/*
* Copyright © 2015-2016 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* Authors:
* Robert Bragg <robert@sixbynine.org>
*/
/**
* DOC: i915 Perf Overview
*
* Gen graphics supports a large number of performance counters that can help
* driver and application developers understand and optimize their use of the
* GPU.
*
* This i915 perf interface enables userspace to configure and open a file
* descriptor representing a stream of GPU metrics which can then be read() as
* a stream of sample records.
*
* The interface is particularly suited to exposing buffered metrics that are
* captured by DMA from the GPU, unsynchronized with and unrelated to the CPU.
*
* Streams representing a single context are accessible to applications with a
* corresponding drm file descriptor, such that OpenGL can use the interface
* without special privileges. Access to system-wide metrics requires root
* privileges by default, unless changed via the dev.i915.perf_event_paranoid
* sysctl option.
*
*/
/**
* DOC: i915 Perf History and Comparison with Core Perf
*
* The interface was initially inspired by the core Perf infrastructure but
* some notable differences are:
*
* i915 perf file descriptors represent a "stream" instead of an "event"; where
* a perf event primarily corresponds to a single 64bit value, while a stream
* might sample sets of tightly-coupled counters, depending on the
* configuration. For example the Gen OA unit isn't designed to support
* orthogonal configurations of individual counters; it's configured for a set
* of related counters. Samples for an i915 perf stream capturing OA metrics
* will include a set of counter values packed in a compact HW specific format.
* The OA unit supports a number of different packing formats which can be
* selected by the user opening the stream. Perf has support for grouping
* events, but each event in the group is configured, validated and
* authenticated individually with separate system calls.
*
* i915 perf stream configurations are provided as an array of u64 (key,value)
* pairs, instead of a fixed struct with multiple miscellaneous config members,
* interleaved with event-type specific members.
*
* i915 perf doesn't support exposing metrics via an mmap'd circular buffer.
* The supported metrics are being written to memory by the GPU unsynchronized
* with the CPU, using HW specific packing formats for counter sets. Sometimes
* the constraints on HW configuration require reports to be filtered before it
* would be acceptable to expose them to unprivileged applications - to hide
* the metrics of other processes/contexts. For these use cases a read() based
* interface is a good fit, and provides an opportunity to filter data as it
* gets copied from the GPU mapped buffers to userspace buffers.
*
*
* Issues hit with first prototype based on Core Perf
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* The first prototype of this driver was based on the core perf
* infrastructure, and while we did make that mostly work, with some changes to
* perf, we found we were breaking or working around too many assumptions baked
* into perf's currently cpu centric design.
*
* In the end we didn't see a clear benefit to making perf's implementation and
* interface more complex by changing design assumptions while we knew we still
* wouldn't be able to use any existing perf based userspace tools.
*
* Also considering the Gen specific nature of the Observability hardware and
* how userspace will sometimes need to combine i915 perf OA metrics with
* side-band OA data captured via MI_REPORT_PERF_COUNT commands; we're
* expecting the interface to be used by a platform specific userspace such as
* OpenGL or tools. This is to say; we aren't inherently missing out on having
* a standard vendor/architecture agnostic interface by not using perf.
*
*
* For posterity, in case we might re-visit trying to adapt core perf to be
* better suited to exposing i915 metrics these were the main pain points we
* hit:
*
* - The perf based OA PMU driver broke some significant design assumptions:
*
* Existing perf pmus are used for profiling work on a cpu and we were
* introducing the idea of _IS_DEVICE pmus with different security
* implications, the need to fake cpu-related data (such as user/kernel
* registers) to fit with perf's current design, and adding _DEVICE records
* as a way to forward device-specific status records.
*
* The OA unit writes reports of counters into a circular buffer, without
* involvement from the CPU, making our PMU driver the first of a kind.
*
* Given the way we were periodically forward data from the GPU-mapped, OA
* buffer to perf's buffer, those bursts of sample writes looked to perf like
* we were sampling too fast and so we had to subvert its throttling checks.
*
* Perf supports groups of counters and allows those to be read via
* transactions internally but transactions currently seem designed to be
* explicitly initiated from the cpu (say in response to a userspace read())
* and while we could pull a report out of the OA buffer we can't
* trigger a report from the cpu on demand.
*
* Related to being report based; the OA counters are configured in HW as a
* set while perf generally expects counter configurations to be orthogonal.
* Although counters can be associated with a group leader as they are
* opened, there's no clear precedent for being able to provide group-wide
* configuration attributes (for example we want to let userspace choose the
* OA unit report format used to capture all counters in a set, or specify a
* GPU context to filter metrics on). We avoided using perf's grouping
* feature and forwarded OA reports to userspace via perf's 'raw' sample
* field. This suited our userspace well considering how coupled the counters
* are when dealing with normalizing. It would be inconvenient to split
* counters up into separate events, only to require userspace to recombine
* them. For Mesa it's also convenient to be forwarded raw, periodic reports
* for combining with the side-band raw reports it captures using
* MI_REPORT_PERF_COUNT commands.
*
* - As a side note on perf's grouping feature; there was also some concern
* that using PERF_FORMAT_GROUP as a way to pack together counter values
* would quite drastically inflate our sample sizes, which would likely
* lower the effective sampling resolutions we could use when the available
* memory bandwidth is limited.
*
* With the OA unit's report formats, counters are packed together as 32
* or 40bit values, with the largest report size being 256 bytes.
*
* PERF_FORMAT_GROUP values are 64bit, but there doesn't appear to be a
* documented ordering to the values, implying PERF_FORMAT_ID must also be
* used to add a 64bit ID before each value; giving 16 bytes per counter.
*
* Related to counter orthogonality; we can't time share the OA unit, while
* event scheduling is a central design idea within perf for allowing
* userspace to open + enable more events than can be configured in HW at any
* one time. The OA unit is not designed to allow re-configuration while in
* use. We can't reconfigure the OA unit without losing internal OA unit
* state which we can't access explicitly to save and restore. Reconfiguring
* the OA unit is also relatively slow, involving ~100 register writes. From
* userspace Mesa also depends on a stable OA configuration when emitting
* MI_REPORT_PERF_COUNT commands and importantly the OA unit can't be
* disabled while there are outstanding MI_RPC commands lest we hang the
* command streamer.
*
* The contents of sample records aren't extensible by device drivers (i.e.
* the sample_type bits). As an example; Sourab Gupta had been looking to
* attach GPU timestamps to our OA samples. We were shoehorning OA reports
* into sample records by using the 'raw' field, but it's tricky to pack more
* than one thing into this field because events/core.c currently only lets a
* pmu give a single raw data pointer plus len which will be copied into the
* ring buffer. To include more than the OA report we'd have to copy the
* report into an intermediate larger buffer. I'd been considering allowing a
* vector of data+len values to be specified for copying the raw data, but
* it felt like a kludge to being using the raw field for this purpose.
*
* - It felt like our perf based PMU was making some technical compromises
* just for the sake of using perf:
*
* perf_event_open() requires events to either relate to a pid or a specific
* cpu core, while our device pmu related to neither. Events opened with a
* pid will be automatically enabled/disabled according to the scheduling of
* that process - so not appropriate for us. When an event is related to a
* cpu id, perf ensures pmu methods will be invoked via an inter process
* interrupt on that core. To avoid invasive changes our userspace opened OA
* perf events for a specific cpu. This was workable but it meant the
* majority of the OA driver ran in atomic context, including all OA report
* forwarding, which wasn't really necessary in our case and seems to make
* our locking requirements somewhat complex as we handled the interaction
* with the rest of the i915 driver.
*/
#include <linux/anon_inodes.h>
#include <linux/sizes.h>
#include "i915_drv.h"
#include "i915_oa_hsw.h"
/* HW requires this to be a power of two, between 128k and 16M, though driver
* is currently generally designed assuming the largest 16M size is used such
* that the overflow cases are unlikely in normal operation.
*/
#define OA_BUFFER_SIZE SZ_16M
#define OA_TAKEN(tail, head) ((tail - head) & (OA_BUFFER_SIZE - 1))
/* There's a HW race condition between OA unit tail pointer register updates and
* writes to memory whereby the tail pointer can sometimes get ahead of what's
* been written out to the OA buffer so far.
*
* Although this can be observed explicitly by checking for a zeroed report-id
* field in tail reports, it seems preferable to account for this earlier e.g.
* as part of the _oa_buffer_is_empty checks to minimize -EAGAIN polling cycles
* in this situation.
*
* To give time for the most recent reports to land before they may be copied to
* userspace, the driver operates as if the tail pointer effectively lags behind
* the HW tail pointer by 'tail_margin' bytes. The margin in bytes is calculated
* based on this constant in nanoseconds, the current OA sampling exponent
* and current report size.
*
* There is also a fallback check while reading to simply skip over reports with
* a zeroed report-id.
*/
#define OA_TAIL_MARGIN_NSEC 100000ULL
/* frequency for checking whether the OA unit has written new reports to the
* circular OA buffer...
*/
#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.
*
* Since the timestamps included in OA reports are only 32bits it seems
* reasonable to limit the OA exponent where it's still possible to account for
* overflow in OA report timestamps.
*/
#define OA_EXPONENT_MAX 31
#define INVALID_CTX_ID 0xffffffff
/* For sysctl proc_dointvec_minmax of i915_oa_max_sample_rate
*
* 160ns is the smallest sampling period we can theoretically program the OA
* unit with on Haswell, corresponding to 6.25MHz.
*/
static int oa_sample_rate_hard_limit = 6250000;
/* Theoretically we can program the OA unit to sample every 160ns but don't
* allow that by default unless root...
*
* The default threshold of 100000Hz is based on perf's similar
* kernel.perf_event_max_sample_rate sysctl parameter.
*/
static u32 i915_oa_max_sample_rate = 100000;
/* XXX: beware if future OA HW adds new report formats that the current
* code assumes all reports have a power-of-two size and ~(size - 1) can
* be used as a mask to align the OA tail pointer.
*/
static struct i915_oa_format hsw_oa_formats[I915_OA_FORMAT_MAX] = {
[I915_OA_FORMAT_A13] = { 0, 64 },
[I915_OA_FORMAT_A29] = { 1, 128 },
[I915_OA_FORMAT_A13_B8_C8] = { 2, 128 },
/* A29_B8_C8 Disallowed as 192 bytes doesn't factor into buffer size */
[I915_OA_FORMAT_B4_C8] = { 4, 64 },
[I915_OA_FORMAT_A45_B8_C8] = { 5, 256 },
[I915_OA_FORMAT_B4_C8_A16] = { 6, 128 },
[I915_OA_FORMAT_C4_B8] = { 7, 64 },
};
#define SAMPLE_OA_REPORT (1<<0)
/**
* struct perf_open_properties - for validated properties given to open a stream
* @sample_flags: `DRM_I915_PERF_PROP_SAMPLE_*` properties are tracked as flags
* @single_context: Whether a single or all gpu contexts should be monitored
* @ctx_handle: A gem ctx handle for use with @single_context
* @metrics_set: An ID for an OA unit metric set advertised via sysfs
* @oa_format: An OA unit HW report format
* @oa_periodic: Whether to enable periodic OA unit sampling
* @oa_period_exponent: The OA unit sampling period is derived from this
*
* As read_properties_unlocked() enumerates and validates the properties given
* to open a stream of metrics the configuration is built up in the structure
* which starts out zero initialized.
*/
struct perf_open_properties {
u32 sample_flags;
u64 single_context:1;
u64 ctx_handle;
/* OA sampling state */
int metrics_set;
int oa_format;
bool oa_periodic;
int oa_period_exponent;
};
/* NB: This is either called via fops or the poll check hrtimer (atomic ctx)
*
* It's safe to read OA config state here unlocked, assuming that this is only
* called while the stream is enabled, while the global OA configuration can't
* be modified.
*
* Note: we don't lock around the head/tail reads even though there's the slim
* possibility of read() fop errors forcing a re-init of the OA buffer
* pointers. A race here could result in a false positive !empty status which
* is acceptable.
*/
static bool gen7_oa_buffer_is_empty_fop_unlocked(struct drm_i915_private *dev_priv)
{
int report_size = dev_priv->perf.oa.oa_buffer.format_size;
u32 oastatus2 = I915_READ(GEN7_OASTATUS2);
u32 oastatus1 = I915_READ(GEN7_OASTATUS1);
u32 head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
u32 tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
return OA_TAKEN(tail, head) <
dev_priv->perf.oa.tail_margin + report_size;
}
/**
* append_oa_status - Appends a status record to a userspace read() buffer.
* @stream: An i915-perf stream opened for OA metrics
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @offset: (inout): the current position for writing into @buf
* @type: The kind of status to report to userspace
*
* Writes a status record (such as `DRM_I915_PERF_RECORD_OA_REPORT_LOST`)
* into the userspace read() buffer.
*
* The @buf @offset will only be updated on success.
*
* Returns: 0 on success, negative error code on failure.
*/
static int append_oa_status(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset,
enum drm_i915_perf_record_type type)
{
struct drm_i915_perf_record_header header = { type, 0, sizeof(header) };
if ((count - *offset) < header.size)
return -ENOSPC;
if (copy_to_user(buf + *offset, &header, sizeof(header)))
return -EFAULT;
(*offset) += header.size;
return 0;
}
/**
* append_oa_sample - Copies single OA report into userspace read() buffer.
* @stream: An i915-perf stream opened for OA metrics
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @offset: (inout): the current position for writing into @buf
* @report: A single OA report to (optionally) include as part of the sample
*
* The contents of a sample are configured through `DRM_I915_PERF_PROP_SAMPLE_*`
* properties when opening a stream, tracked as `stream->sample_flags`. This
* function copies the requested components of a single sample to the given
* read() @buf.
*
* The @buf @offset will only be updated on success.
*
* Returns: 0 on success, negative error code on failure.
*/
static int append_oa_sample(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset,
const u8 *report)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
int report_size = dev_priv->perf.oa.oa_buffer.format_size;
struct drm_i915_perf_record_header header;
u32 sample_flags = stream->sample_flags;
header.type = DRM_I915_PERF_RECORD_SAMPLE;
header.pad = 0;
header.size = stream->sample_size;
if ((count - *offset) < header.size)
return -ENOSPC;
buf += *offset;
if (copy_to_user(buf, &header, sizeof(header)))
return -EFAULT;
buf += sizeof(header);
if (sample_flags & SAMPLE_OA_REPORT) {
if (copy_to_user(buf, report, report_size))
return -EFAULT;
}
(*offset) += header.size;
return 0;
}
/**
* Copies all buffered OA reports into userspace read() buffer.
* @stream: An i915-perf stream opened for OA metrics
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @offset: (inout): the current position for writing into @buf
* @head_ptr: (inout): the current oa buffer cpu read position
* @tail: the current oa buffer gpu write position
*
* Notably any error condition resulting in a short read (-%ENOSPC or
* -%EFAULT) will be returned even though one or more records may
* have been successfully copied. In this case it's up to the caller
* to decide if the error should be squashed before returning to
* userspace.
*
* Note: reports are consumed from the head, and appended to the
* tail, so the head chases the tail?... If you think that's mad
* and back-to-front you're not alone, but this follows the
* Gen PRM naming convention.
*
* Returns: 0 on success, negative error code on failure.
*/
static int gen7_append_oa_reports(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset,
u32 *head_ptr,
u32 tail)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
int report_size = dev_priv->perf.oa.oa_buffer.format_size;
u8 *oa_buf_base = dev_priv->perf.oa.oa_buffer.vaddr;
int tail_margin = dev_priv->perf.oa.tail_margin;
u32 gtt_offset = i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma);
u32 mask = (OA_BUFFER_SIZE - 1);
u32 head;
u32 taken;
int ret = 0;
if (WARN_ON(!stream->enabled))
return -EIO;
head = *head_ptr - gtt_offset;
tail -= gtt_offset;
/* The OA unit is expected to wrap the tail pointer according to the OA
* buffer size and since we should never write a misaligned head
* pointer we don't expect to read one back either...
*/
if (tail > OA_BUFFER_SIZE || head > OA_BUFFER_SIZE ||
head % report_size) {
DRM_ERROR("Inconsistent OA buffer pointer (head = %u, tail = %u): force restart\n",
head, tail);
dev_priv->perf.oa.ops.oa_disable(dev_priv);
dev_priv->perf.oa.ops.oa_enable(dev_priv);
*head_ptr = I915_READ(GEN7_OASTATUS2) &
GEN7_OASTATUS2_HEAD_MASK;
return -EIO;
}
/* The tail pointer increases in 64 byte increments, not in report_size
* steps...
*/
tail &= ~(report_size - 1);
/* Move the tail pointer back by the current tail_margin to account for
* the possibility that the latest reports may not have really landed
* in memory yet...
*/
if (OA_TAKEN(tail, head) < report_size + tail_margin)
return -EAGAIN;
tail -= tail_margin;
tail &= mask;
for (/* none */;
(taken = OA_TAKEN(tail, head));
head = (head + report_size) & mask) {
u8 *report = oa_buf_base + head;
u32 *report32 = (void *)report;
/* All the report sizes factor neatly into the buffer
* size so we never expect to see a report split
* between the beginning and end of the buffer.
*
* Given the initial alignment check a misalignment
* here would imply a driver bug that would result
* in an overrun.
*/
if (WARN_ON((OA_BUFFER_SIZE - head) < report_size)) {
DRM_ERROR("Spurious OA head ptr: non-integral report offset\n");
break;
}
/* The report-ID field for periodic samples includes
* some undocumented flags related to what triggered
* the report and is never expected to be zero so we
* can check that the report isn't invalid before
* copying it to userspace...
*/
if (report32[0] == 0) {
DRM_NOTE("Skipping spurious, invalid OA report\n");
continue;
}
ret = append_oa_sample(stream, buf, count, offset, report);
if (ret)
break;
/* The above report-id field sanity check is based on
* the assumption that the OA buffer is initially
* zeroed and we reset the field after copying so the
* check is still meaningful once old reports start
* being overwritten.
*/
report32[0] = 0;
}
*head_ptr = gtt_offset + head;
return ret;
}
/**
* gen7_oa_read - copy status records then buffered OA reports
* @stream: An i915-perf stream opened for OA metrics
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @offset: (inout): the current position for writing into @buf
*
* Checks Gen 7 specific OA unit status registers and if necessary appends
* corresponding status records for userspace (such as for a buffer full
* condition) and then initiate appending any buffered OA reports.
*
* Updates @offset according to the number of bytes successfully copied into
* the userspace buffer.
*
* Returns: zero on success or a negative error code
*/
static int gen7_oa_read(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
int report_size = dev_priv->perf.oa.oa_buffer.format_size;
u32 oastatus2;
u32 oastatus1;
u32 head;
u32 tail;
int ret;
if (WARN_ON(!dev_priv->perf.oa.oa_buffer.vaddr))
return -EIO;
oastatus2 = I915_READ(GEN7_OASTATUS2);
oastatus1 = I915_READ(GEN7_OASTATUS1);
head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
/* XXX: On Haswell we don't have a safe way to clear oastatus1
* bits while the OA unit is enabled (while the tail pointer
* may be updated asynchronously) so we ignore status bits
* that have already been reported to userspace.
*/
oastatus1 &= ~dev_priv->perf.oa.gen7_latched_oastatus1;
/* We treat OABUFFER_OVERFLOW as a significant error:
*
* - The status can be interpreted to mean that the buffer is
* currently full (with a higher precedence than OA_TAKEN()
* which will start to report a near-empty buffer after an
* overflow) but it's awkward that we can't clear the status
* on Haswell, so without a reset we won't be able to catch
* the state again.
*
* - Since it also implies the HW has started overwriting old
* reports it may also affect our sanity checks for invalid
* reports when copying to userspace that assume new reports
* are being written to cleared memory.
*
* - In the future we may want to introduce a flight recorder
* mode where the driver will automatically maintain a safe
* guard band between head/tail, avoiding this overflow
* condition, but we avoid the added driver complexity for
* now.
*/
if (unlikely(oastatus1 & GEN7_OASTATUS1_OABUFFER_OVERFLOW)) {
ret = append_oa_status(stream, buf, count, offset,
DRM_I915_PERF_RECORD_OA_BUFFER_LOST);
if (ret)
return ret;
DRM_DEBUG("OA buffer overflow: force restart\n");
dev_priv->perf.oa.ops.oa_disable(dev_priv);
dev_priv->perf.oa.ops.oa_enable(dev_priv);
oastatus2 = I915_READ(GEN7_OASTATUS2);
oastatus1 = I915_READ(GEN7_OASTATUS1);
head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
}
if (unlikely(oastatus1 & GEN7_OASTATUS1_REPORT_LOST)) {
ret = append_oa_status(stream, buf, count, offset,
DRM_I915_PERF_RECORD_OA_REPORT_LOST);
if (ret)
return ret;
dev_priv->perf.oa.gen7_latched_oastatus1 |=
GEN7_OASTATUS1_REPORT_LOST;
}
ret = gen7_append_oa_reports(stream, buf, count, offset,
&head, tail);
/* All the report sizes are a power of two and the
* head should always be incremented by some multiple
* of the report size.
*
* A warning here, but notably if we later read back a
* misaligned pointer we will treat that as a bug since
* it could lead to a buffer overrun.
*/
WARN_ONCE(head & (report_size - 1),
"i915: Writing misaligned OA head pointer");
/* Note: we update the head pointer here even if an error
* was returned since the error may represent a short read
* where some some reports were successfully copied.
*/
I915_WRITE(GEN7_OASTATUS2,
((head & GEN7_OASTATUS2_HEAD_MASK) |
OA_MEM_SELECT_GGTT));
return ret;
}
/**
* i915_oa_wait_unlocked - handles blocking IO until OA data available
* @stream: An i915-perf stream opened for OA metrics
*
* Called when userspace tries to read() from a blocking stream FD opened
* for OA metrics. It waits until the hrtimer callback finds a non-empty
* OA buffer and wakes us.
*
* Note: it's acceptable to have this return with some false positives
* since any subsequent read handling will return -EAGAIN if there isn't
* really data ready for userspace yet.
*
* Returns: zero on success or a negative error code
*/
static int i915_oa_wait_unlocked(struct i915_perf_stream *stream)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
/* We would wait indefinitely if periodic sampling is not enabled */
if (!dev_priv->perf.oa.periodic)
return -EIO;
/* Note: the oa_buffer_is_empty() condition is ok to run unlocked as it
* just performs mmio reads of the OA buffer head + tail pointers and
* it's assumed we're handling some operation that implies the stream
* can't be destroyed until completion (such as a read()) that ensures
* the device + OA buffer can't disappear
*/
return wait_event_interruptible(dev_priv->perf.oa.poll_wq,
!dev_priv->perf.oa.ops.oa_buffer_is_empty(dev_priv));
}
/**
* i915_oa_poll_wait - call poll_wait() for an OA stream poll()
* @stream: An i915-perf stream opened for OA metrics
* @file: An i915 perf stream file
* @wait: poll() state table
*
* For handling userspace polling on an i915 perf stream opened for OA metrics,
* this starts a poll_wait with the wait queue that our hrtimer callback wakes
* when it sees data ready to read in the circular OA buffer.
*/
static void i915_oa_poll_wait(struct i915_perf_stream *stream,
struct file *file,
poll_table *wait)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
poll_wait(file, &dev_priv->perf.oa.poll_wq, wait);
}
/**
* i915_oa_read - just calls through to &i915_oa_ops->read
* @stream: An i915-perf stream opened for OA metrics
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @offset: (inout): the current position for writing into @buf
*
* Updates @offset according to the number of bytes successfully copied into
* the userspace buffer.
*
* Returns: zero on success or a negative error code
*/
static int i915_oa_read(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
return dev_priv->perf.oa.ops.read(stream, buf, count, offset);
}
/**
* oa_get_render_ctx_id - determine and hold ctx hw id
* @stream: An i915-perf stream opened for OA metrics
*
* Determine the render context hw id, and ensure it remains fixed for the
* lifetime of the stream. This ensures that we don't have to worry about
* updating the context ID in OACONTROL on the fly.
*
* Returns: zero on success or a negative error code
*/
static int oa_get_render_ctx_id(struct i915_perf_stream *stream)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
struct intel_engine_cs *engine = dev_priv->engine[RCS];
int ret;
ret = i915_mutex_lock_interruptible(&dev_priv->drm);
if (ret)
return ret;
/* As the ID is the gtt offset of the context's vma we pin
* the vma to ensure the ID remains fixed.
*
* NB: implied RCS engine...
*/
ret = engine->context_pin(engine, stream->ctx);
if (ret)
goto unlock;
/* Explicitly track the ID (instead of calling i915_ggtt_offset()
* on the fly) considering the difference with gen8+ and
* execlists
*/
dev_priv->perf.oa.specific_ctx_id =
i915_ggtt_offset(stream->ctx->engine[engine->id].state);
unlock:
mutex_unlock(&dev_priv->drm.struct_mutex);
return ret;
}
/**
* oa_put_render_ctx_id - counterpart to oa_get_render_ctx_id releases hold
* @stream: An i915-perf stream opened for OA metrics
*
* In case anything needed doing to ensure the context HW ID would remain valid
* for the lifetime of the stream, then that can be undone here.
*/
static void oa_put_render_ctx_id(struct i915_perf_stream *stream)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
struct intel_engine_cs *engine = dev_priv->engine[RCS];
mutex_lock(&dev_priv->drm.struct_mutex);
dev_priv->perf.oa.specific_ctx_id = INVALID_CTX_ID;
engine->context_unpin(engine, stream->ctx);
mutex_unlock(&dev_priv->drm.struct_mutex);
}
static void
free_oa_buffer(struct drm_i915_private *i915)
{
mutex_lock(&i915->drm.struct_mutex);
i915_gem_object_unpin_map(i915->perf.oa.oa_buffer.vma->obj);
i915_vma_unpin(i915->perf.oa.oa_buffer.vma);
i915_gem_object_put(i915->perf.oa.oa_buffer.vma->obj);
i915->perf.oa.oa_buffer.vma = NULL;
i915->perf.oa.oa_buffer.vaddr = NULL;
mutex_unlock(&i915->drm.struct_mutex);
}
static void i915_oa_stream_destroy(struct i915_perf_stream *stream)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
BUG_ON(stream != dev_priv->perf.oa.exclusive_stream);
dev_priv->perf.oa.ops.disable_metric_set(dev_priv);
free_oa_buffer(dev_priv);
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
intel_runtime_pm_put(dev_priv);
if (stream->ctx)
oa_put_render_ctx_id(stream);
dev_priv->perf.oa.exclusive_stream = NULL;
}
static void gen7_init_oa_buffer(struct drm_i915_private *dev_priv)
{
u32 gtt_offset = i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma);
/* Pre-DevBDW: OABUFFER must be set with counters off,
* before OASTATUS1, but after OASTATUS2
*/
I915_WRITE(GEN7_OASTATUS2, gtt_offset | OA_MEM_SELECT_GGTT); /* head */
I915_WRITE(GEN7_OABUFFER, gtt_offset);
I915_WRITE(GEN7_OASTATUS1, gtt_offset | OABUFFER_SIZE_16M); /* tail */
/* On Haswell we have to track which OASTATUS1 flags we've
* already seen since they can't be cleared while periodic
* sampling is enabled.
*/
dev_priv->perf.oa.gen7_latched_oastatus1 = 0;
/* NB: although the OA buffer will initially be allocated
* zeroed via shmfs (and so this memset is redundant when
* first allocating), we may re-init the OA buffer, either
* when re-enabling a stream or in error/reset paths.
*
* The reason we clear the buffer for each re-init is for the
* sanity check in gen7_append_oa_reports() that looks at the
* report-id field to make sure it's non-zero which relies on
* the assumption that new reports are being written to zeroed
* memory...
*/
memset(dev_priv->perf.oa.oa_buffer.vaddr, 0, OA_BUFFER_SIZE);
/* Maybe make ->pollin per-stream state if we support multiple
* concurrent streams in the future.
*/
dev_priv->perf.oa.pollin = false;
}
static int alloc_oa_buffer(struct drm_i915_private *dev_priv)
{
struct drm_i915_gem_object *bo;
struct i915_vma *vma;
int ret;
if (WARN_ON(dev_priv->perf.oa.oa_buffer.vma))
return -ENODEV;
ret = i915_mutex_lock_interruptible(&dev_priv->drm);
if (ret)
return ret;
BUILD_BUG_ON_NOT_POWER_OF_2(OA_BUFFER_SIZE);
BUILD_BUG_ON(OA_BUFFER_SIZE < SZ_128K || OA_BUFFER_SIZE > SZ_16M);
bo = i915_gem_object_create(dev_priv, OA_BUFFER_SIZE);
if (IS_ERR(bo)) {
DRM_ERROR("Failed to allocate OA buffer\n");
ret = PTR_ERR(bo);
goto unlock;
}
ret = i915_gem_object_set_cache_level(bo, I915_CACHE_LLC);
if (ret)
goto err_unref;
/* PreHSW required 512K alignment, HSW requires 16M */
vma = i915_gem_object_ggtt_pin(bo, NULL, 0, SZ_16M, 0);
if (IS_ERR(vma)) {
ret = PTR_ERR(vma);
goto err_unref;
}
dev_priv->perf.oa.oa_buffer.vma = vma;
dev_priv->perf.oa.oa_buffer.vaddr =
i915_gem_object_pin_map(bo, I915_MAP_WB);
if (IS_ERR(dev_priv->perf.oa.oa_buffer.vaddr)) {
ret = PTR_ERR(dev_priv->perf.oa.oa_buffer.vaddr);
goto err_unpin;
}
dev_priv->perf.oa.ops.init_oa_buffer(dev_priv);
DRM_DEBUG_DRIVER("OA Buffer initialized, gtt offset = 0x%x, vaddr = %p\n",
i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma),
dev_priv->perf.oa.oa_buffer.vaddr);
goto unlock;
err_unpin:
__i915_vma_unpin(vma);
err_unref:
i915_gem_object_put(bo);
dev_priv->perf.oa.oa_buffer.vaddr = NULL;
dev_priv->perf.oa.oa_buffer.vma = NULL;
unlock:
mutex_unlock(&dev_priv->drm.struct_mutex);
return ret;
}
static void config_oa_regs(struct drm_i915_private *dev_priv,
const struct i915_oa_reg *regs,
int n_regs)
{
int i;
for (i = 0; i < n_regs; i++) {
const struct i915_oa_reg *reg = regs + i;
I915_WRITE(reg->addr, reg->value);
}
}
static int hsw_enable_metric_set(struct drm_i915_private *dev_priv)
{
int ret = i915_oa_select_metric_set_hsw(dev_priv);
if (ret)
return ret;
I915_WRITE(GDT_CHICKEN_BITS, (I915_READ(GDT_CHICKEN_BITS) |
GT_NOA_ENABLE));
/* PRM:
*
* OA unit is using “crclk” for its functionality. When trunk
* level clock gating takes place, OA clock would be gated,
* unable to count the events from non-render clock domain.
* Render clock gating must be disabled when OA is enabled to
* count the events from non-render domain. Unit level clock
* gating for RCS should also be disabled.
*/
I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) &
~GEN7_DOP_CLOCK_GATE_ENABLE));
I915_WRITE(GEN6_UCGCTL1, (I915_READ(GEN6_UCGCTL1) |
GEN6_CSUNIT_CLOCK_GATE_DISABLE));
config_oa_regs(dev_priv, dev_priv->perf.oa.mux_regs,
dev_priv->perf.oa.mux_regs_len);
/* It apparently takes a fairly long time for a new MUX
* configuration to be be applied after these register writes.
* This delay duration was derived empirically based on the
* render_basic config but hopefully it covers the maximum
* configuration latency.
*
* As a fallback, the checks in _append_oa_reports() to skip
* invalid OA reports do also seem to work to discard reports
* generated before this config has completed - albeit not
* silently.
*
* Unfortunately this is essentially a magic number, since we
* don't currently know of a reliable mechanism for predicting
* how long the MUX config will take to apply and besides
* seeing invalid reports we don't know of a reliable way to
* explicitly check that the MUX config has landed.
*
* It's even possible we've miss characterized the underlying
* problem - it just seems like the simplest explanation why
* a delay at this location would mitigate any invalid reports.
*/
usleep_range(15000, 20000);
config_oa_regs(dev_priv, dev_priv->perf.oa.b_counter_regs,
dev_priv->perf.oa.b_counter_regs_len);
return 0;
}
static void hsw_disable_metric_set(struct drm_i915_private *dev_priv)
{
I915_WRITE(GEN6_UCGCTL1, (I915_READ(GEN6_UCGCTL1) &
~GEN6_CSUNIT_CLOCK_GATE_DISABLE));
I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) |
GEN7_DOP_CLOCK_GATE_ENABLE));
I915_WRITE(GDT_CHICKEN_BITS, (I915_READ(GDT_CHICKEN_BITS) &
~GT_NOA_ENABLE));
}
static void gen7_update_oacontrol_locked(struct drm_i915_private *dev_priv)
{
lockdep_assert_held(&dev_priv->perf.hook_lock);
if (dev_priv->perf.oa.exclusive_stream->enabled) {
struct i915_gem_context *ctx =
dev_priv->perf.oa.exclusive_stream->ctx;
u32 ctx_id = dev_priv->perf.oa.specific_ctx_id;
bool periodic = dev_priv->perf.oa.periodic;
u32 period_exponent = dev_priv->perf.oa.period_exponent;
u32 report_format = dev_priv->perf.oa.oa_buffer.format;
I915_WRITE(GEN7_OACONTROL,
(ctx_id & GEN7_OACONTROL_CTX_MASK) |
(period_exponent <<
GEN7_OACONTROL_TIMER_PERIOD_SHIFT) |
(periodic ? GEN7_OACONTROL_TIMER_ENABLE : 0) |
(report_format << GEN7_OACONTROL_FORMAT_SHIFT) |
(ctx ? GEN7_OACONTROL_PER_CTX_ENABLE : 0) |
GEN7_OACONTROL_ENABLE);
} else
I915_WRITE(GEN7_OACONTROL, 0);
}
static void gen7_oa_enable(struct drm_i915_private *dev_priv)
{
unsigned long flags;
/* Reset buf pointers so we don't forward reports from before now.
*
* Think carefully if considering trying to avoid this, since it
* also ensures status flags and the buffer itself are cleared
* in error paths, and we have checks for invalid reports based
* on the assumption that certain fields are written to zeroed
* memory which this helps maintains.
*/
gen7_init_oa_buffer(dev_priv);
spin_lock_irqsave(&dev_priv->perf.hook_lock, flags);
gen7_update_oacontrol_locked(dev_priv);
spin_unlock_irqrestore(&dev_priv->perf.hook_lock, flags);
}
/**
* i915_oa_stream_enable - handle `I915_PERF_IOCTL_ENABLE` for OA stream
* @stream: An i915 perf stream opened for OA metrics
*
* [Re]enables hardware periodic sampling according to the period configured
* when opening the stream. This also starts a hrtimer that will periodically
* check for data in the circular OA buffer for notifying userspace (e.g.
* during a read() or poll()).
*/
static void i915_oa_stream_enable(struct i915_perf_stream *stream)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
dev_priv->perf.oa.ops.oa_enable(dev_priv);
if (dev_priv->perf.oa.periodic)
hrtimer_start(&dev_priv->perf.oa.poll_check_timer,
ns_to_ktime(POLL_PERIOD),
HRTIMER_MODE_REL_PINNED);
}
static void gen7_oa_disable(struct drm_i915_private *dev_priv)
{
I915_WRITE(GEN7_OACONTROL, 0);
}
/**
* i915_oa_stream_disable - handle `I915_PERF_IOCTL_DISABLE` for OA stream
* @stream: An i915 perf stream opened for OA metrics
*
* Stops the OA unit from periodically writing counter reports into the
* circular OA buffer. This also stops the hrtimer that periodically checks for
* data in the circular OA buffer, for notifying userspace.
*/
static void i915_oa_stream_disable(struct i915_perf_stream *stream)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
dev_priv->perf.oa.ops.oa_disable(dev_priv);
if (dev_priv->perf.oa.periodic)
hrtimer_cancel(&dev_priv->perf.oa.poll_check_timer);
}
static u64 oa_exponent_to_ns(struct drm_i915_private *dev_priv, int exponent)
{
return div_u64(1000000000ULL * (2ULL << exponent),
dev_priv->perf.oa.timestamp_frequency);
}
static const struct i915_perf_stream_ops i915_oa_stream_ops = {
.destroy = i915_oa_stream_destroy,
.enable = i915_oa_stream_enable,
.disable = i915_oa_stream_disable,
.wait_unlocked = i915_oa_wait_unlocked,
.poll_wait = i915_oa_poll_wait,
.read = i915_oa_read,
};
/**
* i915_oa_stream_init - validate combined props for OA stream and init
* @stream: An i915 perf stream
* @param: The open parameters passed to `DRM_I915_PERF_OPEN`
* @props: The property state that configures stream (individually validated)
*
* While read_properties_unlocked() validates properties in isolation it
* doesn't ensure that the combination necessarily makes sense.
*
* At this point it has been determined that userspace wants a stream of
* OA metrics, but still we need to further validate the combined
* properties are OK.
*
* If the configuration makes sense then we can allocate memory for
* a circular OA buffer and apply the requested metric set configuration.
*
* Returns: zero on success or a negative error code.
*/
static int i915_oa_stream_init(struct i915_perf_stream *stream,
struct drm_i915_perf_open_param *param,
struct perf_open_properties *props)
{
struct drm_i915_private *dev_priv = stream->dev_priv;
int format_size;
int ret;
/* If the sysfs metrics/ directory wasn't registered for some
* reason then don't let userspace try their luck with config
* IDs
*/
if (!dev_priv->perf.metrics_kobj) {
DRM_DEBUG("OA metrics weren't advertised via sysfs\n");
return -EINVAL;
}
if (!(props->sample_flags & SAMPLE_OA_REPORT)) {
DRM_DEBUG("Only OA report sampling supported\n");
return -EINVAL;
}
if (!dev_priv->perf.oa.ops.init_oa_buffer) {
DRM_DEBUG("OA unit not supported\n");
return -ENODEV;
}
/* To avoid the complexity of having to accurately filter
* counter reports and marshal to the appropriate client
* we currently only allow exclusive access
*/
if (dev_priv->perf.oa.exclusive_stream) {
DRM_DEBUG("OA unit already in use\n");
return -EBUSY;
}
if (!props->metrics_set) {
DRM_DEBUG("OA metric set not specified\n");
return -EINVAL;
}
if (!props->oa_format) {
DRM_DEBUG("OA report format not specified\n");
return -EINVAL;
}
stream->sample_size = sizeof(struct drm_i915_perf_record_header);
format_size = dev_priv->perf.oa.oa_formats[props->oa_format].size;
stream->sample_flags |= SAMPLE_OA_REPORT;
stream->sample_size += format_size;
dev_priv->perf.oa.oa_buffer.format_size = format_size;
if (WARN_ON(dev_priv->perf.oa.oa_buffer.format_size == 0))
return -EINVAL;
dev_priv->perf.oa.oa_buffer.format =
dev_priv->perf.oa.oa_formats[props->oa_format].format;
dev_priv->perf.oa.metrics_set = props->metrics_set;
dev_priv->perf.oa.periodic = props->oa_periodic;
if (dev_priv->perf.oa.periodic) {
u32 tail;
dev_priv->perf.oa.period_exponent = props->oa_period_exponent;
/* See comment for OA_TAIL_MARGIN_NSEC for details
* about this tail_margin...
*/
tail = div64_u64(OA_TAIL_MARGIN_NSEC,
oa_exponent_to_ns(dev_priv,
props->oa_period_exponent));
dev_priv->perf.oa.tail_margin = (tail + 1) * format_size;
}
if (stream->ctx) {
ret = oa_get_render_ctx_id(stream);
if (ret)
return ret;
}
ret = alloc_oa_buffer(dev_priv);
if (ret)
goto err_oa_buf_alloc;
/* PRM - observability performance counters:
*
* OACONTROL, performance counter enable, note:
*
* "When this bit is set, in order to have coherent counts,
* RC6 power state and trunk clock gating must be disabled.
* This can be achieved by programming MMIO registers as
* 0xA094=0 and 0xA090[31]=1"
*
* In our case we are expecting that taking pm + FORCEWAKE
* references will effectively disable RC6.
*/
intel_runtime_pm_get(dev_priv);
intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
ret = dev_priv->perf.oa.ops.enable_metric_set(dev_priv);
if (ret)
goto err_enable;
stream->ops = &i915_oa_stream_ops;
dev_priv->perf.oa.exclusive_stream = stream;
return 0;
err_enable:
intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
intel_runtime_pm_put(dev_priv);
free_oa_buffer(dev_priv);
err_oa_buf_alloc:
if (stream->ctx)
oa_put_render_ctx_id(stream);
return ret;
}
/**
* i915_perf_read_locked - &i915_perf_stream_ops->read with error normalisation
* @stream: An i915 perf stream
* @file: An i915 perf stream file
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @ppos: (inout) file seek position (unused)
*
* Besides wrapping &i915_perf_stream_ops->read this provides a common place to
* ensure that if we've successfully copied any data then reporting that takes
* precedence over any internal error status, so the data isn't lost.
*
* For example ret will be -ENOSPC whenever there is more buffered data than
* can be copied to userspace, but that's only interesting if we weren't able
* to copy some data because it implies the userspace buffer is too small to
* receive a single record (and we never split records).
*
* Another case with ret == -EFAULT is more of a grey area since it would seem
* like bad form for userspace to ask us to overrun its buffer, but the user
* knows best:
*
* http://yarchive.net/comp/linux/partial_reads_writes.html
*
* Returns: The number of bytes copied or a negative error code on failure.
*/
static ssize_t i915_perf_read_locked(struct i915_perf_stream *stream,
struct file *file,
char __user *buf,
size_t count,
loff_t *ppos)
{
/* Note we keep the offset (aka bytes read) separate from any
* error status so that the final check for whether we return
* the bytes read with a higher precedence than any error (see
* comment below) doesn't need to be handled/duplicated in
* stream->ops->read() implementations.
*/
size_t offset = 0;
int ret = stream->ops->read(stream, buf, count, &offset);
return offset ?: (ret ?: -EAGAIN);
}
/**
* i915_perf_read - handles read() FOP for i915 perf stream FDs
* @file: An i915 perf stream file
* @buf: destination buffer given by userspace
* @count: the number of bytes userspace wants to read
* @ppos: (inout) file seek position (unused)
*
* The entry point for handling a read() on a stream file descriptor from
* userspace. Most of the work is left to the i915_perf_read_locked() and
* &i915_perf_stream_ops->read but to save having stream implementations (of
* which we might have multiple later) we handle blocking read here.
*
* We can also consistently treat trying to read from a disabled stream
* as an IO error so implementations can assume the stream is enabled
* while reading.
*
* Returns: The number of bytes copied or a negative error code on failure.
*/
static ssize_t i915_perf_read(struct file *file,
char __user *buf,
size_t count,
loff_t *ppos)
{
struct i915_perf_stream *stream = file->private_data;
struct drm_i915_private *dev_priv = stream->dev_priv;
ssize_t ret;
/* To ensure it's handled consistently we simply treat all reads of a
* disabled stream as an error. In particular it might otherwise lead
* to a deadlock for blocking file descriptors...
*/
if (!stream->enabled)
return -EIO;
if (!(file->f_flags & O_NONBLOCK)) {
/* There's the small chance of false positives from
* stream->ops->wait_unlocked.
*
* E.g. with single context filtering since we only wait until
* oabuffer has >= 1 report we don't immediately know whether
* any reports really belong to the current context
*/
do {
ret = stream->ops->wait_unlocked(stream);
if (ret)
return ret;
mutex_lock(&dev_priv->perf.lock);
ret = i915_perf_read_locked(stream, file,
buf, count, ppos);
mutex_unlock(&dev_priv->perf.lock);
} while (ret == -EAGAIN);
} else {
mutex_lock(&dev_priv->perf.lock);
ret = i915_perf_read_locked(stream, file, buf, count, ppos);
mutex_unlock(&dev_priv->perf.lock);
}
if (ret >= 0) {
/* Maybe make ->pollin per-stream state if we support multiple
* concurrent streams in the future.
*/
dev_priv->perf.oa.pollin = false;
}
return ret;
}
static enum hrtimer_restart oa_poll_check_timer_cb(struct hrtimer *hrtimer)
{
struct drm_i915_private *dev_priv =
container_of(hrtimer, typeof(*dev_priv),
perf.oa.poll_check_timer);
if (!dev_priv->perf.oa.ops.oa_buffer_is_empty(dev_priv)) {
dev_priv->perf.oa.pollin = true;
wake_up(&dev_priv->perf.oa.poll_wq);
}
hrtimer_forward_now(hrtimer, ns_to_ktime(POLL_PERIOD));
return HRTIMER_RESTART;
}
/**
* i915_perf_poll_locked - poll_wait() with a suitable wait queue for stream
* @dev_priv: i915 device instance
* @stream: An i915 perf stream
* @file: An i915 perf stream file
* @wait: poll() state table
*
* For handling userspace polling on an i915 perf stream, this calls through to
* &i915_perf_stream_ops->poll_wait to call poll_wait() with a wait queue that
* will be woken for new stream data.
*
* Note: The &drm_i915_private->perf.lock mutex has been taken to serialize
* with any non-file-operation driver hooks.
*
* Returns: any poll events that are ready without sleeping
*/
static unsigned int i915_perf_poll_locked(struct drm_i915_private *dev_priv,
struct i915_perf_stream *stream,
struct file *file,
poll_table *wait)
{
unsigned int events = 0;
stream->ops->poll_wait(stream, file, wait);
/* Note: we don't explicitly check whether there's something to read
* here since this path may be very hot depending on what else
* userspace is polling, or on the timeout in use. We rely solely on
* the hrtimer/oa_poll_check_timer_cb to notify us when there are
* samples to read.
*/
if (dev_priv->perf.oa.pollin)
events |= POLLIN;
return events;
}
/**
* i915_perf_poll - call poll_wait() with a suitable wait queue for stream
* @file: An i915 perf stream file
* @wait: poll() state table
*
* For handling userspace polling on an i915 perf stream, this ensures
* poll_wait() gets called with a wait queue that will be woken for new stream
* data.
*
* Note: Implementation deferred to i915_perf_poll_locked()
*
* Returns: any poll events that are ready without sleeping
*/
static unsigned int i915_perf_poll(struct file *file, poll_table *wait)
{
struct i915_perf_stream *stream = file->private_data;
struct drm_i915_private *dev_priv = stream->dev_priv;
int ret;
mutex_lock(&dev_priv->perf.lock);
ret = i915_perf_poll_locked(dev_priv, stream, file, wait);
mutex_unlock(&dev_priv->perf.lock);
return ret;
}
/**
* i915_perf_enable_locked - handle `I915_PERF_IOCTL_ENABLE` ioctl
* @stream: A disabled i915 perf stream
*
* [Re]enables the associated capture of data for this stream.
*
* If a stream was previously enabled then there's currently no intention
* to provide userspace any guarantee about the preservation of previously
* buffered data.
*/
static void i915_perf_enable_locked(struct i915_perf_stream *stream)
{
if (stream->enabled)
return;
/* Allow stream->ops->enable() to refer to this */
stream->enabled = true;
if (stream->ops->enable)
stream->ops->enable(stream);
}
/**
* i915_perf_disable_locked - handle `I915_PERF_IOCTL_DISABLE` ioctl
* @stream: An enabled i915 perf stream
*
* Disables the associated capture of data for this stream.
*
* The intention is that disabling an re-enabling a stream will ideally be
* cheaper than destroying and re-opening a stream with the same configuration,
* though there are no formal guarantees about what state or buffered data
* must be retained between disabling and re-enabling a stream.
*
* Note: while a stream is disabled it's considered an error for userspace
* to attempt to read from the stream (-EIO).
*/
static void i915_perf_disable_locked(struct i915_perf_stream *stream)
{
if (!stream->enabled)
return;
/* Allow stream->ops->disable() to refer to this */
stream->enabled = false;
if (stream->ops->disable)
stream->ops->disable(stream);
}
/**
* i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
* @stream: An i915 perf stream
* @cmd: the ioctl request
* @arg: the ioctl data
*
* Note: The &drm_i915_private->perf.lock mutex has been taken to serialize
* with any non-file-operation driver hooks.
*
* Returns: zero on success or a negative error code. Returns -EINVAL for
* an unknown ioctl request.
*/
static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
unsigned int cmd,
unsigned long arg)
{
switch (cmd) {
case I915_PERF_IOCTL_ENABLE:
i915_perf_enable_locked(stream);
return 0;
case I915_PERF_IOCTL_DISABLE:
i915_perf_disable_locked(stream);
return 0;
}
return -EINVAL;
}
/**
* i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
* @file: An i915 perf stream file
* @cmd: the ioctl request
* @arg: the ioctl data
*
* Implementation deferred to i915_perf_ioctl_locked().
*
* Returns: zero on success or a negative error code. Returns -EINVAL for
* an unknown ioctl request.
*/
static long i915_perf_ioctl(struct file *file,
unsigned int cmd,
unsigned long arg)
{
struct i915_perf_stream *stream = file->private_data;
struct drm_i915_private *dev_priv = stream->dev_priv;
long ret;
mutex_lock(&dev_priv->perf.lock);
ret = i915_perf_ioctl_locked(stream, cmd, arg);
mutex_unlock(&dev_priv->perf.lock);
return ret;
}
/**
* i915_perf_destroy_locked - destroy an i915 perf stream
* @stream: An i915 perf stream
*
* Frees all resources associated with the given i915 perf @stream, disabling
* any associated data capture in the process.
*
* Note: The &drm_i915_private->perf.lock mutex has been taken to serialize
* with any non-file-operation driver hooks.
*/
static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
{
if (stream->enabled)
i915_perf_disable_locked(stream);
if (stream->ops->destroy)
stream->ops->destroy(stream);
list_del(&stream->link);
if (stream->ctx)
i915_gem_context_put_unlocked(stream->ctx);
kfree(stream);
}
/**
* i915_perf_release - handles userspace close() of a stream file
* @inode: anonymous inode associated with file
* @file: An i915 perf stream file
*
* Cleans up any resources associated with an open i915 perf stream file.
*
* NB: close() can't really fail from the userspace point of view.
*
* Returns: zero on success or a negative error code.
*/
static int i915_perf_release(struct inode *inode, struct file *file)
{
struct i915_perf_stream *stream = file->private_data;
struct drm_i915_private *dev_priv = stream->dev_priv;
mutex_lock(&dev_priv->perf.lock);
i915_perf_destroy_locked(stream);
mutex_unlock(&dev_priv->perf.lock);
return 0;
}
static const struct file_operations fops = {
.owner = THIS_MODULE,
.llseek = no_llseek,
.release = i915_perf_release,
.poll = i915_perf_poll,
.read = i915_perf_read,
.unlocked_ioctl = i915_perf_ioctl,
};
static struct i915_gem_context *
lookup_context(struct drm_i915_private *dev_priv,
struct drm_i915_file_private *file_priv,
u32 ctx_user_handle)
{
struct i915_gem_context *ctx;
int ret;
ret = i915_mutex_lock_interruptible(&dev_priv->drm);
if (ret)
return ERR_PTR(ret);
ctx = i915_gem_context_lookup(file_priv, ctx_user_handle);
if (!IS_ERR(ctx))
i915_gem_context_get(ctx);
mutex_unlock(&dev_priv->drm.struct_mutex);
return ctx;
}
/**
* i915_perf_open_ioctl_locked - DRM ioctl() for userspace to open a stream FD
* @dev_priv: i915 device instance
* @param: The open parameters passed to 'DRM_I915_PERF_OPEN`
* @props: individually validated u64 property value pairs
* @file: drm file
*
* See i915_perf_ioctl_open() for interface details.
*
* Implements further stream config validation and stream initialization on
* behalf of i915_perf_open_ioctl() with the &drm_i915_private->perf.lock mutex
* taken to serialize with any non-file-operation driver hooks.
*
* Note: at this point the @props have only been validated in isolation and
* it's still necessary to validate that the combination of properties makes
* sense.
*
* In the case where userspace is interested in OA unit metrics then further
* config validation and stream initialization details will be handled by
* i915_oa_stream_init(). The code here should only validate config state that
* will be relevant to all stream types / backends.
*
* Returns: zero on success or a negative error code.
*/
static int
i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
struct drm_i915_perf_open_param *param,
struct perf_open_properties *props,
struct drm_file *file)
{
struct i915_gem_context *specific_ctx = NULL;
struct i915_perf_stream *stream = NULL;
unsigned long f_flags = 0;
int stream_fd;
int ret;
if (props->single_context) {
u32 ctx_handle = props->ctx_handle;
struct drm_i915_file_private *file_priv = file->driver_priv;
specific_ctx = lookup_context(dev_priv, file_priv, ctx_handle);
if (IS_ERR(specific_ctx)) {
ret = PTR_ERR(specific_ctx);
if (ret != -EINTR)
DRM_DEBUG("Failed to look up context with ID %u for opening perf stream\n",
ctx_handle);
goto err;
}
}
/* 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_DEBUG("Insufficient privileges to open system-wide i915 perf stream\n");
ret = -EACCES;
goto err_ctx;
}
stream = kzalloc(sizeof(*stream), GFP_KERNEL);
if (!stream) {
ret = -ENOMEM;
goto err_ctx;
}
stream->dev_priv = dev_priv;
stream->ctx = specific_ctx;
ret = i915_oa_stream_init(stream, param, props);
if (ret)
goto err_alloc;
/* we avoid simply assigning stream->sample_flags = props->sample_flags
* to have _stream_init check the combination of sample flags more
* thoroughly, but still this is the expected result at this point.
*/
if (WARN_ON(stream->sample_flags != props->sample_flags)) {
ret = -ENODEV;
goto err_flags;
}
list_add(&stream->link, &dev_priv->perf.streams);
if (param->flags & I915_PERF_FLAG_FD_CLOEXEC)
f_flags |= O_CLOEXEC;
if (param->flags & I915_PERF_FLAG_FD_NONBLOCK)
f_flags |= O_NONBLOCK;
stream_fd = anon_inode_getfd("[i915_perf]", &fops, stream, f_flags);
if (stream_fd < 0) {
ret = stream_fd;
goto err_open;
}
if (!(param->flags & I915_PERF_FLAG_DISABLED))
i915_perf_enable_locked(stream);
return stream_fd;
err_open:
list_del(&stream->link);
err_flags:
if (stream->ops->destroy)
stream->ops->destroy(stream);
err_alloc:
kfree(stream);
err_ctx:
if (specific_ctx)
i915_gem_context_put_unlocked(specific_ctx);
err:
return ret;
}
/**
* read_properties_unlocked - validate + copy userspace stream open properties
* @dev_priv: i915 device instance
* @uprops: The array of u64 key value pairs given by userspace
* @n_props: The number of key value pairs expected in @uprops
* @props: The stream configuration built up while validating properties
*
* Note this function only validates properties in isolation it doesn't
* validate that the combination of properties makes sense or that all
* properties necessary for a particular kind of stream have been set.
*
* Note that there currently aren't any ordering requirements for properties so
* we shouldn't validate or assume anything about ordering here. This doesn't
* rule out defining new properties with ordering requirements in the future.
*/
static int read_properties_unlocked(struct drm_i915_private *dev_priv,
u64 __user *uprops,
u32 n_props,
struct perf_open_properties *props)
{
u64 __user *uprop = uprops;
int i;
memset(props, 0, sizeof(struct perf_open_properties));
if (!n_props) {
DRM_DEBUG("No i915 perf properties given\n");
return -EINVAL;
}
/* Considering that ID = 0 is reserved and assuming that we don't
* (currently) expect any configurations to ever specify duplicate
* values for a particular property ID then the last _PROP_MAX value is
* one greater than the maximum number of properties we expect to get
* from userspace.
*/
if (n_props >= DRM_I915_PERF_PROP_MAX) {
DRM_DEBUG("More i915 perf properties specified than exist\n");
return -EINVAL;
}
for (i = 0; i < n_props; i++) {
u64 oa_period, oa_freq_hz;
u64 id, value;
int ret;
ret = get_user(id, uprop);
if (ret)
return ret;
ret = get_user(value, uprop + 1);
if (ret)
return ret;
if (id == 0 || id >= DRM_I915_PERF_PROP_MAX) {
DRM_DEBUG("Unknown i915 perf property ID\n");
return -EINVAL;
}
switch ((enum drm_i915_perf_property_id)id) {
case DRM_I915_PERF_PROP_CTX_HANDLE:
props->single_context = 1;
props->ctx_handle = value;
break;
case DRM_I915_PERF_PROP_SAMPLE_OA:
props->sample_flags |= SAMPLE_OA_REPORT;
break;
case DRM_I915_PERF_PROP_OA_METRICS_SET:
if (value == 0 ||
value > dev_priv->perf.oa.n_builtin_sets) {
DRM_DEBUG("Unknown OA metric set ID\n");
return -EINVAL;
}
props->metrics_set = value;
break;
case DRM_I915_PERF_PROP_OA_FORMAT:
if (value == 0 || value >= I915_OA_FORMAT_MAX) {
DRM_DEBUG("Invalid OA report format\n");
return -EINVAL;
}
if (!dev_priv->perf.oa.oa_formats[value].size) {
DRM_DEBUG("Invalid OA report format\n");
return -EINVAL;
}
props->oa_format = value;
break;
case DRM_I915_PERF_PROP_OA_EXPONENT:
if (value > OA_EXPONENT_MAX) {
DRM_DEBUG("OA timer exponent too high (> %u)\n",
OA_EXPONENT_MAX);
return -EINVAL;
}
/* Theoretically we can program the OA unit to sample
* every 160ns but don't allow that by default unless
* root.
*
* On Haswell the period is derived from the exponent
* as:
*
* period = 80ns * 2^(exponent + 1)
*/
BUILD_BUG_ON(sizeof(oa_period) != 8);
oa_period = 80ull * (2ull << value);
/* This check is primarily to ensure that oa_period <=
* UINT32_MAX (before passing to do_div which only
* accepts a u32 denominator), but we can also skip
* checking anything < 1Hz which implicitly can't be
* limited via an integer oa_max_sample_rate.
*/
if (oa_period <= NSEC_PER_SEC) {
u64 tmp = NSEC_PER_SEC;
do_div(tmp, oa_period);
oa_freq_hz = tmp;
} else
oa_freq_hz = 0;
if (oa_freq_hz > i915_oa_max_sample_rate &&
!capable(CAP_SYS_ADMIN)) {
DRM_DEBUG("OA exponent would exceed the max sampling frequency (sysctl dev.i915.oa_max_sample_rate) %uHz without root privileges\n",
i915_oa_max_sample_rate);
return -EACCES;
}
props->oa_periodic = true;
props->oa_period_exponent = value;
break;
case DRM_I915_PERF_PROP_MAX:
MISSING_CASE(id);
return -EINVAL;
}
uprop += 2;
}
return 0;
}
/**
* i915_perf_open_ioctl - DRM ioctl() for userspace to open a stream FD
* @dev: drm device
* @data: ioctl data copied from userspace (unvalidated)
* @file: drm file
*
* Validates the stream open parameters given by userspace including flags
* and an array of u64 key, value pair properties.
*
* Very little is assumed up front about the nature of the stream being
* opened (for instance we don't assume it's for periodic OA unit metrics). An
* i915-perf stream is expected to be a suitable interface for other forms of
* buffered data written by the GPU besides periodic OA metrics.
*
* Note we copy the properties from userspace outside of the i915 perf
* mutex to avoid an awkward lockdep with mmap_sem.
*
* Most of the implementation details are handled by
* i915_perf_open_ioctl_locked() after taking the &drm_i915_private->perf.lock
* mutex for serializing with any non-file-operation driver hooks.
*
* Return: A newly opened i915 Perf stream file descriptor or negative
* error code on failure.
*/
int i915_perf_open_ioctl(struct drm_device *dev, void *data,
struct drm_file *file)
{
struct drm_i915_private *dev_priv = dev->dev_private;
struct drm_i915_perf_open_param *param = data;
struct perf_open_properties props;
u32 known_open_flags;
int ret;
if (!dev_priv->perf.initialized) {
DRM_DEBUG("i915 perf interface not available for this system\n");
return -ENOTSUPP;
}
known_open_flags = I915_PERF_FLAG_FD_CLOEXEC |
I915_PERF_FLAG_FD_NONBLOCK |
I915_PERF_FLAG_DISABLED;
if (param->flags & ~known_open_flags) {
DRM_DEBUG("Unknown drm_i915_perf_open_param flag\n");
return -EINVAL;
}
ret = read_properties_unlocked(dev_priv,
u64_to_user_ptr(param->properties_ptr),
param->num_properties,
&props);
if (ret)
return ret;
mutex_lock(&dev_priv->perf.lock);
ret = i915_perf_open_ioctl_locked(dev_priv, param, &props, file);
mutex_unlock(&dev_priv->perf.lock);
return ret;
}
/**
* i915_perf_register - exposes i915-perf to userspace
* @dev_priv: i915 device instance
*
* In particular OA metric sets are advertised under a sysfs metrics/
* directory allowing userspace to enumerate valid IDs that can be
* used to open an i915-perf stream.
*/
void i915_perf_register(struct drm_i915_private *dev_priv)
{
if (!IS_HASWELL(dev_priv))
return;
if (!dev_priv->perf.initialized)
return;
/* To be sure we're synchronized with an attempted
* i915_perf_open_ioctl(); considering that we register after
* being exposed to userspace.
*/
mutex_lock(&dev_priv->perf.lock);
dev_priv->perf.metrics_kobj =
kobject_create_and_add("metrics",
&dev_priv->drm.primary->kdev->kobj);
if (!dev_priv->perf.metrics_kobj)
goto exit;
if (i915_perf_register_sysfs_hsw(dev_priv)) {
kobject_put(dev_priv->perf.metrics_kobj);
dev_priv->perf.metrics_kobj = NULL;
}
exit:
mutex_unlock(&dev_priv->perf.lock);
}
/**
* i915_perf_unregister - hide i915-perf from userspace
* @dev_priv: i915 device instance
*
* i915-perf state cleanup is split up into an 'unregister' and
* 'deinit' phase where the interface is first hidden from
* userspace by i915_perf_unregister() before cleaning up
* remaining state in i915_perf_fini().
*/
void i915_perf_unregister(struct drm_i915_private *dev_priv)
{
if (!IS_HASWELL(dev_priv))
return;
if (!dev_priv->perf.metrics_kobj)
return;
i915_perf_unregister_sysfs_hsw(dev_priv);
kobject_put(dev_priv->perf.metrics_kobj);
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,
},
{
.procname = "oa_max_sample_rate",
.data = &i915_oa_max_sample_rate,
.maxlen = sizeof(i915_oa_max_sample_rate),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
.extra1 = &zero,
.extra2 = &oa_sample_rate_hard_limit,
},
{}
};
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,
},
{}
};
/**
* i915_perf_init - initialize i915-perf state on module load
* @dev_priv: i915 device instance
*
* Initializes i915-perf state without exposing anything to userspace.
*
* Note: i915-perf initialization is split into an 'init' and 'register'
* phase with the i915_perf_register() exposing state to userspace.
*/
void i915_perf_init(struct drm_i915_private *dev_priv)
{
if (!IS_HASWELL(dev_priv))
return;
hrtimer_init(&dev_priv->perf.oa.poll_check_timer,
CLOCK_MONOTONIC, HRTIMER_MODE_REL);
dev_priv->perf.oa.poll_check_timer.function = oa_poll_check_timer_cb;
init_waitqueue_head(&dev_priv->perf.oa.poll_wq);
INIT_LIST_HEAD(&dev_priv->perf.streams);
mutex_init(&dev_priv->perf.lock);
spin_lock_init(&dev_priv->perf.hook_lock);
dev_priv->perf.oa.ops.init_oa_buffer = gen7_init_oa_buffer;
dev_priv->perf.oa.ops.enable_metric_set = hsw_enable_metric_set;
dev_priv->perf.oa.ops.disable_metric_set = hsw_disable_metric_set;
dev_priv->perf.oa.ops.oa_enable = gen7_oa_enable;
dev_priv->perf.oa.ops.oa_disable = gen7_oa_disable;
dev_priv->perf.oa.ops.read = gen7_oa_read;
dev_priv->perf.oa.ops.oa_buffer_is_empty =
gen7_oa_buffer_is_empty_fop_unlocked;
dev_priv->perf.oa.timestamp_frequency = 12500000;
dev_priv->perf.oa.oa_formats = hsw_oa_formats;
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;
}
/**
* i915_perf_fini - Counter part to i915_perf_init()
* @dev_priv: i915 device instance
*/
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;
}
