[PATCH v5 00/20] KVM RISC-V Support

Anup Patel
2019-08-22T08:42:23Z

This series adds initial KVM RISC-V support. Currently, we are able to boot
RISC-V 64bit Linux Guests with multiple VCPUs.

Few key aspects of KVM RISC-V added by this series are:
1. Minimal possible KVM world-switch which touches only GPRs and few CSRs.
2. Full Guest/VM switch is done via vcpu_get/vcpu_put infrastructure.
3. KVM ONE_REG interface for VCPU register access from user-space.
4. PLIC emulation is done in user-space. In-kernel PLIC emulation, will
be added in future.
5. Timer and IPI emuation is done in-kernel.
6. MMU notifiers supported.
7. FP lazy save/restore supported.
8. SBI v0.1 emulation for KVM Guest available.

Here's a brief TODO list which we will work upon after this series:
1. Handle trap from unpriv access in reading Guest instruction
2. Handle trap from unpriv access in SBI v0.1 emulation
3. Implement recursive stage2 page table programing
4. SBI v0.2 emulation in-kernel
5. SBI v0.2 hart hotplug emulation in-kernel
6. In-kernel PLIC emulation
7. ..... and more .....

This series can be found in riscv_kvm_v5 branch at:
https//github.com/avpatel/linux.git

Our work-in-progress KVMTOOL RISC-V port can be found in riscv_v1 branch at:
https//github.com/avpatel/kvmtool.git

We need OpenSBI with RISC-V hypervisor extension support which can be
found in hyp_ext_changes_v1 branch at:
https://github.com/riscv/opensbi.git

The QEMU RISC-V hypervisor emulation is done by Alistair and is available
in riscv-hyp-work.next branch at:
https://github.com/alistair23/qemu.git

To play around with KVM RISC-V, here are few reference commands:
1) To cross-compile KVMTOOL:
$ make lkvm-static
2) To launch RISC-V Host Linux:
$ qemu-system-riscv64 -monitor null -cpu rv64,h=true -M virt \
-m 512M -display none -serial mon:stdio \
-kernel opensbi/build/platform/qemu/virt/firmware/fw_jump.elf \
-device loader,file=build-riscv64/arch/riscv/boot/Image,addr=0x80200000 \
-initrd ./rootfs_kvm_riscv64.img \
-append "root=/dev/ram rw console=ttyS0 earlycon=sbi"
3) To launch RISC-V Guest Linux with 9P rootfs:
$ ./apps/lkvm-static run -m 128 -c2 --console serial \
-p "console=ttyS0 earlycon=uart8250,mmio,0x3f8" -k ./apps/Image --debug
4) To launch RISC-V Guest Linux with initrd:
$ ./apps/lkvm-static run -m 128 -c2 --console serial \
-p "console=ttyS0 earlycon=uart8250,mmio,0x3f8" -k ./apps/Image \
-i ./apps/rootfs.img --debug

Changes since v4:
- Rebased patches on Linux-5.3-rc5
- Added Paolo's Acked-by and Reviewed-by
- Updated mailing list in MAINTAINERS entry

Changes since v3:
- Moved patch for ISA bitmap from KVM prep series to this series
- Make vsip_shadow as run-time percpu variable instead of compile-time
- Flush Guest TLBs on all Host CPUs whenever we run-out of VMIDs

Changes since v2:
- Removed references of KVM_REQ_IRQ_PENDING from all patches
- Use kvm->srcu within in-kernel KVM run loop
- Added percpu vsip_shadow to track last value programmed in VSIP CSR
- Added comments about irqs_pending and irqs_pending_mask
- Used kvm_arch_vcpu_runnable() in-place-of kvm_riscv_vcpu_has_interrupt()
in system_opcode_insn()
- Removed unwanted smp_wmb() in kvm_riscv_stage2_vmid_update()
- Use kvm_flush_remote_tlbs() in kvm_riscv_stage2_vmid_update()
- Use READ_ONCE() in kvm_riscv_stage2_update_hgatp() for vmid

Changes since v1:
- Fixed compile errors in building KVM RISC-V as module
- Removed unused kvm_riscv_halt_guest() and kvm_riscv_resume_guest()
- Set KVM_CAP_SYNC_MMU capability only after MMU notifiers are implemented
- Made vmid_version as unsigned long instead of atomic
- Renamed KVM_REQ_UPDATE_PGTBL to KVM_REQ_UPDATE_HGATP
- Renamed kvm_riscv_stage2_update_pgtbl() to kvm_riscv_stage2_update_hgatp()
- Configure HIDELEG and HEDELEG in kvm_arch_hardware_enable()
- Updated ONE_REG interface for CSR access to user-space
- Removed irqs_pending_lock and use atomic bitops instead
- Added separate patch for FP ONE_REG interface
- Added separate patch for updating MAINTAINERS file

Anup Patel (15):
KVM: RISC-V: Add KVM_REG_RISCV for ONE_REG interface
RISC-V: Add bitmap reprensenting ISA features common across CPUs
RISC-V: Add hypervisor extension related CSR defines
RISC-V: Add initial skeletal KVM support
RISC-V: KVM: Implement VCPU create, init and destroy functions
RISC-V: KVM: Implement VCPU interrupts and requests handling
RISC-V: KVM: Implement KVM_GET_ONE_REG/KVM_SET_ONE_REG ioctls
RISC-V: KVM: Implement VCPU world-switch
RISC-V: KVM: Handle MMIO exits for VCPU
RISC-V: KVM: Handle WFI exits for VCPU
RISC-V: KVM: Implement VMID allocator
RISC-V: KVM: Implement stage2 page table programming
RISC-V: KVM: Implement MMU notifiers
RISC-V: Enable VIRTIO drivers in RV64 and RV32 defconfig
RISC-V: KVM: Add MAINTAINERS entry

Atish Patra (5):
RISC-V: Export few kernel symbols
RISC-V: KVM: Add timer functionality
RISC-V: KVM: FP lazy save/restore
RISC-V: KVM: Implement ONE REG interface for FP registers
RISC-V: KVM: Add SBI v0.1 support

MAINTAINERS | 10 +
arch/riscv/Kconfig | 2 +
arch/riscv/Makefile | 2 +
arch/riscv/configs/defconfig | 11 +
arch/riscv/configs/rv32_defconfig | 11 +
arch/riscv/include/asm/csr.h | 58 ++
arch/riscv/include/asm/hwcap.h | 26 +
arch/riscv/include/asm/kvm_host.h | 246 ++++++
arch/riscv/include/asm/kvm_vcpu_timer.h | 32 +
arch/riscv/include/asm/pgtable-bits.h | 1 +
arch/riscv/include/uapi/asm/kvm.h | 98 +++
arch/riscv/kernel/asm-offsets.c | 148 ++++
arch/riscv/kernel/cpufeature.c | 79 +-
arch/riscv/kernel/smp.c | 2 +-
arch/riscv/kernel/time.c | 1 +
arch/riscv/kvm/Kconfig | 34 +
arch/riscv/kvm/Makefile | 14 +
arch/riscv/kvm/main.c | 92 +++
arch/riscv/kvm/mmu.c | 905 ++++++++++++++++++++++
arch/riscv/kvm/tlb.S | 43 ++
arch/riscv/kvm/vcpu.c | 989 ++++++++++++++++++++++++
arch/riscv/kvm/vcpu_exit.c | 556 +++++++++++++
arch/riscv/kvm/vcpu_sbi.c | 119 +++
arch/riscv/kvm/vcpu_switch.S | 368 +++++++++
arch/riscv/kvm/vcpu_timer.c | 106 +++
arch/riscv/kvm/vm.c | 86 +++
arch/riscv/kvm/vmid.c | 123 +++
drivers/clocksource/timer-riscv.c | 8 +
include/clocksource/timer-riscv.h | 16 +
include/uapi/linux/kvm.h | 1 +
30 files changed, 4183 insertions(+), 4 deletions(-)
create mode 100644 arch/riscv/include/asm/kvm_host.h
create mode 100644 arch/riscv/include/asm/kvm_vcpu_timer.h
create mode 100644 arch/riscv/include/uapi/asm/kvm.h
create mode 100644 arch/riscv/kvm/Kconfig
create mode 100644 arch/riscv/kvm/Makefile
create mode 100644 arch/riscv/kvm/main.c
create mode 100644 arch/riscv/kvm/mmu.c
create mode 100644 arch/riscv/kvm/tlb.S
create mode 100644 arch/riscv/kvm/vcpu.c
create mode 100644 arch/riscv/kvm/vcpu_exit.c
create mode 100644 arch/riscv/kvm/vcpu_sbi.c
create mode 100644 arch/riscv/kvm/vcpu_switch.S
create mode 100644 arch/riscv/kvm/vcpu_timer.c
create mode 100644 arch/riscv/kvm/vm.c
create mode 100644 arch/riscv/kvm/vmid.c
create mode 100644 include/clocksource/timer-riscv.h

--
2.17.1