drm/i915/perf: Add OA unit support for Gen 8+

Enables access to OA unit metrics for BDW, CHV, SKL and BXT which all
share (more-or-less) the same OA unit design.

Of particular note in comparison to Haswell: some OA unit HW config
state has become per-context state and as a consequence it is somewhat
more complicated to manage synchronous state changes from the cpu while
there's no guarantee of what context (if any) is currently actively
running on the gpu.

The periodic sampling frequency which can be particularly useful for
system-wide analysis (as opposed to command stream synchronised
MI_REPORT_PERF_COUNT commands) is perhaps the most surprising state to
have become per-context save and restored (while the OABUFFER
destination is still a shared, system-wide resource).

This support for gen8+ takes care to consider a number of timing
challenges involved in synchronously updating per-context state
primarily by programming all config state from the cpu and updating all
current and saved contexts synchronously while the OA unit is still
disabled.

The driver intentionally avoids depending on command streamer
programming to update OA state considering the lack of synchronization
between the automatic loading of OACTXCONTROL state (that includes the
periodic sampling state and enable state) on context restore and the
parsing of any general purpose BB the driver can control. I.e. this
implementation is careful to avoid the possibility of a context restore
temporarily enabling any out-of-date periodic sampling state. In
addition to the risk of transiently-out-of-date state being loaded
automatically; there are also internal HW latencies involved in the
loading of MUX configurations which would be difficult to account for
from the command streamer (and we only want to enable the unit when once
the MUX configuration is complete).

Since the Gen8+ OA unit design no longer supports clock gating the unit
off for a single given context (which effectively stopped any progress
of counters while any other context was running) and instead supports
tagging OA reports with a context ID for filtering on the CPU, it means
we can no longer hide the system-wide progress of counters from a
non-privileged application only interested in metrics for its own
context. Although we could theoretically try and subtract the progress
of other contexts before forwarding reports via read() we aren't in a
position to filter reports captured via MI_REPORT_PERF_COUNT commands.
As a result, for Gen8+, we always require the
dev.i915.perf_stream_paranoid to be unset for any access to OA metrics
if not root.

v5: Drain submitted requests when enabling metric set to ensure no
    lite-restore erases the context image we just updated (Lionel)

v6: In addition to drain, switch to kernel context & update all
    context in place (Chris)

v7: Add missing mutex_unlock() if switching to kernel context fails
    (Matthew)

v8: Simplify OA period/flex-eu-counters programming by using the
    batchbuffer instead of modifying ctx-image (Lionel)

v9: Back to updating the context image (due to erroneous testing,
    batchbuffer programming the OA unit doesn't actually work)
    (Lionel)
    Pin context before updating context image (Chris)
    Drop MMIO programming now that we switch to a kernel context with
    right values in initial context image (Chris)

v10: Just pin_map the contexts we want to modify or let the
     configuration happen on first use (Chris)

v11: Update kernel context OA config through the batchbuffer rather
     than on the fly ctx-image update (Lionel)

v12: Rework OA context registers update again by swithing away from
     user contexts and reconfiguring the kernel context through the
     batchbuffer and updating all the other contexts' context image.
     Also take care to lock slice/subslice configuration when OA is
     on. (Lionel)

v13: Request rpcs updates on all engine when updating the OA config
     (Lionel)

v14: Drop any kind of rpcs management now that we monitor sseu
     configuration changes in a later patch (Lionel)
     Remove usleep after programming the NOA configs on Gen8+, this
     doesn't seem to be needed (Lionel)

v15: Respect coding style for block comments (Chris)

v16: Add missing i915_add_request() in case we fail to emit OA
     configuration (Matthew)
Signed-off-by: Robert Bragg <robert@sixbynine.org>
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com> \o/
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>

drivers/gpu/drm/i915/i915_drv.h

@@ -2018,9 +2018,17 @@ struct i915_oa_ops {
 	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
+	 * @select_metric_set: The auto generated code that checks whether a
+	 * requested OA config is applicable to the system and if so sets up
+	 * the mux, oa and flex eu register config pointers according to the
+	 * current dev_priv->perf.oa.metrics_set.
+	 */
+	int (*select_metric_set)(struct drm_i915_private *dev_priv);
+
+	/**
+	 * @enable_metric_set: Selects and 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);
@@ -2051,20 +2059,13 @@ struct i915_oa_ops {
 		    size_t *offset);
 
 	/**
-	 * @oa_buffer_check: Check for OA buffer data + update tail
-	 *
-	 * This is either called via fops or the poll check hrtimer (atomic
-	 * ctx) without any locks taken.
+	 * @oa_hw_tail_read: read the OA tail pointer register
 	 *
-	 * 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.
+	 * In particular this enables us to share all the fiddly code for
+	 * handling the OA unit tail pointer race that affects multiple
+	 * generations.
 	 */
-	bool (*oa_buffer_check)(struct drm_i915_private *dev_priv);
+	u32 (*oa_hw_tail_read)(struct drm_i915_private *dev_priv);
 };
 
 struct intel_cdclk_state {
@@ -2429,6 +2430,7 @@ struct drm_i915_private {
 			struct {
 				struct i915_vma *vma;
 				u8 *vaddr;
+				u32 last_ctx_id;
 				int format;
 				int format_size;
 
@@ -2498,6 +2500,15 @@ struct drm_i915_private {
 			} oa_buffer;
 
 			u32 gen7_latched_oastatus1;
+			u32 ctx_oactxctrl_offset;
+			u32 ctx_flexeu0_offset;
+
+			/**
+			 * The RPT_ID/reason field for Gen8+ includes a bit
+			 * to determine if the CTX ID in the report is valid
+			 * but the specific bit differs between Gen 8 and 9
+			 */
+			u32 gen8_valid_ctx_bit;
 
 			struct i915_oa_ops ops;
 			const struct i915_oa_format *oa_formats;
@@ -2810,6 +2821,8 @@ intel_info(const struct drm_i915_private *dev_priv)
 #define IS_KBL_ULX(dev_priv)	(INTEL_DEVID(dev_priv) == 0x590E || \
 				 INTEL_DEVID(dev_priv) == 0x5915 || \
 				 INTEL_DEVID(dev_priv) == 0x591E)
+#define IS_SKL_GT2(dev_priv)	(IS_SKYLAKE(dev_priv) && \
+				 (INTEL_DEVID(dev_priv) & 0x00F0) == 0x0010)
 #define IS_SKL_GT3(dev_priv)	(IS_SKYLAKE(dev_priv) && \
 				 (INTEL_DEVID(dev_priv) & 0x00F0) == 0x0020)
 #define IS_SKL_GT4(dev_priv)	(IS_SKYLAKE(dev_priv) && \
@@ -3554,6 +3567,9 @@ i915_gem_context_lookup_timeline(struct i915_gem_context *ctx,
 
 int i915_perf_open_ioctl(struct drm_device *dev, void *data,
 			 struct drm_file *file);
+void i915_oa_init_reg_state(struct intel_engine_cs *engine,
+			    struct i915_gem_context *ctx,
+			    uint32_t *reg_state);
 
 /* i915_gem_evict.c */
 int __must_check i915_gem_evict_something(struct i915_address_space *vm,

drivers/gpu/drm/i915/i915_perf.c

@@ -196,6 +196,12 @@
 
 #include "i915_drv.h"
 #include "i915_oa_hsw.h"
+#include "i915_oa_bdw.h"
+#include "i915_oa_chv.h"
+#include "i915_oa_sklgt2.h"
+#include "i915_oa_sklgt3.h"
+#include "i915_oa_sklgt4.h"
+#include "i915_oa_bxt.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
@@ -215,7 +221,7 @@
  *
  * Although this can be observed explicitly while copying reports to userspace
  * by checking for a zeroed report-id field in tail reports, we want to account
- * for this earlier, as part of the _oa_buffer_check to avoid lots of redundant
+ * for this earlier, as part of the oa_buffer_check to avoid lots of redundant
  * read() attempts.
  *
  * In effect we define a tail pointer for reading that lags the real tail
@@ -237,7 +243,7 @@
  * indicates that an updated tail pointer is needed.
  *
  * Most of the implementation details for this workaround are in
- * gen7_oa_buffer_check_unlocked() and gen7_appand_oa_reports()
+ * oa_buffer_check_unlocked() and _append_oa_reports()
  *
  * Note for posterity: previously the driver used to define an effective tail
  * pointer that lagged the real pointer by a 'tail margin' measured in bytes
@@ -272,6 +278,13 @@ static u32 i915_perf_stream_paranoid = true;
 
 #define INVALID_CTX_ID 0xffffffff
 
+/* On Gen8+ automatically triggered OA reports include a 'reason' field... */
+#define OAREPORT_REASON_MASK           0x3f
+#define OAREPORT_REASON_SHIFT          19
+#define OAREPORT_REASON_TIMER          (1<<0)
+#define OAREPORT_REASON_CTX_SWITCH     (1<<3)
+#define OAREPORT_REASON_CLK_RATIO      (1<<5)
+
 
 /* For sysctl proc_dointvec_minmax of i915_oa_max_sample_rate
  *
@@ -303,6 +316,13 @@ static struct i915_oa_format hsw_oa_formats[I915_OA_FORMAT_MAX] = {
 	[I915_OA_FORMAT_C4_B8]	    = { 7, 64 },
 };
 
+static struct i915_oa_format gen8_plus_oa_formats[I915_OA_FORMAT_MAX] = {
+	[I915_OA_FORMAT_A12]		    = { 0, 64 },
+	[I915_OA_FORMAT_A12_B8_C8]	    = { 2, 128 },
+	[I915_OA_FORMAT_A32u40_A4u32_B8_C8] = { 5, 256 },
+	[I915_OA_FORMAT_C4_B8]		    = { 7, 64 },
+};
+
 #define SAMPLE_OA_REPORT      (1<<0)
 
 /**
@@ -332,8 +352,20 @@ struct perf_open_properties {
 	int oa_period_exponent;
 };
 
+static u32 gen8_oa_hw_tail_read(struct drm_i915_private *dev_priv)
+{
+	return I915_READ(GEN8_OATAILPTR) & GEN8_OATAILPTR_MASK;
+}
+
+static u32 gen7_oa_hw_tail_read(struct drm_i915_private *dev_priv)
+{
+	u32 oastatus1 = I915_READ(GEN7_OASTATUS1);
+
+	return oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
+}
+
 /**
- * gen7_oa_buffer_check_unlocked - check for data and update tail ptr state
+ * oa_buffer_check_unlocked - check for data and update tail ptr state
  * @dev_priv: i915 device instance
  *
  * This is either called via fops (for blocking reads in user ctx) or the poll
@@ -356,12 +388,11 @@ struct perf_open_properties {
  *
  * Returns: %true if the OA buffer contains data, else %false
  */
-static bool gen7_oa_buffer_check_unlocked(struct drm_i915_private *dev_priv)
+static bool oa_buffer_check_unlocked(struct drm_i915_private *dev_priv)
 {
 	int report_size = dev_priv->perf.oa.oa_buffer.format_size;
 	unsigned long flags;
 	unsigned int aged_idx;
-	u32 oastatus1;
 	u32 head, hw_tail, aged_tail, aging_tail;
 	u64 now;
 
@@ -381,8 +412,7 @@ static bool gen7_oa_buffer_check_unlocked(struct drm_i915_private *dev_priv)
 	aged_tail = dev_priv->perf.oa.oa_buffer.tails[aged_idx].offset;
 	aging_tail = dev_priv->perf.oa.oa_buffer.tails[!aged_idx].offset;
 
-	oastatus1 = I915_READ(GEN7_OASTATUS1);
-	hw_tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
+	hw_tail = dev_priv->perf.oa.ops.oa_hw_tail_read(dev_priv);
 
 	/* The tail pointer increases in 64 byte increments,
 	 * not in report_size steps...
@@ -404,6 +434,7 @@ static bool gen7_oa_buffer_check_unlocked(struct drm_i915_private *dev_priv)
 	if (aging_tail != INVALID_TAIL_PTR &&
 	    ((now - dev_priv->perf.oa.oa_buffer.aging_timestamp) >
 	     OA_TAIL_MARGIN_NSEC)) {
+
 		aged_idx ^= 1;
 		dev_priv->perf.oa.oa_buffer.aged_tail_idx = aged_idx;
 
@@ -533,6 +564,300 @@ static int append_oa_sample(struct i915_perf_stream *stream,
 	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
+ *
+ * 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 tail chases the head?... 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 gen8_append_oa_reports(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;
+	u8 *oa_buf_base = dev_priv->perf.oa.oa_buffer.vaddr;
+	u32 gtt_offset = i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma);
+	u32 mask = (OA_BUFFER_SIZE - 1);
+	size_t start_offset = *offset;
+	unsigned long flags;
+	unsigned int aged_tail_idx;
+	u32 head, tail;
+	u32 taken;
+	int ret = 0;
+
+	if (WARN_ON(!stream->enabled))
+		return -EIO;
+
+	spin_lock_irqsave(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
+
+	head = dev_priv->perf.oa.oa_buffer.head;
+	aged_tail_idx = dev_priv->perf.oa.oa_buffer.aged_tail_idx;
+	tail = dev_priv->perf.oa.oa_buffer.tails[aged_tail_idx].offset;
+
+	spin_unlock_irqrestore(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
+
+	/*
+	 * An invalid tail pointer here means we're still waiting for the poll
+	 * hrtimer callback to give us a pointer
+	 */
+	if (tail == INVALID_TAIL_PTR)
+		return -EAGAIN;
+
+	/*
+	 * NB: oa_buffer.head/tail include the gtt_offset which we don't want
+	 * while indexing relative to oa_buf_base.
+	 */
+	head -= gtt_offset;
+	tail -= gtt_offset;
+
+	/*
+	 * An out of bounds or misaligned head or tail pointer implies a driver
+	 * bug since we validate + align the tail pointers we read from the
+	 * hardware and we are in full control of the head pointer which should
+	 * only be incremented by multiples of the report size (notably also
+	 * all a power of two).
+	 */
+	if (WARN_ONCE(head > OA_BUFFER_SIZE || head % report_size ||
+		      tail > OA_BUFFER_SIZE || tail % report_size,
+		      "Inconsistent OA buffer pointers: head = %u, tail = %u\n",
+		      head, tail))
+		return -EIO;
+
+
+	for (/* none */;
+	     (taken = OA_TAKEN(tail, head));
+	     head = (head + report_size) & mask) {
+		u8 *report = oa_buf_base + head;
+		u32 *report32 = (void *)report;
+		u32 ctx_id;
+		u32 reason;
+
+		/*
+		 * 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 reason field includes flags identifying what
+		 * triggered this specific report (mostly timer
+		 * triggered or e.g. due to a context switch).
+		 *
+		 * This field is never expected to be zero so we can
+		 * check that the report isn't invalid before copying
+		 * it to userspace...
+		 */
+		reason = ((report32[0] >> OAREPORT_REASON_SHIFT) &
+			  OAREPORT_REASON_MASK);
+		if (reason == 0) {
+			if (__ratelimit(&dev_priv->perf.oa.spurious_report_rs))
+				DRM_NOTE("Skipping spurious, invalid OA report\n");
+			continue;
+		}
+
+		/*
+		 * XXX: Just keep the lower 21 bits for now since I'm not
+		 * entirely sure if the HW touches any of the higher bits in
+		 * this field
+		 */
+		ctx_id = report32[2] & 0x1fffff;
+
+		/*
+		 * Squash whatever is in the CTX_ID field if it's marked as
+		 * invalid to be sure we avoid false-positive, single-context
+		 * filtering below...
+		 *
+		 * Note: that we don't clear the valid_ctx_bit so userspace can
+		 * understand that the ID has been squashed by the kernel.
+		 */
+		if (!(report32[0] & dev_priv->perf.oa.gen8_valid_ctx_bit))
+			ctx_id = report32[2] = INVALID_CTX_ID;
+
+		/*
+		 * NB: For Gen 8 the OA unit no longer supports clock gating
+		 * off for a specific context and the kernel can't securely
+		 * stop the counters from updating as system-wide / global
+		 * values.
+		 *
+		 * Automatic reports now include a context ID so reports can be
+		 * filtered on the cpu but it's not worth trying to
+		 * automatically subtract/hide counter progress for other
+		 * contexts while filtering since we can't stop userspace
+		 * issuing MI_REPORT_PERF_COUNT commands which would still
+		 * provide a side-band view of the real values.
+		 *
+		 * To allow userspace (such as Mesa/GL_INTEL_performance_query)
+		 * to normalize counters for a single filtered context then it
+		 * needs be forwarded bookend context-switch reports so that it
+		 * can track switches in between MI_REPORT_PERF_COUNT commands
+		 * and can itself subtract/ignore the progress of counters
+		 * associated with other contexts. Note that the hardware
+		 * automatically triggers reports when switching to a new
+		 * context which are tagged with the ID of the newly active
+		 * context. To avoid the complexity (and likely fragility) of
+		 * reading ahead while parsing reports to try and minimize
+		 * forwarding redundant context switch reports (i.e. between
+		 * other, unrelated contexts) we simply elect to forward them
+		 * all.
+		 *
+		 * We don't rely solely on the reason field to identify context
+		 * switches since it's not-uncommon for periodic samples to
+		 * identify a switch before any 'context switch' report.
+		 */
+		if (!dev_priv->perf.oa.exclusive_stream->ctx ||
+		    dev_priv->perf.oa.specific_ctx_id == ctx_id ||
+		    (dev_priv->perf.oa.oa_buffer.last_ctx_id ==
+		     dev_priv->perf.oa.specific_ctx_id) ||
+		    reason & OAREPORT_REASON_CTX_SWITCH) {
+
+			/*
+			 * While filtering for a single context we avoid
+			 * leaking the IDs of other contexts.
+			 */
+			if (dev_priv->perf.oa.exclusive_stream->ctx &&
+			    dev_priv->perf.oa.specific_ctx_id != ctx_id) {
+				report32[2] = INVALID_CTX_ID;
+			}
+
+			ret = append_oa_sample(stream, buf, count, offset,
+					       report);
+			if (ret)
+				break;
+
+			dev_priv->perf.oa.oa_buffer.last_ctx_id = ctx_id;
+		}
+
+		/*
+		 * The above reason 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;
+	}
+
+	if (start_offset != *offset) {
+		spin_lock_irqsave(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
+
+		/*
+		 * We removed the gtt_offset for the copy loop above, indexing
+		 * relative to oa_buf_base so put back here...
+		 */
+		head += gtt_offset;
+
+		I915_WRITE(GEN8_OAHEADPTR, head & GEN8_OAHEADPTR_MASK);
+		dev_priv->perf.oa.oa_buffer.head = head;
+
+		spin_unlock_irqrestore(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
+	}
+
+	return ret;
+}
+
+/**
+ * gen8_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 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.
+ *
+ * NB: some data may be successfully copied to the userspace buffer
+ * even if an error is returned, and this is reflected in the
+ * updated @offset.
+ *
+ * Returns: zero on success or a negative error code
+ */
+static int gen8_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;
+	u32 oastatus;
+	int ret;
+
+	if (WARN_ON(!dev_priv->perf.oa.oa_buffer.vaddr))
+		return -EIO;
+
+	oastatus = I915_READ(GEN8_OASTATUS);
+
+	/*
+	 * We treat OABUFFER_OVERFLOW as a significant error:
+	 *
+	 * Although theoretically we could handle this more gracefully
+	 * sometimes, some Gens don't correctly suppress certain
+	 * automatically triggered reports in this condition and so we
+	 * have to assume that old reports are now being trampled
+	 * over.
+	 *
+	 * Considering how we don't currently give userspace control
+	 * over the OA buffer size and always configure a large 16MB
+	 * buffer, then a buffer overflow does anyway likely indicate
+	 * that something has gone quite badly wrong.
+	 */
+	if (oastatus & GEN8_OASTATUS_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 (exponent = %d): force restart\n",
+			  dev_priv->perf.oa.period_exponent);
+
+		dev_priv->perf.oa.ops.oa_disable(dev_priv);
+		dev_priv->perf.oa.ops.oa_enable(dev_priv);
+
+		/*
+		 * Note: .oa_enable() is expected to re-init the oabuffer and
+		 * reset GEN8_OASTATUS for us
+		 */
+		oastatus = I915_READ(GEN8_OASTATUS);
+	}
+
+	if (oastatus & GEN8_OASTATUS_REPORT_LOST) {
+		ret = append_oa_status(stream, buf, count, offset,
+				       DRM_I915_PERF_RECORD_OA_REPORT_LOST);
+		if (ret)
+			return ret;
+		I915_WRITE(GEN8_OASTATUS,
+			   oastatus & ~GEN8_OASTATUS_REPORT_LOST);
+	}
+
+	return gen8_append_oa_reports(stream, buf, count, offset);
+}
+
 /**
  * Copies all buffered OA reports into userspace read() buffer.
  * @stream: An i915-perf stream opened for OA metrics
@@ -732,7 +1057,8 @@ static int gen7_oa_read(struct i915_perf_stream *stream,
 		if (ret)
 			return ret;
 
-		DRM_DEBUG("OA buffer overflow: force restart\n");
+		DRM_DEBUG("OA buffer overflow (exponent = %d): force restart\n",
+			  dev_priv->perf.oa.period_exponent);
 
 		dev_priv->perf.oa.ops.oa_disable(dev_priv);
 		dev_priv->perf.oa.ops.oa_enable(dev_priv);
@@ -775,7 +1101,7 @@ static int i915_oa_wait_unlocked(struct i915_perf_stream *stream)
 		return -EIO;
 
 	return wait_event_interruptible(dev_priv->perf.oa.poll_wq,
-					dev_priv->perf.oa.ops.oa_buffer_check(dev_priv));
+					oa_buffer_check_unlocked(dev_priv));
 }
 
 /**
@@ -832,30 +1158,38 @@ static int i915_oa_read(struct i915_perf_stream *stream,
 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];
-	struct intel_ring *ring;
-	int ret;
 
-	ret = i915_mutex_lock_interruptible(&dev_priv->drm);
-	if (ret)
-		return ret;
+	if (i915.enable_execlists)
+		dev_priv->perf.oa.specific_ctx_id = stream->ctx->hw_id;
+	else {
+		struct intel_engine_cs *engine = dev_priv->engine[RCS];
+		struct intel_ring *ring;
+		int 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...
-	 */
-	ring = engine->context_pin(engine, stream->ctx);
-	mutex_unlock(&dev_priv->drm.struct_mutex);
-	if (IS_ERR(ring))
-		return PTR_ERR(ring);
+		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...
+		 */
+		ring = engine->context_pin(engine, stream->ctx);
+		mutex_unlock(&dev_priv->drm.struct_mutex);
+		if (IS_ERR(ring))
+			return PTR_ERR(ring);
 
-	/* 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);
+
+		/*
+		 * 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);
+	}
 
 	return 0;
 }
@@ -870,14 +1204,19 @@ static int oa_get_render_ctx_id(struct i915_perf_stream *stream)
 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);
+	if (i915.enable_execlists) {
+		dev_priv->perf.oa.specific_ctx_id = INVALID_CTX_ID;
+	} else {
+		struct intel_engine_cs *engine = dev_priv->engine[RCS];
 
-	dev_priv->perf.oa.specific_ctx_id = INVALID_CTX_ID;
-	engine->context_unpin(engine, stream->ctx);
+		mutex_lock(&dev_priv->drm.struct_mutex);
 
-	mutex_unlock(&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
@@ -901,6 +1240,12 @@ static void i915_oa_stream_destroy(struct i915_perf_stream *stream)
 
 	BUG_ON(stream != dev_priv->perf.oa.exclusive_stream);
 
+	/*
+	 * Unset exclusive_stream first, it might be checked while
+	 * disabling the metric set on gen8+.
+	 */
+	dev_priv->perf.oa.exclusive_stream = NULL;
+
 	dev_priv->perf.oa.ops.disable_metric_set(dev_priv);
 
 	free_oa_buffer(dev_priv);
@@ -911,8 +1256,6 @@ static void i915_oa_stream_destroy(struct i915_perf_stream *stream)
 	if (stream->ctx)
 		oa_put_render_ctx_id(stream);
 
-	dev_priv->perf.oa.exclusive_stream = NULL;
-
 	if (dev_priv->perf.oa.spurious_report_rs.missed) {
 		DRM_NOTE("%d spurious OA report notices suppressed due to ratelimiting\n",
 			 dev_priv->perf.oa.spurious_report_rs.missed);
@@ -967,6 +1310,65 @@ static void gen7_init_oa_buffer(struct drm_i915_private *dev_priv)
 	dev_priv->perf.oa.pollin = false;
 }
 
+static void gen8_init_oa_buffer(struct drm_i915_private *dev_priv)
+{
+	u32 gtt_offset = i915_ggtt_offset(dev_priv->perf.oa.oa_buffer.vma);
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
+
+	I915_WRITE(GEN8_OASTATUS, 0);
+	I915_WRITE(GEN8_OAHEADPTR, gtt_offset);
+	dev_priv->perf.oa.oa_buffer.head = gtt_offset;
+
+	I915_WRITE(GEN8_OABUFFER_UDW, 0);
+
+	/*
+	 * PRM says:
+	 *
+	 *  "This MMIO must be set before the OATAILPTR
+	 *  register and after the OAHEADPTR register. This is
+	 *  to enable proper functionality of the overflow
+	 *  bit."
+	 */
+	I915_WRITE(GEN8_OABUFFER, gtt_offset |
+		   OABUFFER_SIZE_16M | OA_MEM_SELECT_GGTT);
+	I915_WRITE(GEN8_OATAILPTR, gtt_offset & GEN8_OATAILPTR_MASK);
+
+	/* Mark that we need updated tail pointers to read from... */
+	dev_priv->perf.oa.oa_buffer.tails[0].offset = INVALID_TAIL_PTR;
+	dev_priv->perf.oa.oa_buffer.tails[1].offset = INVALID_TAIL_PTR;
+
+	/*
+	 * Reset state used to recognise context switches, affecting which
+	 * reports we will forward to userspace while filtering for a single
+	 * context.
+	 */
+	dev_priv->perf.oa.oa_buffer.last_ctx_id = INVALID_CTX_ID;
+
+	spin_unlock_irqrestore(&dev_priv->perf.oa.oa_buffer.ptr_lock, flags);
+
+	/*
+	 * 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 gen8_append_oa_reports() that looks at the
+	 * reason 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;
@@ -1114,6 +1516,324 @@ static void hsw_disable_metric_set(struct drm_i915_private *dev_priv)
 				      ~GT_NOA_ENABLE));
 }
 
+/*
+ * NB: It must always remain pointer safe to run this even if the OA unit
+ * has been disabled.
+ *
+ * It's fine to put out-of-date values into these per-context registers
+ * in the case that the OA unit has been disabled.
+ */
+static void gen8_update_reg_state_unlocked(struct i915_gem_context *ctx,
+					   u32 *reg_state)
+{
+	struct drm_i915_private *dev_priv = ctx->i915;
+	const struct i915_oa_reg *flex_regs = dev_priv->perf.oa.flex_regs;
+	int n_flex_regs = dev_priv->perf.oa.flex_regs_len;
+	u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
+	u32 ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
+	/* The MMIO offsets for Flex EU registers aren't contiguous */
+	u32 flex_mmio[] = {
+		i915_mmio_reg_offset(EU_PERF_CNTL0),
+		i915_mmio_reg_offset(EU_PERF_CNTL1),
+		i915_mmio_reg_offset(EU_PERF_CNTL2),
+		i915_mmio_reg_offset(EU_PERF_CNTL3),
+		i915_mmio_reg_offset(EU_PERF_CNTL4),
+		i915_mmio_reg_offset(EU_PERF_CNTL5),
+		i915_mmio_reg_offset(EU_PERF_CNTL6),
+	};
+	int i;
+
+	reg_state[ctx_oactxctrl] = i915_mmio_reg_offset(GEN8_OACTXCONTROL);
+	reg_state[ctx_oactxctrl+1] = (dev_priv->perf.oa.period_exponent <<
+				      GEN8_OA_TIMER_PERIOD_SHIFT) |
+				     (dev_priv->perf.oa.periodic ?
+				      GEN8_OA_TIMER_ENABLE : 0) |
+				     GEN8_OA_COUNTER_RESUME;
+
+	for (i = 0; i < ARRAY_SIZE(flex_mmio); i++) {
+		u32 state_offset = ctx_flexeu0 + i * 2;
+		u32 mmio = flex_mmio[i];
+
+		/*
+		 * This arbitrary default will select the 'EU FPU0 Pipeline
+		 * Active' event. In the future it's anticipated that there
+		 * will be an explicit 'No Event' we can select, but not yet...
+		 */
+		u32 value = 0;
+		int j;
+
+		for (j = 0; j < n_flex_regs; j++) {
+			if (i915_mmio_reg_offset(flex_regs[j].addr) == mmio) {
+				value = flex_regs[j].value;
+				break;
+			}
+		}
+
+		reg_state[state_offset] = mmio;
+		reg_state[state_offset+1] = value;
+	}
+}
+
+/*
+ * Same as gen8_update_reg_state_unlocked only through the batchbuffer. This
+ * is only used by the kernel context.
+ */
+static int gen8_emit_oa_config(struct drm_i915_gem_request *req)
+{
+	struct drm_i915_private *dev_priv = req->i915;
+	const struct i915_oa_reg *flex_regs = dev_priv->perf.oa.flex_regs;
+	int n_flex_regs = dev_priv->perf.oa.flex_regs_len;
+	/* The MMIO offsets for Flex EU registers aren't contiguous */
+	u32 flex_mmio[] = {
+		i915_mmio_reg_offset(EU_PERF_CNTL0),
+		i915_mmio_reg_offset(EU_PERF_CNTL1),
+		i915_mmio_reg_offset(EU_PERF_CNTL2),
+		i915_mmio_reg_offset(EU_PERF_CNTL3),
+		i915_mmio_reg_offset(EU_PERF_CNTL4),
+		i915_mmio_reg_offset(EU_PERF_CNTL5),
+		i915_mmio_reg_offset(EU_PERF_CNTL6),
+	};
+	u32 *cs;
+	int i;
+
+	cs = intel_ring_begin(req, n_flex_regs * 2 + 4);
+	if (IS_ERR(cs))
+		return PTR_ERR(cs);
+
+	*cs++ = MI_LOAD_REGISTER_IMM(n_flex_regs + 1);
+
+	*cs++ = i915_mmio_reg_offset(GEN8_OACTXCONTROL);
+	*cs++ = (dev_priv->perf.oa.period_exponent << GEN8_OA_TIMER_PERIOD_SHIFT) |
+		(dev_priv->perf.oa.periodic ? GEN8_OA_TIMER_ENABLE : 0) |
+		GEN8_OA_COUNTER_RESUME;
+
+	for (i = 0; i < ARRAY_SIZE(flex_mmio); i++) {
+		u32 mmio = flex_mmio[i];
+
+		/*
+		 * This arbitrary default will select the 'EU FPU0 Pipeline
+		 * Active' event. In the future it's anticipated that there
+		 * will be an explicit 'No Event' we can select, but not
+		 * yet...
+		 */
+		u32 value = 0;
+		int j;
+
+		for (j = 0; j < n_flex_regs; j++) {
+			if (i915_mmio_reg_offset(flex_regs[j].addr) == mmio) {
+				value = flex_regs[j].value;
+				break;
+			}
+		}
+
+		*cs++ = mmio;
+		*cs++ = value;
+	}
+
+	*cs++ = MI_NOOP;
+	intel_ring_advance(req, cs);
+
+	return 0;
+}
+
+static int gen8_switch_to_updated_kernel_context(struct drm_i915_private *dev_priv)
+{
+	struct intel_engine_cs *engine = dev_priv->engine[RCS];
+	struct i915_gem_timeline *timeline;
+	struct drm_i915_gem_request *req;
+	int ret;
+
+	lockdep_assert_held(&dev_priv->drm.struct_mutex);
+
+	i915_gem_retire_requests(dev_priv);
+
+	req = i915_gem_request_alloc(engine, dev_priv->kernel_context);
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	ret = gen8_emit_oa_config(req);
+	if (ret) {
+		i915_add_request(req);
+		return ret;
+	}
+
+	/* Queue this switch after all other activity */
+	list_for_each_entry(timeline, &dev_priv->gt.timelines, link) {
+		struct drm_i915_gem_request *prev;
+		struct intel_timeline *tl;
+
+		tl = &timeline->engine[engine->id];
+		prev = i915_gem_active_raw(&tl->last_request,
+					   &dev_priv->drm.struct_mutex);
+		if (prev)
+			i915_sw_fence_await_sw_fence_gfp(&req->submit,
+							 &prev->submit,
+							 GFP_KERNEL);
+	}
+
+	ret = i915_switch_context(req);
+	i915_add_request(req);
+
+	return ret;
+}
+
+/*
+ * Manages updating the per-context aspects of the OA stream
+ * configuration across all contexts.
+ *
+ * The awkward consideration here is that OACTXCONTROL controls the
+ * exponent for periodic sampling which is primarily used for system
+ * wide profiling where we'd like a consistent sampling period even in
+ * the face of context switches.
+ *
+ * Our approach of updating the register state context (as opposed to
+ * say using a workaround batch buffer) ensures that the hardware
+ * won't automatically reload an out-of-date timer exponent even
+ * transiently before a WA BB could be parsed.
+ *
+ * This function needs to:
+ * - Ensure the currently running context's per-context OA state is
+ *   updated
+ * - Ensure that all existing contexts will have the correct per-context
+ *   OA state if they are scheduled for use.
+ * - Ensure any new contexts will be initialized with the correct
+ *   per-context OA state.
+ *
+ * Note: it's only the RCS/Render context that has any OA state.
+ */
+static int gen8_configure_all_contexts(struct drm_i915_private *dev_priv,
+				       bool interruptible)
+{
+	struct i915_gem_context *ctx;
+	int ret;
+	unsigned int wait_flags = I915_WAIT_LOCKED;
+
+	if (interruptible) {
+		ret = i915_mutex_lock_interruptible(&dev_priv->drm);
+		if (ret)
+			return ret;
+
+		wait_flags |= I915_WAIT_INTERRUPTIBLE;
+	} else {
+		mutex_lock(&dev_priv->drm.struct_mutex);
+	}
+
+	/* Switch away from any user context. */
+	ret = gen8_switch_to_updated_kernel_context(dev_priv);
+	if (ret)
+		goto out;
+
+	/*
+	 * The OA register config is setup through the context image. This image
+	 * might be written to by the GPU on context switch (in particular on
+	 * lite-restore). This means we can't safely update a context's image,
+	 * if this context is scheduled/submitted to run on the GPU.
+	 *
+	 * We could emit the OA register config through the batch buffer but
+	 * this might leave small interval of time where the OA unit is
+	 * configured at an invalid sampling period.
+	 *
+	 * So far the best way to work around this issue seems to be draining
+	 * the GPU from any submitted work.
+	 */
+	ret = i915_gem_wait_for_idle(dev_priv, wait_flags);
+	if (ret)
+		goto out;
+
+	/* Update all contexts now that we've stalled the submission. */
+	list_for_each_entry(ctx, &dev_priv->context_list, link) {
+		struct intel_context *ce = &ctx->engine[RCS];
+		u32 *regs;
+
+		/* OA settings will be set upon first use */
+		if (!ce->state)
+			continue;
+
+		regs = i915_gem_object_pin_map(ce->state->obj, I915_MAP_WB);
+		if (IS_ERR(regs)) {
+			ret = PTR_ERR(regs);
+			goto out;
+		}
+
+		ce->state->obj->mm.dirty = true;
+		regs += LRC_STATE_PN * PAGE_SIZE / sizeof(*regs);
+
+		gen8_update_reg_state_unlocked(ctx, regs);
+
+		i915_gem_object_unpin_map(ce->state->obj);
+	}
+
+ out:
+	mutex_unlock(&dev_priv->drm.struct_mutex);
+
+	return ret;
+}
+
+static int gen8_enable_metric_set(struct drm_i915_private *dev_priv)
+{
+	int ret = dev_priv->perf.oa.ops.select_metric_set(dev_priv);
+	int i;
+
+	if (ret)
+		return ret;
+
+	/*
+	 * We disable slice/unslice clock ratio change reports on SKL since
+	 * they are too noisy. The HW generates a lot of redundant reports
+	 * where the ratio hasn't really changed causing a lot of redundant
+	 * work to processes and increasing the chances we'll hit buffer
+	 * overruns.
+	 *
+	 * Although we don't currently use the 'disable overrun' OABUFFER
+	 * feature it's worth noting that clock ratio reports have to be
+	 * disabled before considering to use that feature since the HW doesn't
+	 * correctly block these reports.
+	 *
+	 * Currently none of the high-level metrics we have depend on knowing
+	 * this ratio to normalize.
+	 *
+	 * Note: This register is not power context saved and restored, but
+	 * that's OK considering that we disable RC6 while the OA unit is
+	 * enabled.
+	 *
+	 * The _INCLUDE_CLK_RATIO bit allows the slice/unslice frequency to
+	 * be read back from automatically triggered reports, as part of the
+	 * RPT_ID field.
+	 */
+	if (IS_SKYLAKE(dev_priv) || IS_BROXTON(dev_priv)) {
+		I915_WRITE(GEN8_OA_DEBUG,
+			   _MASKED_BIT_ENABLE(GEN9_OA_DEBUG_DISABLE_CLK_RATIO_REPORTS |
+					      GEN9_OA_DEBUG_INCLUDE_CLK_RATIO));
+	}
+
+	/*
+	 * Update all contexts prior writing the mux configurations as we need
+	 * to make sure all slices/subslices are ON before writing to NOA
+	 * registers.
+	 */
+	ret = gen8_configure_all_contexts(dev_priv, true);
+	if (ret)
+		return ret;
+
+	I915_WRITE(GDT_CHICKEN_BITS, 0xA0);
+	for (i = 0; i < dev_priv->perf.oa.n_mux_configs; i++) {
+		config_oa_regs(dev_priv, dev_priv->perf.oa.mux_regs[i],
+			       dev_priv->perf.oa.mux_regs_lens[i]);
+	}
+	I915_WRITE(GDT_CHICKEN_BITS, 0x80);
+
+	config_oa_regs(dev_priv, dev_priv->perf.oa.b_counter_regs,
+		       dev_priv->perf.oa.b_counter_regs_len);
+
+	return 0;
+}
+
+static void gen8_disable_metric_set(struct drm_i915_private *dev_priv)
+{
+	/* Reset all contexts' slices/subslices configurations. */
+	gen8_configure_all_contexts(dev_priv, false);
+}
+
 static void gen7_update_oacontrol_locked(struct drm_i915_private *dev_priv)
 {
 	lockdep_assert_held(&dev_priv->perf.hook_lock);
@@ -1158,6 +1878,31 @@ static void gen7_oa_enable(struct drm_i915_private *dev_priv)
 	spin_unlock_irqrestore(&dev_priv->perf.hook_lock, flags);
 }
 
+static void gen8_oa_enable(struct drm_i915_private *dev_priv)
+{
+	u32 report_format = dev_priv->perf.oa.oa_buffer.format;
+
+	/*
+	 * 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.
+	 */
+	gen8_init_oa_buffer(dev_priv);
+
+	/*
+	 * Note: we don't rely on the hardware to perform single context
+	 * filtering and instead filter on the cpu based on the context-id
+	 * field of reports
+	 */
+	I915_WRITE(GEN8_OACONTROL, (report_format <<
+				    GEN8_OA_REPORT_FORMAT_SHIFT) |
+				   GEN8_OA_COUNTER_ENABLE);
+}
+
 /**
  * i915_oa_stream_enable - handle `I915_PERF_IOCTL_ENABLE` for OA stream
  * @stream: An i915 perf stream opened for OA metrics
@@ -1184,6 +1929,11 @@ static void gen7_oa_disable(struct drm_i915_private *dev_priv)
 	I915_WRITE(GEN7_OACONTROL, 0);
 }
 
+static void gen8_oa_disable(struct drm_i915_private *dev_priv)
+{
+	I915_WRITE(GEN8_OACONTROL, 0);
+}
+
 /**
  * i915_oa_stream_disable - handle `I915_PERF_IOCTL_DISABLE` for OA stream
  * @stream: An i915 perf stream opened for OA metrics
@@ -1362,6 +2112,21 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
 	return ret;
 }
 
+void i915_oa_init_reg_state(struct intel_engine_cs *engine,
+			    struct i915_gem_context *ctx,
+			    u32 *reg_state)
+{
+	struct drm_i915_private *dev_priv = engine->i915;
+
+	if (engine->id != RCS)
+		return;
+
+	if (!dev_priv->perf.initialized)
+		return;
+
+	gen8_update_reg_state_unlocked(ctx, reg_state);
+}
+
 /**
  * i915_perf_read_locked - &i915_perf_stream_ops->read with error normalisation
  * @stream: An i915 perf stream
@@ -1487,7 +2252,7 @@ static enum hrtimer_restart oa_poll_check_timer_cb(struct hrtimer *hrtimer)
 		container_of(hrtimer, typeof(*dev_priv),
 			     perf.oa.poll_check_timer);
 
-	if (dev_priv->perf.oa.ops.oa_buffer_check(dev_priv)) {
+	if (oa_buffer_check_unlocked(dev_priv)) {
 		dev_priv->perf.oa.pollin = true;
 		wake_up(&dev_priv->perf.oa.poll_wq);
 	}
@@ -1776,6 +2541,7 @@ i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
 	struct i915_gem_context *specific_ctx = NULL;
 	struct i915_perf_stream *stream = NULL;
 	unsigned long f_flags = 0;
+	bool privileged_op = true;
 	int stream_fd;
 	int ret;
 
@@ -1793,12 +2559,29 @@ i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv,
 		}
 	}
 
+	/*
+	 * On Haswell the OA unit supports clock gating off for a specific
+	 * context and in this mode there's no visibility of metrics for the
+	 * rest of the system, which we consider acceptable for a
+	 * non-privileged client.
+	 *
+	 * For Gen8+ the OA unit no longer supports clock gating off for a
+	 * specific context and the kernel can't securely stop the counters
+	 * from updating as system-wide / global values. Even though we can
+	 * filter reports based on the included context ID we can't block
+	 * clients from seeing the raw / global counter values via
+	 * MI_REPORT_PERF_COUNT commands and so consider it a privileged op to
+	 * enable the OA unit by default.
+	 */
+	if (IS_HASWELL(dev_priv) && specific_ctx)
+		privileged_op = false;
+
 	/* 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 &&
+	if (privileged_op &&
 	    i915_perf_stream_paranoid && !capable(CAP_SYS_ADMIN)) {
 		DRM_DEBUG("Insufficient privileges to open system-wide i915 perf stream\n");
 		ret = -EACCES;
@@ -2070,9 +2853,6 @@ int i915_perf_open_ioctl(struct drm_device *dev, void *data,
  */
 void i915_perf_register(struct drm_i915_private *dev_priv)
 {
-	if (!IS_HASWELL(dev_priv))
-		return;
-
 	if (!dev_priv->perf.initialized)
 		return;
 
@@ -2088,11 +2868,38 @@ void i915_perf_register(struct drm_i915_private *dev_priv)
 	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;
+	if (IS_HASWELL(dev_priv)) {
+		if (i915_perf_register_sysfs_hsw(dev_priv))
+			goto sysfs_error;
+	} else if (IS_BROADWELL(dev_priv)) {
+		if (i915_perf_register_sysfs_bdw(dev_priv))
+			goto sysfs_error;
+	} else if (IS_CHERRYVIEW(dev_priv)) {
+		if (i915_perf_register_sysfs_chv(dev_priv))
+			goto sysfs_error;
+	} else if (IS_SKYLAKE(dev_priv)) {
+		if (IS_SKL_GT2(dev_priv)) {
+			if (i915_perf_register_sysfs_sklgt2(dev_priv))
+				goto sysfs_error;
+		} else if (IS_SKL_GT3(dev_priv)) {
+			if (i915_perf_register_sysfs_sklgt3(dev_priv))
+				goto sysfs_error;
+		} else if (IS_SKL_GT4(dev_priv)) {
+			if (i915_perf_register_sysfs_sklgt4(dev_priv))
+				goto sysfs_error;
+		} else
+			goto sysfs_error;
+	} else if (IS_BROXTON(dev_priv)) {
+		if (i915_perf_register_sysfs_bxt(dev_priv))
+			goto sysfs_error;
 	}
 
+	goto exit;
+
+sysfs_error:
+	kobject_put(dev_priv->perf.metrics_kobj);
+	dev_priv->perf.metrics_kobj = NULL;
+
 exit:
 	mutex_unlock(&dev_priv->perf.lock);
 }
@@ -2108,13 +2915,24 @@ void i915_perf_register(struct drm_i915_private *dev_priv)
  */
 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);
+	if (IS_HASWELL(dev_priv))
+		i915_perf_unregister_sysfs_hsw(dev_priv);
+	else if (IS_BROADWELL(dev_priv))
+		i915_perf_unregister_sysfs_bdw(dev_priv);
+	else if (IS_CHERRYVIEW(dev_priv))
+		i915_perf_unregister_sysfs_chv(dev_priv);
+	else if (IS_SKYLAKE(dev_priv)) {
+		if (IS_SKL_GT2(dev_priv))
+			i915_perf_unregister_sysfs_sklgt2(dev_priv);
+		else if (IS_SKL_GT3(dev_priv))
+			i915_perf_unregister_sysfs_sklgt3(dev_priv);
+		else if (IS_SKL_GT4(dev_priv))
+			i915_perf_unregister_sysfs_sklgt4(dev_priv);
+	} else if (IS_BROXTON(dev_priv))
+		i915_perf_unregister_sysfs_bxt(dev_priv);
 
 	kobject_put(dev_priv->perf.metrics_kobj);
 	dev_priv->perf.metrics_kobj = NULL;
@@ -2173,36 +2991,105 @@ static struct ctl_table dev_root[] = {
  */
 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);
+	dev_priv->perf.oa.n_builtin_sets = 0;
+
+	if (IS_HASWELL(dev_priv)) {
+		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_hw_tail_read =
+			gen7_oa_hw_tail_read;
+
+		dev_priv->perf.oa.oa_formats = hsw_oa_formats;
+
+		dev_priv->perf.oa.n_builtin_sets =
+			i915_oa_n_builtin_metric_sets_hsw;
+	} else if (i915.enable_execlists) {
+		/* Note: that although we could theoretically also support the
+		 * legacy ringbuffer mode on BDW (and earlier iterations of
+		 * this driver, before upstreaming did this) it didn't seem
+		 * worth the complexity to maintain now that BDW+ enable
+		 * execlist mode by default.
+		 */
 
-	INIT_LIST_HEAD(&dev_priv->perf.streams);
-	mutex_init(&dev_priv->perf.lock);
-	spin_lock_init(&dev_priv->perf.hook_lock);
-	spin_lock_init(&dev_priv->perf.oa.oa_buffer.ptr_lock);
+		if (IS_GEN8(dev_priv)) {
+			dev_priv->perf.oa.ctx_oactxctrl_offset = 0x120;
+			dev_priv->perf.oa.ctx_flexeu0_offset = 0x2ce;
+			dev_priv->perf.oa.gen8_valid_ctx_bit = (1<<25);
+
+			if (IS_BROADWELL(dev_priv)) {
+				dev_priv->perf.oa.n_builtin_sets =
+					i915_oa_n_builtin_metric_sets_bdw;
+				dev_priv->perf.oa.ops.select_metric_set =
+					i915_oa_select_metric_set_bdw;
+			} else if (IS_CHERRYVIEW(dev_priv)) {
+				dev_priv->perf.oa.n_builtin_sets =
+					i915_oa_n_builtin_metric_sets_chv;
+				dev_priv->perf.oa.ops.select_metric_set =
+					i915_oa_select_metric_set_chv;
+			}
+		} else if (IS_GEN9(dev_priv)) {
+			dev_priv->perf.oa.ctx_oactxctrl_offset = 0x128;
+			dev_priv->perf.oa.ctx_flexeu0_offset = 0x3de;
+			dev_priv->perf.oa.gen8_valid_ctx_bit = (1<<16);
+
+			if (IS_SKL_GT2(dev_priv)) {
+				dev_priv->perf.oa.n_builtin_sets =
+					i915_oa_n_builtin_metric_sets_sklgt2;
+				dev_priv->perf.oa.ops.select_metric_set =
+					i915_oa_select_metric_set_sklgt2;
+			} else if (IS_SKL_GT3(dev_priv)) {
+				dev_priv->perf.oa.n_builtin_sets =
+					i915_oa_n_builtin_metric_sets_sklgt3;
+				dev_priv->perf.oa.ops.select_metric_set =
+					i915_oa_select_metric_set_sklgt3;
+			} else if (IS_SKL_GT4(dev_priv)) {
+				dev_priv->perf.oa.n_builtin_sets =
+					i915_oa_n_builtin_metric_sets_sklgt4;
+				dev_priv->perf.oa.ops.select_metric_set =
+					i915_oa_select_metric_set_sklgt4;
+			} else if (IS_BROXTON(dev_priv)) {
+				dev_priv->perf.oa.n_builtin_sets =
+					i915_oa_n_builtin_metric_sets_bxt;
+				dev_priv->perf.oa.ops.select_metric_set =
+					i915_oa_select_metric_set_bxt;
+			}
+		}
 
-	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_check =
-		gen7_oa_buffer_check_unlocked;
+		if (dev_priv->perf.oa.n_builtin_sets) {
+			dev_priv->perf.oa.ops.init_oa_buffer = gen8_init_oa_buffer;
+			dev_priv->perf.oa.ops.enable_metric_set =
+				gen8_enable_metric_set;
+			dev_priv->perf.oa.ops.disable_metric_set =
+				gen8_disable_metric_set;
+			dev_priv->perf.oa.ops.oa_enable = gen8_oa_enable;
+			dev_priv->perf.oa.ops.oa_disable = gen8_oa_disable;
+			dev_priv->perf.oa.ops.read = gen8_oa_read;
+			dev_priv->perf.oa.ops.oa_hw_tail_read =
+				gen8_oa_hw_tail_read;
+
+			dev_priv->perf.oa.oa_formats = gen8_plus_oa_formats;
+		}
+	}
 
-	dev_priv->perf.oa.oa_formats = hsw_oa_formats;
+	if (dev_priv->perf.oa.n_builtin_sets) {
+		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);
 
-	dev_priv->perf.oa.n_builtin_sets =
-		i915_oa_n_builtin_metric_sets_hsw;
+		INIT_LIST_HEAD(&dev_priv->perf.streams);
+		mutex_init(&dev_priv->perf.lock);
+		spin_lock_init(&dev_priv->perf.hook_lock);
+		spin_lock_init(&dev_priv->perf.oa.oa_buffer.ptr_lock);
 
-	dev_priv->perf.sysctl_header = register_sysctl_table(dev_root);
+		dev_priv->perf.sysctl_header = register_sysctl_table(dev_root);
 
-	dev_priv->perf.initialized = true;
+		dev_priv->perf.initialized = true;
+	}
 }
 
 /**
@@ -2217,5 +3104,6 @@ void i915_perf_fini(struct drm_i915_private *dev_priv)
 	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;
 }

drivers/gpu/drm/i915/i915_reg.h

@@ -656,6 +656,12 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 
 #define GEN8_OACTXID _MMIO(0x2364)
 
+#define GEN8_OA_DEBUG _MMIO(0x2B04)
+#define  GEN9_OA_DEBUG_DISABLE_CLK_RATIO_REPORTS    (1<<5)
+#define  GEN9_OA_DEBUG_INCLUDE_CLK_RATIO	    (1<<6)
+#define  GEN9_OA_DEBUG_DISABLE_GO_1_0_REPORTS	    (1<<2)
+#define  GEN9_OA_DEBUG_DISABLE_CTX_SWITCH_REPORTS   (1<<1)
+
 #define GEN8_OACONTROL _MMIO(0x2B00)
 #define  GEN8_OA_REPORT_FORMAT_A12	    (0<<2)
 #define  GEN8_OA_REPORT_FORMAT_A12_B8_C8    (2<<2)
@@ -677,6 +683,7 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define  GEN7_OABUFFER_STOP_RESUME_ENABLE   (1<<1)
 #define  GEN7_OABUFFER_RESUME		    (1<<0)
 
+#define GEN8_OABUFFER_UDW _MMIO(0x23b4)
 #define GEN8_OABUFFER _MMIO(0x2b14)
 
 #define GEN7_OASTATUS1 _MMIO(0x2364)
@@ -695,7 +702,9 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 #define  GEN8_OASTATUS_REPORT_LOST	    (1<<0)
 
 #define GEN8_OAHEADPTR _MMIO(0x2B0C)
+#define GEN8_OAHEADPTR_MASK    0xffffffc0
 #define GEN8_OATAILPTR _MMIO(0x2B10)
+#define GEN8_OATAILPTR_MASK    0xffffffc0
 
 #define OABUFFER_SIZE_128K  (0<<3)
 #define OABUFFER_SIZE_256K  (1<<3)
@@ -708,7 +717,17 @@ static inline bool i915_mmio_reg_valid(i915_reg_t reg)
 
 #define OA_MEM_SELECT_GGTT  (1<<0)
 
+/*
+ * Flexible, Aggregate EU Counter Registers.
+ * Note: these aren't contiguous
+ */
 #define EU_PERF_CNTL0	    _MMIO(0xe458)
+#define EU_PERF_CNTL1	    _MMIO(0xe558)
+#define EU_PERF_CNTL2	    _MMIO(0xe658)
+#define EU_PERF_CNTL3	    _MMIO(0xe758)
+#define EU_PERF_CNTL4	    _MMIO(0xe45c)
+#define EU_PERF_CNTL5	    _MMIO(0xe55c)
+#define EU_PERF_CNTL6	    _MMIO(0xe65c)
 
 #define GDT_CHICKEN_BITS    _MMIO(0x9840)
 #define GT_NOA_ENABLE	    0x00000080
@@ -2494,6 +2513,9 @@ enum skl_disp_power_wells {
 #define   GEN8_RC_SEMA_IDLE_MSG_DISABLE	(1 << 12)
 #define   GEN8_FF_DOP_CLOCK_GATE_DISABLE	(1<<10)
 
+#define GEN6_RCS_PWR_FSM _MMIO(0x22ac)
+#define GEN9_RCS_FE_FSM2 _MMIO(0x22a4)
+
 /* Fuse readout registers for GT */
 #define CHV_FUSE_GT			_MMIO(VLV_DISPLAY_BASE + 0x2168)
 #define   CHV_FGT_DISABLE_SS0		(1 << 10)

drivers/gpu/drm/i915/intel_lrc.c

@@ -1962,6 +1962,8 @@ static void execlists_init_reg_state(u32 *regs,
 		regs[CTX_LRI_HEADER_2] = MI_LOAD_REGISTER_IMM(1);
 		CTX_REG(regs, CTX_R_PWR_CLK_STATE, GEN8_R_PWR_CLK_STATE,
 			make_rpcs(dev_priv));
+
+		i915_oa_init_reg_state(engine, ctx, regs);
 	}
 }
 

include/uapi/drm/i915_drm.h

@@ -1316,13 +1316,18 @@ struct drm_i915_gem_context_param {
 };
 
 enum drm_i915_oa_format {
-	I915_OA_FORMAT_A13 = 1,
-	I915_OA_FORMAT_A29,
-	I915_OA_FORMAT_A13_B8_C8,
-	I915_OA_FORMAT_B4_C8,
-	I915_OA_FORMAT_A45_B8_C8,
-	I915_OA_FORMAT_B4_C8_A16,
-	I915_OA_FORMAT_C4_B8,
+	I915_OA_FORMAT_A13 = 1,	    /* HSW only */
+	I915_OA_FORMAT_A29,	    /* HSW only */
+	I915_OA_FORMAT_A13_B8_C8,   /* HSW only */
+	I915_OA_FORMAT_B4_C8,	    /* HSW only */
+	I915_OA_FORMAT_A45_B8_C8,   /* HSW only */
+	I915_OA_FORMAT_B4_C8_A16,   /* HSW only */
+	I915_OA_FORMAT_C4_B8,	    /* HSW+ */
+
+	/* Gen8+ */
+	I915_OA_FORMAT_A12,
+	I915_OA_FORMAT_A12_B8_C8,
+	I915_OA_FORMAT_A32u40_A4u32_B8_C8,
 
 	I915_OA_FORMAT_MAX	    /* non-ABI */
 };