arm: dirty page logging support for ARMv7

This patch adds support for ARMv7 dirty page logging. Some functions of dirty page logging have been split to generic and arch specific implementations, details below. Dirty page logging is one of serveral features required for live migration, live migration has been tested for ARMv7.

Testing:
- 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 and memory test.
- x86_64 QEMU basic migration on same platform.

See https://github.com/mjsmar/arm-migration-howto for details testing and setup (see 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 support overivew-
- initially write protects VM RAM memory regions - 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.
- In the event migration is canceled, normal behavior is resumed huge pages are rebuilt over time.

- Future Work
o Completed ARMv8 additions - need to validate, on hardware juno
o ARMv8 Validation test - with no migration support yet, implement replication of memory DB using dirty page logging in HA environment.

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-specific TLB flush implementations
KVM: Add generic implementation of kvm_vm_ioctl_get_dirty_log
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                  |    1 +
 arch/arm/kvm/arm.c                    |   13 ++-
 arch/arm/kvm/interrupts.S             |   12 ++
 arch/arm/kvm/mmu.c                    |  196 ++++++++++++++++++++++++++++++++-
 arch/arm64/kvm/Kconfig                |    1 +
 arch/ia64/kvm/Kconfig                 |    1 +
 arch/ia64/kvm/kvm-ia64.c              |    2 +-
 arch/mips/kvm/Kconfig                 |    1 +
 arch/mips/kvm/mips.c                  |    2 +-
 arch/powerpc/kvm/Kconfig              |    1 +
 arch/powerpc/kvm/book3s.c             |    2 +-
 arch/powerpc/kvm/booke.c              |    2 +-
 arch/s390/kvm/Kconfig                 |    1 +
 arch/s390/kvm/kvm-s390.c              |    2 +-
 arch/x86/kvm/x86.c                    |   86 ---------------
 include/linux/kvm_host.h              |    7 ++
 virt/kvm/Kconfig                      |    6 +
 virt/kvm/kvm_main.c                   |   95 ++++++++++++++++
 22 files changed, 369 insertions(+), 98 deletions(-)

1.7.9.5