[v4, 0/6] riscv: support kernel-mode Vector

[Andy Chiu]

This series provides support for running Vector code in kernel mode.
Along with the suport, we add some Vector optimized routines. And
provide a simple threshold to decide when to run the vectorized
functions.

We decided to split the patch series into 2 parts. The first part
contains running kernel-mode Vector with preemption disabled. The second
part will add support for running Vector with preemption.

This patch is tested on a QEMU with V and verified that booting, normal
userspace operations all work as usual with thresholds set to 0.

v3 of this series can be found at [1]

Link: https://lore.kernel.org/all/20231019154552.23351-1-andy.chiu@sifive.com/

Patch summary (on current order):
 - Updated patches: 1, 4
 - New patch: 2, 5, 6
 - Unchanged patch: 3
 - Deleted patch: Patches related to preempt_v will be sent separately

Changelog v4:
 - Rebase on top of riscv for-next (6.7-rc1)
 - Use kernel_v_flags and helpers to track vector context.
 - Prevent softirq from nesting V context for non-preempt V
 - Add user copy and mem* routines

Changelog v3:
 - Rebase on top of riscv for-next (6.6-rc1)
 - Fix a build issue (Conor)
 - Guard vstate_save, vstate_restore with {get,put}_cpu_vector_context.
 - Save V context after disabling preemption. (Guo)
 - Remove irqs_disabled() check from may_use_simd(). (Björn)
 - Comment about nesting V context.

Changelog v2:
 - fix build issues
 - Follow arm's way of starting kernel-mode simd code:
   - add include/asm/simd.h and rename may_use_vector() ->
     may_use_simd()
   - return void in kernel_vector_begin(), and BUG_ON if may_use_simd()
     fails
 - Change naming scheme for functions/macros (Conor):
   - remove KMV
   - 's/rvv/vector/'
   - 's/RISCV_ISA_V_PREEMPTIVE_KMV/RISCV_ISA_V_PREEMPTIVE/'
   - 's/TIF_RISCV_V_KMV/TIF_RISCV_V_KERNEL_MODE/'

Andy Chiu (4):
  riscv: vector: make Vector always available for softirq context
  riscv: sched: defer restoring Vector context for user
  riscv: lib: vectorize copy_to_user/copy_from_user
  riscv: lib: add vectorized mem* routines

Greentime Hu (2):
  riscv: Add support for kernel mode vector
  riscv: Add vector extension XOR implementation

 arch/riscv/include/asm/entry-common.h  |  17 +++++
 arch/riscv/include/asm/processor.h     |  15 +++-
 arch/riscv/include/asm/simd.h          |  46 +++++++++++
 arch/riscv/include/asm/thread_info.h   |   2 +
 arch/riscv/include/asm/vector.h        |  32 +++++++-
 arch/riscv/include/asm/xor.h           |  82 ++++++++++++++++++++
 arch/riscv/kernel/Makefile             |   1 +
 arch/riscv/kernel/kernel_mode_vector.c | 101 +++++++++++++++++++++++++
 arch/riscv/kernel/process.c            |   4 +-
 arch/riscv/kernel/ptrace.c             |   5 +-
 arch/riscv/kernel/signal.c             |   5 +-
 arch/riscv/kernel/vector.c             |   2 +-
 arch/riscv/lib/Makefile                |   6 ++
 arch/riscv/lib/memcpy_vector.S         |  29 +++++++
 arch/riscv/lib/memmove_vector.S        |  49 ++++++++++++
 arch/riscv/lib/memset.S                |   2 +-
 arch/riscv/lib/memset_vector.S         |  33 ++++++++
 arch/riscv/lib/riscv_v_helpers.c       |  59 +++++++++++++++
 arch/riscv/lib/uaccess.S               |  11 +++
 arch/riscv/lib/uaccess_vector.S        |  55 ++++++++++++++
 arch/riscv/lib/xor.S                   |  81 ++++++++++++++++++++
 21 files changed, 630 insertions(+), 7 deletions(-)
 create mode 100644 arch/riscv/include/asm/simd.h
 create mode 100644 arch/riscv/include/asm/xor.h
 create mode 100644 arch/riscv/kernel/kernel_mode_vector.c
 create mode 100644 arch/riscv/lib/memcpy_vector.S
 create mode 100644 arch/riscv/lib/memmove_vector.S
 create mode 100644 arch/riscv/lib/memset_vector.S
 create mode 100644 arch/riscv/lib/riscv_v_helpers.c
 create mode 100644 arch/riscv/lib/uaccess_vector.S
 create mode 100644 arch/riscv/lib/xor.S

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2.17.1