On Thu, Jul 1, 2010 at 4:12 PM, Alexander Graf <agraf@xxxxxxx> wrote:
> On PPC we run PR=0 (kernel mode) code in PR=1 (user mode) and don't use the
> hypervisor extensions.
>
> While that is all great to show that virtualization is possible, there are
> quite some cases where the emulation overhead of privileged instructions is
> killing performance.
>
> This patchset tackles exactly that issue. It introduces a paravirtual framework
> using which KVM and Linux share a page to exchange register state with. That
KVM and Linux or KVM and GuestOS ?
> way we don't have to switch to the hypervisor just to change a value of a
> privileged register.
>
> To prove my point, I ran the same test I did for the MMU optimizations against
> the PV framework. Here are the results:
>
> [without]
>
> debian-powerpc:~# time for i in {1..1000}; do /bin/echo hello > /dev/null; done
>
> real 0m14.659s
> user 0m8.967s
> sys 0m5.688s
>
> [with]
>
> debian-powerpc:~# time for i in {1..1000}; do /bin/echo hello > /dev/null; done
>
> real 0m7.557s
> user 0m4.121s
> sys 0m3.426s
>
>
> So this is a significant performance improvement! I'm quite happy how fast this
> whole thing becomes :)
>
> I tried to take all comments I've heard from people so far about such a PV
> framework into account. In case you told me something before that is a no-go
> and I still did it, please just tell me again.
>
> Now go and have fun with fast VMs on PPC! Get yourself a G5 on ebay and start
> experiencing the power yourself. - heh
>
> v1 -> v2:
>
> - change hypervisor calls to use r0 and r3
> - make crit detection only trigger in supervisor mode
> - RMO -> PAM
> - introduce kvm_patch_ins
> - only flush icache when patching
> - introduce kvm_patch_ins_b
> - update documentation
>
> Alexander Graf (27):
> KVM: PPC: Introduce shared page
> KVM: PPC: Convert MSR to shared page
> KVM: PPC: Convert DSISR to shared page
> KVM: PPC: Convert DAR to shared page.
> KVM: PPC: Convert SRR0 and SRR1 to shared page
> KVM: PPC: Convert SPRG[0-4] to shared page
> KVM: PPC: Implement hypervisor interface
> KVM: PPC: Add PV guest critical sections
> KVM: PPC: Add PV guest scratch registers
> KVM: PPC: Tell guest about pending interrupts
> KVM: PPC: Make RMO a define
> KVM: PPC: First magic page steps
> KVM: PPC: Magic Page Book3s support
> KVM: PPC: Magic Page BookE support
> KVM: PPC: Expose magic page support to guest
> KVM: Move kvm_guest_init out of generic code
> KVM: PPC: Generic KVM PV guest support
> KVM: PPC: KVM PV guest stubs
> KVM: PPC: PV instructions to loads and stores
> KVM: PPC: PV tlbsync to nop
> KVM: PPC: Introduce kvm_tmp framework
> KVM: PPC: Introduce branch patching helper
> KVM: PPC: PV assembler helpers
> KVM: PPC: PV mtmsrd L=1
> KVM: PPC: PV mtmsrd L=0 and mtmsr
> KVM: PPC: PV wrteei
> KVM: PPC: Add Documentation about PV interface
>
> Documentation/kvm/ppc-pv.txt | 185 ++++++++++++++
> arch/powerpc/include/asm/kvm_book3s.h | 1 -
> arch/powerpc/include/asm/kvm_host.h | 15 +-
> arch/powerpc/include/asm/kvm_para.h | 121 +++++++++-
> arch/powerpc/include/asm/kvm_ppc.h | 1 +
> arch/powerpc/kernel/Makefile | 2 +
> arch/powerpc/kernel/asm-offsets.c | 18 ++-
> arch/powerpc/kernel/kvm.c | 408 ++++++++++++++++++++++++++++++
> arch/powerpc/kernel/kvm_emul.S | 237 +++++++++++++++++
> arch/powerpc/kvm/44x.c | 7 +
> arch/powerpc/kvm/44x_tlb.c | 8 +-
> arch/powerpc/kvm/book3s.c | 165 ++++++++-----
> arch/powerpc/kvm/book3s_32_mmu.c | 28 ++-
> arch/powerpc/kvm/book3s_32_mmu_host.c | 16 +-
> arch/powerpc/kvm/book3s_64_mmu.c | 42 +++-
> arch/powerpc/kvm/book3s_64_mmu_host.c | 16 +-
> arch/powerpc/kvm/book3s_emulate.c | 25 +-
> arch/powerpc/kvm/book3s_paired_singles.c | 11 +-
> arch/powerpc/kvm/booke.c | 113 +++++++--
> arch/powerpc/kvm/booke.h | 6 +-
> arch/powerpc/kvm/booke_emulate.c | 14 +-
> arch/powerpc/kvm/booke_interrupts.S | 3 +-
> arch/powerpc/kvm/e500.c | 7 +
> arch/powerpc/kvm/e500_tlb.c | 31 ++-
> arch/powerpc/kvm/e500_tlb.h | 2 +-
> arch/powerpc/kvm/emulate.c | 47 +++-
> arch/powerpc/kvm/powerpc.c | 42 +++-
> arch/powerpc/platforms/Kconfig | 10 +
> arch/x86/include/asm/kvm_para.h | 6 +
> include/linux/kvm_para.h | 7 +-
> 30 files changed, 1420 insertions(+), 174 deletions(-)
> create mode 100644 Documentation/kvm/ppc-pv.txt
> create mode 100644 arch/powerpc/kernel/kvm.c
> create mode 100644 arch/powerpc/kernel/kvm_emul.S
>
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