This adds a 'Perf' section to i915.rst with the following sub sections:
- Overview
- Comparison with Core Perf
- i915 Driver Entry Points
- i915 Perf Stream
- i915 Perf Observation Architecture Stream
- All i915 Perf Internals
Signed-off-by: Robert Bragg <rob...@sixbynine.org>
Cc: Daniel Vetter <daniel.vet...@ffwll.ch>
---
Documentation/gpu/i915.rst | 92 +++++++++++++
drivers/gpu/drm/i915/i915_drv.h | 151 ++++++++++++++++----
drivers/gpu/drm/i915/i915_perf.c | 289 +++++++++++++++++++++++++++++++++++----
3 files changed, 478 insertions(+), 54 deletions(-)
diff --git a/Documentation/gpu/i915.rst b/Documentation/gpu/i915.rst
index 117d2ab..714bd4b 100644
--- a/Documentation/gpu/i915.rst
+++ b/Documentation/gpu/i915.rst
@@ -356,4 +356,96 @@ switch_mm
.. kernel-doc:: drivers/gpu/drm/i915/i915_trace.h
:doc: switch_mm tracepoint
+Perf
+====
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :doc: i915 Perf Overview
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :doc: i915 Perf History and Comparison with Core Perf
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :doc: i915 Perf File Operations
+
+i915 Driver Entry Points
+------------------------
+
+This section covers the entrypoints exported outside of i915_perf.c to
+integrate with drm/i915 and to handle the `DRM_I915_PERF_OPEN` ioctl.
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_init
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_fini
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_register
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_unregister
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_open_ioctl
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_release
+
+i915 Perf Stream
+----------------
+
+This section covers the stream-semantics-agnostic structures and functions
+for representing an i915 perf stream FD and associated file operations.
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_drv.h
+ :functions: i915_perf_stream
+.. kernel-doc:: drivers/gpu/drm/i915/i915_drv.h
+ :functions: i915_perf_stream_ops
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: read_properties_unlocked
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_open_ioctl_unlocked
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_destroy_unlocked
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_read
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_ioctl
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_enable_unlocked
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_disable_unlocked
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_poll
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_perf_poll_unlocked
+
+i915 Perf Observation Architecture Stream
+-----------------------------------------
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: OA_BUFFER_SIZE
+.. kernel-doc:: drivers/gpu/drm/i915/i915_drv.h
+ :functions: i915_oa_ops
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_oa_stream_init
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_oa_read
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_oa_stream_enable
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_oa_stream_disable
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_oa_wait_unlocked
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :functions: i915_oa_poll_wait
+
+All i915 Perf Internals
+-----------------------
+
+This section simply includes all currently documented i915 perf internals, in
+no particular order, but may include some more minor utilities or platform
+specific details than found in the more high-level sections.
+
+.. kernel-doc:: drivers/gpu/drm/i915/i915_perf.c
+ :internal:
+
.. WARNING: DOCPROC directive not supported: !Cdrivers/gpu/drm/i915/i915_irq.c
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 1ec9619..9f92755 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1827,89 +1827,186 @@ struct i915_oa_reg {
struct i915_perf_stream;
+/**
+ * struct i915_perf_stream_ops - the OPs to support a specific stream type
+ */
struct i915_perf_stream_ops {
- /* Enables the collection of HW samples, either in response to
- * I915_PERF_IOCTL_ENABLE or implicitly called when stream is
- * opened without I915_PERF_FLAG_DISABLED.
+ /**
+ * @enable: Enables the collection of HW samples, either in response to
+ * I915_PERF_IOCTL_ENABLE or implicitly called when stream is opened
+ * without I915_PERF_FLAG_DISABLED.
*/
void (*enable)(struct i915_perf_stream *stream);
- /* Disables the collection of HW samples, either in response to
- * I915_PERF_IOCTL_DISABLE or implicitly called before
- * destroying the stream.
+ /**
+ * @disable: Disables the collection of HW samples, either in response
+ * to I915_PERF_IOCTL_DISABLE or implicitly called before destroying
+ * the stream.
*/
void (*disable)(struct i915_perf_stream *stream);
- /* Call poll_wait, passing a wait queue that will be woken
+ /**
+ * @poll_wait: Call poll_wait, passing a wait queue that will be woken
* once there is something ready to read() for the stream
*/
void (*poll_wait)(struct i915_perf_stream *stream,
struct file *file,
poll_table *wait);
- /* For handling a blocking read, wait until there is something
- * to ready to read() for the stream. E.g. wait on the same
+ /**
+ * @wait_unlocked: For handling a blocking read, wait until there is
+ * something to ready to read() for the stream. E.g. wait on the same
* wait queue that would be passed to poll_wait().
*/
int (*wait_unlocked)(struct i915_perf_stream *stream);
- /* read - Copy buffered metrics as records to userspace
- * @buf: the userspace, destination buffer
- * @count: the number of bytes to copy, requested by userspace
- * @offset: zero at the start of the read, updated as the read
- * proceeds, it represents how many bytes have been
- * copied so far and the buffer offset for copying the
- * next record.
+ /**
+ * @read: Copy buffered metrics as records to userspace
+ * **buf**: the userspace, destination buffer
+ * **count**: the number of bytes to copy, requested by userspace
+ * **offset**: zero at the start of the read, updated as the read
+ * proceeds, it represents how many bytes have been copied so far and
+ * the buffer offset for copying the next record.
*
- * Copy as many buffered i915 perf samples and records for
- * this stream to userspace as will fit in the given buffer.
+ * Copy as many buffered i915 perf samples and records for this stream
+ * to userspace as will fit in the given buffer.
*
- * Only write complete records; returning -ENOSPC if there
- * isn't room for a complete record.
+ * Only write complete records; returning -ENOSPC if there isn't room
+ * for a complete record.
*
- * Return any error condition that results in a short read
- * such as -ENOSPC or -EFAULT, even though these may be
- * squashed before returning to userspace.
+ * Return any error condition that results in a short read such as
+ * -ENOSPC or -EFAULT, even though these may be squashed before
+ * returning to userspace.
*/
int (*read)(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset);
- /* Cleanup any stream specific resources.
+ /**
+ * @destroy: Cleanup any stream specific resources.
*
* The stream will always be disabled before this is called.
*/
void (*destroy)(struct i915_perf_stream *stream);
};
+/**
+ * struct i915_perf_stream - state for a single open stream FD
+ */
struct i915_perf_stream {
+ /**
+ * @dev_priv: i915 drm device
+ */
struct drm_i915_private *dev_priv;
+ /**
+ * @link: Links the stream into ``&drm_i915_private->streams``
+ */
struct list_head link;
+ /**
+ * @sample_flags: Flags representing the `DRM_I915_PERF_PROP_SAMPLE_*`
+ * properties given when opening a stream, representing the contents
+ * of a single sample as read() by userspace.
+ */
u32 sample_flags;
+
+ /**
+ * @sample_size: Considering the configured contents of a sample
+ * combined with the required header size, this is the total size
+ * of a single sample record.
+ */
int sample_size;
+ /**
+ * @ctx: %NULL if measuring system-wide across all contexts or a
+ * specific context that is being monitored.
+ */
struct i915_gem_context *ctx;
+
+ /**
+ * @enabled: Whether the stream is currently enabled, considering
+ * whether the stream was opened in a disabled state and based
+ * on `I915_PERF_IOCTL_ENABLE` and `I915_PERF_IOCTL_DISABLE` calls.
+ */
bool enabled;
+ /**
+ * @ops: The callbacks providing the implementation of this specific
+ * type of configured stream.
+ */
const struct i915_perf_stream_ops *ops;
};
+/**
+ * struct i915_oa_ops - Gen specific implementation of an OA unit stream
+ */
struct i915_oa_ops {
+ /**
+ * @init_oa_buffer: Resets the head and tail pointers of the
+ * circular buffer for periodic OA reports.
+ *
+ * Called when first opening a stream for OA metrics, but also may be
+ * called in response to an OA buffer overflow or other error
+ * condition.
+ *
+ * Note it may be necessary to clear the full OA buffer here as part of
+ * maintaining the invariable that new reports must be written to
+ * zeroed memory for us to be able to reliable detect if an expected
+ * report has not yet landed in memory. (At least on Haswell the OA
+ * buffer tail pointer is not synchronized with reports being visible
+ * to the CPU)
+ */
void (*init_oa_buffer)(struct drm_i915_private *dev_priv);
+
+ /**
+ * @enable_metric_set: Applies any MUX configuration to set up the
+ * Boolean and Custom (B/C) counters that are part of the counter
+ * reports being sampled. May apply system constraints such as
+ * disabling EU clock gating as required.
+ */
int (*enable_metric_set)(struct drm_i915_private *dev_priv);
+
+ /**
+ * @disable_metric_set: Remove system constraints associated with using
+ * the OA unit.
+ */
void (*disable_metric_set)(struct drm_i915_private *dev_priv);
+
+ /**
+ * @oa_enable: Enable periodic sampling
+ */
void (*oa_enable)(struct drm_i915_private *dev_priv);
+
+ /**
+ * @oa_disable: Disable periodic sampling
+ */
void (*oa_disable)(struct drm_i915_private *dev_priv);
- void (*update_oacontrol)(struct drm_i915_private *dev_priv);
- void (*update_hw_ctx_id_locked)(struct drm_i915_private *dev_priv,
- u32 ctx_id);
+
+ /**
+ * @read: Copy data from the circular OA buffer into a given userspace
+ * buffer.
+ */
int (*read)(struct i915_perf_stream *stream,
char __user *buf,
size_t count,
size_t *offset);
+
+ /**
+ * @oa_buffer_is_empty: Check if OA buffer empty (false positives OK)
+ *
+ * This is either called via fops or the poll check hrtimer (atomic
+ * ctx) without any locks taken.
+ *
+ * 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.
+ *
+ * Efficiency is more important than avoiding some false positives
+ * here, which will be handled gracefully - likely resulting in an
+ * EAGAIN error for userspace.
+ */
bool (*oa_buffer_is_empty)(struct drm_i915_private *dev_priv);
};
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 68b7c27..0be8cef 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -26,7 +26,10 @@
/**
- * DOC: i915 Perf, streaming API for GPU metrics
+ * DOC: i915 Perf Overview
+ *
+ * Overview
+ * --------
*
* Gen graphics supports a large number of performance counters that can help
* driver and application developers understand and optimize their use of the
@@ -45,6 +48,13 @@
* privileges by default, unless changed via the dev.i915.perf_event_paranoid
* sysctl option.
*
+ */
+
+/**
+ * DOC: i915 Perf History and Comparison with Core Perf
+ *
+ * Comparison with Core Perf
+ * -------------------------
*
* The interface was initially inspired by the core Perf infrastructure but
* some notable differences are:
@@ -75,8 +85,8 @@
* gets copied from the GPU mapped buffers to userspace buffers.
*
*
- * Some notes regarding Linux Perf:
- * --------------------------------
+ * 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
@@ -135,7 +145,7 @@
* 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
+ * - 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
@@ -277,6 +287,20 @@ static struct i915_oa_format
hsw_oa_formats[I915_OA_FORMAT_MAX] = {
#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;
@@ -314,7 +338,19 @@ static bool gen7_oa_buffer_is_empty_fop_unlocked(struct
drm_i915_private *dev_pr
}
/**
- * Appends a status record to a userspace read() buffer.
+ * 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,
@@ -336,7 +372,21 @@ static int append_oa_status(struct i915_perf_stream
*stream,
}
/**
- * Copies single OA report into userspace read() buffer.
+ * 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,
@@ -380,8 +430,6 @@ static int append_oa_sample(struct i915_perf_stream *stream,
* @head_ptr: (inout): the current oa buffer cpu read position
* @tail: the current oa buffer gpu write position
*
- * Returns 0 on success, negative error code on failure.
- *
* 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
@@ -392,6 +440,8 @@ static int append_oa_sample(struct i915_perf_stream *stream,
* 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,
@@ -496,6 +546,22 @@ static int gen7_append_oa_reports(struct i915_perf_stream
*stream,
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,
@@ -597,6 +663,20 @@ static int gen7_oa_read(struct i915_perf_stream *stream,
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;
@@ -615,6 +695,16 @@ static int i915_oa_wait_unlocked(struct i915_perf_stream
*stream)
!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)
@@ -624,6 +714,18 @@ static void i915_oa_poll_wait(struct i915_perf_stream
*stream,
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,
@@ -634,9 +736,15 @@ static int i915_oa_read(struct i915_perf_stream *stream,
return dev_priv->perf.oa.ops.read(stream, buf, count, offset);
}
-/* Determine the render context hw id, and ensure it remains fixed for the
+/**
+ * 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)
{
@@ -673,6 +781,13 @@ static int oa_get_render_ctx_id(struct i915_perf_stream
*stream)
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;
@@ -945,6 +1060,15 @@ static void gen7_oa_enable(struct drm_i915_private
*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;
@@ -962,6 +1086,14 @@ 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;
@@ -987,6 +1119,24 @@ static const struct i915_perf_stream_ops
i915_oa_stream_ops = {
.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)
@@ -1110,6 +1260,31 @@ static int i915_oa_stream_init(struct i915_perf_stream
*stream,
return ret;
}
+/**
+ * i915_perf_read_locked - wrap stream->ops->read with error notmalisation
+ * @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 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,
@@ -1125,25 +1300,27 @@ static ssize_t i915_perf_read_locked(struct
i915_perf_stream *stream,
size_t offset = 0;
int ret = stream->ops->read(stream, buf, count, &offset);
- /* 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
- */
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
+ * stream->op->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 disable 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,
@@ -1458,12 +1635,20 @@ i915_perf_open_ioctl_locked(struct drm_i915_private
*dev_priv,
return ret;
}
-/* Note we copy the properties from userspace outside of the i915 perf
- * mutex to avoid an awkward lockdep with mmap_sem.
+/**
+ * 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,
@@ -1585,6 +1770,26 @@ static int read_properties_unlocked(struct
drm_i915_private *dev_priv,
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.
+ *
+ * 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)
{
@@ -1621,6 +1826,14 @@ int i915_perf_open_ioctl(struct drm_device *dev, void
*data,
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))
@@ -1650,6 +1863,15 @@ void i915_perf_register(struct drm_i915_private
*dev_priv)
mutex_unlock(&dev_priv->perf.lock);
}
+/**
+ * i915_perf_register - 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))
@@ -1706,6 +1928,15 @@ static struct ctl_table dev_root[] = {
{}
};
+/**
+ * i915_perf_init - initialize i915-perf state on module load
+ * @dev_priv: i915 device instance
+ *
+ * Initializes state 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))
@@ -1741,6 +1972,10 @@ void i915_perf_init(struct drm_i915_private *dev_priv)
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)
--
2.10.2
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