The branch stable/14 has been updated by andrew: URL: https://cgit.FreeBSD.org/src/commit/?id=2210c15b08b9f70054d4de46a5a8566d395e0abe
commit 2210c15b08b9f70054d4de46a5a8566d395e0abe Author: Andrew Turner <[email protected]> AuthorDate: 2025-09-04 14:45:09 +0000 Commit: Andrew Turner <[email protected]> CommitDate: 2026-01-14 21:14:12 +0000 arm64: Support managing features from loader Allow the user to enable/disable supported cpu features/errata from a known tunable. This will allow the user to disable features, e.g. to work around broken firmware. It can also be used to enable workarounds for rare errata. Reviewed by: imp Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D52358 (cherry picked from commit 4bc68fa98f68211ee7943d77cfc91f60ccb5880d) --- sys/arm64/arm64/cpu_feat.c | 22 +++++++++++++++++++++- sys/arm64/include/cpu_feat.h | 27 ++++++++++++++++++++++++++- 2 files changed, 47 insertions(+), 2 deletions(-) diff --git a/sys/arm64/arm64/cpu_feat.c b/sys/arm64/arm64/cpu_feat.c index fd1b8429295f..986d5079e980 100644 --- a/sys/arm64/arm64/cpu_feat.c +++ b/sys/arm64/arm64/cpu_feat.c @@ -40,10 +40,13 @@ static cpu_feat_errata_check_fn cpu_feat_check_cb = NULL; void enable_cpu_feat(uint32_t stage) { + char tunable[32]; struct cpu_feat **featp, *feat; uint32_t midr; u_int errata_count, *errata_list; cpu_feat_errata errata_status; + cpu_feat_en check_status; + bool val; MPASS((stage & ~CPU_FEAT_STAGE_MASK) == 0); @@ -60,9 +63,26 @@ enable_cpu_feat(uint32_t stage) PCPU_GET(cpuid) != 0) continue; - if (feat->feat_check != NULL && !feat->feat_check(feat, midr)) + if (feat->feat_check != NULL) continue; + check_status = feat->feat_check(feat, midr); + /* Ignore features that are not present */ + if (check_status == FEAT_ALWAYS_DISABLE) + continue; + + snprintf(tunable, sizeof(tunable), "hw.feat.%s", + feat->feat_name); + if (TUNABLE_BOOL_FETCH(tunable, &val)) { + /* Is the feature disabled by the tunable? */ + if (!val) + continue; + /* If enabled by the tunable then enable it */ + } else if (check_status == FEAT_DEFAULT_DISABLE) { + /* No tunable set and disabled by default */ + continue; + } + /* * Check if the feature has any errata that may need a * workaround applied (or it is to install the workaround for diff --git a/sys/arm64/include/cpu_feat.h b/sys/arm64/include/cpu_feat.h index f62f3e334dc1..6a554b6baedf 100644 --- a/sys/arm64/include/cpu_feat.h +++ b/sys/arm64/include/cpu_feat.h @@ -40,6 +40,31 @@ typedef enum { /* kernel component. */ } cpu_feat_errata; +typedef enum { + /* + * Don't implement the feature or erratum wrokarount, + * e.g. the feature is not implemented or erratum is + * for another CPU. + */ + FEAT_ALWAYS_DISABLE, + + /* + * Disable by default, but allow the user to enable, + * e.g. For a rare erratum with a workaround, Arm + * Category B (rare) or similar. + */ + FEAT_DEFAULT_DISABLE, + + /* + * Enabled by default, bit allow the user to disable, + * e.g. For a common erratum with a workaround, Arm + * Category A or B or similar. + */ + FEAT_DEFAULT_ENABLE, + + /* We could add FEAT_ALWAYS_ENABLE if a need was found. */ +} cpu_feat_en; + #define CPU_FEAT_STAGE_MASK 0x00000001 #define CPU_FEAT_EARLY_BOOT 0x00000000 #define CPU_FEAT_AFTER_DEV 0x00000001 @@ -50,7 +75,7 @@ typedef enum { struct cpu_feat; -typedef bool (cpu_feat_check)(const struct cpu_feat *, u_int); +typedef cpu_feat_en (cpu_feat_check)(const struct cpu_feat *, u_int); typedef bool (cpu_feat_has_errata)(const struct cpu_feat *, u_int, u_int **, u_int *); typedef bool (cpu_feat_enable)(const struct cpu_feat *, cpu_feat_errata,
