Hi Mark, On Thu, 9 Jul 2026 at 19:40, Mark Brown <[email protected]> wrote: > > In preparation for reuising it for SME pull the code for discovering the > maximum virtualizable vector length out of sve_setup() into a separate > function. > > Signed-off-by: Mark Brown <[email protected]> > --- > arch/arm64/kernel/fpsimd.c | 41 ++++++++++++++++++++++++----------------- > 1 file changed, 24 insertions(+), 17 deletions(-) > > diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c > index dc1ad10e39a2..5c156e2a47ea 100644 > --- a/arch/arm64/kernel/fpsimd.c > +++ b/arch/arm64/kernel/fpsimd.c > @@ -1114,6 +1114,29 @@ int vec_verify_vq_map(enum vec_type type) > return 0; > } > > +static int vec_virtualisable_vl(struct vl_info *info) > +{ > + DECLARE_BITMAP(partial_only_map, SVE_VQ_MAX); > + unsigned long b_min_partial, b_max_virt; > + > + bitmap_andnot(partial_only_map, info->vq_partial_map, info->vq_map, > + SVE_VQ_MAX); > + b_min_partial = find_last_bit(partial_only_map, SVE_VQ_MAX); > + > + /* All implemented VLs are virtualisable */ > + if (b_min_partial >= SVE_VQ_MAX) > + return info->max_vl; > + > + b_max_virt = find_next_bit(info->vq_map, SVE_VQ_MAX, b_min_partial); > + > + /* No implemented VLs are virtualisable */ > + if (b_max_virt >= SVE_VQ_MAX) > + return 0;
nit: this is a reimplementation rather than a straight move, the no-virtualisable case returns 0 (and drops the WARN_ON) where sve_setup() returned SVE_VQ_MIN. No change for SVE (that case isn't architecturally possible), and 0 is correct for the SME case this helper now also serves. Might be worth a word in the changelog, since "pull ... into a separate function" reads as pure code motion. Reviewed-by: Fuad Tabba <[email protected]> Cheers, /fuad > + > + /* At least one virtualisable VL exists */ > + return sve_vl_from_vq(__bit_to_vq(b_max_virt)); > +} > + > void cpu_enable_sve(const struct arm64_cpu_capabilities *__always_unused p) > { > write_sysreg(read_sysreg(CPACR_EL1) | CPACR_EL1_ZEN_EL1EN, CPACR_EL1); > @@ -1125,8 +1148,6 @@ void cpu_enable_sve(const struct arm64_cpu_capabilities > *__always_unused p) > void __init sve_setup(void) > { > struct vl_info *info = &vl_info[ARM64_VEC_SVE]; > - DECLARE_BITMAP(tmp_map, SVE_VQ_MAX); > - unsigned long b; > int max_bit; > > if (!system_supports_sve()) > @@ -1149,21 +1170,7 @@ void __init sve_setup(void) > */ > set_sve_default_vl(find_supported_vector_length(ARM64_VEC_SVE, 64)); > > - bitmap_andnot(tmp_map, info->vq_partial_map, info->vq_map, > - SVE_VQ_MAX); > - > - b = find_last_bit(tmp_map, SVE_VQ_MAX); > - if (b >= SVE_VQ_MAX) > - /* No non-virtualisable VLs found */ > - info->max_virtualisable_vl = SVE_VQ_MAX; > - else if (WARN_ON(b == SVE_VQ_MAX - 1)) > - /* No virtualisable VLs? This is architecturally forbidden. > */ > - info->max_virtualisable_vl = SVE_VQ_MIN; > - else /* b + 1 < SVE_VQ_MAX */ > - info->max_virtualisable_vl = sve_vl_from_vq(__bit_to_vq(b + > 1)); > - > - if (info->max_virtualisable_vl > info->max_vl) > - info->max_virtualisable_vl = info->max_vl; > + info->max_virtualisable_vl = vec_virtualisable_vl(info); > > pr_info("%s: maximum available vector length %u bytes per vector\n", > info->name, info->max_vl); > > -- > 2.47.3 >
