[v5,00/30] Add KVM LoongArch support

  This series adds KVM LoongArch support. Loongson 3A5000 supports hardware
assisted virtualization. With cpu virtualization, there are separate
hw-supported user mode and kernel mode in guest mode. With memory
virtualization, there are two-level hw mmu table for guest mode and host
mode. Also there is separate hw cpu timer with consant frequency in
guest mode, so that vm can migrate between hosts with different freq.
Currently, we are able to boot LoongArch Linux Guests.

Few key aspects of KVM LoongArch added by this series are:
1. Enable kvm hardware function when kvm module is loaded.
2. Implement VM and vcpu related ioctl interface such as vcpu create,
   vcpu run etc. GET_ONE_REG/SET_ONE_REG ioctl commands are use to
   get general registers one by one.
3. Hardware access about MMU, timer and csr are emulated in kernel.
4. Hardwares such as mmio and iocsr device are emulated in user space
   such as APIC, IPI, pci devices etc.

The running environment of LoongArch virt machine:
1. Cross tools to build kernel and uefi:
   $ wget https://github.com/loongson/build-tools/releases/download/2022.09.06/loongarch64-clfs-6.3-cross-tools-gcc-glibc.tar.xz
   tar -vxf loongarch64-clfs-6.3-cross-tools-gcc-glibc.tar.xz  -C /opt
   export PATH=/opt/cross-tools/bin:$PATH
   export LD_LIBRARY_PATH=/opt/cross-tools/lib:$LD_LIBRARY_PATH
   export LD_LIBRARY_PATH=/opt/cross-tools/loongarch64-unknown-linux-gnu/lib/:$LD_LIBRARY_PATH
2. This series is based on the linux source code:
   https://github.com/loongson/linux-loongarch-kvm
   Build command:
   git checkout kvm-loongarch
   make ARCH=loongarch CROSS_COMPILE=loongarch64-unknown-linux-gnu- loongson3_defconfig
   make ARCH=loongarch CROSS_COMPILE=loongarch64-unknown-linux-gnu-
3. QEMU hypervisor with LoongArch supported:
   https://github.com/loongson/qemu
   Build command:
   git checkout kvm-loongarch
   ./configure --target-list="loongarch64-softmmu"  --enable-kvm
   make
4. Uefi bios of LoongArch virt machine:
   Link: https://github.com/tianocore/edk2-platforms/tree/master/Platform/Loongson/LoongArchQemuPkg#readme
5. you can also access the binary files we have already build:
   https://github.com/yangxiaojuan-loongson/qemu-binary

The command to boot loongarch virt machine:
   $ qemu-system-loongarch64 -machine virt -m 4G -cpu la464 \
   -smp 1 -bios QEMU_EFI.fd -kernel vmlinuz.efi -initrd ramdisk \
   -serial stdio   -monitor telnet:localhost:4495,server,nowait \
   -append "root=/dev/ram rdinit=/sbin/init console=ttyS0,115200" \
   --nographic

Changes for v5:
1. Implement get/set mp_state ioctl interface, and only the
KVM_MP_STATE_RUNNABLE state is supported now, and other states
will be completed in the future. The state is also used when vcpu
run idle instruction, if vcpu state is changed to RUNNABLE, the
vcpu will have the possibility to be woken up.
2. Supplement kvm document about loongarch-specific part, such as add
api introduction for GET/SET_ONE_REG, GET/SET_FPU, GET/SET_MP_STATE,
etc.
3. Improve the kvm_switch_to_guest function in switch.S, remove the
previous tmp,tmp1 arguments and replace it with t0,t1 reg.

Changes for v4:
1. Add a csr_need_update flag in _vcpu_put, as most csr registers keep
unchanged during process context switch, so we need not to update it
every time. We can do this only if the soft csr is different form hardware.
That is to say all of csrs should update after vcpu enter guest, as for
set_csr_ioctl, we have written soft csr to keep consistent with hardware.
2. Improve get/set_csr_ioctl interface, we set SW or HW or INVALID flag
for all csrs according to it's features when kvm init. In get/set_csr_ioctl,
if csr is HW, we use gcsrrd/ gcsrwr instruction to access it, else if csr is
SW, we use software to emulate it, and others return false.
3. Add set_hw_gcsr function in csr_ops.S, and it is used in set_csr_ioctl.
We have splited hw gcsr into three parts, so we can calculate the code offset
by gcsrid and jump here to run the gcsrwr instruction. We use this function to
make the code easier and avoid to use the previous SET_HW_GCSR(XXX) interface.
4. Improve kvm mmu functions, such as flush page table and make clean page table
interface.

Changes for v3:
1. Remove the vpid array list in kvm_vcpu_arch and use a vpid variable here,
because a vpid will never be recycled if a vCPU migrates from physical CPU A
to B and back to A.
2. Make some constant variables in kvm_context to global such as vpid_mask,
guest_eentry, enter_guest, etc.
3. Add some new tracepoints, such as kvm_trace_idle, kvm_trace_cache,
kvm_trace_gspr, etc.
4. There are some duplicate codes in kvm_handle_exit and kvm_vcpu_run,
so we move it to a new function kvm_pre_enter_guest.
5. Change the RESUME_HOST, RESUME_GUEST value, return 1 for resume guest
and "<= 0" for resume host.
6. Fcsr and fpu registers are saved/restored together.

Changes for v2:
1. Seprate the original patch-01 and patch-03 into small patches, and the
patches mainly contain kvm module init, module exit, vcpu create, vcpu run,
etc.
2. Remove the original KVM_{GET,SET}_CSRS ioctl in the kvm uapi header,
and we use the common KVM_{GET,SET}_ONE_REG to access register.
3. Use BIT(x) to replace the "1 << n_bits" statement.

Tianrui Zhao (30):
  LoongArch: KVM: Add kvm related header files
  LoongArch: KVM: Implement kvm module related interface
  LoongArch: KVM: Implement kvm hardware enable, disable interface
  LoongArch: KVM: Implement VM related functions
  LoongArch: KVM: Add vcpu related header files
  LoongArch: KVM: Implement vcpu create and destroy interface
  LoongArch: KVM: Implement vcpu run interface
  LoongArch: KVM: Implement vcpu handle exit interface
  LoongArch: KVM: Implement vcpu get, vcpu set registers
  LoongArch: KVM: Implement vcpu ENABLE_CAP ioctl interface
  LoongArch: KVM: Implement fpu related operations for vcpu
  LoongArch: KVM: Implement vcpu interrupt operations
  LoongArch: KVM: Implement misc vcpu related interfaces
  LoongArch: KVM: Implement vcpu load and vcpu put operations
  LoongArch: KVM: Implement vcpu status description
  LoongArch: KVM: Implement update VM id function
  LoongArch: KVM: Implement virtual machine tlb operations
  LoongArch: KVM: Implement vcpu timer operations
  LoongArch: KVM: Implement kvm mmu operations
  LoongArch: KVM: Implement handle csr excption
  LoongArch: KVM: Implement handle iocsr exception
  LoongArch: KVM: Implement handle idle exception
  LoongArch: KVM: Implement handle gspr exception
  LoongArch: KVM: Implement handle mmio exception
  LoongArch: KVM: Implement handle fpu exception
  LoongArch: KVM: Implement kvm exception vector
  LoongArch: KVM: Implement vcpu world switch
  LoongArch: KVM: Implement probe virtualization when loongarch cpu init
  LoongArch: KVM: Enable kvm config and add the makefile
  LoongArch: KVM: Supplement kvm document about loongarch-specific part

 Documentation/virt/kvm/api.rst             |  75 +-
 arch/loongarch/Kbuild                      |   1 +
 arch/loongarch/Kconfig                     |   2 +
 arch/loongarch/configs/loongson3_defconfig |   2 +
 arch/loongarch/include/asm/cpu-features.h  |  22 +
 arch/loongarch/include/asm/cpu-info.h      |  13 +
 arch/loongarch/include/asm/inst.h          |  16 +
 arch/loongarch/include/asm/kvm_csr.h       |  55 ++
 arch/loongarch/include/asm/kvm_host.h      | 268 +++++++
 arch/loongarch/include/asm/kvm_types.h     |  11 +
 arch/loongarch/include/asm/kvm_vcpu.h      | 114 +++
 arch/loongarch/include/asm/loongarch.h     | 209 ++++-
 arch/loongarch/include/uapi/asm/kvm.h      | 107 +++
 arch/loongarch/kernel/asm-offsets.c        |  32 +
 arch/loongarch/kernel/cpu-probe.c          |  53 ++
 arch/loongarch/kvm/Kconfig                 |  38 +
 arch/loongarch/kvm/Makefile                |  22 +
 arch/loongarch/kvm/csr_ops.S               |  76 ++
 arch/loongarch/kvm/exit.c                  | 709 +++++++++++++++++
 arch/loongarch/kvm/interrupt.c             | 126 +++
 arch/loongarch/kvm/main.c                  | 340 ++++++++
 arch/loongarch/kvm/mmu.c                   | 730 +++++++++++++++++
 arch/loongarch/kvm/switch.S                | 301 +++++++
 arch/loongarch/kvm/timer.c                 | 266 +++++++
 arch/loongarch/kvm/tlb.c                   |  31 +
 arch/loongarch/kvm/trace.h                 | 160 ++++
 arch/loongarch/kvm/vcpu.c                  | 882 +++++++++++++++++++++
 arch/loongarch/kvm/vm.c                    |  79 ++
 arch/loongarch/kvm/vmid.c                  |  65 ++
 include/uapi/linux/kvm.h                   |   9 +
 30 files changed, 4799 insertions(+), 15 deletions(-)
 create mode 100644 arch/loongarch/include/asm/kvm_csr.h
 create mode 100644 arch/loongarch/include/asm/kvm_host.h
 create mode 100644 arch/loongarch/include/asm/kvm_types.h
 create mode 100644 arch/loongarch/include/asm/kvm_vcpu.h
 create mode 100644 arch/loongarch/include/uapi/asm/kvm.h
 create mode 100644 arch/loongarch/kvm/Kconfig
 create mode 100644 arch/loongarch/kvm/Makefile
 create mode 100644 arch/loongarch/kvm/csr_ops.S
 create mode 100644 arch/loongarch/kvm/exit.c
 create mode 100644 arch/loongarch/kvm/interrupt.c
 create mode 100644 arch/loongarch/kvm/main.c
 create mode 100644 arch/loongarch/kvm/mmu.c
 create mode 100644 arch/loongarch/kvm/switch.S
 create mode 100644 arch/loongarch/kvm/timer.c
 create mode 100644 arch/loongarch/kvm/tlb.c
 create mode 100644 arch/loongarch/kvm/trace.h
 create mode 100644 arch/loongarch/kvm/vcpu.c
 create mode 100644 arch/loongarch/kvm/vm.c
 create mode 100644 arch/loongarch/kvm/vmid.c