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

Matt Roper
2019-01-30T00:49:46Z

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@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@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