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ampere iter2: HEVC EXT_SPS_ST_RPS / _LT_RPS dynamic-array submission (VDPU381)

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Fixes the rkvdec_hevc_prepare_hw_st_rps out-of-bounds kernel OOPS that
blocked HEVC decode on ampere (RK3588) per
marfrit/libva-v4l2-request-fourier#3 and ampere-fourier iter1 close.

Mechanism (Phase 5 amendment to issue body):
The new EXT_SPS controls are registered as V4L2_CTRL_FLAG_DYNAMIC_ARRAY
in vdpu38x_hevc_ctrl_descs (rkvdec.c:279/284) with cfg.dims = { 65 }.
The v4l2-ctrl framework init-allocates 1 zeroed element (ctrls-core.c:2116).
When num_short_term_ref_pic_sets > 1, rkvdec_hevc_prepare_hw_st_rps
(rkvdec-hevc-common.c:393-405) iterates idx 0..N-1 and overruns the
1-element kernel allocation. Submitting an N-element dynamic-array
control via S_EXT_CTRLS extends the framework allocation.

Userspace fix:
  - VIDIOC_QUERY_EXT_CTRL probe at first HEVC CreateContext sets
    driver_data->has_ext_sps_rps (true on VDPU381/383, false on legacy
    RK3399 — control unregistered there, so fresnel iter38 5/5 + iter39
    sub-profile paths are byte-identical to pre-iter2).
  - When set, h265_set_controls appends EXT_SPS_ST_RPS + _LT_RPS as
    calloc'd zero arrays, sized by VAAPI's count fields and capped at
    H.265 §7.4.3.2 spec maxima (ST 64, LT 32). Min 1 (kernel rejects 0).
  - Free post-S_EXT_CTRLS.

Decode correctness scope:
VAAPI does NOT expose per-set st_ref_pic_set syntax elements
(delta_idx_minus1, delta_rps_sign, etc.) — confirmed in va_dec_hevc.h.
All-zero entries give empty inter-pred RPS per set, which is correct
for IDR-only streams and incorrect for streams with inter-pred RPS
dependence. iter2 acceptance: stop the OOPS. Decode-correctness for
inter-RPS content is a known follow-up requiring either bitstream-snoop
or SPS-passthrough via a new VAAPI extension.

Files:
  - include/hevc-ctrls.h: #ifndef-guarded fallback definitions for
    V4L2_CID_STATELESS_HEVC_EXT_SPS_{ST,LT}_RPS + structs (ampere host
    is on linux-api-headers 6.19-1; the new CIDs land in 7.0).
  - src/request.h: driver_data->has_ext_sps_rps (persists for driver
    lifetime; gated solely by HEVC code path so cross-codec leakage
    impossible).
  - src/context.c: probe at HEVC CreateContext via v4l2_query_ext_ctrl.
  - src/h265.c: controls[5] → controls[7]; #include <hevc-ctrls.h>
    (replaces <linux/v4l2-controls.h>) for forward UAPI compatibility.

Compile-tested on boltzmann (aarch64 native, gcc 15.2.1): clean .so,
0 new warnings. Fresnel cross-device safety: legacy RK3399 rkvdec_ctrl
table omits the CIDs; probe returns false; new code path never executes.

iter39 sub-profile work (commits 662f887 + 8746690) is preserved
in-tree; iter2 is a forward-compatible additive change.

Refs:
  marfrit/libva-v4l2-request-fourier#3
  ampere-fourier/iter1_close.md HEVC blocker
  ampere-fourier/iter2_phase0_findings.md

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
Claude (noether)
2026-05-17 09:34:58 +00:00
parent 8746690739
commit f61f736380
4 changed files with 135 additions and 3 deletions
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include/hevc-ctrls.h
+34 -1
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@@ -2,8 +2,41 @@
/* Fourier-local override: HEVC controls are upstream since linux-media
* 6.6+, so defer to the kernel's linux/v4l2-controls.h instead of
* duplicating the struct definitions (duplication causes redefinition
* errors on newer linux-api-headers). */
* errors on newer linux-api-headers).
*
* iter2 (ampere-fourier, 2026-05-17): the new EXT_SPS_ST_RPS / _LT_RPS
* controls landed in linux-media v8 series (linux-mmind-v7.0 has them)
* but linux-api-headers <7.0 doesn't. Ship guarded fallback definitions
* so the backend builds on older Arch hosts. Newer headers no-op these.
*/
#ifndef _LIBVA_V4L2_REQUEST_HEVC_CTRLS_H
#define _LIBVA_V4L2_REQUEST_HEVC_CTRLS_H
#include <linux/v4l2-controls.h>
#ifndef V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS
#define V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS (V4L2_CID_CODEC_STATELESS_BASE + 408)
#define V4L2_CID_STATELESS_HEVC_EXT_SPS_LT_RPS (V4L2_CID_CODEC_STATELESS_BASE + 409)
#define V4L2_HEVC_EXT_SPS_ST_RPS_FLAG_INTER_REF_PIC_SET_PRED 0x1
#define V4L2_HEVC_EXT_SPS_LT_RPS_FLAG_USED_LT 0x1
struct v4l2_ctrl_hevc_ext_sps_st_rps {
__u8 delta_idx_minus1;
__u8 delta_rps_sign;
__u8 num_negative_pics;
__u8 num_positive_pics;
__u32 used_by_curr_pic;
__u32 use_delta_flag;
__u16 abs_delta_rps_minus1;
__u16 delta_poc_s0_minus1[16];
__u16 delta_poc_s1_minus1[16];
__u16 flags;
};
struct v4l2_ctrl_hevc_ext_sps_lt_rps {
__u16 lt_ref_pic_poc_lsb_sps;
__u16 flags;
};
#endif /* V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS */
#endif