Hyper-V: Enable Linux guests on Hyper-V on ARM64

From: "K. Y. Srinivasan" <[email protected]>

This series enables Linux guests running on Hyper-V on ARM64 hardware. New ARM64-specific code in arch/arm64/hyperv initializes Hyper-V, including its synthetic clocks and hypercall mechanism. Existing architecture independent drivers for Hyper-V's VMbus and synthetic devices just work when built for ARM64. Hyper-V code is built and included in the image and modules only if CONFIG_HYPERV is enabled.

The four patches are organized as follows:
1) Add include files that define the Hyper-V interface as described in the Hyper-V Top Level Functional Spec (TLFS), plus additional definitions specific to Linux running on Hyper-V.

2) Add core Hyper-V support on ARM64, including hypercalls, synthetic clock initialization, and interrupt handlers.

3) Update the existing VMbus driver to generalize interrupt management across x86/x64 and ARM64.

4) Make CONFIG_HYPERV selectable on ARM64 in addition to x86/x64.

Some areas of Linux guests on Hyper-V on ARM64 are a work- in-progress, primarily due to work still being done in Hyper-V:

* Hyper-V on ARM64 currently runs with a 4 Kbyte page size, and only supports guests with a 4 Kbyte page size. Because Hyper-V uses shared pages to communicate between the guest and the hypervisor, there are open design decisions on the page size to use when the guest is using 16K/64K pages. Once those issues are resolved and Hyper-V fully supports 16K/64K guest pages, changes may be needed in the Linux drivers for Hyper-V synthetic devices.

* Hyper-V on ARM64 does not currently support mapping PCI devices into the guest address space. The Hyper-V PCI driver at drivers/pci/host/pci-hyperv.c has x86/x64-specific code and is not being built for ARM64.

In a few cases, terminology from the x86/x64 world has been carried over into the ARM64 code ("MSR", "TSC"). Hyper-V still uses the x86/x64 terminology and has not replaced it with something more generic, so the code uses the Hyper-V terminology. This will be fixed when Hyper-V updates the usage in the TLFS.

Michael Kelley (4):
arm64: hyperv: Add core Hyper-V include files
arm64: hyperv: Add support for Hyper-V as a hypervisor
Drivers: hv: vmbus: Add hooks for per-CPU IRQ
Drivers: hv: Enable CONFIG_HYPERV on ARM64

 MAINTAINERS                          |   4 +
 arch/arm64/Makefile                  |   1 +
 arch/arm64/hyperv/Makefile           |   2 +
 arch/arm64/hyperv/hv_hvc.S           |  54 ++++
 arch/arm64/hyperv/hv_init.c          | 441 +++++++++++++++++++++++++++
 arch/arm64/hyperv/mshyperv.c         | 178 +++++++++++
 arch/arm64/include/asm/hyperv-tlfs.h | 338 ++++++++++++++++++++
 arch/arm64/include/asm/mshyperv.h    | 116 +++++++
 arch/x86/include/asm/mshyperv.h      |   4 +
 drivers/hv/Kconfig                   |   3 +-
 drivers/hv/hv.c                      |   2 +
 include/asm-generic/mshyperv.h       | 240 +++++++++++++++
 12 files changed, 1382 insertions(+), 1 deletion(-)
 create mode 100644 arch/arm64/hyperv/Makefile
 create mode 100644 arch/arm64/hyperv/hv_hvc.S
 create mode 100644 arch/arm64/hyperv/hv_init.c
 create mode 100644 arch/arm64/hyperv/mshyperv.c
 create mode 100644 arch/arm64/include/asm/hyperv-tlfs.h
 create mode 100644 arch/arm64/include/asm/mshyperv.h
 create mode 100644 include/asm-generic/mshyperv.h

2.19.1