riscv: mm: Add support for Svinval extension

The Svinval extension splits SFENCE.VMA instruction into finer-grained
invalidation and ordering operations and is mandatory for RVA23S64 profile.
When Svinval is enabled the local_flush_tlb_range_threshold_asid function
should use the following sequence to optimize the tlb flushes instead of
a simple sfence.vma:

sfence.w.inval
svinval.vma
  .
  .
svinval.vma
sfence.inval.ir

The maximum number of consecutive svinval.vma instructions that
can be executed in local_flush_tlb_range_threshold_asid function
is limited to 64. This is required to avoid soft lockups and the
approach is similar to that used in arm64.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240702102637.9074-1-mchitale@ventanamicro.com


Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>