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drm/i915/sseu: Don't try to store EU mask internally in UAPI format
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Storing the EU mask internally in the same format the I915_QUERY
topology queries use makes the final copy_to_user() a bit simpler, but
makes the rest of the driver's SSEU more complicated and harder to
follow.  Let's switch to an internal representation that's more natural:
Xe_HP platforms will be a simple array of u16 masks, whereas pre-Xe_HP
platforms will be a two-dimensional array, indexed by [slice][subslice].
We'll convert to the uapi format only when the query uapi is called.

v2:
 - Drop has_common_ss_eumask.  We waste some space repeating identical
   EU masks for every single DSS, but the code is simpler without it.
   (Tvrtko)

v3:
 - Mask down EUs passed to sseu_set_eus at the callsite rather than
   inside the function.  (Tvrtko)
 - Eliminate sseu->eu_stride and calculate it when needed.  (Tvrtko)

Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.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/20220601150725.521468-5-matthew.d.roper@intel.com
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@mattrope
mattrope committed Jun 2, 2022
1 parent 4cfd166 commit bc3c5e0
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Showing 3 changed files with 73 additions and 38 deletions.
88 changes: 58 additions & 30 deletions drivers/gpu/drm/i915/gt/intel_sseu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,8 +19,6 @@ void intel_sseu_set_info(struct sseu_dev_info *sseu, u8 max_slices,

sseu->ss_stride = GEN_SSEU_STRIDE(sseu->max_subslices);
GEM_BUG_ON(sseu->ss_stride > GEN_MAX_SUBSLICE_STRIDE);
sseu->eu_stride = GEN_SSEU_STRIDE(sseu->max_eus_per_subslice);
GEM_BUG_ON(sseu->eu_stride > GEN_MAX_EU_STRIDE);
}

unsigned int
Expand Down Expand Up @@ -78,47 +76,77 @@ intel_sseu_subslices_per_slice(const struct sseu_dev_info *sseu, u8 slice)
return hweight32(intel_sseu_get_subslices(sseu, slice));
}

static int sseu_eu_idx(const struct sseu_dev_info *sseu, int slice,
int subslice)
{
int slice_stride = sseu->max_subslices * sseu->eu_stride;

return slice * slice_stride + subslice * sseu->eu_stride;
}

static u16 sseu_get_eus(const struct sseu_dev_info *sseu, int slice,
int subslice)
{
int i, offset = sseu_eu_idx(sseu, slice, subslice);
u16 eu_mask = 0;

for (i = 0; i < sseu->eu_stride; i++)
eu_mask |=
((u16)sseu->eu_mask[offset + i]) << (i * BITS_PER_BYTE);

return eu_mask;
if (sseu->has_xehp_dss) {
WARN_ON(slice > 0);
return sseu->eu_mask.xehp[subslice];
} else {
return sseu->eu_mask.hsw[slice][subslice];
}
}

static void sseu_set_eus(struct sseu_dev_info *sseu, int slice, int subslice,
u16 eu_mask)
{
int i, offset = sseu_eu_idx(sseu, slice, subslice);

for (i = 0; i < sseu->eu_stride; i++)
sseu->eu_mask[offset + i] =
(eu_mask >> (BITS_PER_BYTE * i)) & 0xff;
GEM_WARN_ON(eu_mask && __fls(eu_mask) >= sseu->max_eus_per_subslice);
if (sseu->has_xehp_dss) {
GEM_WARN_ON(slice > 0);
sseu->eu_mask.xehp[subslice] = eu_mask;
} else {
sseu->eu_mask.hsw[slice][subslice] = eu_mask;
}
}

static u16 compute_eu_total(const struct sseu_dev_info *sseu)
{
u16 i, total = 0;
int s, ss, total = 0;

for (i = 0; i < ARRAY_SIZE(sseu->eu_mask); i++)
total += hweight8(sseu->eu_mask[i]);
for (s = 0; s < sseu->max_slices; s++)
for (ss = 0; ss < sseu->max_subslices; ss++)
if (sseu->has_xehp_dss)
total += hweight16(sseu->eu_mask.xehp[ss]);
else
total += hweight16(sseu->eu_mask.hsw[s][ss]);

return total;
}

/**
* intel_sseu_copy_eumask_to_user - Copy EU mask into a userspace buffer
* @to: Pointer to userspace buffer to copy to
* @sseu: SSEU structure containing EU mask to copy
*
* Copies the EU mask to a userspace buffer in the format expected by
* the query ioctl's topology queries.
*
* Returns the result of the copy_to_user() operation.
*/
int intel_sseu_copy_eumask_to_user(void __user *to,
const struct sseu_dev_info *sseu)
{
u8 eu_mask[GEN_SS_MASK_SIZE * GEN_MAX_EU_STRIDE] = {};
int eu_stride = GEN_SSEU_STRIDE(sseu->max_eus_per_subslice);
int len = sseu->max_slices * sseu->max_subslices * eu_stride;
int s, ss, i;

for (s = 0; s < sseu->max_slices; s++) {
for (ss = 0; ss < sseu->max_subslices; ss++) {
int uapi_offset =
s * sseu->max_subslices * eu_stride +
ss * eu_stride;
u16 mask = sseu_get_eus(sseu, s, ss);

for (i = 0; i < eu_stride; i++)
eu_mask[uapi_offset + i] =
(mask >> (BITS_PER_BYTE * i)) & 0xff;
}
}

return copy_to_user(to, eu_mask, len);
}

static void gen11_compute_sseu_info(struct sseu_dev_info *sseu,
u32 g_ss_en, u32 c_ss_en, u16 eu_en)
{
Expand Down Expand Up @@ -278,7 +306,7 @@ static void cherryview_sseu_info_init(struct intel_gt *gt)
CHV_FGT_EU_DIS_SS0_R1_SHIFT) << 4);

subslice_mask |= BIT(0);
sseu_set_eus(sseu, 0, 0, ~disabled_mask);
sseu_set_eus(sseu, 0, 0, ~disabled_mask & 0xFF);
}

if (!(fuse & CHV_FGT_DISABLE_SS1)) {
Expand All @@ -289,7 +317,7 @@ static void cherryview_sseu_info_init(struct intel_gt *gt)
CHV_FGT_EU_DIS_SS1_R1_SHIFT) << 4);

subslice_mask |= BIT(1);
sseu_set_eus(sseu, 0, 1, ~disabled_mask);
sseu_set_eus(sseu, 0, 1, ~disabled_mask & 0xFF);
}

intel_sseu_set_subslices(sseu, 0, sseu->subslice_mask, subslice_mask);
Expand Down Expand Up @@ -362,7 +390,7 @@ static void gen9_sseu_info_init(struct intel_gt *gt)

eu_disabled_mask = (eu_disable >> (ss * 8)) & eu_mask;

sseu_set_eus(sseu, s, ss, ~eu_disabled_mask);
sseu_set_eus(sseu, s, ss, ~eu_disabled_mask & eu_mask);

eu_per_ss = sseu->max_eus_per_subslice -
hweight8(eu_disabled_mask);
Expand Down Expand Up @@ -475,7 +503,7 @@ static void bdw_sseu_info_init(struct intel_gt *gt)
eu_disabled_mask =
eu_disable[s] >> (ss * sseu->max_eus_per_subslice);

sseu_set_eus(sseu, s, ss, ~eu_disabled_mask);
sseu_set_eus(sseu, s, ss, ~eu_disabled_mask & 0xFF);

n_disabled = hweight8(eu_disabled_mask);

Expand Down
10 changes: 8 additions & 2 deletions drivers/gpu/drm/i915/gt/intel_sseu.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,11 @@ struct sseu_dev_info {
u8 subslice_mask[GEN_SS_MASK_SIZE];
u8 geometry_subslice_mask[GEN_SS_MASK_SIZE];
u8 compute_subslice_mask[GEN_SS_MASK_SIZE];
u8 eu_mask[GEN_SS_MASK_SIZE * GEN_MAX_EU_STRIDE];
union {
u16 hsw[GEN_MAX_HSW_SLICES][GEN_MAX_SS_PER_HSW_SLICE];
u16 xehp[GEN_MAX_DSS];
} eu_mask;

u16 eu_total;
u8 eu_per_subslice;
u8 min_eu_in_pool;
Expand All @@ -78,7 +82,6 @@ struct sseu_dev_info {
u8 max_eus_per_subslice;

u8 ss_stride;
u8 eu_stride;
};

/*
Expand Down Expand Up @@ -150,4 +153,7 @@ void intel_sseu_print_topology(struct drm_i915_private *i915,

u16 intel_slicemask_from_dssmask(u64 dss_mask, int dss_per_slice);

int intel_sseu_copy_eumask_to_user(void __user *to,
const struct sseu_dev_info *sseu);

#endif /* __INTEL_SSEU_H__ */
13 changes: 7 additions & 6 deletions drivers/gpu/drm/i915/i915_query.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ static int fill_topology_info(const struct sseu_dev_info *sseu,
{
struct drm_i915_query_topology_info topo;
u32 slice_length, subslice_length, eu_length, total_length;
int eu_stride = GEN_SSEU_STRIDE(sseu->max_eus_per_subslice);
int ret;

BUILD_BUG_ON(sizeof(u8) != sizeof(sseu->slice_mask));
Expand All @@ -44,7 +45,7 @@ static int fill_topology_info(const struct sseu_dev_info *sseu,

slice_length = sizeof(sseu->slice_mask);
subslice_length = sseu->max_slices * sseu->ss_stride;
eu_length = sseu->max_slices * sseu->max_subslices * sseu->eu_stride;
eu_length = sseu->max_slices * sseu->max_subslices * eu_stride;
total_length = sizeof(topo) + slice_length + subslice_length +
eu_length;

Expand All @@ -61,7 +62,7 @@ static int fill_topology_info(const struct sseu_dev_info *sseu,
topo.subslice_offset = slice_length;
topo.subslice_stride = sseu->ss_stride;
topo.eu_offset = slice_length + subslice_length;
topo.eu_stride = sseu->eu_stride;
topo.eu_stride = eu_stride;

if (copy_to_user(u64_to_user_ptr(query_item->data_ptr),
&topo, sizeof(topo)))
Expand All @@ -76,10 +77,10 @@ static int fill_topology_info(const struct sseu_dev_info *sseu,
subslice_mask, subslice_length))
return -EFAULT;

if (copy_to_user(u64_to_user_ptr(query_item->data_ptr +
sizeof(topo) +
slice_length + subslice_length),
sseu->eu_mask, eu_length))
if (intel_sseu_copy_eumask_to_user(u64_to_user_ptr(query_item->data_ptr +
sizeof(topo) +
slice_length + subslice_length),
sseu))
return -EFAULT;

return total_length;
Expand Down

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