[RFC PATCH 3/3] i915: Expose PMU for Observation Architecture

From: Robert Bragg
Date: Wed Oct 22 2014 - 11:30:00 EST

Gen graphics hardware can be set up to periodically write snapshots of
performance counters into a circular buffer and this patch exposes that
capability to userspace via the perf interface.

Only Haswell is supported currently.

Signed-off-by: Robert Bragg <robert@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/i915_dma.c | 2 +
drivers/gpu/drm/i915/i915_drv.h | 33 ++
drivers/gpu/drm/i915/i915_oa_perf.c | 675 ++++++++++++++++++++++++++++++++++++
drivers/gpu/drm/i915/i915_reg.h | 87 +++++
include/uapi/drm/i915_drm.h | 21 ++
6 files changed, 819 insertions(+)
create mode 100644 drivers/gpu/drm/i915/i915_oa_perf.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index c1dd485..2ddd97d 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -14,6 +14,7 @@ i915-y := i915_drv.o \
intel_pm.o
i915-$(CONFIG_COMPAT) += i915_ioc32.o
i915-$(CONFIG_DEBUG_FS) += i915_debugfs.o
+i915-$(CONFIG_PERF_EVENTS) += i915_oa_perf.o

# GEM code
i915-y += i915_cmd_parser.o \
diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 3f676f9..ce1e1ea 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -1792,6 +1792,7 @@ int i915_driver_load(struct drm_device *dev, unsigned long flags)
intel_gpu_ips_init(dev_priv);

intel_init_runtime_pm(dev_priv);
+ i915_oa_pmu_register(dev);

return 0;

@@ -1839,6 +1840,7 @@ int i915_driver_unload(struct drm_device *dev)
return ret;
}

+ i915_oa_pmu_unregister(dev);
intel_fini_runtime_pm(dev_priv);

intel_gpu_ips_teardown();
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 6fbd316..1b2c557 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -45,6 +45,7 @@
#include <linux/hashtable.h>
#include <linux/intel-iommu.h>
#include <linux/kref.h>
+#include <linux/perf_event.h>
#include <linux/pm_qos.h>

/* General customization:
@@ -1636,6 +1637,29 @@ struct drm_i915_private {
*/
struct workqueue_struct *dp_wq;

+#ifdef CONFIG_PERF_EVENTS
+ struct {
+ struct pmu pmu;
+ spinlock_t lock;
+ struct hrtimer timer;
+ struct pt_regs dummy_regs;
+
+ struct perf_event *exclusive_event;
+ struct intel_context *specific_ctx;
+
+ struct {
+ struct kref refcount;
+ struct drm_i915_gem_object *obj;
+ u32 gtt_offset;
+ u8 *addr;
+ u32 head;
+ u32 tail;
+ int format;
+ int format_size;
+ } oa_buffer;
+ } oa_pmu;
+#endif
+
/* Old dri1 support infrastructure, beware the dragons ya fools entering
* here! */
struct i915_dri1_state dri1;
@@ -2688,6 +2712,15 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
u32 batch_start_offset,
bool is_master);

+/* i915_oa_perf.c */
+#ifdef CONFIG_PERF_EVENTS
+extern void i915_oa_pmu_register(struct drm_device *dev);
+extern void i915_oa_pmu_unregister(struct drm_device *dev);
+#else
+static inline void i915_oa_pmu_register(struct drm_device *dev) {}
+static inline void i915_oa_pmu_unregister(struct drm_device *dev) {}
+#endif
+
/* i915_suspend.c */
extern int i915_save_state(struct drm_device *dev);
extern int i915_restore_state(struct drm_device *dev);
diff --git a/drivers/gpu/drm/i915/i915_oa_perf.c b/drivers/gpu/drm/i915/i915_oa_perf.c
new file mode 100644
index 0000000..d86aaf0
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_oa_perf.c
@@ -0,0 +1,675 @@
+#include <linux/perf_event.h>
+#include <linux/sizes.h>
+
+#include "i915_drv.h"
+#include "intel_ringbuffer.h"
+
+/* Must be a power of two */
+#define OA_BUFFER_SIZE SZ_16M
+#define OA_TAKEN(tail, head) ((tail - head) & (OA_BUFFER_SIZE - 1))
+
+#define FREQUENCY 200
+#define PERIOD max_t(u64, 10000, NSEC_PER_SEC / FREQUENCY)
+
+static int hsw_perf_format_sizes[] = {
+ 64, /* A13_HSW */
+ 128, /* A29_HSW */
+ 128, /* A13_B8_C8_HSW */
+
+ /* XXX: If we were to disallow this format we could avoid needing to
+ * handle snapshots being split in two when they don't factor into
+ * the buffer size... */
+ 192, /* A29_B8_C8_HSW */
+ 64, /* B4_C8_HSW */
+ 256, /* A45_B8_C8_HSW */
+ 128, /* B4_C8_A16_HSW */
+ 64 /* C4_B8_HSW */
+};
+
+static void forward_one_oa_snapshot_to_event(struct drm_i915_private *dev_priv,
+ u8 *snapshot,
+ struct perf_event *event)
+{
+ struct perf_sample_data data;
+ int snapshot_size = dev_priv->oa_pmu.oa_buffer.format_size;
+ struct perf_raw_record raw;
+
+ perf_sample_data_init(&data, 0, event->hw.last_period);
+
+ /* XXX: It seems strange that kernel/events/core.c only initialises
+ * data->type if event->attr.sample_id_all is set
+ *
+ * For now, we explicitly set this otherwise perf_event_overflow()
+ * may reference an uninitialised sample_type and may not actually
+ * forward our raw data.
+ */
+ data.type = event->attr.sample_type;
+
+ /* Note: the 32 bit size + raw data must be 8 byte aligned.
+ *
+ * So that we don't have to first copy the data out of the
+ * OABUFFER, we instead allow an overrun and forward the 32 bit
+ * report id of the next snapshot...
+ */
+ raw.size = snapshot_size + 4;
+ raw.data = snapshot;
+
+ data.raw = &raw;
+
+ perf_event_overflow(event, &data, &dev_priv->oa_pmu.dummy_regs);
+}
+
+static u32 forward_oa_snapshots(struct drm_i915_private *dev_priv,
+ u32 head,
+ u32 tail)
+{
+ struct perf_event *exclusive_event = dev_priv->oa_pmu.exclusive_event;
+ int snapshot_size = dev_priv->oa_pmu.oa_buffer.format_size;
+ u8 *oa_buf_base = dev_priv->oa_pmu.oa_buffer.addr;
+ u32 mask = (OA_BUFFER_SIZE - 1);
+ u8 scratch[snapshot_size + 4];
+ u8 *snapshot;
+ u32 taken;
+
+ head -= dev_priv->oa_pmu.oa_buffer.gtt_offset;
+ tail -= dev_priv->oa_pmu.oa_buffer.gtt_offset;
+
+ /* Note: the gpu doesn't wrap the tail according to the OA buffer size
+ * so when we need to make sure our head/tail values are in-bounds we
+ * use the above mask.
+ */
+
+ while ((taken = OA_TAKEN(tail, head))) {
+ u32 before;
+
+ /* The tail increases in 64 byte increments, not in
+ * format_size steps. */
+ if (taken < snapshot_size)
+ break;
+
+ /* As well as handling snapshots that are split in two we also
+ * need to pad snapshots at the end of the oabuffer so that
+ * forward_one_oa_snapshot_to_event() can safely overrun by 4
+ * bytes for alignment. */
+ before = OA_BUFFER_SIZE - (head & mask);
+ if (before <= snapshot_size) {
+ u32 after = snapshot_size - before;
+
+ memcpy(scratch, oa_buf_base + (head & mask), before);
+ if (after)
+ memcpy(scratch + before, oa_buf_base, after);
+ snapshot = scratch;
+ } else
+ snapshot = oa_buf_base + (head & mask);
+
+ head += snapshot_size;
+
+ /* We currently only allow exclusive access to the counters
+ * so only have one event to forward too... */
+ if (exclusive_event->state == PERF_EVENT_STATE_ACTIVE)
+ forward_one_oa_snapshot_to_event(dev_priv, snapshot,
+ exclusive_event);
+ }
+
+ return dev_priv->oa_pmu.oa_buffer.gtt_offset + head;
+}
+
+static void flush_oa_snapshots(struct drm_i915_private *dev_priv,
+ bool force_wake)
+{
+ unsigned long flags;
+ u32 oastatus2;
+ u32 oastatus1;
+ u32 head;
+ u32 tail;
+
+ /* Can either flush via hrtimer callback or pmu methods/fops */
+ if (!force_wake) {
+
+ /* If the hrtimer triggers at the same time that we are
+ * responding to a userspace initiated flush then we can
+ * just bail out...
+ *
+ * FIXME: strictly this lock doesn't imply we are already
+ * flushing though it shouldn't really be a problem to skip
+ * the odd hrtimer flush anyway.
+ */
+ if (!spin_trylock_irqsave(&dev_priv->oa_pmu.lock, flags))
+ return;
+ } else
+ spin_lock_irqsave(&dev_priv->oa_pmu.lock, flags);
+
+ WARN_ON(!dev_priv->oa_pmu.oa_buffer.addr);
+
+ oastatus2 = I915_READ(OASTATUS2);
+ oastatus1 = I915_READ(OASTATUS1);
+
+ head = oastatus2 & OASTATUS2_HEAD_MASK;
+ tail = oastatus1 & OASTATUS1_TAIL_MASK;
+
+ if (oastatus1 & (OASTATUS1_OABUFFER_OVERFLOW |
+ OASTATUS1_REPORT_LOST)) {
+
+ /* XXX: How can we convey report-lost errors to userspace? It
+ * doesn't look like perf's _REPORT_LOST mechanism is
+ * appropriate in this case; that's just for cases where we
+ * run out of space for samples in the perf circular buffer.
+ *
+ * Maybe we can claim a special report-id and use that to
+ * forward status flags?
+ */
+ pr_debug("OA buffer read error: addr = %p, head = %u, offset = %u, tail = %u cnt o'flow = %d, buf o'flow = %d, rpt lost = %d\n",
+ dev_priv->oa_pmu.oa_buffer.addr,
+ head,
+ head - dev_priv->oa_pmu.oa_buffer.gtt_offset,
+ tail,
+ oastatus1 & OASTATUS1_COUNTER_OVERFLOW ? 1 : 0,
+ oastatus1 & OASTATUS1_OABUFFER_OVERFLOW ? 1 : 0,
+ oastatus1 & OASTATUS1_REPORT_LOST ? 1 : 0);
+
+ I915_WRITE(OASTATUS1, oastatus1 &
+ ~(OASTATUS1_OABUFFER_OVERFLOW |
+ OASTATUS1_REPORT_LOST));
+ }
+
+ head = forward_oa_snapshots(dev_priv, head, tail);
+
+ I915_WRITE(OASTATUS2, (head & OASTATUS2_HEAD_MASK) | OASTATUS2_GGTT);
+
+ spin_unlock_irqrestore(&dev_priv->oa_pmu.lock, flags);
+}
+
+static void
+oa_buffer_free(struct kref *kref)
+{
+ struct drm_i915_private *i915 =
+ container_of(kref, typeof(*i915), oa_pmu.oa_buffer.refcount);
+
+ BUG_ON(!mutex_is_locked(&i915->dev->struct_mutex));
+
+ vunmap(i915->oa_pmu.oa_buffer.addr);
+ i915_gem_object_ggtt_unpin(i915->oa_pmu.oa_buffer.obj);
+ drm_gem_object_unreference(&i915->oa_pmu.oa_buffer.obj->base);
+
+ i915->oa_pmu.oa_buffer.obj = NULL;
+ i915->oa_pmu.oa_buffer.gtt_offset = 0;
+ i915->oa_pmu.oa_buffer.addr = NULL;
+}
+
+static inline void oa_buffer_reference(struct drm_i915_private *i915)
+{
+ kref_get(&i915->oa_pmu.oa_buffer.refcount);
+}
+
+static void oa_buffer_unreference(struct drm_i915_private *i915)
+{
+ WARN_ON(!i915->oa_pmu.oa_buffer.obj);
+
+ kref_put(&i915->oa_pmu.oa_buffer.refcount, oa_buffer_free);
+}
+
+static void i915_oa_event_destroy(struct perf_event *event)
+{
+ struct drm_i915_private *i915 =
+ container_of(event->pmu, typeof(*i915), oa_pmu.pmu);
+
+ WARN_ON(event->parent);
+
+ mutex_lock(&i915->dev->struct_mutex);
+
+ oa_buffer_unreference(i915);
+
+ if (i915->oa_pmu.specific_ctx) {
+ struct drm_i915_gem_object *obj;
+
+ obj = i915->oa_pmu.specific_ctx->legacy_hw_ctx.rcs_state;
+ if (i915_gem_obj_is_pinned(obj))
+ i915_gem_object_ggtt_unpin(obj);
+ i915->oa_pmu.specific_ctx = NULL;
+ }
+
+ BUG_ON(i915->oa_pmu.exclusive_event != event);
+ i915->oa_pmu.exclusive_event = NULL;
+
+ mutex_unlock(&i915->dev->struct_mutex);
+
+ gen6_gt_force_wake_put(i915, FORCEWAKE_ALL);
+}
+
+static void *vmap_oa_buffer(struct drm_i915_gem_object *obj)
+{
+ int i;
+ void *addr = NULL;
+ struct sg_page_iter sg_iter;
+ struct page **pages;
+
+ pages = drm_malloc_ab(obj->base.size >> PAGE_SHIFT, sizeof(*pages));
+ if (pages == NULL) {
+ DRM_DEBUG_DRIVER("Failed to get space for pages\n");
+ goto finish;
+ }
+
+ i = 0;
+ for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) {
+ pages[i] = sg_page_iter_page(&sg_iter);
+ i++;
+ }
+
+ addr = vmap(pages, i, 0, PAGE_KERNEL);
+ if (addr == NULL) {
+ DRM_DEBUG_DRIVER("Failed to vmap pages\n");
+ goto finish;
+ }
+
+finish:
+ if (pages)
+ drm_free_large(pages);
+ return addr;
+}
+
+static int init_oa_buffer(struct perf_event *event)
+{
+ struct drm_i915_private *dev_priv =
+ container_of(event->pmu, typeof(*dev_priv), oa_pmu.pmu);
+ struct drm_i915_gem_object *bo;
+ int ret;
+
+ BUG_ON(!IS_HASWELL(dev_priv->dev));
+ BUG_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
+ BUG_ON(dev_priv->oa_pmu.oa_buffer.obj);
+
+ kref_init(&dev_priv->oa_pmu.oa_buffer.refcount);
+
+ bo = i915_gem_alloc_object(dev_priv->dev, OA_BUFFER_SIZE);
+ if (bo == NULL) {
+ DRM_ERROR("Failed to allocate OA buffer\n");
+ ret = -ENOMEM;
+ goto err;
+ }
+ dev_priv->oa_pmu.oa_buffer.obj = bo;
+
+ ret = i915_gem_object_set_cache_level(bo, I915_CACHE_LLC);
+ if (ret)
+ goto err_unref;
+
+ /* PreHSW required 512K alignment, HSW requires 16M */
+ ret = i915_gem_obj_ggtt_pin(bo, SZ_16M, 0);
+ if (ret)
+ goto err_unref;
+
+ dev_priv->oa_pmu.oa_buffer.gtt_offset = i915_gem_obj_ggtt_offset(bo);
+ dev_priv->oa_pmu.oa_buffer.addr = vmap_oa_buffer(bo);
+
+ /* Pre-DevBDW: OABUFFER must be set with counters off,
+ * before OASTATUS1, but after OASTATUS2 */
+ I915_WRITE(OASTATUS2, dev_priv->oa_pmu.oa_buffer.gtt_offset |
+ OASTATUS2_GGTT); /* head */
+ I915_WRITE(GEN7_OABUFFER, dev_priv->oa_pmu.oa_buffer.gtt_offset);
+ I915_WRITE(OASTATUS1, dev_priv->oa_pmu.oa_buffer.gtt_offset |
+ OASTATUS1_OABUFFER_SIZE_16M); /* tail */
+
+ DRM_DEBUG_DRIVER("OA Buffer initialized, gtt offset = 0x%x, vaddr = %p",
+ dev_priv->oa_pmu.oa_buffer.gtt_offset,
+ dev_priv->oa_pmu.oa_buffer.addr);
+
+ return 0;
+
+err_unref:
+ drm_gem_object_unreference_unlocked(&bo->base);
+err:
+ return ret;
+}
+
+static enum hrtimer_restart hrtimer_sample(struct hrtimer *hrtimer)
+{
+ struct drm_i915_private *i915 =
+ container_of(hrtimer, typeof(*i915), oa_pmu.timer);
+
+ flush_oa_snapshots(i915, false);
+
+ hrtimer_forward_now(hrtimer, ns_to_ktime(PERIOD));
+ return HRTIMER_RESTART;
+}
+
+static struct intel_context *
+lookup_context(struct drm_i915_private *dev_priv,
+ struct file *user_filp,
+ u32 ctx_user_handle)
+{
+ struct intel_context *ctx;
+
+ mutex_lock(&dev_priv->dev->struct_mutex);
+ list_for_each_entry(ctx, &dev_priv->context_list, link) {
+ struct drm_file *drm_file;
+
+ if (!ctx->file_priv)
+ continue;
+
+ drm_file = ctx->file_priv->file;
+
+ if (user_filp->private_data == drm_file &&
+ ctx->user_handle == ctx_user_handle) {
+ mutex_unlock(&dev_priv->dev->struct_mutex);
+ return ctx;
+ }
+ }
+ mutex_unlock(&dev_priv->dev->struct_mutex);
+
+ return NULL;
+}
+
+static int i915_oa_event_init(struct perf_event *event)
+{
+ struct perf_event_context *ctx = event->ctx;
+ struct drm_i915_private *dev_priv =
+ container_of(event->pmu, typeof(*dev_priv), oa_pmu.pmu);
+ int ret = 0;
+
+ if (event->attr.type != event->pmu->type)
+ return -ENOENT;
+
+ /* When tracing a specific pid events/core will enable/disable
+ * the event only while that pid is running on a cpu but that
+ * doesn't really make sense here. */
+ if (ctx) {
+ if (ctx->task)
+ return -EINVAL;
+ }
+#if 0
+ else
+ pr_err("Unexpected NULL perf_event_context\n");
+
+ /* XXX: it looks like we get a NULL ctx, so check if setting
+ * pmu->task_ctx_nr to perf_invalid_context in _pmu_register
+ * implies events/core.c will also implicitly disallow
+ * associating a perf_oa event with a task?
+ */
+#endif
+
+ /* To avoid the complexity of having to accurately filter
+ * counter snapshots and marshal to the appropriate client
+ * we currently only allow exclusive access */
+ if (dev_priv->oa_pmu.oa_buffer.obj)
+ return -EBUSY;
+
+ /* TODO: improve cooperation with the cmd_parser which provides
+ * another mechanism for enabling the OA counters. */
+ if (I915_READ(OACONTROL) & OACONTROL_ENABLE)
+ return -EBUSY;
+
+ /* Since we are limited to an exponential scale for
+ * programming the OA sampling period we don't allow userspace
+ * to pass a precise attr.sample_period. */
+ if (event->attr.freq ||
+ (event->attr.sample_period != 0 &&
+ event->attr.sample_period != 1))
+ return -EINVAL;
+
+ /* Instead of allowing userspace to configure the period via
+ * attr.sample_period we instead accept an exponent whereby
+ * the sample_period will be:
+ *
+ * 80ns * 2^(period_exponent + 1)
+ *
+ * Programming a period of 160 nanoseconds would not be very
+ * polite, so higher frequencies are reserved for root.
+ */
+ if (event->attr.sample_period) {
+ u64 period_exponent =
+ event->attr.config & I915_PERF_OA_TIMER_EXPONENT_MASK;
+ period_exponent >>= I915_PERF_OA_TIMER_EXPONENT_SHIFT;
+
+ if (period_exponent < 15 && !capable(CAP_SYS_ADMIN))
+ return -EACCES;
+ }
+
+ if (!IS_HASWELL(dev_priv->dev))
+ return -ENODEV;
+
+ /* We bypass the default perf core perf_paranoid_cpu() ||
+ * CAP_SYS_ADMIN check by using the PERF_PMU_CAP_IS_DEVICE
+ * flag and instead authenticate based on whether the current
+ * pid owns the specified context, or require CAP_SYS_ADMIN
+ * when collecting cross-context metrics.
+ */
+ dev_priv->oa_pmu.specific_ctx = NULL;
+ if (event->attr.config & I915_PERF_OA_SINGLE_CONTEXT_ENABLE) {
+ u32 ctx_id = event->attr.config & I915_PERF_OA_CTX_ID_MASK;
+ unsigned int drm_fd = event->attr.config1;
+ struct fd fd = fdget(drm_fd);
+
+ if (fd.file) {
+ dev_priv->oa_pmu.specific_ctx =
+ lookup_context(dev_priv, fd.file, ctx_id);
+ }
+ }
+
+ if (!dev_priv->oa_pmu.specific_ctx && !capable(CAP_SYS_ADMIN))
+ return -EACCES;
+
+ mutex_lock(&dev_priv->dev->struct_mutex);
+
+ /* XXX: Not sure that this is really acceptable...
+ *
+ * i915_gem_context.c currently owns pinning/unpinning legacy
+ * context buffers and although that code has a
+ * get_context_alignment() func to handle a different
+ * constraint for gen6 we are assuming it's fixed for gen7
+ * here. Another option besides pinning here would be to
+ * instead hook into context switching and update the
+ * OACONTROL configuration on the fly.
+ */
+ if (dev_priv->oa_pmu.specific_ctx) {
+ struct intel_context *ctx = dev_priv->oa_pmu.specific_ctx;
+ int ret;
+
+ ret = i915_gem_obj_ggtt_pin(ctx->legacy_hw_ctx.rcs_state,
+ 4096, 0);
+ if (ret) {
+ DRM_DEBUG_DRIVER("Couldn't pin %d\n", ret);
+ ret = -EBUSY;
+ goto err;
+ }
+ }
+
+ if (!dev_priv->oa_pmu.oa_buffer.obj)
+ ret = init_oa_buffer(event);
+ else
+ oa_buffer_reference(dev_priv);
+
+ if (ret)
+ goto err;
+
+ BUG_ON(dev_priv->oa_pmu.exclusive_event);
+ dev_priv->oa_pmu.exclusive_event = event;
+
+ event->destroy = i915_oa_event_destroy;
+
+ mutex_unlock(&dev_priv->dev->struct_mutex);
+
+ /* 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"
+ *
+ * 0xA094 corresponds to GEN6_RC_STATE
+ * 0xA090[31] corresponds to GEN6_RC_CONTROL, GEN6_RC_CTL_HW_ENABLE
+ */
+ /* XXX: We should probably find a more refined way of disabling RC6
+ * in cooperation with intel_pm.c.
+ * TODO: Find a way to disable clock gating too
+ */
+ gen6_gt_force_wake_get(dev_priv, FORCEWAKE_ALL);
+
+ return 0;
+
+err:
+ mutex_unlock(&dev_priv->dev->struct_mutex);
+
+ return ret;
+}
+
+static void i915_oa_event_start(struct perf_event *event, int flags)
+{
+ struct drm_i915_private *dev_priv =
+ container_of(event->pmu, typeof(*dev_priv), oa_pmu.pmu);
+ u64 report_format;
+ int snapshot_size;
+ unsigned long ctx_id;
+ u64 period_exponent;
+
+ /* PRM - observability performance counters:
+ *
+ * OACONTROL, specific context enable:
+ *
+ * "OA unit level clock gating must be ENABLED when using
+ * specific ContextID feature."
+ *
+ * Assuming we don't ever disable OA unit level clock gating
+ * lets just assert that this condition is met...
+ */
+ WARN_ONCE(I915_READ(GEN6_UCGCTL3) & GEN6_OACSUNIT_CLOCK_GATE_DISABLE,
+ "disabled OA unit level clock gating will result in incorrect per-context OA counters");
+
+ /* XXX: On Haswell, when threshold disable mode is desired,
+ * instead of setting the threshold enable to '0', we need to
+ * program it to '1' and set OASTARTTRIG1 bits 15:0 to 0
+ * (threshold value of 0)
+ */
+ I915_WRITE(OASTARTTRIG6, (OASTARTTRIG6_B4_TO_B7_THRESHOLD_ENABLE |
+ OASTARTTRIG6_B4_CUSTOM_EVENT_ENABLE));
+ I915_WRITE(OASTARTTRIG5, 0); /* threshold value */
+
+ I915_WRITE(OASTARTTRIG2, (OASTARTTRIG2_B0_TO_B3_THRESHOLD_ENABLE |
+ OASTARTTRIG2_B0_CUSTOM_EVENT_ENABLE));
+ I915_WRITE(OASTARTTRIG1, 0); /* threshold value */
+
+ /* Setup B0 as the gpu clock counter... */
+ I915_WRITE(OACEC0_0, OACEC0_0_B0_COMPARE_GREATER_OR_EQUAL); /* to 0 */
+ I915_WRITE(OACEC0_1, 0xfffe); /* Select NOA[0] */
+
+ period_exponent = event->attr.config & I915_PERF_OA_TIMER_EXPONENT_MASK;
+ period_exponent >>= I915_PERF_OA_TIMER_EXPONENT_SHIFT;
+
+ if (dev_priv->oa_pmu.specific_ctx) {
+ struct intel_context *ctx = dev_priv->oa_pmu.specific_ctx;
+
+ ctx_id = i915_gem_obj_ggtt_offset(ctx->legacy_hw_ctx.rcs_state);
+ } else
+ ctx_id = 0;
+
+ report_format = event->attr.config & I915_PERF_OA_FORMAT_MASK;
+ report_format >>= I915_PERF_OA_FORMAT_SHIFT;
+ snapshot_size = hsw_perf_format_sizes[report_format];
+
+ I915_WRITE(OACONTROL, 0 |
+ (ctx_id & OACONTROL_CTX_MASK) |
+ period_exponent << OACONTROL_TIMER_PERIOD_SHIFT |
+ (event->attr.sample_period ? OACONTROL_TIMER_ENABLE : 0) |
+ report_format << OACONTROL_FORMAT_SHIFT|
+ (ctx_id ? OACONTROL_PER_CTX_ENABLE : 0) |
+ OACONTROL_ENABLE);
+
+ if (event->attr.sample_period) {
+ __hrtimer_start_range_ns(&dev_priv->oa_pmu.timer,
+ ns_to_ktime(PERIOD), 0,
+ HRTIMER_MODE_REL_PINNED, 0);
+ }
+
+ dev_priv->oa_pmu.oa_buffer.format = report_format;
+ dev_priv->oa_pmu.oa_buffer.format_size = snapshot_size;
+
+ event->hw.state = 0;
+}
+
+static void i915_oa_event_stop(struct perf_event *event, int flags)
+{
+ struct drm_i915_private *dev_priv =
+ container_of(event->pmu, typeof(*dev_priv), oa_pmu.pmu);
+
+ I915_WRITE(OACONTROL, I915_READ(OACONTROL) & ~OACONTROL_ENABLE);
+
+ if (event->attr.sample_period) {
+ hrtimer_cancel(&dev_priv->oa_pmu.timer);
+ flush_oa_snapshots(dev_priv, true);
+ }
+
+ event->hw.state = PERF_HES_STOPPED;
+}
+
+static int i915_oa_event_add(struct perf_event *event, int flags)
+{
+ if (flags & PERF_EF_START)
+ i915_oa_event_start(event, flags);
+
+ return 0;
+}
+
+static void i915_oa_event_del(struct perf_event *event, int flags)
+{
+ i915_oa_event_stop(event, flags);
+}
+
+static void i915_oa_event_read(struct perf_event *event)
+{
+ struct drm_i915_private *i915 =
+ container_of(event->pmu, typeof(*i915), oa_pmu.pmu);
+
+ /* We want userspace to be able to use a read() to explicitly
+ * flush OA counter snapshots... */
+ if (event->attr.sample_period)
+ flush_oa_snapshots(i915, true);
+
+ /* XXX: What counter would be useful here? */
+ local64_set(&event->count, 0);
+}
+
+static int i915_oa_event_event_idx(struct perf_event *event)
+{
+ return 0;
+}
+
+void i915_oa_pmu_register(struct drm_device *dev)
+{
+ struct drm_i915_private *i915 = to_i915(dev);
+
+ /* We need to be careful about forwarding cpu metrics to
+ * userspace considering that PERF_PMU_CAP_IS_DEVICE bypasses
+ * the events/core security check that stops an unprivileged
+ * process collecting metrics for other processes.
+ */
+ i915->oa_pmu.dummy_regs = *task_pt_regs(current);
+
+ hrtimer_init(&i915->oa_pmu.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ i915->oa_pmu.timer.function = hrtimer_sample;
+
+ spin_lock_init(&i915->oa_pmu.lock);
+
+ i915->oa_pmu.pmu.capabilities = PERF_PMU_CAP_IS_DEVICE;
+ i915->oa_pmu.pmu.task_ctx_nr = perf_invalid_context;
+ i915->oa_pmu.pmu.event_init = i915_oa_event_init;
+ i915->oa_pmu.pmu.add = i915_oa_event_add;
+ i915->oa_pmu.pmu.del = i915_oa_event_del;
+ i915->oa_pmu.pmu.start = i915_oa_event_start;
+ i915->oa_pmu.pmu.stop = i915_oa_event_stop;
+ i915->oa_pmu.pmu.read = i915_oa_event_read;
+ i915->oa_pmu.pmu.event_idx = i915_oa_event_event_idx;
+
+ if (perf_pmu_register(&i915->oa_pmu.pmu, "i915_oa", -1))
+ i915->oa_pmu.pmu.event_init = NULL;
+}
+
+void i915_oa_pmu_unregister(struct drm_device *dev)
+{
+ struct drm_i915_private *i915 = to_i915(dev);
+
+ if (i915->oa_pmu.pmu.event_init == NULL)
+ return;
+
+ perf_pmu_unregister(&i915->oa_pmu.pmu);
+ i915->oa_pmu.pmu.event_init = NULL;
+}
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 203062e..1e7cfd4 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -457,6 +457,92 @@
#define GEN7_3DPRIM_BASE_VERTEX 0x2440

#define OACONTROL 0x2360
+#define OACONTROL_CTX_MASK 0xFFFFF000
+#define OACONTROL_TIMER_PERIOD_MASK 0x3F
+#define OACONTROL_TIMER_PERIOD_SHIFT 6
+#define OACONTROL_TIMER_ENABLE (1<<5)
+#define OACONTROL_FORMAT_A13_HSW (0<<2)
+#define OACONTROL_FORMAT_A29_HSW (1<<2)
+#define OACONTROL_FORMAT_A13_B8_C8_HSW (2<<2)
+#define OACONTROL_FORMAT_A29_B8_C8_HSW (3<<2)
+#define OACONTROL_FORMAT_B4_C8_HSW (4<<2)
+#define OACONTROL_FORMAT_A45_B8_C8_HSW (5<<2)
+#define OACONTROL_FORMAT_B4_C8_A16_HSW (6<<2)
+#define OACONTROL_FORMAT_C4_B8_HSW (7<<2)
+#define OACONTROL_FORMAT_SHIFT 2
+#define OACONTROL_PER_CTX_ENABLE (1<<1)
+#define OACONTROL_ENABLE (1<<0)
+
+#define OASTARTTRIG5 0x02720
+#define OASTARTTRIG5_THRESHOLD_VALUE_MASK 0xffff
+
+#define OASTARTTRIG6 0x02724
+#define OASTARTTRIG6_B4_TO_B7_THRESHOLD_ENABLE (1<<23)
+#define OASTARTTRIG6_B4_CUSTOM_EVENT_ENABLE (1<<28)
+
+#define OASTARTTRIG1 0x02710
+#define OASTARTTRIG1_THRESHOLD_VALUE_MASK 0xffff
+
+#define OASTARTTRIG2 0x02714
+#define OASTARTTRIG2_B0_TO_B3_THRESHOLD_ENABLE (1<<23)
+#define OASTARTTRIG2_B0_CUSTOM_EVENT_ENABLE (1<<28)
+
+#define OACEC0_0 0x2770
+#define OACEC0_0_B0_COMPARE_ANY_EQUAL 0
+#define OACEC0_0_B0_COMPARE_OR 0
+#define OACEC0_0_B0_COMPARE_GREATER_THAN 1
+#define OACEC0_0_B0_COMPARE_EQUAL 2
+#define OACEC0_0_B0_COMPARE_GREATER_OR_EQUAL 3
+#define OACEC0_0_B0_COMPARE_LESS_THAN 4
+#define OACEC0_0_B0_COMPARE_NOT_EQUAL 5
+#define OACEC0_0_B0_COMPARE_LESS_OR_EQUAL 6
+#define OACEC0_0_B0_COMPARE_VALUE_MASK 0xffff
+#define OACEC0_0_B0_COMPARE_VALUE_SHIFT 3
+
+#define OACEC0_1 0x2774
+#define OACEC0_1_B0_NOA_SELECT_MASK 0xffff
+
+#define GEN7_OABUFFER 0x23B0 /* R/W */
+#define GEN7_OABUFFER_OVERRUN_DISABLE (1<<3)
+#define GEN7_OABUFFER_EDGE_TRIGGER (1<<2)
+#define GEN7_OABUFFER_STOP_RESUME_ENABLE (1<<1)
+#define GEN7_OABUFFER_RESUME (1<<0)
+
+#define GEN8_OABUFFER 0x2B14 /* R/W */
+#define GEN8_OABUFFER_SIZE_MASK 0x7
+#define GEN8_OABUFFER_SIZE_128K (0<<3)
+#define GEN8_OABUFFER_SIZE_256K (1<<3)
+#define GEN8_OABUFFER_SIZE_512K (2<<3)
+#define GEN8_OABUFFER_SIZE_1M (3<<3)
+#define GEN8_OABUFFER_SIZE_2M (4<<3)
+#define GEN8_OABUFFER_SIZE_4M (5<<3)
+#define GEN8_OABUFFER_SIZE_8M (6<<3)
+#define GEN8_OABUFFER_SIZE_16M (7<<3)
+#define GEN8_OABUFFER_EDGE_TRIGGER (1<<2)
+#define GEN8_OABUFFER_OVERRUN_DISABLE (1<<1)
+#define GEN8_OABUFFER_MEM_SELECT_GGTT (1<<0)
+
+#define OASTATUS1 0x2364
+#define OASTATUS1_TAIL_MASK 0xffffffc0
+#define OASTATUS1_OABUFFER_SIZE_128K (0<<3)
+#define OASTATUS1_OABUFFER_SIZE_256K (1<<3)
+#define OASTATUS1_OABUFFER_SIZE_512K (2<<3)
+#define OASTATUS1_OABUFFER_SIZE_1M (3<<3)
+#define OASTATUS1_OABUFFER_SIZE_2M (4<<3)
+#define OASTATUS1_OABUFFER_SIZE_4M (5<<3)
+#define OASTATUS1_OABUFFER_SIZE_8M (6<<3)
+#define OASTATUS1_OABUFFER_SIZE_16M (7<<3)
+#define OASTATUS1_COUNTER_OVERFLOW (1<<2)
+#define OASTATUS1_OABUFFER_OVERFLOW (1<<1)
+#define OASTATUS1_REPORT_LOST (1<<0)
+
+
+#define OASTATUS2 0x2368
+#define OASTATUS2_HEAD_MASK 0xffffffc0
+#define OASTATUS2_GGTT 0x1
+
+#define GEN8_OAHEADPTR 0x2B0C
+#define GEN8_OATAILPTR 0x2B10

#define _GEN7_PIPEA_DE_LOAD_SL 0x70068
#define _GEN7_PIPEB_DE_LOAD_SL 0x71068
@@ -5551,6 +5637,7 @@ enum punit_power_well {
# define GEN6_RCCUNIT_CLOCK_GATE_DISABLE (1 << 11)

#define GEN6_UCGCTL3 0x9408
+# define GEN6_OACSUNIT_CLOCK_GATE_DISABLE (1 << 20)

#define GEN7_UCGCTL4 0x940c
#define GEN7_L3BANK2X_CLOCK_GATE_DISABLE (1<<25)
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index ff57f07..fd3b0cb 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -58,6 +58,27 @@
#define I915_ERROR_UEVENT "ERROR"
#define I915_RESET_UEVENT "RESET"

+/**
+ * DOC: perf events configuration exposed by i915 through /sys/bus/event_sources/drivers/i915_oa
+ *
+ */
+#define I915_PERF_OA_CTX_ID_MASK 0xffffffff
+#define I915_PERF_OA_SINGLE_CONTEXT_ENABLE (1ULL << 32)
+
+#define I915_PERF_OA_FORMAT_SHIFT 33
+#define I915_PERF_OA_FORMAT_MASK (0x7ULL << 33)
+#define I915_PERF_OA_FORMAT_A13_HSW (0ULL << 33)
+#define I915_PERF_OA_FORMAT_A29_HSW (1ULL << 33)
+#define I915_PERF_OA_FORMAT_A13_B8_C8_HSW (2ULL << 33)
+#define I915_PERF_OA_FORMAT_A29_B8_C8_HSW (3ULL << 33)
+#define I915_PERF_OA_FORMAT_B4_C8_HSW (4ULL << 33)
+#define I915_PERF_OA_FORMAT_A45_B8_C8_HSW (5ULL << 33)
+#define I915_PERF_OA_FORMAT_B4_C8_A16_HSW (6ULL << 33)
+#define I915_PERF_OA_FORMAT_C4_B8_HSW (7ULL << 33)
+
+#define I915_PERF_OA_TIMER_EXPONENT_SHIFT 36
+#define I915_PERF_OA_TIMER_EXPONENT_MASK (0x3fULL << 36)
+
/* Each region is a minimum of 16k, and there are at most 255 of them.
*/
#define I915_NR_TEX_REGIONS 255 /* table size 2k - maximum due to use
--
2.1.2

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