[PATCH v2 00/21] arm64: Virtualization Host Extension support

[Marc Zyngier]

ARMv8.1 comes with the "Virtualization Host Extension" (VHE for
short), which enables simpler support of Type-2 hypervisors.

This extension allows the kernel to directly run at EL2, and
significantly reduces the number of system registers shared between
host and guest, reducing the overhead of virtualization.

In order to have the same kernel binary running on all versions of the
architecture, this series makes heavy use of runtime code patching.

The first 20 patches massage the KVM code to deal with VHE and enable
Linux to run at EL2. The last patch catches an ugly case when VHE
capable CPUs are paired with some of their less capable siblings. This
should never happen, but hey...

I have deliberately left out some of the more "advanced"
optimizations, as they are likely to distract the reviewer from the
core infrastructure, which is what I care about at the moment.

A few things to note:

- Given that the code has been almost entierely rewritten, I've
  dropped all Acks from the new patches

- GDB is currently busted on VHE systems, as it checks for version 6
  on the debug architecture, while VHE is version 7. The binutils
  people are on the case.

This has been tested on the FVP_Base_SLV-V8-A model, and based on
v4.5-rc1. I've put a branch out on:

git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/vhe

* From v1:
  - Full rewrite now that the World Switch is written in C code.
  - Dropped the "early IRQ handling" for the moment.

Marc Zyngier (21):
  arm/arm64: Add new is_kernel_in_hyp_mode predicate
  arm64: Allow the arch timer to use the HYP timer
  arm64: Add ARM64_HAS_VIRT_HOST_EXTN feature
  arm64: KVM: Skip HYP setup when already running in HYP
  arm64: KVM: VHE: Turn VTCR_EL2 setup into a reusable macro
  arm64: KVM: VHE: Patch out use of HVC
  arm64: KVM: VHE: Patch out kern_hyp_va
  arm64: KVM: VHE: Introduce unified system register accessors
  arm64: KVM: VHE: Differenciate host/guest sysreg save/restore
  arm64: KVM: VHE: Split save/restore of sysregs shared between EL1 and
    EL2
  arm64: KVM: VHE: Use unified system register accessors
  arm64: KVM: VHE: Enable minimal sysreg save/restore
  arm64: KVM: VHE: Make __fpsimd_enabled VHE aware
  arm64: KVM: VHE: Implement VHE activate/deactivate_traps
  arm64: KVM: VHE: Use unified sysreg accessors for timer
  arm64: KVM: VHE: Add fpsimd enabling on guest access
  arm64: KVM: VHE: Add alternative panic handling
  arm64: KVM: Introduce hyp_alternate_value helper
  arm64: KVM: Move most of the fault decoding to C
  arm64: VHE: Add support for running Linux in EL2 mode
  arm64: Panic when VHE and non VHE CPUs coexist

 arch/arm/include/asm/virt.h          |   5 ++
 arch/arm/kvm/arm.c                   | 151 +++++++++++++++++++------------
 arch/arm/kvm/mmu.c                   |   7 ++
 arch/arm64/Kconfig                   |  13 +++
 arch/arm64/include/asm/cpufeature.h  |   3 +-
 arch/arm64/include/asm/kvm_arm.h     |   1 +
 arch/arm64/include/asm/kvm_emulate.h |   3 +
 arch/arm64/include/asm/kvm_mmu.h     |  34 ++++++-
 arch/arm64/include/asm/virt.h        |  27 ++++++
 arch/arm64/kernel/asm-offsets.c      |   3 -
 arch/arm64/kernel/cpufeature.c       |  15 +++-
 arch/arm64/kernel/head.S             |  51 ++++++++++-
 arch/arm64/kernel/smp.c              |   3 +
 arch/arm64/kvm/hyp-init.S            |  18 +---
 arch/arm64/kvm/hyp.S                 |   7 ++
 arch/arm64/kvm/hyp/entry.S           |   6 ++
 arch/arm64/kvm/hyp/hyp-entry.S       | 107 +++++++---------------
 arch/arm64/kvm/hyp/hyp.h             | 119 ++++++++++++++++++++++--
 arch/arm64/kvm/hyp/switch.c          | 170 +++++++++++++++++++++++++++++++----
 arch/arm64/kvm/hyp/sysreg-sr.c       | 147 ++++++++++++++++++++----------
 arch/arm64/kvm/hyp/timer-sr.c        |  10 +--
 drivers/clocksource/arm_arch_timer.c |  96 ++++++++++++--------
 22 files changed, 724 insertions(+), 272 deletions(-)

-- 
2.1.4