[v1, 0/6] Support Zve32[xf] and Zve64[xfd] Vector subextensions

[Stefan O'Rear]

On Tue, Mar 12, 2024, at 8:36 AM, Andy Chiu wrote:
> The series composes of two parts. The first part provides a quick fix for
> the issue on a recent thread[1]. The issue happens when a platform has
> ununified vector register length across multiple cores. Specifically,
> patch 1 adds a comment at a callsite of riscv_setup_vsize to clarify how
> vlenb is observed by the system. Patch 2 fixes the issue by failing the
> boot process of a secondary core if vlenb mismatches.
>
> The second part of the series provide a finer grain view of the Vector
> extension. Patch 3 give the obsolete ISA parser the ability to expand
> ISA extensions for sigle letter extensions. Patch 3, 4 introduces Zve32x,
> Zve32f, Zve64x, Zve64f, Zve64d for isa parsing and hwprobe. Patch 5
> updates all callsites such that Vector subextensions are maximumly
> supported by the kernel.

What is the end user programming interface for this intended to be? prctl
call using inline asm ecall in the ifunc resolver, possibly automated using
function multi-versioning? Can we do better with a different interface?

-s

> Two parts of the series are sent together to ease the effort of picking
> dependency patches. The first part can be merged independent of the
> second one if necessary.
>
> The series is tested on a QEMU and verified that booting, Vector
> programs context-switch, signal, ptrace, prctl(sysctl knob) interfaces
> works when we only report partial V from the ISA.
>
> This patch should be able to apply on risc-v for-next branch on top of
> the commit 886516fae2b7 ("RISC-V: fix check for zvkb with tip-of-tree clang")
>
> [1]: 
> https://lore.kernel.org/all/20240228-vicinity-cornstalk-4b8eb5fe5730@spud/T/#u
>
> Andy Chiu (6):
>   riscv: vector: add a comment when calling riscv_setup_vsize()
>   riscv: smp: fail booting up smp if inconsistent vlen is detected
>   riscv: cpufeature: call match_isa_ext() for single-letter extensions
>   riscv: cpufeature: add zve32[xf] and zve64[xfd] isa detection
>   riscv: hwprobe: add zve Vector subextesnions into hwprobe interface
>   riscv: vector: adjust minimum Vector requirement to ZVE32X
>
>  Documentation/arch/riscv/hwprobe.rst   | 15 +++++++
>  arch/riscv/include/asm/hwcap.h         |  5 +++
>  arch/riscv/include/asm/switch_to.h     |  2 +-
>  arch/riscv/include/asm/vector.h        | 21 ++++++----
>  arch/riscv/include/asm/xor.h           |  2 +-
>  arch/riscv/include/uapi/asm/hwprobe.h  |  5 +++
>  arch/riscv/kernel/cpufeature.c         | 57 +++++++++++++++++++++++---
>  arch/riscv/kernel/head.S               | 14 +++----
>  arch/riscv/kernel/kernel_mode_vector.c |  4 +-
>  arch/riscv/kernel/process.c            |  4 +-
>  arch/riscv/kernel/signal.c             |  6 +--
>  arch/riscv/kernel/smpboot.c            | 14 ++++---
>  arch/riscv/kernel/sys_hwprobe.c        | 12 ++++--
>  arch/riscv/kernel/vector.c             | 15 ++++---
>  arch/riscv/lib/uaccess.S               |  2 +-
>  15 files changed, 135 insertions(+), 43 deletions(-)
>
> -- 
> 2.17.1
>
>
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