Implement Hardware page table walker(PTW for short) feature in KVM mode.
Use OnOffAuto type variable ptw to check the PTW feature. If the PTW
feature is not supported with KVM host, it reports error if there is
ptw=on option.

This patchset is based on PTW feature on TCG mode:
https://lore.kernel.org/qemu-devel/20251016015027.1695116-1-maobibo@loongson.cn/

With PTW enabled, there is no obvious performance improvement with
generic macro benchmark, and somewhat improvement with micro benchmark
such as test-tlb located at https://github.com/torvalds/test-tlb,
overwall there is no negative effective with PTW enabled.

Here is result about test-tlb with command ./test-tlb 0x40000000 0x8000
             host    VM without HW PTW    VM with HW PTW   improvement
cycles       180         320                 261              20%

And TLB miss rate is about 52% n this scenerary.
Performance counter stats for 'taskset 0xf ./test-tlb 0x40000000 0x8000':
   67,724,819      dTLB-load-misses     #52.24% of all dTLB cache accesses
  129,639,899      dTLB-loads 

Bibo Mao (2):
  linux-headers: Update to Linux v6.18-rc2
  target/loongarch: Add PTW feature support in KVM mode

 include/standard-headers/linux/ethtool.h      |  1 +
 include/standard-headers/linux/fuse.h         | 22 ++++++++++--
 .../linux/input-event-codes.h                 |  1 +
 include/standard-headers/linux/input.h        | 22 +++++++++++-
 include/standard-headers/linux/pci_regs.h     | 10 ++++++
 include/standard-headers/linux/virtio_ids.h   |  1 +
 linux-headers/asm-loongarch/kvm.h             |  1 +
 linux-headers/asm-riscv/kvm.h                 | 23 +++++++++++-
 linux-headers/asm-riscv/ptrace.h              |  4 +--
 linux-headers/asm-x86/kvm.h                   | 34 ++++++++++++++++++
 linux-headers/asm-x86/unistd_64.h             |  1 +
 linux-headers/asm-x86/unistd_x32.h            |  1 +
 linux-headers/linux/kvm.h                     |  3 ++
 linux-headers/linux/psp-sev.h                 | 10 +++++-
 linux-headers/linux/stddef.h                  |  1 -
 linux-headers/linux/vduse.h                   |  2 +-
 linux-headers/linux/vhost.h                   |  4 +--
 target/loongarch/cpu.c                        |  5 +--
 target/loongarch/cpu.h                        |  1 +
 target/loongarch/kvm/kvm.c                    | 35 +++++++++++++++++++
 20 files changed, 169 insertions(+), 13 deletions(-)


base-commit: 36df9f3764a5d18683e79f743bc9fa1550d76da0
-- 
2.39.3