From: Michael Kelley <mikelley@xxxxxxxxxxxxx> Sent: Monday, March 8, 2021 11:57 AM
>
> 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 interrupts 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.
ARM64 maintainers --
What are the prospects for getting your review and Ack on this patch set?
We're wanting to get the Hyper-V support on ARM64 finally accepted upstream.
Previous comments should be addressed in this revision, with perhaps a
remaining discussion point around the alternate SMCCC hypercall interface
in Patch 1 that makes use of changes in v1.2 of the SMCCC spec. There are
several viable approaches that I've noted in the patch, depending on
your preferences.
Michael
>
> The seven patches are organized as follows:
>
> 1) Update include/linux/arm-smccc.h to provide an HVC wrapper
> variant that returns results in other than X0 thru X3
>
> 2) Add definitions and functions for making Hyper-V hypercalls
> and getting/setting virtual processor registers provided by
> Hyper-V
>
> 3) Add architecture specific definitions needed by the
> architecture independent Hyper-V clocksource driver in
> drivers/clocksource/hyperv_timer.c. Update the clocksource
> driver to be initialized on ARM64.
>
> 4) Add functions needed by the arch independent VMbus driver
> for reporting a panic to Hyper-V and as stubs for the kexec
> and crash handlers.
>
> 5) Add Hyper-V initialization code and utility functions that
> report Hyper-v status.
>
> 6) Export screen_info so it may be used by the Hyper-V frame buffer
> driver built as a module. It is already exported for x86,
> powerpc, and alpha architectures.
>
> 7) Make CONFIG_HYPERV selectable on ARM64 in addition to x86/x64.
>
> Hyper-V on ARM64 runs with a 4 Kbyte page size, but allows guests
> with 4K/16K/64K page size. Linux guests with this ARM64 enablement
> code work with all three supported ARM64 page sizes.
>
> The Hyper-V vPCI driver at drivers/pci/host/pci-hyperv.c has
> x86/x64-specific code and is not being built for ARM64. Fixing
> this driver to enable vPCI devices on ARM64 will be done later.
>
> 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.
>
> This patch set is based on the hyperv-next branch of the code tree
> https://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux.git/
>
> Changes in v9:
> * Added Patch 1 to enable making an SMCCC compliant hypercall
> that returns results in other than registers X0 thru X3, per
> version 1.2 and later of the SMCCC spec.
> * Using the ability to return results in registers X6 and X7,
> converted hv_get_vpreg_128() to use a "fast" hypercall that
> passes inputs and outputs in registers, and in doing so eliminated
> a lot of memory allocation complexity.
> * Cleaned up some extra blank lines and use of spaces in aligning
> local variables. [Sunil Muthuswamy]
> * Based on discussion about future directions, reverted the
> population of hv_vp_index array to use a cpuhp state instead
> of a hypercall, which is like it was in v7 and earlier.
>
> Changes in v8:
> * Removed a lot of code based on refactoring the boundary between
> arch independent and arch dependent code for Hyper-V, per comments
> from Arnd Bergmann. The removed code was either duplicated on
> the x86 side, or has been folded into architecture independent
> code as not really being architecture dependent.
> * Added config dependency on !CONFIG_CPU_BIG_ENDIAN [Arnd Bergmann]
> * Reworked the approach to Hyper-V initialization. The functionality
> is the same, but is now structured like the Xen code with an early
> init function called in setup_arch() and an early initcall to
> finish the initialization. [Arnd Bergmann]
>
> Changes in v7:
> * Separately upstreamed split of hyperv-tlfs.h into arch dependent
> and independent versions. In this patch set, update the ARM64
> hyperv-tlfs.h to include architecture independent definitions.
> This approach eliminates a lot of lines of otherwise duplicated
> code on the ARM64 side.
> * Break ARM64 mshyperv.h into smaller pieces. Have an initial
> baseline, and add code along with patches for a particular
> functional area. [Marc Zyngier]
> * In mshyperv.h, use static inline functions instead of #defines
> where possible. [Arnd Bergmann]
> * Use VMbus INTID obtained from ACPI DSDT instead of hardcoding.
> The STIMER INTID is still hardcoded because it is needed
> before Linux has initialized the ACPI subsystem, so it can't
> be obtained from the DSDT. Wedging it into the GTDT seems
> dubious, so was not done. [Marc Zyngier]
> * Update Hyper-V page size allocation functions to use
> alloc_page() if PAGE_SIZE == HV_HYP_PAGE_SIZE [Arnd
> Bergmann]
> * Various other minor changes based on feedback and to rebase
> to latest linux-next [Marc Zyngier and Arnd Bergmann]
>
> Changes in v6:
> * Use SMCCC hypercall interface instead of direct invocation
> of HVC instruction and the Hyper-V hypercall interface
> [Marc Zyngier]
> * Reimplemented functions to alloc/free Hyper-V size pages
> using kmalloc/kfree since kmalloc now guarantees alignment of
> power of 2 size allocations [Marc Zyngier]
> * Export screen_info in arm64 architecture so it can be used
> by the Hyper-V buffer driver built as a module
> * Renamed source file arch/arm64/hyperv/hv_init.c to hv_core.c
> to better reflect its content
> * Fixed the bit position of certain feature flags presented by
> Hyper-V to the guest. The bit positions on ARM64 don't match
> the position on x86 like originally thought.
> * Minor fixups to rebase to 5.6-rc5 linux-next
>
> Changes in v5:
> * Minor fixups to rebase to 5.4-rc1 linux-next
>
> Changes in v4:
> * Moved clock-related code into an architecture independent
> Hyper-V clocksource driver that is already upstream. Clock
> related code is removed from this patch set except for the
> ARM64 specific interrupt handler. [Marc Zyngier]
> * Separately upstreamed the split of mshyperv.h into arch independent
> and arch dependent portions. The arch independent portion has been
> removed from this patch set.
> * Divided patch #2 of the series into multiple smaller patches
> [Marc Zyngier]
> * Changed a dozen or so smaller things based on feedback
> [Marc Zyngier, Will Deacon]
> * Added functions to alloc/free Hyper-V size pages for use by
> drivers for Hyper-V synthetic devices when updated to not assume
> guest page size and Hyper-v page size are the same
>
> Changes in v3:
> * Added initialization of hv_vp_index array like was recently
> added on x86 branch [KY Srinivasan]
> * Changed Hyper-V ARM64 register symbols to be all uppercase
> instead of mixed case [KY Srinivasan]
> * Separated mshyperv.h into two files, one architecture
> independent and one architecture dependent. After this code
> is upstream, will make changes to the x86 code to use the
> architecture independent file and remove duplication. And
> once we have a multi-architecture Hyper-V TLFS, will do a
> separate patch to split hyperv-tlfs.h in the same way.
> [KY Srinivasan]
> * Minor tweaks to rebase to latest linux-next code
>
> Changes in v2:
> * Removed patch to implement slow_virt_to_phys() on ARM64.
> Use of slow_virt_to_phys() in arch independent Hyper-V
> drivers has been eliminated by commit 6ba34171bcbd
> ("Drivers: hv: vmbus: Remove use of slow_virt_to_phys()")
> * Minor tweaks to rebase to latest linux-next code
> *** BLURB HERE ***
>
> Michael Kelley (7):
> smccc: Add HVC call variant with result registers other than 0 thru 3
> arm64: hyperv: Add Hyper-V hypercall and register access utilities
> arm64: hyperv: Add Hyper-V clocksource/clockevent support
> arm64: hyperv: Add kexec and panic handlers
> arm64: hyperv: Initialize hypervisor on boot
> arm64: efi: Export screen_info
> Drivers: hv: Enable Hyper-V code to be built on ARM64
>
> MAINTAINERS | 3 +
> arch/arm64/Kbuild | 1 +
> arch/arm64/hyperv/Makefile | 2 +
> arch/arm64/hyperv/hv_core.c | 178 +++++++++++++++++++++++++++++++++++
> arch/arm64/hyperv/mshyperv.c | 173 ++++++++++++++++++++++++++++++++++
> arch/arm64/include/asm/hyperv-tlfs.h | 69 ++++++++++++++
> arch/arm64/include/asm/mshyperv.h | 72 ++++++++++++++
> arch/arm64/kernel/efi.c | 1 +
> arch/arm64/kernel/setup.c | 4 +
> drivers/clocksource/hyperv_timer.c | 14 +++
> drivers/hv/Kconfig | 3 +-
> include/linux/arm-smccc.h | 29 ++++--
> 12 files changed, 542 insertions(+), 7 deletions(-)
> create mode 100644 arch/arm64/hyperv/Makefile
> create mode 100644 arch/arm64/hyperv/hv_core.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
>
> --
> 1.8.3.1
