Re: [PATCH v12 0/6] 2nd-request for review comments: arm/KVM: dirty page logging support for ARMv7 (

[Mario Smarduch <m.smarduch@samsung.com>]

Architecture maintainers (the To: folks) please provide your comments.
This patch series has gone through quite a few itterations it
would be nice to see the light at the end of the tunnel.

Thanks.
  Mario


On 10/22/2014 03:34 PM, Mario Smarduch wrote:
> This patch series introduces dirty page logging for ARMv7 and adds some degree 
> of generic dirty logging support for x86, armv7 and later armv8.
> 
> I implemented Alex's  suggestion after he took a look at the patches at kvm
> forum to simplify the generic/arch split - leaving mips, powerpc, s390, 
> (ia64 although broken) unchanged. x86/armv7 now share some dirty logging code. 
> armv8 dirty log patches have been posted and tested but for time being armv8
> is non-generic as well.
> 
> I briefly spoke to most of you at kvm forum, and this is the patch series
> I was referring to. Implementation changed from previous version (patches
> 1 & 2), those who acked previous revision, please review again.
> 
> Last 4 patches (ARM) have been rebased for newer kernel, with no signifcant
> changes.
>  
> Testing:
> - Generally live migration + checksumming of source/destination memory regions 
>   is used validate correctness. 
> - qemu machvirt, VExpress - Exynos 5440, FastModels - lmbench + dirty guest
>   memory cycling.
> - ARMv8 Foundation Model/kvmtool - Due to slight overlap in 2nd stage handlers
>   did a basic bringup using qemu.
> - x86_64 qemu  default machine model, tested migration on HP Z620, tested 
>   convergence for several dirty page rates
> 
> See https://github.com/mjsmar/arm-dirtylog-tests
>     - Dirtlogtest-setup.pdf for ARMv7
>     - https://github.com/mjsmar/arm-dirtylog-tests/tree/master/v7 - README
> 
> The patch affects armv7,armv8, mips, ia64, powerpc, s390, x86_64. Patch
> series has been compiled for affected architectures:
> 
> - x86_64 - defconfig 
> - ia64 - ia64-linux-gcc4.6.3 - defconfig, ia64 Kconfig defines BROKEN worked 
>   around that to make sure new changes don't break build. Eventually build
>   breaks due to other reasons.
> - mips - mips64-linux-gcc4.6.3 - malta_kvm_defconfig
> - ppc - powerpc64-linux-gcc4.6.3 - pseries_defconfig
> - s390 - s390x-linux-gcc4.6.3 - defconfig
> - armv8 - aarch64-linux-gnu-gcc4.8.1 - defconfig
> 
> ARMv7 Dirty page logging implementation overivew-
> - initially write protects VM RAM memory region - 2nd stage page tables
> - add support to read dirty page log and again write protect the dirty pages 
>   - second stage page table for next pass.
> - second stage huge page are dissolved into small page tables to keep track of
>   dirty pages at page granularity. Tracking at huge page granularity limits
>   migration to an almost idle system. Small page size logging supports higher 
>   memory dirty rates.
> - In the event migration is canceled, normal behavior is resumed huge pages
>   are rebuilt over time.
> 
> Changes since v11:
> - Implemented Alex's comments to simplify generic layer.
> 
> Changes since v10:
> - addressed wanghaibin comments 
> - addressed Christoffers comments
> 
> Changes since v9:
> - Split patches into generic and architecture specific variants for TLB Flushing
>   and dirty log read (patches 1,2 & 3,4,5,6)
> - rebased to 3.16.0-rc1
> - Applied Christoffers comments.
> 
> Mario Smarduch (6):
>   KVM: Add architecture-defined TLB flush support
>   KVM: Add generic support for dirty page logging
>   arm: KVM: Add ARMv7 API to flush TLBs
>   arm: KVM: Add initial dirty page locking infrastructure
>   arm: KVM: dirty log read write protect support
>   arm: KVM: ARMv7 dirty page logging 2nd stage page fault
> 
>  arch/arm/include/asm/kvm_asm.h        |    1 +
>  arch/arm/include/asm/kvm_host.h       |   14 +++
>  arch/arm/include/asm/kvm_mmu.h        |   20 ++++
>  arch/arm/include/asm/pgtable-3level.h |    1 +
>  arch/arm/kvm/Kconfig                  |    2 +
>  arch/arm/kvm/Makefile                 |    1 +
>  arch/arm/kvm/arm.c                    |    2 +
>  arch/arm/kvm/interrupts.S             |   11 ++
>  arch/arm/kvm/mmu.c                    |  209 +++++++++++++++++++++++++++++++--
>  arch/x86/include/asm/kvm_host.h       |    3 -
>  arch/x86/kvm/Kconfig                  |    1 +
>  arch/x86/kvm/Makefile                 |    1 +
>  arch/x86/kvm/x86.c                    |   86 --------------
>  include/linux/kvm_host.h              |    4 +
>  virt/kvm/Kconfig                      |    6 +
>  virt/kvm/dirtylog.c                   |  112 ++++++++++++++++++
>  virt/kvm/kvm_main.c                   |    2 +
>  17 files changed, 380 insertions(+), 96 deletions(-)
>  create mode 100644 virt/kvm/dirtylog.c
>