Re: [PATCH 1/3] drm/xe/oa: Use xe_map layer

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Fri, 24 Apr 2026 16:56:04 -0700, Dixit, Ashutosh wrote:
>
> On Fri, 24 Apr 2026 14:05:16 -0700, Umesh Nerlige Ramappa wrote:
> >
>
> Hi Umesh,
>
> > On Tue, Apr 14, 2026 at 07:03:40PM -0700, Ashutosh Dixit wrote:
> > > OA code should have used xe_map layer to begin with. In CRI, the OA buffer
> > > can be located both in system and device memory. For these reasons, move OA
> > > code to use the xe_map layer when accessing the OA buffer.
> > >
> > > v2: Use xe_map layer and put_user in xe_oa_copy_to_user (Umesh)
> > > v3: To avoid performance impact in v2, revert to v1 but move
> > >    xe_map_copy_to_user() to xe_map.h
> > > v4: Use bounce buffer and copy_to_user in xe_oa_copy_to_user
> > >
> > > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> > > ---
> > > drivers/gpu/drm/xe/xe_oa.c       | 95 +++++++++++++++++++-------------
> > > drivers/gpu/drm/xe/xe_oa_types.h |  4 +-
> > > 2 files changed, 58 insertions(+), 41 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
> > > index 6337e671c97ae..4d13d8ef8103f 100644
> > > --- a/drivers/gpu/drm/xe/xe_oa.c
> > > +++ b/drivers/gpu/drm/xe/xe_oa.c
> > > @@ -213,32 +213,40 @@ static u32 xe_oa_hw_tail_read(struct xe_oa_stream *stream)
> > > #define oa_report_header_64bit(__s) \
> > >	((__s)->oa_buffer.format->header == HDR_64_BIT)
> > >
> > > -static u64 oa_report_id(struct xe_oa_stream *stream, void *report)
> > > +static u64 oa_report_id(struct xe_oa_stream *stream, u32 tail)
> > > {
> > > -	return oa_report_header_64bit(stream) ? *(u64 *)report : *(u32 *)report;
> > > +	struct iosys_map *map = &stream->oa_buffer.bo->vmap;
> > > +
> > > +	return oa_report_header_64bit(stream) ?
> > > +		xe_map_rd(stream->oa->xe, map, tail, u64) :
> > > +		xe_map_rd(stream->oa->xe, map, tail, u32);
> > > }
> >
> > (1) The helper is just returning the report id for a report passed. In this
> > case it is tail, but the code would work for any report. I would keep the
> > name as report or report_offset. Let the caller use specific names like
> > tail.
> >
> > >
> > > -static void oa_report_id_clear(struct xe_oa_stream *stream, u32 *report)
> > > +static void oa_report_id_clear(struct xe_oa_stream *stream, u32 head)
> > > {
> > > -	if (oa_report_header_64bit(stream))
> > > -		*(u64 *)report = 0;
> > > -	else
> > > -		*report = 0;
> > > +	struct iosys_map *map = &stream->oa_buffer.bo->vmap;
> > > +
> > > +	oa_report_header_64bit(stream) ?
> > > +		xe_map_wr(stream->oa->xe, map, head, u64, 0) :
> > > +		xe_map_wr(stream->oa->xe, map, head, u32, 0);
> > > }
> > >
> > > -static u64 oa_timestamp(struct xe_oa_stream *stream, void *report)
> > > +static u64 oa_timestamp(struct xe_oa_stream *stream, u32 tail)
> > > {
> > > +	struct iosys_map *map = &stream->oa_buffer.bo->vmap;
> > > +
> > >	return oa_report_header_64bit(stream) ?
> > > -		*((u64 *)report + 1) :
> > > -		*((u32 *)report + 1);
> > > +		xe_map_rd(stream->oa->xe, map, tail + 2, u64) :
> > > +		xe_map_rd(stream->oa->xe, map, tail + 1, u32);
> >
> > (2) I think this should be tail + 8 and tail + 4. Can you please double
> > check? The u32/u64 is only being used to access the data at the offset
> > rather than determine how to calculate the actual offset.
>
> Hmm, you are right!!! I don't believe I made such a basic mistake :/ And
> all the xe_oa tests work fine even with this.
>
> Anyway thanks for catching this, I'm fixing this in the next rev.
>
> >
> > > }
> > >
> > > -static void oa_timestamp_clear(struct xe_oa_stream *stream, u32 *report)
> > > +static void oa_timestamp_clear(struct xe_oa_stream *stream, u32 head)
> > > {
> > > -	if (oa_report_header_64bit(stream))
> > > -		*(u64 *)&report[2] = 0;
> > > -	else
> > > -		report[1] = 0;
> > > +	struct iosys_map *map = &stream->oa_buffer.bo->vmap;
> > > +
> > > +	oa_report_header_64bit(stream) ?
> > > +		xe_map_wr(stream->oa->xe, map, head + 2, u64, 0) :
> > > +		xe_map_wr(stream->oa->xe, map, head + 1, u32, 0);
> >
> > Same here - comment (2)
> >
> > > }
> >
> > Same comment (1) for all the above helpers - the name can be generic -
> > report_offset. I see similar change in other functions below as well. If
> > you think it is necessary, I suggest trying to move it to a separate patch
> > with commit message explaining why you want to rename them. That would also
> > help review this patch easily.
>
> So, as we know HW writes to tail and SW reads from head. So the helpers
> with head as the arg are invoked from the read side only and the helpers
> with tail as the arg are invoked from the write side only. That was the
> reason for naming the arg as head/tail, rather than just "offset". I
> thought it will make the code easier to understand and also maybe prevent
> mistakes in the future.
>
> So anyway, let me ask once again if you think I should change it. Of
> course, there's no problem changing the arg name in the helpers.
>
> I'll also see if it's possible to split the patch some way to make the
> review a bit easier.

I just sent out v5 in which I have let all this stay as is. Anyway, please
let me know what you prefer. Thanks.

>
> Thanks.
> --
> Ashutosh
>
>
> >
> > >
> > > static bool xe_oa_buffer_check_unlocked(struct xe_oa_stream *stream)
> > > @@ -275,9 +283,7 @@ static bool xe_oa_buffer_check_unlocked(struct xe_oa_stream *stream)
> > >	 * they were written.  If not : (╯°□°）╯︵ ┻━┻
> > >	 */
> > >	while (xe_oa_circ_diff(stream, tail, stream->oa_buffer.tail) >= report_size) {
> > > -		void *report = stream->oa_buffer.vaddr + tail;
> > > -
> > > -		if (oa_report_id(stream, report) || oa_timestamp(stream, report))
> > > +		if (oa_report_id(stream, tail) || oa_timestamp(stream, tail))
> > >			break;
> > >
> > >		tail = xe_oa_circ_diff(stream, tail, report_size);
> > > @@ -311,30 +317,35 @@ static enum hrtimer_restart xe_oa_poll_check_timer_cb(struct hrtimer *hrtimer)
> > >	return HRTIMER_RESTART;
> > > }
> > >
> > > +static unsigned long
> > > +xe_oa_copy_to_user(struct xe_oa_stream *stream, void __user *dst, u32 head, u32 len)
> > > +{
> > > +	xe_map_memcpy_from(stream->oa->xe, stream->oa_buffer.bounce,
> > > +			   &stream->oa_buffer.bo->vmap, head, len);
> > > +	return copy_to_user(dst, stream->oa_buffer.bounce, len);
> > > +}
> > > +
> >
> > Still need to look at the patch below this point. Will send that out next
> > week...
> >
> > Regards,
> > Umesh
> >
> > > static int xe_oa_append_report(struct xe_oa_stream *stream, char __user *buf,
> > > -			       size_t count, size_t *offset, const u8 *report)
> > > +			       size_t count, size_t *offset, u32 head)
> > > {
> > >	int report_size = stream->oa_buffer.format->size;
> > >	int report_size_partial;
> > > -	u8 *oa_buf_end;
> > >
> > >	if ((count - *offset) < report_size)
> > >		return -ENOSPC;
> > >
> > >	buf += *offset;
> > >
> > > -	oa_buf_end = stream->oa_buffer.vaddr + stream->oa_buffer.circ_size;
> > > -	report_size_partial = oa_buf_end - report;
> > > +	report_size_partial = stream->oa_buffer.circ_size - head;
> > >
> > >	if (report_size_partial < report_size) {
> > > -		if (copy_to_user(buf, report, report_size_partial))
> > > +		if (xe_oa_copy_to_user(stream, buf, head, report_size_partial))
> > >			return -EFAULT;
> > >		buf += report_size_partial;
> > >
> > > -		if (copy_to_user(buf, stream->oa_buffer.vaddr,
> > > -				 report_size - report_size_partial))
> > > +		if (xe_oa_copy_to_user(stream, buf, 0, report_size - report_size_partial))
> > >			return -EFAULT;
> > > -	} else if (copy_to_user(buf, report, report_size)) {
> > > +	} else if (xe_oa_copy_to_user(stream, buf, head, report_size)) {
> > >		return -EFAULT;
> > >	}
> > >
> > > @@ -347,7 +358,6 @@ static int xe_oa_append_reports(struct xe_oa_stream *stream, char __user *buf,
> > >				size_t count, size_t *offset)
> > > {
> > >	int report_size = stream->oa_buffer.format->size;
> > > -	u8 *oa_buf_base = stream->oa_buffer.vaddr;
> > >	u32 gtt_offset = xe_bo_ggtt_addr(stream->oa_buffer.bo);
> > >	size_t start_offset = *offset;
> > >	unsigned long flags;
> > > @@ -364,26 +374,24 @@ static int xe_oa_append_reports(struct xe_oa_stream *stream, char __user *buf,
> > >
> > >	for (; xe_oa_circ_diff(stream, tail, head);
> > >	     head = xe_oa_circ_incr(stream, head, report_size)) {
> > > -		u8 *report = oa_buf_base + head;
> > > -
> > > -		ret = xe_oa_append_report(stream, buf, count, offset, report);
> > > +		ret = xe_oa_append_report(stream, buf, count, offset, head);
> > >		if (ret)
> > >			break;
> > >
> > >		if (!(stream->oa_buffer.circ_size % report_size)) {
> > >			/* Clear out report id and timestamp to detect unlanded reports */
> > > -			oa_report_id_clear(stream, (void *)report);
> > > -			oa_timestamp_clear(stream, (void *)report);
> > > +			oa_report_id_clear(stream, head);
> > > +			oa_timestamp_clear(stream, head);
> > >		} else {
> > > -			u8 *oa_buf_end = stream->oa_buffer.vaddr + stream->oa_buffer.circ_size;
> > > -			u32 part = oa_buf_end - report;
> > > +			struct iosys_map *map = &stream->oa_buffer.bo->vmap;
> > > +			u32 part = stream->oa_buffer.circ_size - head;
> > >
> > >			/* Zero out the entire report */
> > >			if (report_size <= part) {
> > > -				memset(report, 0, report_size);
> > > +				xe_map_memset(stream->oa->xe, map, head, 0, report_size);
> > >			} else {
> > > -				memset(report, 0, part);
> > > -				memset(oa_buf_base, 0, report_size - part);
> > > +				xe_map_memset(stream->oa->xe, map, head, 0, part);
> > > +				xe_map_memset(stream->oa->xe, map, 0, 0, report_size - part);
> > >			}
> > >		}
> > >	}
> > > @@ -436,7 +444,8 @@ static void xe_oa_init_oa_buffer(struct xe_oa_stream *stream)
> > >	spin_unlock_irqrestore(&stream->oa_buffer.ptr_lock, flags);
> > >
> > >	/* Zero out the OA buffer since we rely on zero report id and timestamp fields */
> > > -	memset(stream->oa_buffer.vaddr, 0, xe_bo_size(stream->oa_buffer.bo));
> > > +	xe_map_memset(stream->oa->xe, &stream->oa_buffer.bo->vmap, 0, 0,
> > > +		      xe_bo_size(stream->oa_buffer.bo));
> > > }
> > >
> > > static u32 __format_to_oactrl(const struct xe_oa_format *format, int counter_sel_mask)
> > > @@ -699,6 +708,7 @@ static int num_lri_dwords(int num_regs)
> > > static void xe_oa_free_oa_buffer(struct xe_oa_stream *stream)
> > > {
> > >	xe_bo_unpin_map_no_vm(stream->oa_buffer.bo);
> > > +	kfree(stream->oa_buffer.bounce);
> > > }
> > >
> > > static void xe_oa_free_configs(struct xe_oa_stream *stream)
> > > @@ -889,9 +899,16 @@ static int xe_oa_alloc_oa_buffer(struct xe_oa_stream *stream, size_t size)
> > >		return PTR_ERR(bo);
> > >
> > >	stream->oa_buffer.bo = bo;
> > > +
> > >	/* mmap implementation requires OA buffer to be in system memory */
> > >	xe_assert(stream->oa->xe, bo->vmap.is_iomem == 0);
> > > -	stream->oa_buffer.vaddr = bo->vmap.vaddr;
> > > +
> > > +	stream->oa_buffer.bounce = kmalloc(stream->oa_buffer.format->size, GFP_KERNEL);
> > > +	if (!stream->oa_buffer.bounce) {
> > > +		xe_bo_unpin_map_no_vm(stream->oa_buffer.bo);
> > > +		return -ENOMEM;
> > > +	}
> > > +
> > >	return 0;
> > > }
> > >
> > > diff --git a/drivers/gpu/drm/xe/xe_oa_types.h b/drivers/gpu/drm/xe/xe_oa_types.h
> > > index b03ffd5134834..99a04b8d586b5 100644
> > > --- a/drivers/gpu/drm/xe/xe_oa_types.h
> > > +++ b/drivers/gpu/drm/xe/xe_oa_types.h
> > > @@ -162,8 +162,8 @@ struct xe_oa_buffer {
> > >	/** @format: xe_bo backing the OA buffer */
> > >	struct xe_bo *bo;
> > >
> > > -	/** @vaddr: mapped vaddr of the OA buffer */
> > > -	u8 *vaddr;
> > > +	/** @bounce: bounce buffer used with xe_map layer */
> > > +	void *bounce;
> > >
> > >	/** @ptr_lock: Lock protecting reads/writes to head/tail pointers */
> > >	spinlock_t ptr_lock;
> > > --
> > > 2.48.1
> > >