Re: [PATCH v3 00/66] KVM: arm64: ARMv8.3/8.4 Nested Virtualization support

[Haibo Xu <haibo.xu@linaro.org>]

Re-send in case the previous email was blocked for the inlined hyper-link.

Hi Marc,

I have tried to enable the NV support in Qemu, and now I can
successfully boot a L2 guest
in Qemu KVM mode.

This patch series looks good from the Qemu side except for two minor
requirements:
(1) Qemu will check whether a feature was supported by the KVM cap
when the user tries
     to enable it in the command line, so a new capability was
prefered for the NV(KVM_CAP_ARM_NV?).
(2) According to the Documentation/virt/kvm/api.rst, userspace can
call KVM_ARM_VCPU_INIT
     multiple times for a given vcpu, but the kvm_vcpu_init_nested()
do have some issue when
     called multiple times(please refer to the detailed comments in patch 63)

Regards,
Haibo

On Fri, 11 Dec 2020 at 00:00, Marc Zyngier <maz@kernel.org> wrote:
>
> This is a rework of the NV series that I posted 10 months ago[1], as a
> lot of the KVM code has changed since, and the series apply anymore
> (not that anybody really cares as the the HW is, as usual, made of
> unobtainium...).
>
> From the previous version:
>
> - Integration with the new page-table code
> - New exception injection code
> - No more messing with the nVHE code
> - No AArch32!!!!
> - Rebased on v5.10-rc4 + kvmarm/next for 5.11
>
> From a functionality perspective, you can expect a L2 guest to work,
> but don't even think of L3, as we only partially emulate the
> ARMv8.{3,4}-NV extensions themselves. Same thing for vgic, debug, PMU,
> as well as anything that would require a Stage-1 PTW. What we want to
> achieve is that with NV disabled, there is no performance overhead and
> no regression.
>
> The series is roughly divided in 5 parts: exception handling, memory
> virtualization, interrupts and timers for ARMv8.3, followed by the
> ARMv8.4 support. There are of course some dependencies, but you'll
> hopefully get the gist of it.
>
> For the most courageous of you, I've put out a branch[2]. Of course,
> you'll need some userspace. Andre maintains a hacked version of
> kvmtool[3] that takes a --nested option, allowing the guest to be
> started at EL2. You can run the whole stack in the Foundation
> model. Don't be in a hurry ;-).
>
> And to be clear: although Jintack and Christoffer have written tons of
> the stuff originaly, I'm the one responsible for breaking it!
>
> [1] https://lore.kernel.org/r/20200211174938.27809-1-maz@kernel.org
> [2] git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/nv-5.11.-WIP
> [3] git://linux-arm.org/kvmtool.git nv/nv-wip-5.2-rc5
>
> Andre Przywara (1):
>   KVM: arm64: nv: vgic: Allow userland to set VGIC maintenance IRQ
>
> Christoffer Dall (15):
>   KVM: arm64: nv: Introduce nested virtualization VCPU feature
>   KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set
>   KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x
>   KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state
>   KVM: arm64: nv: Reset VMPIDR_EL2 and VPIDR_EL2 to sane values
>   KVM: arm64: nv: Handle trapped ERET from virtual EL2
>   KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor
>   KVM: arm64: nv: Trap EL1 VM register accesses in virtual EL2
>   KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2
>     changes
>   KVM: arm64: nv: Implement nested Stage-2 page table walk logic
>   KVM: arm64: nv: Unmap/flush shadow stage 2 page tables
>   KVM: arm64: nv: arch_timer: Support hyp timer emulation
>   KVM: arm64: nv: vgic: Emulate the HW bit in software
>   KVM: arm64: nv: Add nested GICv3 tracepoints
>   KVM: arm64: nv: Sync nested timer state with ARMv8.4
>
> Jintack Lim (19):
>   arm64: Add ARM64_HAS_NESTED_VIRT cpufeature
>   KVM: arm64: nv: Handle HCR_EL2.NV system register traps
>   KVM: arm64: nv: Support virtual EL2 exceptions
>   KVM: arm64: nv: Inject HVC exceptions to the virtual EL2
>   KVM: arm64: nv: Trap SPSR_EL1, ELR_EL1 and VBAR_EL1 from virtual EL2
>   KVM: arm64: nv: Trap CPACR_EL1 access in virtual EL2
>   KVM: arm64: nv: Handle PSCI call via smc from the guest
>   KVM: arm64: nv: Respect virtual HCR_EL2.TWX setting
>   KVM: arm64: nv: Respect virtual CPTR_EL2.{TFP,FPEN} settings
>   KVM: arm64: nv: Respect the virtual HCR_EL2.NV bit setting
>   KVM: arm64: nv: Respect virtual HCR_EL2.TVM and TRVM settings
>   KVM: arm64: nv: Respect the virtual HCR_EL2.NV1 bit setting
>   KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2
>   KVM: arm64: nv: Configure HCR_EL2 for nested virtualization
>   KVM: arm64: nv: Introduce sys_reg_desc.forward_trap
>   KVM: arm64: nv: Set a handler for the system instruction traps
>   KVM: arm64: nv: Trap and emulate AT instructions from virtual EL2
>   KVM: arm64: nv: Trap and emulate TLBI instructions from virtual EL2
>   KVM: arm64: nv: Nested GICv3 Support
>
> Marc Zyngier (31):
>   KVM: arm64: nv: Add EL2 system registers to vcpu context
>   KVM: arm64: nv: Add non-VHE-EL2->EL1 translation helpers
>   KVM: arm64: nv: Handle virtual EL2 registers in
>     vcpu_read/write_sys_reg()
>   KVM: arm64: nv: Handle SPSR_EL2 specially
>   KVM: arm64: nv: Handle HCR_EL2.E2H specially
>   KVM: arm64: nv: Save/Restore vEL2 sysregs
>   KVM: arm64: nv: Forward debug traps to the nested guest
>   KVM: arm64: nv: Filter out unsupported features from ID regs
>   KVM: arm64: nv: Hide RAS from nested guests
>   KVM: arm64: nv: Support multiple nested Stage-2 mmu structures
>   KVM: arm64: nv: Handle shadow stage 2 page faults
>   KVM: arm64: nv: Restrict S2 RD/WR permissions to match the guest's
>   KVM: arm64: nv: Fold guest's HCR_EL2 configuration into the host's
>   KVM: arm64: nv: Add handling of EL2-specific timer registers
>   KVM: arm64: nv: Load timer before the GIC
>   KVM: arm64: nv: Don't load the GICv4 context on entering a nested
>     guest
>   KVM: arm64: nv: Implement maintenance interrupt forwarding
>   KVM: arm64: nv: Allow userspace to request KVM_ARM_VCPU_NESTED_VIRT
>   KVM: arm64: nv: Add handling of ARMv8.4-TTL TLB invalidation
>   KVM: arm64: nv: Invalidate TLBs based on shadow S2 TTL-like
>     information
>   KVM: arm64: Allow populating S2 SW bits
>   KVM: arm64: nv: Tag shadow S2 entries with nested level
>   KVM: arm64: nv: Add include containing the VNCR_EL2 offsets
>   KVM: arm64: Map VNCR-capable registers to a separate page
>   KVM: arm64: nv: Move nested vgic state into the sysreg file
>   KVM: arm64: Add ARMv8.4 Enhanced Nested Virt cpufeature
>   KVM: arm64: nv: Synchronize PSTATE early on exit
>   KVM: arm64: nv: Allocate VNCR page when required
>   KVM: arm64: nv: Enable ARMv8.4-NV support
>   KVM: arm64: nv: Fast-track 'InHost' exception returns
>   KVM: arm64: nv: Fast-track EL1 TLBIs for VHE guests
>
>  .../admin-guide/kernel-parameters.txt         |    4 +
>  .../virt/kvm/devices/arm-vgic-v3.rst          |   12 +-
>  arch/arm64/include/asm/cpucaps.h              |    2 +
>  arch/arm64/include/asm/esr.h                  |    6 +
>  arch/arm64/include/asm/kvm_arm.h              |   28 +-
>  arch/arm64/include/asm/kvm_asm.h              |    4 +
>  arch/arm64/include/asm/kvm_emulate.h          |  145 +-
>  arch/arm64/include/asm/kvm_host.h             |  175 ++-
>  arch/arm64/include/asm/kvm_hyp.h              |    2 +
>  arch/arm64/include/asm/kvm_mmu.h              |   17 +-
>  arch/arm64/include/asm/kvm_nested.h           |  152 ++
>  arch/arm64/include/asm/kvm_pgtable.h          |   10 +
>  arch/arm64/include/asm/sysreg.h               |  104 +-
>  arch/arm64/include/asm/vncr_mapping.h         |   73 +
>  arch/arm64/include/uapi/asm/kvm.h             |    2 +
>  arch/arm64/kernel/cpufeature.c                |   35 +
>  arch/arm64/kvm/Makefile                       |    4 +-
>  arch/arm64/kvm/arch_timer.c                   |  189 ++-
>  arch/arm64/kvm/arm.c                          |   34 +-
>  arch/arm64/kvm/at.c                           |  231 ++++
>  arch/arm64/kvm/emulate-nested.c               |  186 +++
>  arch/arm64/kvm/guest.c                        |    6 +
>  arch/arm64/kvm/handle_exit.c                  |   81 +-
>  arch/arm64/kvm/hyp/exception.c                |   44 +-
>  arch/arm64/kvm/hyp/include/hyp/switch.h       |   31 +-
>  arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h    |   28 +-
>  arch/arm64/kvm/hyp/nvhe/switch.c              |   10 +-
>  arch/arm64/kvm/hyp/nvhe/sysreg-sr.c           |    2 +-
>  arch/arm64/kvm/hyp/pgtable.c                  |    6 +
>  arch/arm64/kvm/hyp/vgic-v3-sr.c               |    2 +-
>  arch/arm64/kvm/hyp/vhe/switch.c               |  207 ++-
>  arch/arm64/kvm/hyp/vhe/sysreg-sr.c            |  125 +-
>  arch/arm64/kvm/hyp/vhe/tlb.c                  |   83 ++
>  arch/arm64/kvm/inject_fault.c                 |   62 +-
>  arch/arm64/kvm/mmu.c                          |  183 ++-
>  arch/arm64/kvm/nested.c                       |  908 ++++++++++++
>  arch/arm64/kvm/reset.c                        |   14 +-
>  arch/arm64/kvm/sys_regs.c                     | 1226 ++++++++++++++++-
>  arch/arm64/kvm/sys_regs.h                     |    6 +
>  arch/arm64/kvm/trace_arm.h                    |   65 +-
>  arch/arm64/kvm/vgic/vgic-init.c               |   30 +
>  arch/arm64/kvm/vgic/vgic-kvm-device.c         |   22 +
>  arch/arm64/kvm/vgic/vgic-nested-trace.h       |  137 ++
>  arch/arm64/kvm/vgic/vgic-v3-nested.c          |  240 ++++
>  arch/arm64/kvm/vgic/vgic-v3.c                 |   39 +-
>  arch/arm64/kvm/vgic/vgic.c                    |   44 +
>  arch/arm64/kvm/vgic/vgic.h                    |   10 +
>  include/kvm/arm_arch_timer.h                  |    7 +
>  include/kvm/arm_vgic.h                        |   16 +
>  tools/arch/arm/include/uapi/asm/kvm.h         |    1 +
>  50 files changed, 4890 insertions(+), 160 deletions(-)
>  create mode 100644 arch/arm64/include/asm/kvm_nested.h
>  create mode 100644 arch/arm64/include/asm/vncr_mapping.h
>  create mode 100644 arch/arm64/kvm/at.c
>  create mode 100644 arch/arm64/kvm/emulate-nested.c
>  create mode 100644 arch/arm64/kvm/nested.c
>  create mode 100644 arch/arm64/kvm/vgic/vgic-nested-trace.h
>  create mode 100644 arch/arm64/kvm/vgic/vgic-v3-nested.c
>
> --
> 2.29.2
>
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