[4/4] drm/i915/perf: Map OA buffer to user space for gen12 performance query
diff mbox series

Message ID 20200721020012.46506-5-umesh.nerlige.ramappa@intel.com
State New
Headers show
Series
  • Allow privileged user to map the OA buffer
Related show

Commit Message

Umesh Nerlige Ramappa July 21, 2020, 2 a.m. UTC
From: Piotr Maciejewski <piotr.maciejewski@intel.com>

i915 used to support time based sampling mode which is good for overall
system monitoring, but is not enough for query mode used to measure a
single draw call or dispatch. Gen9-Gen11 are using current i915 perf
implementation for query, but Gen12+ requires a new approach for query
based on triggered reports within oa buffer.

Triggering reports into the OA buffer is achieved by writing into a
a trigger register. Optionally an unused counter/register is set with a
marker value such that a triggered report can be identified in the OA
buffer. Reports are usually triggered at the start and end of work that
is measured.

Since OA buffer is large and queries can be frequent, an efficient way
to look for triggered reports is required. By knowing the current head
and tail offsets into the OA buffer, it is easier to determine the
locality of the reports of interest.

Current perf OA interface does not expose head/tail information to the
user and it filters out invalid reports before sending data to user.
Also considering limited size of user buffer used during a query,
creating a 1:1 copy of the OA buffer at the user space added undesired
complexity.

The solution was to map the OA buffer to user space provided

(1) that it is accessed from a privileged user.
(2) OA report filtering is not used.

These 2 conditions would satisfy the safety criteria that the current
perf interface addresses.

To enable the query:
- Add an ioctl to expose head and tail to the user
- Add an ioctl to return size and offset of the OA buffer
- Map the OA buffer to the user space

v2:
- Improve commit message (Chris)
- Do not mmap based on gem object filp. Instead, use perf_fd and support
  mmap syscall (Chris)
- Pass non-zero offset in mmap to enforce the right object is mapped (Chris)
- Do not expose gpu_address (Chris)
- Verify start and length of vma for page alignment (Lionel)
- Move SQNTL config out (Lionel)

v3: (Chris)
- Omit redundant checks
- Return VM_FAULT_SIGBUS is old stream is closed
- Maintain reference counts to stream in vm_open and vm_close
- Use switch to identify object to be mapped

Signed-off-by: Piotr Maciejewski <piotr.maciejewski@intel.com>
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
---
 drivers/gpu/drm/i915/gem/i915_gem_mman.c |   2 +-
 drivers/gpu/drm/i915/gem/i915_gem_mman.h |   2 +
 drivers/gpu/drm/i915/i915_perf.c         | 196 ++++++++++++++++++++++-
 drivers/gpu/drm/i915/i915_perf_types.h   |  17 ++
 include/uapi/drm/i915_drm.h              |  32 ++++
 5 files changed, 245 insertions(+), 4 deletions(-)

Comments

Umesh Nerlige Ramappa July 21, 2020, 2:17 a.m. UTC | #1
Hi Chris,

I have added your comments, but I have a few questions below:

Thanks for your help,
Umesh

On Mon, Jul 20, 2020 at 07:00:12PM -0700, Umesh Nerlige Ramappa wrote:
>From: Piotr Maciejewski <piotr.maciejewski@intel.com>
>
>i915 used to support time based sampling mode which is good for overall
>system monitoring, but is not enough for query mode used to measure a
>single draw call or dispatch. Gen9-Gen11 are using current i915 perf
>implementation for query, but Gen12+ requires a new approach for query
>based on triggered reports within oa buffer.
>
>Triggering reports into the OA buffer is achieved by writing into a
>a trigger register. Optionally an unused counter/register is set with a
>marker value such that a triggered report can be identified in the OA
>buffer. Reports are usually triggered at the start and end of work that
>is measured.
>
>Since OA buffer is large and queries can be frequent, an efficient way
>to look for triggered reports is required. By knowing the current head
>and tail offsets into the OA buffer, it is easier to determine the
>locality of the reports of interest.
>
>Current perf OA interface does not expose head/tail information to the
>user and it filters out invalid reports before sending data to user.
>Also considering limited size of user buffer used during a query,
>creating a 1:1 copy of the OA buffer at the user space added undesired
>complexity.
>
>The solution was to map the OA buffer to user space provided
>
>(1) that it is accessed from a privileged user.
>(2) OA report filtering is not used.
>
>These 2 conditions would satisfy the safety criteria that the current
>perf interface addresses.
>
>To enable the query:
>- Add an ioctl to expose head and tail to the user
>- Add an ioctl to return size and offset of the OA buffer
>- Map the OA buffer to the user space
>
>v2:
>- Improve commit message (Chris)
>- Do not mmap based on gem object filp. Instead, use perf_fd and support
>  mmap syscall (Chris)
>- Pass non-zero offset in mmap to enforce the right object is mapped (Chris)
>- Do not expose gpu_address (Chris)
>- Verify start and length of vma for page alignment (Lionel)
>- Move SQNTL config out (Lionel)
>
>v3: (Chris)
>- Omit redundant checks
>- Return VM_FAULT_SIGBUS is old stream is closed
>- Maintain reference counts to stream in vm_open and vm_close
>- Use switch to identify object to be mapped
>
>Signed-off-by: Piotr Maciejewski <piotr.maciejewski@intel.com>
>Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
>---
> drivers/gpu/drm/i915/gem/i915_gem_mman.c |   2 +-
> drivers/gpu/drm/i915/gem/i915_gem_mman.h |   2 +
> drivers/gpu/drm/i915/i915_perf.c         | 196 ++++++++++++++++++++++-
> drivers/gpu/drm/i915/i915_perf_types.h   |  17 ++
> include/uapi/drm/i915_drm.h              |  32 ++++
> 5 files changed, 245 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
>index b23368529a40..7c4b9b0c334b 100644
>--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
>+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
>@@ -204,7 +204,7 @@ compute_partial_view(const struct drm_i915_gem_object *obj,
> 	return view;
> }
>
>-static vm_fault_t i915_error_to_vmf_fault(int err)
>+vm_fault_t i915_error_to_vmf_fault(int err)
> {
> 	switch (err) {
> 	default:
>diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.h b/drivers/gpu/drm/i915/gem/i915_gem_mman.h
>index efee9e0d2508..1190a3a228ea 100644
>--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.h
>+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.h
>@@ -29,4 +29,6 @@ void i915_gem_object_release_mmap_gtt(struct drm_i915_gem_object *obj);
>
> void i915_gem_object_release_mmap_offset(struct drm_i915_gem_object *obj);
>
>+vm_fault_t i915_error_to_vmf_fault(int err);
>+
> #endif
>diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
>index 453afeaee0a7..0e9696fc4ab2 100644
>--- a/drivers/gpu/drm/i915/i915_perf.c
>+++ b/drivers/gpu/drm/i915/i915_perf.c
>@@ -192,10 +192,12 @@
>  */
>
> #include <linux/anon_inodes.h>
>+#include <linux/mman.h>
> #include <linux/sizes.h>
> #include <linux/uuid.h>
>
> #include "gem/i915_gem_context.h"
>+#include "gem/i915_gem_mman.h"
> #include "gt/intel_engine_pm.h"
> #include "gt/intel_engine_user.h"
> #include "gt/intel_gt.h"
>@@ -434,6 +436,30 @@ static u32 gen7_oa_hw_tail_read(struct i915_perf_stream *stream)
> 	return oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
> }
>
>+static u32 gen12_oa_hw_head_read(struct i915_perf_stream *stream)
>+{
>+	struct intel_uncore *uncore = stream->uncore;
>+
>+	return intel_uncore_read(uncore, GEN12_OAG_OAHEADPTR) &
>+	       GEN12_OAG_OAHEADPTR_MASK;
>+}
>+
>+static u32 gen8_oa_hw_head_read(struct i915_perf_stream *stream)
>+{
>+	struct intel_uncore *uncore = stream->uncore;
>+
>+	return intel_uncore_read(uncore, GEN8_OAHEADPTR) &
>+	       GEN8_OAHEADPTR_MASK;
>+}
>+
>+static u32 gen7_oa_hw_head_read(struct i915_perf_stream *stream)
>+{
>+	struct intel_uncore *uncore = stream->uncore;
>+	u32 oastatus2 = intel_uncore_read(uncore, GEN7_OASTATUS2);
>+
>+	return oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
>+}
>+
> /**
>  * oa_buffer_check_unlocked - check for data and update tail ptr state
>  * @stream: i915 stream instance
>@@ -1347,6 +1373,15 @@ free_noa_wait(struct i915_perf_stream *stream)
> 	i915_vma_unpin_and_release(&stream->noa_wait, 0);
> }
>
>+static void
>+free_stream(struct kref *kref)
>+{
>+	struct i915_perf_stream *stream =
>+		container_of(kref, typeof(*stream), refcount);
>+
>+	kfree(stream);
>+}
>+
> static void i915_oa_stream_destroy(struct i915_perf_stream *stream)
> {
> 	struct i915_perf *perf = stream->perf;
>@@ -2934,6 +2969,7 @@ static int i915_oa_stream_init(struct i915_perf_stream *stream,
> 	stream->poll_check_timer.function = oa_poll_check_timer_cb;
> 	init_waitqueue_head(&stream->poll_wq);
> 	spin_lock_init(&stream->oa_buffer.ptr_lock);
>+	kref_init(&stream->refcount);
>
> 	return 0;
>
>@@ -3214,6 +3250,69 @@ static long i915_perf_config_locked(struct i915_perf_stream *stream,
> 	return ret;
> }
>
>+/**
>+ * i915_perf_oa_buffer_head_tail_locked - head and tail of the OA buffer
>+ * @stream: i915 perf stream
>+ * @arg: pointer to oa buffer head and tail filled by this function.
>+ */
>+static int i915_perf_oa_buffer_head_tail_locked(struct i915_perf_stream *stream,
>+						unsigned long arg)
>+{
>+	struct drm_i915_perf_oa_buffer_head_tail ht;
>+	void __user *output = (void __user *)arg;
>+	u32 gtt_offset = i915_ggtt_offset(stream->oa_buffer.vma);
>+
>+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
>+		DRM_DEBUG("Insufficient privileges to access OA buffer info\n");
>+		return -EACCES;
>+	}
>+
>+	if (!output)
>+		return -EINVAL;
>+
>+	memset(&ht, 0, sizeof(ht));
>+
>+	ht.head = stream->perf->ops.oa_hw_head_read(stream) - gtt_offset;
>+	ht.tail = stream->perf->ops.oa_hw_tail_read(stream) - gtt_offset;
>+
>+	if (copy_to_user(output, &ht, sizeof(ht)))
>+		return -EFAULT;
>+
>+	return 0;
>+}
>+
>+#define I915_PERF_OA_BUFFER_MMAP_OFFSET 1
>+
>+/**
>+ * i915_perf_oa_buffer_info_locked - size and offset of the OA buffer
>+ * @stream: i915 perf stream
>+ * @arg: pointer to oa buffer info filled by this function.
>+ */
>+static int i915_perf_oa_buffer_info_locked(struct i915_perf_stream *stream,
>+					   unsigned long arg)
>+{
>+	struct drm_i915_perf_oa_buffer_info info;
>+	void __user *output = (void __user *)arg;
>+
>+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
>+		DRM_DEBUG("Insufficient privileges to access OA buffer info\n");
>+		return -EACCES;
>+	}
>+
>+	if (!output)
>+		return -EINVAL;
>+
>+	memset(&info, 0, sizeof(info));
>+
>+	info.size = stream->oa_buffer.vma->size;
>+	info.offset = I915_PERF_OA_BUFFER_MMAP_OFFSET * PAGE_SIZE;
>+
>+	if (copy_to_user(output, &info, sizeof(info)))
>+		return -EFAULT;
>+
>+	return 0;
>+}
>+
> /**
>  * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
>  * @stream: An i915 perf stream
>@@ -3239,6 +3338,10 @@ static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
> 		return 0;
> 	case I915_PERF_IOCTL_CONFIG:
> 		return i915_perf_config_locked(stream, arg);
>+	case I915_PERF_IOCTL_GET_OA_BUFFER_INFO:
>+		return i915_perf_oa_buffer_info_locked(stream, arg);
>+	case I915_PERF_IOCTL_GET_OA_BUFFER_HEAD_TAIL:
>+		return i915_perf_oa_buffer_head_tail_locked(stream, arg);
> 	}
>
> 	return -EINVAL;
>@@ -3290,8 +3393,6 @@ static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
>
> 	if (stream->ctx)
> 		i915_gem_context_put(stream->ctx);
>-
>-	kfree(stream);
> }
>
> /**
>@@ -3314,12 +3415,93 @@ static int i915_perf_release(struct inode *inode, struct file *file)
> 	i915_perf_destroy_locked(stream);
> 	mutex_unlock(&perf->lock);
>
>+	WRITE_ONCE(stream->closed, true);
>+	unmap_mapping_range(file->f_mapping, 0, OA_BUFFER_SIZE, 1);
>+
> 	/* Release the reference the perf stream kept on the driver. */
> 	drm_dev_put(&perf->i915->drm);
>
> 	return 0;
> }
>
>+static void vm_open_oa(struct vm_area_struct *vma)
>+{
>+	struct i915_perf_stream *stream = vma->vm_private_data;
>+
>+	GEM_BUG_ON(!stream);
>+	kref_get(&stream->refcount);

When user calls mmap, after this call the count is 2 (since kref_init 
started off the count with 1).

>+}
>+
>+static void vm_close_oa(struct vm_area_struct *vma)
>+{
>+	struct i915_perf_stream *stream = vma->vm_private_data;
>+
>+	GEM_BUG_ON(!stream);
>+	kref_put(&stream->refcount, free_stream);

When the user closes perf fd or calls unmap, vm_close_oa is called and 
refcount goes to 1, so not sure how the refcount goes to 0 so that 
free_stream is called. Should I kref_put when closing perf fd also?

>+}
>+
>+static vm_fault_t vm_fault_oa(struct vm_fault *vmf)
>+{
>+	struct vm_area_struct *vma = vmf->vma;
>+	struct i915_perf_stream *stream = vma->vm_private_data;
>+	struct drm_i915_gem_object *obj = stream->oa_buffer.vma->obj;
>+	int err;
>+
>+	if (READ_ONCE(stream->closed))
>+		return VM_FAULT_SIGBUS;
>+
>+	err = i915_gem_object_pin_pages(obj);
>+	if (err)
>+		goto out;
>+
>+	err = remap_io_sg(vma,
>+			  vma->vm_start, vma->vm_end - vma->vm_start,
>+			  obj->mm.pages->sgl, -1);
>+
>+	i915_gem_object_unpin_pages(obj);
>+
>+out:
>+	return i915_error_to_vmf_fault(err);
>+}
>+
>+static const struct vm_operations_struct vm_ops_oa = {
>+	.open = vm_open_oa,
>+	.close = vm_close_oa,
>+	.fault = vm_fault_oa,
>+};
>+
>+int i915_perf_mmap(struct file *file, struct vm_area_struct *vma)
>+{
>+	struct i915_perf_stream *stream = file->private_data;
>+
>+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
>+		DRM_DEBUG("Insufficient privileges to map OA buffer\n");
>+		return -EACCES;
>+	}
>+
>+	switch (vma->vm_pgoff) {
>+	case I915_PERF_OA_BUFFER_MMAP_OFFSET:
>+		if (vma->vm_end - vma->vm_start > OA_BUFFER_SIZE)
>+			return -EINVAL;
>+
>+		if (vma->vm_flags & VM_WRITE)
>+			return -EINVAL;
>+
>+		break;
>+
>+	default:
>+		return -EINVAL;
>+	}
>+
>+	vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC | VM_MAYSHARE);
>+	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
>+	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
>+	vma->vm_private_data = stream;
>+	vma->vm_ops = &vm_ops_oa;
>+	vm_open_oa(vma);

I am calling the open explicitly here to get the reference, otherwise I 
don't see open being called by anyone/anything.

If user calls mmap multiple times, does he get a unique vma each time?
Do I need to track all of them (and their sizes) and then unmap them 
when perf_fd is closed?

>+
>+	return 0;
>+}
>
> static const struct file_operations fops = {
> 	.owner		= THIS_MODULE,
>@@ -3332,6 +3514,7 @@ static const struct file_operations fops = {
> 	 * to handle 32bits compatibility.
> 	 */
> 	.compat_ioctl   = i915_perf_ioctl,
>+	.mmap		= i915_perf_mmap,
> };
>
>
>@@ -4260,6 +4443,7 @@ void i915_perf_init(struct drm_i915_private *i915)
> 		perf->ops.oa_disable = gen7_oa_disable;
> 		perf->ops.read = gen7_oa_read;
> 		perf->ops.oa_hw_tail_read = gen7_oa_hw_tail_read;
>+		perf->ops.oa_hw_head_read = gen7_oa_hw_head_read;
>
> 		perf->oa_formats = hsw_oa_formats;
> 	} else if (HAS_LOGICAL_RING_CONTEXTS(i915)) {
>@@ -4291,6 +4475,7 @@ void i915_perf_init(struct drm_i915_private *i915)
> 			perf->ops.enable_metric_set = gen8_enable_metric_set;
> 			perf->ops.disable_metric_set = gen8_disable_metric_set;
> 			perf->ops.oa_hw_tail_read = gen8_oa_hw_tail_read;
>+			perf->ops.oa_hw_head_read = gen8_oa_hw_head_read;
>
> 			if (IS_GEN(i915, 8)) {
> 				perf->ctx_oactxctrl_offset = 0x120;
>@@ -4318,6 +4503,7 @@ void i915_perf_init(struct drm_i915_private *i915)
> 			perf->ops.enable_metric_set = gen8_enable_metric_set;
> 			perf->ops.disable_metric_set = gen10_disable_metric_set;
> 			perf->ops.oa_hw_tail_read = gen8_oa_hw_tail_read;
>+			perf->ops.oa_hw_head_read = gen8_oa_hw_head_read;
>
> 			if (IS_GEN(i915, 10)) {
> 				perf->ctx_oactxctrl_offset = 0x128;
>@@ -4342,6 +4528,7 @@ void i915_perf_init(struct drm_i915_private *i915)
> 			perf->ops.enable_metric_set = gen12_enable_metric_set;
> 			perf->ops.disable_metric_set = gen12_disable_metric_set;
> 			perf->ops.oa_hw_tail_read = gen12_oa_hw_tail_read;
>+			perf->ops.oa_hw_head_read = gen12_oa_hw_head_read;
>
> 			perf->ctx_flexeu0_offset = 0;
> 			perf->ctx_oactxctrl_offset = 0x144;
>@@ -4453,8 +4640,11 @@ int i915_perf_ioctl_version(void)
> 	 *
> 	 * 7: Whitelist OA buffer head/tail registers for user to identify the
> 	 *    location of triggered reports into the OA buffer.
>+	 *
>+	 * 8: Added an option to map oa buffer at umd driver level and trigger
>+	 *    oa reports within oa buffer from command buffer.
> 	 */
>-	return 7;
>+	return 8;
> }
>
> #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
>diff --git a/drivers/gpu/drm/i915/i915_perf_types.h b/drivers/gpu/drm/i915/i915_perf_types.h
>index a36a455ae336..2efbe35c5fa9 100644
>--- a/drivers/gpu/drm/i915/i915_perf_types.h
>+++ b/drivers/gpu/drm/i915/i915_perf_types.h
>@@ -311,6 +311,18 @@ struct i915_perf_stream {
> 	 * buffer should be checked for available data.
> 	 */
> 	u64 poll_oa_period;
>+
>+	/**
>+	 * @closed: Open or closed state of the stream.
>+	 * True if stream is closed.
>+	 */
>+	bool closed;

closed is part of the stream itself, so I cannot kfree(stream) until the 
refcount goes to 0.

>+
>+	/**
>+	 * @refcount: References to the mapped OA buffer managed by this
>+	 * stream.
>+	 */
>+	struct kref refcount;
> };
>
> /**
>@@ -377,6 +389,11 @@ struct i915_oa_ops {
> 	 * generations.
> 	 */
> 	u32 (*oa_hw_tail_read)(struct i915_perf_stream *stream);
>+
>+	/**
>+	 * @oa_hw_head_read: read the OA head pointer register
>+	 */
>+	u32 (*oa_hw_head_read)(struct i915_perf_stream *stream);
> };
>
> struct i915_perf {
>diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
>index 00546062e023..2042f6339182 100644
>--- a/include/uapi/drm/i915_drm.h
>+++ b/include/uapi/drm/i915_drm.h
>@@ -2048,6 +2048,38 @@ struct drm_i915_perf_open_param {
>  */
> #define I915_PERF_IOCTL_CONFIG	_IO('i', 0x2)
>
>+/**
>+ * Returns OA buffer properties to be used with mmap.
>+ *
>+ * This ioctl is available in perf revision 8.
>+ */
>+#define I915_PERF_IOCTL_GET_OA_BUFFER_INFO _IO('i', 0x3)
>+
>+/**
>+ * OA buffer size and offset.
>+ */
>+struct drm_i915_perf_oa_buffer_info {
>+	__u32 size;
>+	__u32 offset;
>+	__u64 reserved[4];
>+};
>+
>+/**
>+ * Returns current position of OA buffer head and tail.
>+ *
>+ * This ioctl is available in perf revision 8.
>+ */
>+#define I915_PERF_IOCTL_GET_OA_BUFFER_HEAD_TAIL _IO('i', 0x4)
>+
>+/**
>+ * OA buffer head and tail.
>+ */
>+struct drm_i915_perf_oa_buffer_head_tail {
>+	__u32 head;
>+	__u32 tail;
>+	__u64 reserved[4];
>+};
>+
> /**
>  * Common to all i915 perf records
>  */
>-- 
>2.20.1
>
>_______________________________________________
>Intel-gfx mailing list
>Intel-gfx@lists.freedesktop.org
>https://lists.freedesktop.org/mailman/listinfo/intel-gfx
Chris Wilson July 21, 2020, 8:52 a.m. UTC | #2
Quoting Umesh Nerlige Ramappa (2020-07-21 03:17:59)
> Hi Chris,
> 
> I have added your comments, but I have a few questions below:
> 
> Thanks for your help,
> Umesh
> 
> On Mon, Jul 20, 2020 at 07:00:12PM -0700, Umesh Nerlige Ramappa wrote:
> >From: Piotr Maciejewski <piotr.maciejewski@intel.com>
> >+static void vm_open_oa(struct vm_area_struct *vma)
> >+{
> >+      struct i915_perf_stream *stream = vma->vm_private_data;
> >+
> >+      GEM_BUG_ON(!stream);
> >+      kref_get(&stream->refcount);
> 
> When user calls mmap, after this call the count is 2 (since kref_init 
> started off the count with 1).
> 
> >+}
> >+
> >+static void vm_close_oa(struct vm_area_struct *vma)
> >+{
> >+      struct i915_perf_stream *stream = vma->vm_private_data;
> >+
> >+      GEM_BUG_ON(!stream);
> >+      kref_put(&stream->refcount, free_stream);
> 
> When the user closes perf fd or calls unmap, vm_close_oa is called and 
> refcount goes to 1, so not sure how the refcount goes to 0 so that 
> free_stream is called. Should I kref_put when closing perf fd also?

Yes, at a glance, I would say i915_perf_destroy_locked() should replace
the kfree(stream) with a kref_put.

> >+static vm_fault_t vm_fault_oa(struct vm_fault *vmf)
> >+{
> >+      struct vm_area_struct *vma = vmf->vma;
> >+      struct i915_perf_stream *stream = vma->vm_private_data;
> >+      struct drm_i915_gem_object *obj = stream->oa_buffer.vma->obj;
> >+      int err;
> >+
> >+      if (READ_ONCE(stream->closed))
> >+              return VM_FAULT_SIGBUS;
> >+
> >+      err = i915_gem_object_pin_pages(obj);
> >+      if (err)
> >+              goto out;
> >+
> >+      err = remap_io_sg(vma,
> >+                        vma->vm_start, vma->vm_end - vma->vm_start,
> >+                        obj->mm.pages->sgl, -1);
> >+
> >+      i915_gem_object_unpin_pages(obj);
> >+
> >+out:
> >+      return i915_error_to_vmf_fault(err);
> >+}
> >+
> >+static const struct vm_operations_struct vm_ops_oa = {
> >+      .open = vm_open_oa,
> >+      .close = vm_close_oa,
> >+      .fault = vm_fault_oa,
> >+};
> >+
> >+int i915_perf_mmap(struct file *file, struct vm_area_struct *vma)
> >+{
> >+      struct i915_perf_stream *stream = file->private_data;
> >+
> >+      if (i915_perf_stream_paranoid && !perfmon_capable()) {
> >+              DRM_DEBUG("Insufficient privileges to map OA buffer\n");
> >+              return -EACCES;
> >+      }
> >+
> >+      switch (vma->vm_pgoff) {
> >+      case I915_PERF_OA_BUFFER_MMAP_OFFSET:
> >+              if (vma->vm_end - vma->vm_start > OA_BUFFER_SIZE)
> >+                      return -EINVAL;
> >+
> >+              if (vma->vm_flags & VM_WRITE)
> >+                      return -EINVAL;
> >+
> >+              break;
> >+
> >+      default:
> >+              return -EINVAL;
> >+      }
> >+
> >+      vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC | VM_MAYSHARE);
> >+      vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
> >+      vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> >+      vma->vm_private_data = stream;
> >+      vma->vm_ops = &vm_ops_oa;
> >+      vm_open_oa(vma);
> 
> I am calling the open explicitly here to get the reference, otherwise I 
> don't see open being called by anyone/anything.

The initial vm_ops->open is implicit, i.e. the mmap starts opened, and
the vm_ops->open() is only called when the vma is cloned (e.g. on
fork()).

> If user calls mmap multiple times, does he get a unique vma each time?

Yes.

> Do I need to track all of them (and their sizes) and then unmap them 
> when perf_fd is closed?

Yes... But we can zap them all with a single unmap_mapping_range() call,
since they all exist within the perf_fd->f_mapping.

> >diff --git a/drivers/gpu/drm/i915/i915_perf_types.h b/drivers/gpu/drm/i915/i915_perf_types.h
> >index a36a455ae336..2efbe35c5fa9 100644
> >--- a/drivers/gpu/drm/i915/i915_perf_types.h
> >+++ b/drivers/gpu/drm/i915/i915_perf_types.h
> >@@ -311,6 +311,18 @@ struct i915_perf_stream {
> >        * buffer should be checked for available data.
> >        */
> >       u64 poll_oa_period;
> >+
> >+      /**
> >+       * @closed: Open or closed state of the stream.
> >+       * True if stream is closed.
> >+       */
> >+      bool closed;
> 
> closed is part of the stream itself, so I cannot kfree(stream) until the 
> refcount goes to 0.

Correct. kfree must be part of the kref_put cb.

> >+      /**
> >+       * @refcount: References to the mapped OA buffer managed by this
> >+       * stream.
> >+       */
> >+      struct kref refcount;
> > };
---------------------------------------------------------------------
Intel Corporation (UK) Limited
Registered No. 1134945 (England)
Registered Office: Pipers Way, Swindon SN3 1RJ
VAT No: 860 2173 47

This e-mail and any attachments may contain confidential material for
the sole use of the intended recipient(s). Any review or distribution
by others is strictly prohibited. If you are not the intended
recipient, please contact the sender and delete all copies.

Patch
diff mbox series

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index b23368529a40..7c4b9b0c334b 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -204,7 +204,7 @@  compute_partial_view(const struct drm_i915_gem_object *obj,
 	return view;
 }
 
-static vm_fault_t i915_error_to_vmf_fault(int err)
+vm_fault_t i915_error_to_vmf_fault(int err)
 {
 	switch (err) {
 	default:
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.h b/drivers/gpu/drm/i915/gem/i915_gem_mman.h
index efee9e0d2508..1190a3a228ea 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.h
@@ -29,4 +29,6 @@  void i915_gem_object_release_mmap_gtt(struct drm_i915_gem_object *obj);
 
 void i915_gem_object_release_mmap_offset(struct drm_i915_gem_object *obj);
 
+vm_fault_t i915_error_to_vmf_fault(int err);
+
 #endif
diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
index 453afeaee0a7..0e9696fc4ab2 100644
--- a/drivers/gpu/drm/i915/i915_perf.c
+++ b/drivers/gpu/drm/i915/i915_perf.c
@@ -192,10 +192,12 @@ 
  */
 
 #include <linux/anon_inodes.h>
+#include <linux/mman.h>
 #include <linux/sizes.h>
 #include <linux/uuid.h>
 
 #include "gem/i915_gem_context.h"
+#include "gem/i915_gem_mman.h"
 #include "gt/intel_engine_pm.h"
 #include "gt/intel_engine_user.h"
 #include "gt/intel_gt.h"
@@ -434,6 +436,30 @@  static u32 gen7_oa_hw_tail_read(struct i915_perf_stream *stream)
 	return oastatus1 & GEN7_OASTATUS1_TAIL_MASK;
 }
 
+static u32 gen12_oa_hw_head_read(struct i915_perf_stream *stream)
+{
+	struct intel_uncore *uncore = stream->uncore;
+
+	return intel_uncore_read(uncore, GEN12_OAG_OAHEADPTR) &
+	       GEN12_OAG_OAHEADPTR_MASK;
+}
+
+static u32 gen8_oa_hw_head_read(struct i915_perf_stream *stream)
+{
+	struct intel_uncore *uncore = stream->uncore;
+
+	return intel_uncore_read(uncore, GEN8_OAHEADPTR) &
+	       GEN8_OAHEADPTR_MASK;
+}
+
+static u32 gen7_oa_hw_head_read(struct i915_perf_stream *stream)
+{
+	struct intel_uncore *uncore = stream->uncore;
+	u32 oastatus2 = intel_uncore_read(uncore, GEN7_OASTATUS2);
+
+	return oastatus2 & GEN7_OASTATUS2_HEAD_MASK;
+}
+
 /**
  * oa_buffer_check_unlocked - check for data and update tail ptr state
  * @stream: i915 stream instance
@@ -1347,6 +1373,15 @@  free_noa_wait(struct i915_perf_stream *stream)
 	i915_vma_unpin_and_release(&stream->noa_wait, 0);
 }
 
+static void
+free_stream(struct kref *kref)
+{
+	struct i915_perf_stream *stream =
+		container_of(kref, typeof(*stream), refcount);
+
+	kfree(stream);
+}
+
 static void i915_oa_stream_destroy(struct i915_perf_stream *stream)
 {
 	struct i915_perf *perf = stream->perf;
@@ -2934,6 +2969,7 @@  static int i915_oa_stream_init(struct i915_perf_stream *stream,
 	stream->poll_check_timer.function = oa_poll_check_timer_cb;
 	init_waitqueue_head(&stream->poll_wq);
 	spin_lock_init(&stream->oa_buffer.ptr_lock);
+	kref_init(&stream->refcount);
 
 	return 0;
 
@@ -3214,6 +3250,69 @@  static long i915_perf_config_locked(struct i915_perf_stream *stream,
 	return ret;
 }
 
+/**
+ * i915_perf_oa_buffer_head_tail_locked - head and tail of the OA buffer
+ * @stream: i915 perf stream
+ * @arg: pointer to oa buffer head and tail filled by this function.
+ */
+static int i915_perf_oa_buffer_head_tail_locked(struct i915_perf_stream *stream,
+						unsigned long arg)
+{
+	struct drm_i915_perf_oa_buffer_head_tail ht;
+	void __user *output = (void __user *)arg;
+	u32 gtt_offset = i915_ggtt_offset(stream->oa_buffer.vma);
+
+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
+		DRM_DEBUG("Insufficient privileges to access OA buffer info\n");
+		return -EACCES;
+	}
+
+	if (!output)
+		return -EINVAL;
+
+	memset(&ht, 0, sizeof(ht));
+
+	ht.head = stream->perf->ops.oa_hw_head_read(stream) - gtt_offset;
+	ht.tail = stream->perf->ops.oa_hw_tail_read(stream) - gtt_offset;
+
+	if (copy_to_user(output, &ht, sizeof(ht)))
+		return -EFAULT;
+
+	return 0;
+}
+
+#define I915_PERF_OA_BUFFER_MMAP_OFFSET 1
+
+/**
+ * i915_perf_oa_buffer_info_locked - size and offset of the OA buffer
+ * @stream: i915 perf stream
+ * @arg: pointer to oa buffer info filled by this function.
+ */
+static int i915_perf_oa_buffer_info_locked(struct i915_perf_stream *stream,
+					   unsigned long arg)
+{
+	struct drm_i915_perf_oa_buffer_info info;
+	void __user *output = (void __user *)arg;
+
+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
+		DRM_DEBUG("Insufficient privileges to access OA buffer info\n");
+		return -EACCES;
+	}
+
+	if (!output)
+		return -EINVAL;
+
+	memset(&info, 0, sizeof(info));
+
+	info.size = stream->oa_buffer.vma->size;
+	info.offset = I915_PERF_OA_BUFFER_MMAP_OFFSET * PAGE_SIZE;
+
+	if (copy_to_user(output, &info, sizeof(info)))
+		return -EFAULT;
+
+	return 0;
+}
+
 /**
  * i915_perf_ioctl - support ioctl() usage with i915 perf stream FDs
  * @stream: An i915 perf stream
@@ -3239,6 +3338,10 @@  static long i915_perf_ioctl_locked(struct i915_perf_stream *stream,
 		return 0;
 	case I915_PERF_IOCTL_CONFIG:
 		return i915_perf_config_locked(stream, arg);
+	case I915_PERF_IOCTL_GET_OA_BUFFER_INFO:
+		return i915_perf_oa_buffer_info_locked(stream, arg);
+	case I915_PERF_IOCTL_GET_OA_BUFFER_HEAD_TAIL:
+		return i915_perf_oa_buffer_head_tail_locked(stream, arg);
 	}
 
 	return -EINVAL;
@@ -3290,8 +3393,6 @@  static void i915_perf_destroy_locked(struct i915_perf_stream *stream)
 
 	if (stream->ctx)
 		i915_gem_context_put(stream->ctx);
-
-	kfree(stream);
 }
 
 /**
@@ -3314,12 +3415,93 @@  static int i915_perf_release(struct inode *inode, struct file *file)
 	i915_perf_destroy_locked(stream);
 	mutex_unlock(&perf->lock);
 
+	WRITE_ONCE(stream->closed, true);
+	unmap_mapping_range(file->f_mapping, 0, OA_BUFFER_SIZE, 1);
+
 	/* Release the reference the perf stream kept on the driver. */
 	drm_dev_put(&perf->i915->drm);
 
 	return 0;
 }
 
+static void vm_open_oa(struct vm_area_struct *vma)
+{
+	struct i915_perf_stream *stream = vma->vm_private_data;
+
+	GEM_BUG_ON(!stream);
+	kref_get(&stream->refcount);
+}
+
+static void vm_close_oa(struct vm_area_struct *vma)
+{
+	struct i915_perf_stream *stream = vma->vm_private_data;
+
+	GEM_BUG_ON(!stream);
+	kref_put(&stream->refcount, free_stream);
+}
+
+static vm_fault_t vm_fault_oa(struct vm_fault *vmf)
+{
+	struct vm_area_struct *vma = vmf->vma;
+	struct i915_perf_stream *stream = vma->vm_private_data;
+	struct drm_i915_gem_object *obj = stream->oa_buffer.vma->obj;
+	int err;
+
+	if (READ_ONCE(stream->closed))
+		return VM_FAULT_SIGBUS;
+
+	err = i915_gem_object_pin_pages(obj);
+	if (err)
+		goto out;
+
+	err = remap_io_sg(vma,
+			  vma->vm_start, vma->vm_end - vma->vm_start,
+			  obj->mm.pages->sgl, -1);
+
+	i915_gem_object_unpin_pages(obj);
+
+out:
+	return i915_error_to_vmf_fault(err);
+}
+
+static const struct vm_operations_struct vm_ops_oa = {
+	.open = vm_open_oa,
+	.close = vm_close_oa,
+	.fault = vm_fault_oa,
+};
+
+int i915_perf_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	struct i915_perf_stream *stream = file->private_data;
+
+	if (i915_perf_stream_paranoid && !perfmon_capable()) {
+		DRM_DEBUG("Insufficient privileges to map OA buffer\n");
+		return -EACCES;
+	}
+
+	switch (vma->vm_pgoff) {
+	case I915_PERF_OA_BUFFER_MMAP_OFFSET:
+		if (vma->vm_end - vma->vm_start > OA_BUFFER_SIZE)
+			return -EINVAL;
+
+		if (vma->vm_flags & VM_WRITE)
+			return -EINVAL;
+
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC | VM_MAYSHARE);
+	vma->vm_flags |= VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+	vma->vm_private_data = stream;
+	vma->vm_ops = &vm_ops_oa;
+	vm_open_oa(vma);
+
+	return 0;
+}
 
 static const struct file_operations fops = {
 	.owner		= THIS_MODULE,
@@ -3332,6 +3514,7 @@  static const struct file_operations fops = {
 	 * to handle 32bits compatibility.
 	 */
 	.compat_ioctl   = i915_perf_ioctl,
+	.mmap		= i915_perf_mmap,
 };
 
 
@@ -4260,6 +4443,7 @@  void i915_perf_init(struct drm_i915_private *i915)
 		perf->ops.oa_disable = gen7_oa_disable;
 		perf->ops.read = gen7_oa_read;
 		perf->ops.oa_hw_tail_read = gen7_oa_hw_tail_read;
+		perf->ops.oa_hw_head_read = gen7_oa_hw_head_read;
 
 		perf->oa_formats = hsw_oa_formats;
 	} else if (HAS_LOGICAL_RING_CONTEXTS(i915)) {
@@ -4291,6 +4475,7 @@  void i915_perf_init(struct drm_i915_private *i915)
 			perf->ops.enable_metric_set = gen8_enable_metric_set;
 			perf->ops.disable_metric_set = gen8_disable_metric_set;
 			perf->ops.oa_hw_tail_read = gen8_oa_hw_tail_read;
+			perf->ops.oa_hw_head_read = gen8_oa_hw_head_read;
 
 			if (IS_GEN(i915, 8)) {
 				perf->ctx_oactxctrl_offset = 0x120;
@@ -4318,6 +4503,7 @@  void i915_perf_init(struct drm_i915_private *i915)
 			perf->ops.enable_metric_set = gen8_enable_metric_set;
 			perf->ops.disable_metric_set = gen10_disable_metric_set;
 			perf->ops.oa_hw_tail_read = gen8_oa_hw_tail_read;
+			perf->ops.oa_hw_head_read = gen8_oa_hw_head_read;
 
 			if (IS_GEN(i915, 10)) {
 				perf->ctx_oactxctrl_offset = 0x128;
@@ -4342,6 +4528,7 @@  void i915_perf_init(struct drm_i915_private *i915)
 			perf->ops.enable_metric_set = gen12_enable_metric_set;
 			perf->ops.disable_metric_set = gen12_disable_metric_set;
 			perf->ops.oa_hw_tail_read = gen12_oa_hw_tail_read;
+			perf->ops.oa_hw_head_read = gen12_oa_hw_head_read;
 
 			perf->ctx_flexeu0_offset = 0;
 			perf->ctx_oactxctrl_offset = 0x144;
@@ -4453,8 +4640,11 @@  int i915_perf_ioctl_version(void)
 	 *
 	 * 7: Whitelist OA buffer head/tail registers for user to identify the
 	 *    location of triggered reports into the OA buffer.
+	 *
+	 * 8: Added an option to map oa buffer at umd driver level and trigger
+	 *    oa reports within oa buffer from command buffer.
 	 */
-	return 7;
+	return 8;
 }
 
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
diff --git a/drivers/gpu/drm/i915/i915_perf_types.h b/drivers/gpu/drm/i915/i915_perf_types.h
index a36a455ae336..2efbe35c5fa9 100644
--- a/drivers/gpu/drm/i915/i915_perf_types.h
+++ b/drivers/gpu/drm/i915/i915_perf_types.h
@@ -311,6 +311,18 @@  struct i915_perf_stream {
 	 * buffer should be checked for available data.
 	 */
 	u64 poll_oa_period;
+
+	/**
+	 * @closed: Open or closed state of the stream.
+	 * True if stream is closed.
+	 */
+	bool closed;
+
+	/**
+	 * @refcount: References to the mapped OA buffer managed by this
+	 * stream.
+	 */
+	struct kref refcount;
 };
 
 /**
@@ -377,6 +389,11 @@  struct i915_oa_ops {
 	 * generations.
 	 */
 	u32 (*oa_hw_tail_read)(struct i915_perf_stream *stream);
+
+	/**
+	 * @oa_hw_head_read: read the OA head pointer register
+	 */
+	u32 (*oa_hw_head_read)(struct i915_perf_stream *stream);
 };
 
 struct i915_perf {
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 00546062e023..2042f6339182 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -2048,6 +2048,38 @@  struct drm_i915_perf_open_param {
  */
 #define I915_PERF_IOCTL_CONFIG	_IO('i', 0x2)
 
+/**
+ * Returns OA buffer properties to be used with mmap.
+ *
+ * This ioctl is available in perf revision 8.
+ */
+#define I915_PERF_IOCTL_GET_OA_BUFFER_INFO _IO('i', 0x3)
+
+/**
+ * OA buffer size and offset.
+ */
+struct drm_i915_perf_oa_buffer_info {
+	__u32 size;
+	__u32 offset;
+	__u64 reserved[4];
+};
+
+/**
+ * Returns current position of OA buffer head and tail.
+ *
+ * This ioctl is available in perf revision 8.
+ */
+#define I915_PERF_IOCTL_GET_OA_BUFFER_HEAD_TAIL _IO('i', 0x4)
+
+/**
+ * OA buffer head and tail.
+ */
+struct drm_i915_perf_oa_buffer_head_tail {
+	__u32 head;
+	__u32 tail;
+	__u64 reserved[4];
+};
+
 /**
  * Common to all i915 perf records
  */