Re: [Intel-gfx] [PATCH v2] drm/i915/perf: Do not parse context image for HSW

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

On Tue, 22 Nov 2022 18:07:00 -0800, Umesh Nerlige Ramappa wrote:
>

Hi Umesh,

> An earlier commit introduced a mechanism to parse the context image to
> find the OA context control offset. This resulted in an NPD on haswell
> when gem_context was passed into i915_perf_open_ioctl params. Haswell
> does not support logical ring contexts, so ensure that the context image
> is parsed only for platforms with logical ring contexts and also
> validate lrc_reg_state.
>
> v2: Fix build failure
>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/7432
> Fixes: a5c3a3cbf029 ("drm/i915/perf: Determine gen12 oa ctx offset at runtime")
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_perf.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c
> index 00e09bb18b13..dbd785974f20 100644
> --- a/drivers/gpu/drm/i915/i915_perf.c
> +++ b/drivers/gpu/drm/i915/i915_perf.c
> @@ -1383,6 +1383,9 @@ static u32 oa_context_image_offset(struct intel_context *ce, u32 reg)
>	u32 offset, len = (ce->engine->context_size - PAGE_SIZE) / 4;
>	u32 *state = ce->lrc_reg_state;
>
> +	if (drm_WARN_ON(&ce->engine->i915->drm, state == NULL))
> +		return U32_MAX;
> +

So if we didn't add the HAS_LOGICAL_RING_CONTEXTS check below state would
be NULL correct? I couldn't figure out how it is NULL on HSW looking at the
code (with the context image pin/unpin).

>	for (offset = 0; offset < len; ) {
>		if (IS_MI_LRI_CMD(state[offset])) {
>			/*
> @@ -1447,7 +1450,8 @@ static int oa_get_render_ctx_id(struct i915_perf_stream *stream)
>	if (IS_ERR(ce))
>		return PTR_ERR(ce);
>
> -	if (engine_supports_mi_query(stream->engine)) {
> +	if (engine_supports_mi_query(stream->engine) &&
> +	    HAS_LOGICAL_RING_CONTEXTS(stream->perf->i915)) {

This check looks fine since we seem to be looking inside ce->lrc_reg_state
for oactxctrl.

Overall looks fine so this is:

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>


>		/*
>		 * We are enabling perf query here. If we don't find the context
>		 * offset here, just return an error.
> --
> 2.36.1
>