure that oa_period <=
1851 * UINT32_MAX (before passing to do_div which only
1852 * accepts a u32 denominator), but we can also skip
1853 * checking anything < 1Hz which implicitly can't be
1854 * limited via an integer oa_max_sample_rate.
1856 if (oa_period <= NSEC_PER_SEC) {
1857 u64 tmp = NSEC_PER_SEC;
1858 do_div(tmp, oa_period);
1863 if (oa_freq_hz > i915_oa_max_sample_rate &&
1864 !capable(CAP_SYS_ADMIN)) {
1865 DRM_DEBUG("OA exponent would exceed the max sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without root privileges\n",
1866 i915_oa_max_sample_rate);
1870 props->oa_periodic = true;
1871 props->oa_period_exponent = value;
1875 DRM_DEBUG("Unknown i915 perf property ID\n");
1886 * i915_perf_open_ioctl - DRM ioctl() for userspace to open a stream FD
1888 * @data: ioctl data copied from userspace (unvalidated)
1891 * Validates the stream open parameters given by userspace including flags
1892 * and an array of u64 key, value pair properties.
1894 * Very little is assumed up front about the nature of the stream being
1895 * opened (for instance we don't assume it's for periodic OA unit metrics). An
1896 * i915-perf stream is expected to be a suitable interface for other forms of
1897 * buffered data written by the GPU besides periodic OA metrics.
1899 * Note we copy the properties from userspace outside of the i915 perf
1900 * mutex to avoid an awkward lockdep with mmap_sem.
1902 * Most of the implementation details are handled by
1903 * i915_perf_open_ioctl_locked() after taking the &drm_i915_private->perf.lock
1904 * mutex for serializing with any non-file-operation driver hooks.
1906 * Return: A newly opened i915 Perf stream file descriptor or negative
1907 * error code on failure.
1909 int i915_perf_open_ioctl(struct drm_device *dev, void *data,
1910 struct drm_file *file)
1912 struct drm_i915_private *dev_priv = dev->dev_private;
1913 struct drm_i915_perf_open_param *param = data;
1914 struct perf_open_properties props;
1915 u32 known_open_flags;
1918 if (!dev_priv->perf.initialized) {
1919 DRM_DEBUG("i915 perf interface not available for this system\n");
1923 known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
1924 I915_PERF_FLAG_FD_NONBLOCK |
1925 I915_PERF_FLAG_DISABLED;
1926 if (param->flags & ~known_open_flags) {
1927 DRM_DEBUG("Unknown drm_i915_perf_open_param flag\n");
1931 ret = read_properties_unlocked(dev_priv,
1932 u64_to_user_ptr(param->properties_ptr),
1933 param->num_properties,
1938 mutex_lock(&dev_priv->perf.lock);
1939 ret = i915_perf_open_ioctl_locked(dev_priv, param, &props, file);
1940 mutex_unlock(&dev_priv->perf.lock);
1946 * i915_perf_register - exposes i915-perf to userspace
1947 * @dev_priv: i915 device instance
1949 * In particular OA metric sets are advertised under a sysfs metrics/
1950 * directory allowing userspace to enumerate valid IDs that can be
1951 * used to open an i915-perf stream.
1953 void i915_perf_register(struct drm_i915_private *dev_priv)
1955 if (!IS_HASWELL(dev_priv))
1958 if (!dev_priv->perf.initialized)
1961 /* To be sure we're synchronized with an attempted
1962 * i915_perf_open_ioctl(); considering that we register after
1963 * being exposed to userspace.
1965 mutex_lock(&dev_priv->perf.lock);
1967 dev_priv->perf.metrics_kobj =
1968 kobject_create_and_add("metrics",
1969 &dev_priv->drm.primary->kdev->kobj);
1970 if (!dev_priv->perf.metrics_kobj)
1973 if (i915_perf_register_sysfs_hsw(dev_priv)) {
1974 kobject_put(dev_priv->perf.metrics_kobj);
1975 dev_priv->perf.metrics_kobj = NULL;
1979 mutex_unlock(&dev_priv->perf.lock);
1983 * i915_perf_unregister - hide i915-perf from userspace
1984 * @dev_priv: i915 device instance
1986 * i915-perf state cleanup is split up into an 'unregister' and
1987 * 'deinit' phase where the interface is first hidden from
1988 * userspace by i915_perf_unregister() before cleaning up
1989 * remaining state in i915_perf_fini().
1991 void i915_perf_unregister(struct drm_i915_private *dev_priv)
1993 if (!IS_HASWELL(dev_priv))
1996 if (!dev_priv->perf.metrics_kobj)
1999 i915_perf_unregister_sysfs_hsw(dev_priv);
2001 kobject_put(dev_priv->perf.metrics_kobj);
2002 dev_priv->perf.metrics_kobj = NULL;
2005 static struct ctl_table oa_table[] = {
2007 .procname = "perf_stream_paranoid",
2008 .data = &i915_perf_stream_paranoid,
2009 .maxlen = sizeof(i915_perf_stream_paranoid),
2011 .proc_handler = proc_dointvec_minmax,
2016 .procname = "oa_max_sample_rate",
2017 .data = &i915_oa_max_sample_rate,
2018 .maxlen = sizeof(i915_oa_max_sample_rate),
2020 .proc_handler = proc_dointvec_minmax,
2022 .extra2 = &oa_sample_rate_hard_limit,
2027 static struct ctl_table i915_root[] = {
2037 static struct ctl_table dev_root[] = {
2048 * i915_perf_init - initialize i915-perf state on module load
2049 * @dev_priv: i915 device instance
2051 * Initializes i915-perf state without exposing anything to userspace.
2053 * Note: i915-perf initialization is split into an 'init' and 'register'
2054 * phase with the i915_perf_register() exposing state to userspace.
2056 void i915_perf_init(struct drm_i915_private *dev_priv)
2058 if (!IS_HASWELL(dev_priv))
2061 hrtimer_init(&dev_priv->perf.oa.poll_check_timer,
2062 CLOCK_MONOTONIC, HRTIMER_MODE_REL);
2063 dev_priv->perf.oa.poll_check_timer.function = oa_poll_check_timer_cb;
2064 init_waitqueue_head(&dev_priv->perf.oa.poll_wq);
2066 INIT_LIST_HEAD(&dev_priv->perf.streams);
2067 mutex_init(&dev_priv->perf.lock);
2068 spin_lock_init(&dev_priv->perf.hook_lock);
2070 dev_priv->perf.oa.ops.init_oa_buffer = gen7_init_oa_buffer;
2071 dev_priv->perf.oa.ops.enable_metric_set = hsw_enable_metric_set;
2072 dev_priv->perf.oa.ops.disable_metric_set = hsw_disable_metric_set;
2073 dev_priv->perf.oa.ops.oa_enable = gen7_oa_enable;
2074 dev_priv->perf.oa.ops.oa_disable = gen7_oa_disable;
2075 dev_priv->perf.oa.ops.read = gen7_oa_read;
2076 dev_priv->perf.oa.ops.oa_buffer_is_empty =
2077 gen7_oa_buffer_is_empty_fop_unlocked;
2079 dev_priv->perf.oa.timestamp_frequency = 12500000;
2081 dev_priv->perf.oa.oa_formats = hsw_oa_formats;
2083 dev_priv->perf.oa.n_builtin_sets =
2084 i915_oa_n_builtin_metric_sets_hsw;
2086 dev_priv->perf.sysctl_header = register_sysctl_table(dev_root);
2088 dev_priv->perf.initialized = true;
2092 * i915_perf_fini - Counter part to i915_perf_init()
2093 * @dev_priv: i915 device instance
2095 void i915_perf_fini(struct drm_i915_private *dev_priv)
2097 if (!dev_priv->perf.initialized)
2100 unregister_sysctl_table(dev_priv->perf.sysctl_header);
2102 memset(&dev_priv->perf.oa.ops, 0, sizeof(dev_priv->perf.oa.ops));
2103 dev_priv->perf.initialized = false;