KVM: arm/arm64: vgic: Improvements and optimizations

We can improve the performance of our VGIC implementation a bit and clean up a lot of the implementation while we're at it.

At first, patch 1 may seem excessive for a single register, the VMCR, but while it adds complexity it does move logic out of the critical path and into the vcpu_load/put hooks, which are executed much more rarely. It also provides an infrastructure to move more things into the vgic_load/put functions later one.

Avoiding the need to take a spinlock in the common case where there are no virtual interrupts in flight are actually measurable and well worth the effort.

The implementation cleanups boil down to maintaining a single count of the used LRs instead of an additional bitmap, avoiding the need to deal with the MISR and EISR fields, and doing an early init of the VGIC to avoid a number of vgic_initialized() checks.

Tested on Mustang and TC2, and Thunder-X.

Changelogs are in the patches.

Patches also available on:
git://git.kernel.org/pub/scm/linux/kernel/git/cdall/linux.git gic-optimize-v2

Thanks,
-Christoffer

Christoffer Dall (9):
KVM: arm/arm64: vgic: Defer touching GICH_VMCR to vcpu_load/put
KVM: arm/arm64: vgic: Get rid of live_lrs
KVM: arm/arm64: vgic: Only set underflow when actually out of LRs
KVM: arm/arm64: vgic: Get rid of unnecessary process_maintenance
operation
KVM: arm/arm64: vgic: Get rid of unnecessary save_maint_int_state
KVM: arm/arm64: vgic: Get rid of MISR and EISR fields
KVM: arm/arm64: vgic: Implement early VGIC init functionality
KVM: arm/arm64: vgic: Don't check vgic_initialized in sync/flush
KVM: arm/arm64: vgic: Improve sync_hwstate performance

Shih-Wei Li (1):
KVM: arm/arm64: vgic: Avoid flushing vgic state when there's no
pending IRQ

 arch/arm/include/asm/kvm_asm.h   |   3 ++
 arch/arm/kvm/arm.c               |  11 ++--
 arch/arm64/include/asm/kvm_asm.h |   2 +
 include/kvm/arm_vgic.h           |   9 ++--
 virt/kvm/arm/hyp/vgic-v2-sr.c    |  78 +++-------------------------
 virt/kvm/arm/hyp/vgic-v3-sr.c    |  79 +++++++---------------------
 virt/kvm/arm/vgic/vgic-init.c    | 108 ++++++++++++++++++++++++---------------
 virt/kvm/arm/vgic/vgic-v2.c      |  90 ++++++++++++++------------------
 virt/kvm/arm/vgic/vgic-v3.c      |  80 ++++++++++++++---------------
 virt/kvm/arm/vgic/vgic.c         |  60 ++++++++++++++++------
 virt/kvm/arm/vgic/vgic.h         |   8 ++-
 11 files changed, 234 insertions(+), 294 deletions(-)

2.9.0