Re: [PATCH 00/31] KVM/MIPS: Implement hardware virtualization via the MIPS-VZ extensions.

[Gleb Natapov <gleb@redhat.com>]

On Fri, Jun 07, 2013 at 04:15:00PM -0700, David Daney wrote:
> I should also add that I will shortly send patches for the kvm tool
> required to drive this VM as well as a small set of patches that
> create a para-virtualized MIPS/Linux guest kernel.
> 
> The idea is that because there is no standard SMP linux system, we
> create a standard para-virtualized system that uses a handful of
> hypercalls, but mostly just uses virtio devices.  It has no emulated
> real hardware (no 8250 UART, no emulated legacy anything...)
> 
Virtualization is useful for running legacy code. Why dismiss support
for non pv guests so easily? How different MIPS SMP systems are? What
about running non pv UP systems?

> David Daney
> 
> 
> On 06/07/2013 04:03 PM, David Daney wrote:
> >From: David Daney <david.daney@cavium.com>
> >
> >These patches take a somewhat different approach to MIPS
> >virtualization via the MIPS-VZ extensions than the patches previously
> >sent by Sanjay Lal.
> >
> >Several facts about the code:
> >
> >o Existing exception handlers are modified to hook in to KVM instead
> >   of intercepting all exceptions via the EBase register, and then
> >   chaining to real exception handlers.
> >
> >o Able to boot 64-bit SMP guests that use the FPU (I have booted 4-way
> >   SMP 64-bit MIPS/Linux).
> >
> >o Additional overhead on every exception even when *no* vCPU is running.
> >
> >o Lower interrupt overhead, than the EBase interception method, when
> >   vCPU *is* running.
> >
> >o This code is somewhat smaller than the existing trap/emulate
> >   implementation (about 2100 lines vs. about 5300 lines)
> >
> >o Currently probably only usable on the OCTEON III CPU model, as some
> >   MIPS-VZ implementation-defined behaviors were assumed to have the
> >   OCTEON III behavior.
> >
> >Note: I think Ralf already has the 17/31 (MIPS: Quit exposing Kconfig
> >symbols in uapi headers.) queued, but I also include it here.
> >
> >David Daney (31):
> >   MIPS: Move allocate_kscratch to cpu-probe.c and make it public.
> >   MIPS: Save and restore K0/K1 when CONFIG_KVM_MIPSVZ
> >   mips/kvm: Fix 32-bitisms in kvm_locore.S
> >   mips/kvm: Add casts to avoid pointer width mismatch build failures.
> >   mips/kvm: Use generic cache flushing functions.
> >   mips/kvm: Rename kvm_vcpu_arch.pc to  kvm_vcpu_arch.epc
> >   mips/kvm: Rename VCPU_registername to KVM_VCPU_ARCH_registername
> >   mips/kvm: Fix code formatting in arch/mips/kvm/kvm_locore.S
> >   mips/kvm: Factor trap-and-emulate support into a pluggable
> >     implementation.
> >   mips/kvm: Implement ioctls to get and set FPU registers.
> >   MIPS: Rearrange branch.c so it can be used by kvm code.
> >   MIPS: Add instruction format information for WAIT, MTC0, MFC0, et al.
> >   mips/kvm: Add accessors for MIPS VZ registers.
> >   mips/kvm: Add thread_info flag to indicate operation in MIPS VZ Guest
> >     Mode.
> >   mips/kvm: Exception handling to leave and reenter guest mode.
> >   mips/kvm: Add exception handler for MIPSVZ Guest exceptions.
> >   MIPS: Quit exposing Kconfig symbols in uapi headers.
> >   mips/kvm: Add pt_regs slots for BadInstr and BadInstrP
> >   mips/kvm: Add host definitions for MIPS VZ based host.
> >   mips/kvm: Hook into TLB fault handlers.
> >   mips/kvm: Allow set_except_vector() to be used from MIPSVZ code.
> >   mips/kvm: Split get_new_mmu_context into two parts.
> >   mips/kvm: Hook into CP unusable exception handler.
> >   mips/kvm: Add thread_struct fields used by MIPSVZ hosts.
> >   mips/kvm: Add some asm-offsets constants used by MIPSVZ.
> >   mips/kvm: Split up Kconfig and Makefile definitions in preperation
> >     for MIPSVZ.
> >   mips/kvm: Gate the use of kvm_local_flush_tlb_all() by KVM_MIPSTE
> >   mips/kvm: Only use KVM_COALESCED_MMIO_PAGE_OFFSET with KVM_MIPSTE
> >   mips/kvm: Add MIPSVZ support.
> >   mips/kvm: Enable MIPSVZ in Kconfig/Makefile
> >   mips/kvm: Allow for upto 8 KVM vcpus per vm.
> >
> >  arch/mips/Kconfig                   |    1 +
> >  arch/mips/include/asm/branch.h      |    7 +
> >  arch/mips/include/asm/kvm_host.h    |  622 +-----------
> >  arch/mips/include/asm/kvm_mips_te.h |  589 +++++++++++
> >  arch/mips/include/asm/kvm_mips_vz.h |   29 +
> >  arch/mips/include/asm/mipsregs.h    |  264 +++++
> >  arch/mips/include/asm/mmu_context.h |   12 +-
> >  arch/mips/include/asm/processor.h   |    6 +
> >  arch/mips/include/asm/ptrace.h      |   36 +
> >  arch/mips/include/asm/stackframe.h  |  150 ++-
> >  arch/mips/include/asm/thread_info.h |    2 +
> >  arch/mips/include/asm/uasm.h        |    2 +-
> >  arch/mips/include/uapi/asm/inst.h   |   23 +-
> >  arch/mips/include/uapi/asm/ptrace.h |   17 +-
> >  arch/mips/kernel/asm-offsets.c      |  124 ++-
> >  arch/mips/kernel/branch.c           |   63 +-
> >  arch/mips/kernel/cpu-probe.c        |   34 +
> >  arch/mips/kernel/genex.S            |    8 +
> >  arch/mips/kernel/scall64-64.S       |   12 +
> >  arch/mips/kernel/scall64-n32.S      |   12 +
> >  arch/mips/kernel/traps.c            |   15 +-
> >  arch/mips/kvm/Kconfig               |   23 +-
> >  arch/mips/kvm/Makefile              |   15 +-
> >  arch/mips/kvm/kvm_locore.S          |  980 +++++++++---------
> >  arch/mips/kvm/kvm_mips.c            |  768 ++------------
> >  arch/mips/kvm/kvm_mips_comm.h       |    1 +
> >  arch/mips/kvm/kvm_mips_commpage.c   |    9 +-
> >  arch/mips/kvm/kvm_mips_dyntrans.c   |    4 +-
> >  arch/mips/kvm/kvm_mips_emul.c       |  312 +++---
> >  arch/mips/kvm/kvm_mips_int.c        |   53 +-
> >  arch/mips/kvm/kvm_mips_int.h        |    2 -
> >  arch/mips/kvm/kvm_mips_stats.c      |    6 +-
> >  arch/mips/kvm/kvm_mipsvz.c          | 1894 +++++++++++++++++++++++++++++++++++
> >  arch/mips/kvm/kvm_mipsvz_guest.S    |  234 +++++
> >  arch/mips/kvm/kvm_tlb.c             |  140 +--
> >  arch/mips/kvm/kvm_trap_emul.c       |  932 +++++++++++++++--
> >  arch/mips/mm/fault.c                |    8 +
> >  arch/mips/mm/tlbex-fault.S          |    6 +
> >  arch/mips/mm/tlbex.c                |   45 +-
> >  39 files changed, 5299 insertions(+), 2161 deletions(-)
> >  create mode 100644 arch/mips/include/asm/kvm_mips_te.h
> >  create mode 100644 arch/mips/include/asm/kvm_mips_vz.h
> >  create mode 100644 arch/mips/kvm/kvm_mipsvz.c
> >  create mode 100644 arch/mips/kvm/kvm_mipsvz_guest.S
> >
> 
> 
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--
			Gleb.