[Intel-gfx] [PATCH] tests/kms_flip: test a fb backed by a bo too big for its own good

[Ville Syrjälä]

On Fri, May 16, 2014 at 03:04:21PM +0300, Ville Syrjälä wrote:
> On Fri, May 16, 2014 at 12:08:51PM +0100, oscar.mateo at intel.com wrote:
> > From: Oscar Mateo <oscar.mateo at intel.com>
> > 
> > This is a "review by igt test" for a bug located in
> > i915_gem_object_pin_to_display_plane and fixed by:
> > 
> > commit 392013bdd4b6128795e33c84bd6d6d3fd66ff0a3
> > Author: Oscar Mateo <oscar.mateo at intel.com>
> > Date:   Fri May 16 11:23:12 2014 +0100
> > 
> >     drm/i915: Gracefully handle obj not bound to GGTT in is_pin_display
> > 
> >     Otherwise, we do a NULL pointer dereference.
> > 
> >     I've seen this happen while handling an error in
> >     i915_gem_object_pin_to_display_plane():
> > 
> >     If i915_gem_object_set_cache_level() fails, we call is_pin_display()
> >     to handle the error. At this point, the object is still not pinned
> >     to GGTT and maybe not even bound, so we have to check before we
> >     dereference its GGTT vma.
> > 
> >     v2: Chris Wilson says restoring the old value is easier, but that
> >     is_pin_display is useful as a theory of operation. Take the solomonic
> >     decision: at least this way is_pin_display is a little more robust
> >     (until Chris can kill it off).
> > 
> > Signed-off-by: Oscar Mateo <oscar.mateo at intel.com>
> > ---
> >  tests/kms_flip.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 97 insertions(+), 5 deletions(-)
> > 
> > diff --git a/tests/kms_flip.c b/tests/kms_flip.c
> > index bb4f71d..7296122 100644
> > --- a/tests/kms_flip.c
> > +++ b/tests/kms_flip.c
> > @@ -74,6 +74,7 @@
> >  #define TEST_RPM		(1 << 25)
> >  #define TEST_SUSPEND		(1 << 26)
> >  #define TEST_TS_CONT		(1 << 27)
> > +#define TEST_BO_TOOBIG		(1 << 28)
> >  
> >  #define EVENT_FLIP		(1 << 0)
> >  #define EVENT_VBLANK		(1 << 1)
> > @@ -1208,6 +1209,84 @@ static void free_test_output(struct test_output *o)
> >  	}
> >  }
> >  
> > +static int create_bigbo_for_fb(int fd, int width, int height, int bpp,
> > +				   bool tiled, uint32_t *gem_handle_ret,
> > +				   unsigned *size_ret, unsigned *stride_ret)
> > +{
> > +	uint32_t gem_handle;
> > +	int size, ret = 0;
> > +	unsigned stride;
> > +
> > +	if (tiled) {
> > +		int v;
> > +
> > +		v = width * bpp / 8;
> > +		for (stride = 512; stride < v; stride *= 2)
> > +			;
> > +
> > +		v = stride * height;
> > +		for (size = 1024*1024; size < v; size *= 2)
> > +			;
> > +	} else {
> > +		/* Scan-out has a 64 byte alignment restriction */
> > +		stride = (width * (bpp / 8) + 63) & ~63;
> > +		size = stride * height;
> > +	}
> > +
> > +	/* 256 MB is usually the maximum mappable aperture,
> > +	 * (make it 4x times that to ensure failure) */
> > +	gem_handle = gem_create(fd, 4*256*1024*1024);
> > +
> > +	if (tiled)
> > +		ret = __gem_set_tiling(fd, gem_handle, I915_TILING_X, stride);
> > +
> > +	*stride_ret = stride;
> > +	*size_ret = size;
> > +	*gem_handle_ret = gem_handle;
> > +
> > +	return ret;
> > +}
> > +
> > +static unsigned int igt_create_fb_with_bigbo(int fd, int width, int height,
> > +					     uint32_t format, bool tiled,
> > +					     struct igt_fb *fb)
> > +{
> > +	uint32_t handles[4];
> > +	uint32_t pitches[4];
> > +	uint32_t offsets[4];
> > +	uint32_t fb_id;
> > +	int bpp;
> > +	int ret;
> > +
> > +	memset(fb, 0, sizeof(*fb));
> > +
> > +	bpp = igt_drm_format_to_bpp(format);
> > +	ret = create_bigbo_for_fb(fd, width, height, bpp, tiled,
> > +			&fb->gem_handle, &fb->size, &fb->stride);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	memset(handles, 0, sizeof(handles));
> > +	handles[0] = fb->gem_handle;
> > +	memset(pitches, 0, sizeof(pitches));
> > +	pitches[0] = fb->stride;
> > +	memset(offsets, 0, sizeof(offsets));
> > +	if (drmModeAddFB2(fd, width, height, format, handles, pitches,
> > +			  offsets, &fb_id, 0) < 0) {
> > +		gem_close(fd, fb->gem_handle);
> > +
> > +		return 0;
> > +	}
> > +
> > +	fb->width = width;
> > +	fb->height = height;
> > +	fb->tiling = tiled;
> > +	fb->drm_format = format;
> > +	fb->fb_id = fb_id;
> > +
> > +	return fb_id;
> > +}
> 
> Could we avoid a bit of code duplication with something like this?
> 
> create_bo_for_fb(..., bo_size)
> {
> 	...
> 	if (bo_size == 0)
> 		bo_size = size;
> 	gem_handle = gem_create(fd, bo_size);
> 	...
> }
> igt_create_fb_with_bo_size(xxx, bo_size)
> {
> 	...
> 	create_bo_for_fb(..., bo_size);
> 	...
> }
> igt_create_fb(xxx)
> {
> 	return igt_create_fb_with_bo_size(xxx, 0);
> }

Oh and that gives me an idea for another test: try to create fb with
bo_size < size and check that we get back some kind of error. Assuming
we don't have such a test already.

-- 
Ville Syrjälä
Intel OTC