riscv: ASID-related and UP-related TLB flush enhancements

While reviewing Alexandre Ghiti's "riscv: tlb flush improvements"
series[1], I noticed that most TLB flush functions end up as a call to
local_flush_tlb_all() when SMP is disabled. This series resolves that.
Along the way, I realized that we should be using single-ASID flushes
wherever possible, so I implemented that as well.

[1]: https://lore.kernel.org/linux-riscv/20231019140151.21629-...
---
This series is based on v5 of Alexandre's changes, which I have included
here so the series can be built by the CI bots. I will rebase once his
series is merged.

Changes in v2:
 - Rebase on Alexandre's "riscv: tlb flush improvements" series v5
 - Move the SMP/UP merge earlier in the series to avoid build issues
 - Make a copy of __flush_tlb_range() instead of adding ifdefs inside
 - local_flush_tlb_all() is the only function used on !MMU (smpboot.c)

Alexandre Ghiti (4):
  riscv: Improve tlb_flush()
  riscv: Improve flush_tlb_range() for hugetlb pages
  riscv: Make __flush_tlb_range() loop over pte instead of flushing the
    whole tlb
  riscv: Improve flush_tlb_kernel_range()

Samuel Holland (7):
  riscv: mm: Combine the SMP and UP TLB flush code
  riscv: Apply SiFive CIP-1200 workaround to single-ASID sfence.vma
  riscv: mm: Introduce cntx2asid/cntx2version helper macros
  riscv: mm: Use a fixed layout for the MM context ID
  riscv: mm: Make asid_bits a local variable
  riscv: mm: Preserve global TLB entries when switching contexts
  riscv: mm: Always use ASID to flush MM contexts

 arch/riscv/include/asm/errata_list.h |  12 +-
 arch/riscv/include/asm/mmu.h         |   3 +
 arch/riscv/include/asm/mmu_context.h |   2 -
 arch/riscv/include/asm/sbi.h         |   3 -
 arch/riscv/include/asm/tlb.h         |   8 +-
 arch/riscv/include/asm/tlbflush.h    |  59 +++++----
 arch/riscv/kernel/sbi.c              |  32 ++---
 arch/riscv/mm/Makefile               |   5 +-
 arch/riscv/mm/context.c              |  26 ++--
 arch/riscv/mm/tlbflush.c             | 184 ++++++++++++++++-----------
 10 files changed, 186 insertions(+), 148 deletions(-)

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2.42.0