[Intel-gfx] [PATCH] drm/i915: Apply LUT validation checks to platforms more accurately (v2)

[Matt Roper]

Use of the new DRM_COLOR_LUT_NON_DECREASING test was a bit over-zealous;
it doesn't actually need to be applied to the degamma on "bdw-style"
platforms.  Likewise, we overlooked the fact that CHV should have that
test applied to the gamma LUT as well as the degamma LUT.

Rather than adding more complicated platform checking to
intel_color_check(), let's just store the appropriate set of LUT
validation flags for each platform in the intel_device_info structure.

v2:
 - Shuffle around LUT size tests so that the hardware-specific tests
   won't be applied to legacy gamma tables.  (Ville)
 - Add a debug message so that it will be easier to understand why an
   atomic transaction involving incorrectly-sized LUT's got rejected
   by the driver.

Fixes: 85e2d61e4976 ("drm/i915: Validate userspace-provided color management LUT's (v4)")
References: https://lists.freedesktop.org/archives/intel-gfx/2019-January/187634.html
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/i915_pci.c          | 10 ++++--
 drivers/gpu/drm/i915/intel_color.c       | 58 ++++++++++++++++----------------
 drivers/gpu/drm/i915/intel_device_info.h |  2 ++
 3 files changed, 39 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index 44c23ac60347..17f5a605b0b3 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -69,9 +69,15 @@
 #define BDW_COLORS \
 	.color = { .degamma_lut_size = 512, .gamma_lut_size = 512 }
 #define CHV_COLORS \
-	.color = { .degamma_lut_size = 65, .gamma_lut_size = 257 }
+	.color = { .degamma_lut_size = 65, .gamma_lut_size = 257, \
+		   .degamma_lut_tests = DRM_COLOR_LUT_NON_DECREASING, \
+		   .gamma_lut_tests = DRM_COLOR_LUT_NON_DECREASING, \
+	}
 #define GLK_COLORS \
-	.color = { .degamma_lut_size = 0, .gamma_lut_size = 1024 }
+	.color = { .degamma_lut_size = 0, .gamma_lut_size = 1024, \
+		   .degamma_lut_tests = DRM_COLOR_LUT_NON_DECREASING | \
+					DRM_COLOR_LUT_EQUAL_CHANNELS, \
+	}
 
 /* Keep in gen based order, and chronological order within a gen */
 
diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
index bc7589656a8f..59b8a644b218 100644
--- a/drivers/gpu/drm/i915/intel_color.c
+++ b/drivers/gpu/drm/i915/intel_color.c
@@ -605,48 +605,48 @@ void intel_color_load_luts(struct intel_crtc_state *crtc_state)
 	dev_priv->display.load_luts(crtc_state);
 }
 
+static int check_lut_size(const struct drm_property_blob *lut, size_t expected)
+{
+	size_t len;
+
+	if (!lut)
+		return 0;
+
+	len = drm_color_lut_size(lut);
+	if (len != expected) {
+		DRM_DEBUG_KMS("Invalid LUT size; got %lu, expected %lu\n",
+			      len, expected);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 int intel_color_check(struct intel_crtc_state *crtc_state)
 {
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
 	size_t gamma_length, degamma_length;
-	uint32_t tests = DRM_COLOR_LUT_NON_DECREASING;
+	u32 gamma_tests, degamma_tests;
 
 	degamma_length = INTEL_INFO(dev_priv)->color.degamma_lut_size;
 	gamma_length = INTEL_INFO(dev_priv)->color.gamma_lut_size;
+	degamma_tests = INTEL_INFO(dev_priv)->color.degamma_lut_tests;
+	gamma_tests = INTEL_INFO(dev_priv)->color.gamma_lut_tests;
 
-	/*
-	 * All of our platforms mandate that the degamma curve be
-	 * non-decreasing.  Additionally, GLK and gen11 only accept a single
-	 * value for red, green, and blue in the degamma table.  Make sure
-	 * userspace didn't try to pass us something we can't handle.
-	 *
-	 * We don't have any extra hardware constraints on the gamma table,
-	 * so no need to explicitly check it.
-	 */
-	if (IS_GEMINILAKE(dev_priv) || INTEL_GEN(dev_priv) >= 10)
-		tests |= DRM_COLOR_LUT_EQUAL_CHANNELS;
+	/* Always allow legacy gamma LUT with no further checking. */
+	if (crtc_state_is_legacy_gamma(crtc_state))
+		return 0;
 
-	if (drm_color_lut_check(crtc_state->base.degamma_lut, tests) != 0)
+	if (check_lut_size(crtc_state->base.degamma_lut, degamma_length) ||
+	    check_lut_size(crtc_state->base.gamma_lut, gamma_length))
 		return -EINVAL;
 
-	/*
-	 * We allow both degamma & gamma luts at the right size or
-	 * NULL.
-	 */
-	if ((!crtc_state->base.degamma_lut ||
-	     drm_color_lut_size(crtc_state->base.degamma_lut) == degamma_length) &&
-	    (!crtc_state->base.gamma_lut ||
-	     drm_color_lut_size(crtc_state->base.gamma_lut) == gamma_length))
-		return 0;
+	if (drm_color_lut_check(crtc_state->base.degamma_lut, degamma_tests) ||
+	    drm_color_lut_check(crtc_state->base.gamma_lut, gamma_tests))
+		return -EINVAL;
 
-	/*
-	 * We also allow no degamma lut/ctm and a gamma lut at the legacy
-	 * size (256 entries).
-	 */
-	if (crtc_state_is_legacy_gamma(crtc_state))
-		return 0;
 
-	return -EINVAL;
+	return 0;
 }
 
 void intel_color_init(struct intel_crtc *crtc)
diff --git a/drivers/gpu/drm/i915/intel_device_info.h b/drivers/gpu/drm/i915/intel_device_info.h
index 957c6527f76b..7bf09cef591a 100644
--- a/drivers/gpu/drm/i915/intel_device_info.h
+++ b/drivers/gpu/drm/i915/intel_device_info.h
@@ -189,6 +189,8 @@ struct intel_device_info {
 	struct color_luts {
 		u16 degamma_lut_size;
 		u16 gamma_lut_size;
+		u32 degamma_lut_tests;
+		u32 gamma_lut_tests;
 	} color;
 };
 
-- 
2.14.5