drm/i915/sseu: Disassociate internal subslice mask representation from uapi

As with EU masks, it's easier to store subslice/DSS masks internally in
a format that's more natural for the driver to work with, and then only
covert into the u8[] uapi form when the query ioctl is invoked.  Since
the hardware design changed significantly with Xe_HP, we'll use a union
to choose between the old "hsw-style" subslice masks or the newer xehp
mask.  HSW-style masks will be stored in an array of u8's, indexed by
slice (there's never more than 6 subslices per slice on older
platforms).  For Xe_HP and beyond where slices no longer exist, we only
need a single bitmask.  However we already know that this mask is
eventually going to grow too large for a simple u64 to hold, so we'll
represent it in a manner that can be operated on by the utilities in
linux/bitmap.h.

v2:
 - Fix typo: BIT(s) -> BIT(ss) in gen9_sseu_device_status()

v3:
 - Eliminate sseu->ss_stride and just calculate the stride while
   specifically handling uapi.  (Tvrtko)
 - Use BITMAP_BITS() macro to refer to size of masks rather than
   passing I915_MAX_SS_FUSE_BITS directly.  (Tvrtko)
 - Report compute/geometry DSS masks separately when dumping Xe_HP SSEU
   info.  (Tvrtko)
 - Restore dropped range checks to intel_sseu_has_subslice().  (Tvrtko)

v4:
 - Make the bitmap size macro check the size of the .xehp field rather
   than the containing union.  (Tvrtko)
 - Don't add GEM_BUG_ON() intel_sseu_has_subslice()'s check for whether
   slice or subslice ID exceed sseu->max_[sub]slices; various loops
   in the driver are expected to exceed these, so we should just
   silently return 'false.'

v5:
 - Move XEHP_BITMAP_BITS() to the header so that we can also replace a
   usage of I915_MAX_SS_FUSE_BITS in one of the inline functions.
   (Bala)
 - Change the local variable in intel_slicemask_from_xehp_dssmask() from
   u16 to 'unsigned long' to make it a bit more future-proof.

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220601150725.521468-6-matthew.d.roper@intel.com

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_getparam.c b/drivers/gpu/drm/i915/i915_getparam.c
index ac9767c56619..6fd15b39570c 100644
--- a/drivers/gpu/drm/i915/i915_getparam.c
+++ b/drivers/gpu/drm/i915/i915_getparam.c
@@ -162,8 +162,7 @@ int i915_getparam_ioctl(struct drm_device *dev, void *data,
 			return -EINVAL;
 
 		/* Only copy bits from the first slice */
-		memcpy(&value, sseu->subslice_mask,
-		       min(sseu->ss_stride, (u8)sizeof(value)));
+		value = intel_sseu_get_hsw_subslices(sseu, 0);
 		if (!value)
 			return -ENODEV;
 		break;