Re: [PATCH v6 00/48] KVM: PPC: Book3S: C-ify the P9 entry/exit code

[Nicholas Piggin <npiggin@gmail.com>]

Excerpts from Nicholas Piggin's message of April 5, 2021 11:19 am:
> Git tree here
> 
> https://github.com/npiggin/linux/tree/kvm-in-c-v6
> 

In the interest of making things more managable, I would like to submit 
some initial things for merge, which have mostly had pretty good review
(I'll repost them in a new series or set of series if there is no
objection, rather than pick from this series).

> Nicholas Piggin (48):
>   KVM: PPC: Book3S HV: Nested move LPCR sanitising to sanitise_hv_regs
>   KVM: PPC: Book3S HV: Add a function to filter guest LPCR bits
>   KVM: PPC: Book3S HV: Disallow LPCR[AIL] to be set to 1 or 2
>   KVM: PPC: Book3S HV: Prevent radix guests setting LPCR[TC]
>   KVM: PPC: Book3S HV: Remove redundant mtspr PSPB
>   KVM: PPC: Book3S HV: remove unused kvmppc_h_protect argument
>   KVM: PPC: Book3S HV: Fix CONFIG_SPAPR_TCE_IOMMU=n default hcalls
>   powerpc/64s: Remove KVM handler support from CBE_RAS interrupts
>   powerpc/64s: remove KVM SKIP test from instruction breakpoint handler
>   KVM: PPC: Book3S HV: Ensure MSR[ME] is always set in guest MSR
>   KVM: PPC: Book3S HV: Ensure MSR[HV] is always clear in guest MSR

1-11 are pretty small, mostly isolated improvements.

>   KVM: PPC: Book3S 64: move KVM interrupt entry to a common entry point
>   KVM: PPC: Book3S 64: Move GUEST_MODE_SKIP test into KVM
>   KVM: PPC: Book3S 64: add hcall interrupt handler
>   KVM: PPC: Book3S 64: Move hcall early register setup to KVM
>   KVM: PPC: Book3S 64: Move interrupt early register setup to KVM
>   KVM: PPC: Book3S 64: move bad_host_intr check to HV handler
>   KVM: PPC: Book3S 64: Minimise hcall handler calling convention
>     differences

12-18 includes all the exception-64s.S <-> KVM API changes required. I 
think these changes are improvements in their own right, certainly the 
exception-64s.S side is far nicer.

>   KVM: PPC: Book3S HV P9: Move radix MMU switching instructions together

19 I would like to include because these MMU SPRs have a special 
relationship that can't just be set in any order. This code is also much 
better suited to sim and prototyping work for proposed changes to the 
MMU context switching architecture.

>   KVM: PPC: Book3S HV P9: implement kvmppc_xive_pull_vcpu in C
>   KVM: PPC: Book3S HV P9: Move xive vcpu context management into
>     kvmhv_p9_guest_entry

20-21 are stand-alone, I think they're good. Existing asm is duplicated 
in C but the C documents it and anyway matches its inverse which is 
already in C.

And I think it's better to be doing CI MMIOs while we're still mostly in 
host context.

>   KVM: PPC: Book3S HV P9: Stop handling hcalls in real-mode in the P9
>     path

22 move down together with Implement the rest of the P9 path in C.

>   KVM: PPC: Book3S HV P9: Move setting HDEC after switching to guest
>     LPCR
>   KVM: PPC: Book3S HV P9: Use large decrementer for HDEC
>   KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer
>     read
>   KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit
>   KVM: PPC: Book3S HV P9: Reduce irq_work vs guest decrementer races
>   KMV: PPC: Book3S HV: Use set_dec to set decrementer to host
>   powerpc/time: add API for KVM to re-arm the host timer/decrementer

23-29 try to get all these timekeeping things in. They ended up being 
mostly unrelated to the C conversion but the way I started out writing 
the C conversion, these changes fell out and ended up collecting here. I 
think they're generally improvements.

That leaves about 20 patches remaining. Of those, only about the first 5 
are necessary to reimplement the existing P9 path functionality in C, 
which is a lot less scary than nearly 50.

Thanks,
Nick

>   KVM: PPC: Book3S HV P9: Implement the rest of the P9 path in C
>   KVM: PPC: Book3S HV P9: inline kvmhv_load_hv_regs_and_go into
>     __kvmhv_vcpu_entry_p9
>   KVM: PPC: Book3S HV P9: Read machine check registers while MSR[RI] is
>     0
>   KVM: PPC: Book3S HV P9: Improve exit timing accounting coverage
>   KVM: PPC: Book3S HV P9: Move SPR loading after expiry time check
>   KVM: PPC: Book3S HV P9: Add helpers for OS SPR handling
>   KVM: PPC: Book3S HV P9: Switch to guest MMU context as late as
>     possible
>   KVM: PPC: Book3S HV: Implement radix prefetch workaround by disabling
>     MMU
>   KVM: PPC: Book3S HV: Remove support for dependent threads mode on P9
>   KVM: PPC: Book3S HV: Remove radix guest support from P7/8 path
>   KVM: PPC: Book3S HV: Remove virt mode checks from real mode handlers
>   KVM: PPC: Book3S HV: Remove unused nested HV tests in XICS emulation
>   KVM: PPC: Book3S HV P9: Allow all P9 processors to enable nested HV
>   KVM: PPC: Book3S HV: small pseries_do_hcall cleanup
>   KVM: PPC: Book3S HV: add virtual mode handlers for HPT hcalls and page
>     faults
>   KVM: PPC: Book3S HV P9: Reflect userspace hcalls to hash guests to
>     support PR KVM
>   KVM: PPC: Book3S HV P9: implement hash guest support
>   KVM: PPC: Book3S HV P9: implement hash host / hash guest support
>   KVM: PPC: Book3S HV: remove ISA v3.0 and v3.1 support from P7/8 path
> 
>  arch/powerpc/include/asm/asm-prototypes.h |   3 +-
>  arch/powerpc/include/asm/exception-64s.h  |  13 +
>  arch/powerpc/include/asm/kvm_asm.h        |   3 +-
>  arch/powerpc/include/asm/kvm_book3s.h     |   2 +
>  arch/powerpc/include/asm/kvm_book3s_64.h  |   8 +
>  arch/powerpc/include/asm/kvm_host.h       |   8 +-
>  arch/powerpc/include/asm/kvm_ppc.h        |  21 +-
>  arch/powerpc/include/asm/mmu_context.h    |   6 -
>  arch/powerpc/include/asm/time.h           |  11 +
>  arch/powerpc/kernel/asm-offsets.c         |   1 -
>  arch/powerpc/kernel/exceptions-64s.S      | 257 ++-----
>  arch/powerpc/kernel/security.c            |   5 +-
>  arch/powerpc/kernel/time.c                |  43 +-
>  arch/powerpc/kvm/Makefile                 |   4 +
>  arch/powerpc/kvm/book3s.c                 |  17 +-
>  arch/powerpc/kvm/book3s_64_entry.S        | 409 +++++++++++
>  arch/powerpc/kvm/book3s_64_vio_hv.c       |  12 -
>  arch/powerpc/kvm/book3s_hv.c              | 782 ++++++++++++----------
>  arch/powerpc/kvm/book3s_hv_builtin.c      | 138 +---
>  arch/powerpc/kvm/book3s_hv_interrupt.c    | 529 +++++++++++++++
>  arch/powerpc/kvm/book3s_hv_interrupts.S   |   9 +-
>  arch/powerpc/kvm/book3s_hv_nested.c       |  37 +-
>  arch/powerpc/kvm/book3s_hv_ras.c          |   2 +
>  arch/powerpc/kvm/book3s_hv_rm_mmu.c       |  15 +-
>  arch/powerpc/kvm/book3s_hv_rm_xics.c      |  15 -
>  arch/powerpc/kvm/book3s_hv_rmhandlers.S   | 682 +------------------
>  arch/powerpc/kvm/book3s_segment.S         |   3 +
>  arch/powerpc/kvm/book3s_xive.c            | 113 +++-
>  arch/powerpc/kvm/book3s_xive.h            |   7 -
>  arch/powerpc/kvm/book3s_xive_native.c     |  10 -
>  arch/powerpc/mm/book3s64/radix_pgtable.c  |  27 +-
>  arch/powerpc/mm/book3s64/radix_tlb.c      |  46 --
>  arch/powerpc/mm/mmu_context.c             |   4 +-
>  arch/powerpc/platforms/powernv/idle.c     |  52 +-
>  34 files changed, 1735 insertions(+), 1559 deletions(-)
>  create mode 100644 arch/powerpc/kvm/book3s_64_entry.S
>  create mode 100644 arch/powerpc/kvm/book3s_hv_interrupt.c
> 
> -- 
> 2.23.0
> 
>