Pull Request - MPAM mbw hard limit for 6.17 HWE by fyu1 · Pull Request #360 · NVIDIA/NV-Kernels

fyu1 · 2026-04-14T17:04:36Z

Please pull the branch to 6.17 HWE.

The top 9 commits implements MPAM mbw hard limit feature.

LP: https://bugs.launchpad.net/ubuntu/+source/linux-nvidia-6.17/+bug/2150290

jamieNguyenNVIDIA

I think these should be NVIDIA: VR: SAUCE rather than NVIDIA: SAUCE.

Also, did any of these patches originate from elsewhere? If so, you ought to add the "cherry picked from" or "backported from" note in the trailer.

jamieNguyenNVIDIA · 2026-04-14T19:02:23Z

 			break;
 		}
-		fallthrough;
+		break;


What's the desired behavior if configured_by is not set here?

Previously, this would have fallen through to goto err. But now, we'd continue on with variable being uninitialized. Is this intentional?

@jamieNguyenNVIDIA Good catch. I fixed the goto err issue and NVIDIA: VR: SAUCE tags.

jamieNguyenNVIDIA · 2026-04-15T19:43:11Z

Hi @fyu1, this series looks good to me. Thanks!

I only wonder if we want to wait for your LKML posting before sending to Canonical so that you can add (backported from) information to each commit.

nvmochs · 2026-04-16T01:25:52Z

@fyu1 I reviewed the series manually and with claude and did not spot any issues.

Do you anticipate this will be posted to LKML soon? I agree with Jamie that it would be helpful to have a LKML reference for keeping track of the history of these patches.

Add RDT_RESOURCE_MB_HLIM and RESCTRL_SCHEMA_MB_HLIM for per-domain MBW maximum hard-limit control on ARM MPAM. Document the schema in kernel-doc. Extend resctrl_get_default_ctrl() for RESCTRL_SCHEMA_MB_HLIM (default 0). Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

…etup Add mb_hlim parsing and validation (0/1), wire RESCTRL_SCHEMA_MB_HLIM into schemata and control-group setup, align MB_HLIM with MBA for exclusive mode and pseudo-locking, and default new groups to hardlim off. Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

…lim_rw Read mbw_max_lim from MPAMF_MBW_IDR.MAX_LIM when MBW_MAX is present, derive mpam_feat_mbw_max_hardlim_rw when both soft and hard limiting are supported, and merge mbw_max_lim and the feature across MSCs. Add mpam_props_sync_mbw_max_hardlim_rw() and propagate merged state in __props_mismatch(). Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

Add mbw_max_hardlim to mpam_config. When reprogramming MBW_MAX, OR in HARDLIM (MPAMCFG_MBW_MAX bit 31) when either MBW_MAX or HARDLIM_RW features are active. Merge HARDLIM in mpam_update_config(). Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

When mpam_feat_mbw_max_hardlim_rw is present, share the MBA MPAM class with RDT_RESOURCE_MB_HLIM. Wire resctrl_arch_get_config and resctrl_arch_update_one for MB_HLIM, and tear down MBA and MB_HLIM controls together on class removal. Handle RDT_RESOURCE_MB_HLIM in fflags_from_resource() so creating info/MB_HLIM at resctrl mount does not hit the unhandled-rid WARN. Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

Add mb_max_lim and arch_has_mb_max_lim to struct resctrl_membw with kernel-doc: MPAM MAX_LIM encoding (MPAMF_MBW_IDR), invalid elsewhere unless arch sets arch_has_mb_max_lim. Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

When mpam_feat_mbw_max is present, set membw.mb_max_lim from cprops->mbw_max_lim and membw.arch_has_mb_max_lim so generic resctrl can expose max_lim. Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

… init Add rdt_mb_max_lim_show() and the max_lim entry in res_common_files[]. Add mb_max_lim_init() to call resctrl_file_fflags_init("max_lim", ...) when arch_has_mb_max_lim, and invoke it from resctrl_init() after io_alloc_init(). Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

…IM for MPAM MBA Document the MBA max_lim sysfs file, MB_HLIM schemata (0/1 per domain), and how they relate to MPAM MBW_MAX, HARDLIM, and MPAMF_MBW_IDR.MAX_LIM. Add schema_format for mb_hlim under the MB allocation info directory. max_lim is exposed as a single decimal integer (MPAMF_MBW_IDR.MAX_LIM [1:0], 0–3), matching rdt_mb_max_lim_show(). MB_HLIM appears when the probe treats HARDLIM as read/write, which this series ties to max_lim reading zero (see mpam_props_sync_mbw_max_hardlim_rw()). Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

fyu1 · 2026-04-24T23:03:20Z

Rebase the hardlimit patches to the latest 6.17 hwe kernel. There is no conflict. The hardlimit and basic functions are tested.

nvmochs · 2026-04-24T23:04:27Z

Verified no change between when I last reviewed and the rebase.

 1:  64b04bc6b52c =  1:  62a1422201d6 NVIDIA: VR: SAUCE: resctrl: add MB_HLIM resource ID and schema type
 2:  15114bfd7243 =  2:  b05aae044c5f NVIDIA: VR: SAUCE: resctrl: wire MB_HLIM schemata parsing and group setup
 3:  c1d6f83f78f6 =  3:  0320b591dc27 NVIDIA: VR: SAUCE: resctrl/mpam: probe MPAMF_MBW_IDR MAX_LIM and hardlim_rw
 4:  f7d03d7ee5d9 =  4:  0b8e57af9945 NVIDIA: VR: SAUCE: resctrl/mpam: track MBW max hard-limit in config
 5:  9be5038a1cc9 =  5:  397a4db69ce2 NVIDIA: VR: SAUCE: resctrl/mpam: bind MB_HLIM resource to MBA MPAM class
 6:  6ce8d18d8cad =  6:  f82a933ec983 NVIDIA: VR: SAUCE: resctrl: add membw.mb_max_lim and arch_has_mb_max_lim
 7:  9b2f52de5649 =  7:  bc9488c36fcf NVIDIA: VR: SAUCE: resctrl/mpam: populate MBA mb_max_lim from MPAM probe
 8:  c6a798951f02 =  8:  522b71c12ce4 NVIDIA: VR: SAUCE: resctrl: add MBA max_lim sysfs and visibility from init
 9:  af26ddcfeb72 =  9:  c939503d0b7a NVIDIA: VR: SAUCE: Documentation: resctrl: document max_lim and MB_HLIM for MPAM MBA

No further issues from me.

Acked-by: Matthew R. Ochs <mochs@nvidia.com>

github-actions · 2026-04-24T23:08:34Z

PR Validation Report

Patchscan ✅ No Missing Fixes

All cherry-picked commits checked — no missing upstream fixes found.

PR Lint ❌ Errors found

Details

Checking 9 commits...

Cherry-pick digest:
┌──────────────┬───────────────────────────────────────────────┬────────────┬─────────┬───────────────────────────┐
│ Local        │ Referenced upstream / Patch subject           │ Patch-ID   │ Subject │ SoB chain                 │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ c939503d0b7a │ [SAUCE] documentation: resctrl: document max_ │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ 522b71c12ce4 │ [SAUCE] resctrl: add mba max_lim sysfs and vi │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ bc9488c36fcf │ [SAUCE] resctrl/mpam: populate mba mb_max_lim │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ f82a933ec983 │ [SAUCE] resctrl: add membw.mb_max_lim and arc │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ 397a4db69ce2 │ [SAUCE] resctrl/mpam: bind mb_hlim resource t │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ 0b8e57af9945 │ [SAUCE] resctrl/mpam: track mbw max hard-limi │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ 0320b591dc27 │ [SAUCE] resctrl/mpam: probe mpamf_mbw_idr max │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ b05aae044c5f │ [SAUCE] resctrl: wire mb_hlim schemata parsin │ N/A        │ N/A     │ fenghuay                  │
├──────────────┼───────────────────────────────────────────────┼────────────┼─────────┼───────────────────────────┤
│ 62a1422201d6 │ [SAUCE] resctrl: add mb_hlim resource id and  │ N/A        │ N/A     │ fenghuay                  │
└──────────────┴───────────────────────────────────────────────┴────────────┴─────────┴───────────────────────────┘

Lint: all checks passed.

PR metadata:
W: PR title missing [<branch>] prefix: "Pull Request - MPAM mbw hard limit for 6.17 HWE"
E: PR targets 24.04_linux-nvidia-6.17-next but body has no 'BugLink:' or 'LP:' https://bugs.launchpad.net/... line

jamieNguyenNVIDIA · 2026-04-24T23:12:21Z

Acked-by: Jamie Nguyen <jamien@nvidia.com>

Thanks @fyu1!

nvmochs · 2026-04-25T01:43:50Z

Merged, closing PR.

93e1b6a2b372 (nnoble/nvidia-6.17-next) NVIDIA: VR: SAUCE: Documentation: resctrl: document max_lim and MB_HLIM for MPAM MBA
be13cad9cd15 NVIDIA: VR: SAUCE: resctrl: add MBA max_lim sysfs and visibility from init
05b9bc183101 NVIDIA: VR: SAUCE: resctrl/mpam: populate MBA mb_max_lim from MPAM probe
7939f1e41019 NVIDIA: VR: SAUCE: resctrl: add membw.mb_max_lim and arch_has_mb_max_lim
04e2ea343852 NVIDIA: VR: SAUCE: resctrl/mpam: bind MB_HLIM resource to MBA MPAM class
114894b316e4 NVIDIA: VR: SAUCE: resctrl/mpam: track MBW max hard-limit in config
ced4d460ce56 NVIDIA: VR: SAUCE: resctrl/mpam: probe MPAMF_MBW_IDR MAX_LIM and hardlim_rw
6911e81a21d2 NVIDIA: VR: SAUCE: resctrl: wire MB_HLIM schemata parsing and group setup
9fc8c60cb42b NVIDIA: VR: SAUCE: resctrl: add MB_HLIM resource ID and schema type

fyu1 assigned nvmochs and jamieNguyenNVIDIA Apr 14, 2026

fyu1 requested review from jamieNguyenNVIDIA and nvmochs April 14, 2026 17:06

jamieNguyenNVIDIA reviewed Apr 14, 2026

View reviewed changes

fyu1 force-pushed the 24.04_linux-nvidia-6.17-next.hardlimit2 branch 2 times, most recently from c2b44d4 to af26ddc Compare April 15, 2026 01:39

fyu1 requested review from clsotog and nirmoy April 15, 2026 19:20

nvidia-bfigg force-pushed the 24.04_linux-nvidia-6.17-next branch from 8b07926 to 80bac29 Compare April 21, 2026 12:02

fyu1 added 9 commits April 24, 2026 22:47

NVIDIA: VR: SAUCE: resctrl/mpam: populate MBA mb_max_lim from MPAM probe

bc9488c

When mpam_feat_mbw_max is present, set membw.mb_max_lim from cprops->mbw_max_lim and membw.arch_has_mb_max_lim so generic resctrl can expose max_lim. Signed-off-by: Fenghua Yu <fenghuay@nvidia.com>

fyu1 force-pushed the 24.04_linux-nvidia-6.17-next.hardlimit2 branch from af26ddc to c939503 Compare April 24, 2026 22:58

nvmochs closed this Apr 25, 2026

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Pull Request - MPAM mbw hard limit for 6.17 HWE#360

Pull Request - MPAM mbw hard limit for 6.17 HWE#360
fyu1 wants to merge 9 commits into
NVIDIA:24.04_linux-nvidia-6.17-nextfrom
fyu1:24.04_linux-nvidia-6.17-next.hardlimit2

fyu1 commented Apr 14, 2026 •

edited by nvmochs

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