Re: [PATCH 0/5] Add new headers for Hyper-V Dom0

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

On 10/10/2024 11:21 AM, Michael Kelley wrote:
> From: Nuno Das Neves <nunodasneves@linux.microsoft.com> Sent: Thursday, October 3, 2024 12:51 PM
>>>> An intermediary header "hv_defs.h" is introduced to conditionally
>> include either hyperv-tlfs.h or hvhdk.h. This is required because
>> several headers which today include hyperv-tlfs.h, are shared
>> between Hyper-V and KVM code (e.g. mshyperv.h).
> 
> Have you considered user space code that uses
> include/linux/hyperv.h? Which of the two schemes will it use? That code
> needs to compile correctly on x86 and ARM64 after your changes.
> User space code includes the separate DPDK project, and some of the
> tools in the kernel tree under tools/hv. Anything that uses the
> uio_hv_generic.c driver falls into this category.
> 
Unless I misunderstand something, the uapi code isn't affected at all
by this patch set. e.g. the code in tools/hv uses include/uapi/linux/hyperv.h,
which doesn't include any other Hyper-V headers.

I'm not aware of how the DPDK project uses the Hyper-V definitions, but if it
is getting headers from uapi it should also be unaffected.

> I think there's also user space code that is built for vDSO that might pull
> in the .h files you are modifying. There are in-progress patches dealing
> with vDSO include files, such as [1]. My general comment on vDSO
> is to be careful in making #include file changes that it uses, but I'm
> not knowledgeable enough on how vDSO is built to give specific
> guidance. :-(
> 
Hmm, interesting, looks like it does get used by userspace. The tsc page
is mapped into userspace in vdso.vma.c, and read in vdso/gettimeofday.h.

That is unexpected for me, since these things aren't in uapi. However I don't
anticipate a problem. The definitions used haven't changed, just the headers
they are included from.

Thanks
Nuno

> Michael
> 
> [1] https://lore.kernel.org/lkml/20241010135146.181175-1-vincenzo.frascino@arm.com/
> 
>>
>> Summary:
>> Patch 1-2: Cleanup patches
>> Patch 3: Add the new headers (hvhdk.h, etc..) in include/hyperv/
>> Patch 4: Add hv_defs.h and use it in mshyperv.h, svm.h,
>>          hyperv_timer.h
>> Patch 5: Switch to the new headers, only in Hyper-V code
>>
>> Nuno Das Neves (5):
>>   hyperv: Move hv_connection_id to hyperv-tlfs.h
>>   hyperv: Remove unnecessary #includes
>>   hyperv: Add new Hyper-V headers
>>   hyperv: Add hv_defs.h to conditionally include hyperv-tlfs.h or
>>     hvhdk.h
>>   hyperv: Use hvhdk.h instead of hyperv-tlfs.h in Hyper-V code
>>
>>  arch/arm64/hyperv/hv_core.c              |    3 +-
>>  arch/arm64/hyperv/mshyperv.c             |    1 +
>>  arch/arm64/include/asm/mshyperv.h        |    2 +-
>>  arch/x86/entry/vdso/vma.c                |    1 +
>>  arch/x86/hyperv/hv_apic.c                |    2 +-
>>  arch/x86/hyperv/hv_init.c                |    3 +-
>>  arch/x86/hyperv/hv_proc.c                |    4 +-
>>  arch/x86/hyperv/hv_spinlock.c            |    1 +
>>  arch/x86/hyperv/hv_vtl.c                 |    1 +
>>  arch/x86/hyperv/irqdomain.c              |    1 +
>>  arch/x86/hyperv/ivm.c                    |    2 +-
>>  arch/x86/hyperv/mmu.c                    |    2 +-
>>  arch/x86/hyperv/nested.c                 |    2 +-
>>  arch/x86/include/asm/kvm_host.h          |    1 -
>>  arch/x86/include/asm/mshyperv.h          |    3 +-
>>  arch/x86/include/asm/svm.h               |    2 +-
>>  arch/x86/include/asm/vdso/gettimeofday.h |    1 +
>>  arch/x86/kernel/cpu/mshyperv.c           |    2 +-
>>  arch/x86/kernel/cpu/mtrr/generic.c       |    1 +
>>  arch/x86/kvm/vmx/vmx_onhyperv.h          |    1 -
>>  arch/x86/mm/pat/set_memory.c             |    2 -
>>  drivers/clocksource/hyperv_timer.c       |    2 +-
>>  drivers/hv/channel.c                     |    1 +
>>  drivers/hv/channel_mgmt.c                |    1 +
>>  drivers/hv/connection.c                  |    1 +
>>  drivers/hv/hv.c                          |    1 +
>>  drivers/hv/hv_balloon.c                  |    5 +-
>>  drivers/hv/hv_common.c                   |    2 +-
>>  drivers/hv/hv_kvp.c                      |    1 -
>>  drivers/hv/hv_snapshot.c                 |    1 -
>>  drivers/hv/hv_util.c                     |    1 +
>>  drivers/hv/hyperv_vmbus.h                |    1 -
>>  drivers/hv/ring_buffer.c                 |    1 +
>>  drivers/hv/vmbus_drv.c                   |    1 +
>>  drivers/iommu/hyperv-iommu.c             |    1 +
>>  drivers/net/hyperv/netvsc.c              |    1 +
>>  drivers/pci/controller/pci-hyperv.c      |    1 +
>>  include/asm-generic/hyperv-tlfs.h        |    9 +
>>  include/asm-generic/mshyperv.h           |    2 +-
>>  include/clocksource/hyperv_timer.h       |    2 +-
>>  include/hyperv/hv_defs.h                 |   29 +
>>  include/hyperv/hvgdk.h                   |   66 ++
>>  include/hyperv/hvgdk_ext.h               |   46 +
>>  include/hyperv/hvgdk_mini.h              | 1212 ++++++++++++++++++++++
>>  include/hyperv/hvhdk.h                   |  733 +++++++++++++
>>  include/hyperv/hvhdk_mini.h              |  310 ++++++
>>  include/linux/hyperv.h                   |   12 +-
>>  net/vmw_vsock/hyperv_transport.c         |    1 -
>>  48 files changed, 2442 insertions(+), 40 deletions(-)
>>  create mode 100644 include/hyperv/hv_defs.h
>>  create mode 100644 include/hyperv/hvgdk.h
>>  create mode 100644 include/hyperv/hvgdk_ext.h
>>  create mode 100644 include/hyperv/hvgdk_mini.h
>>  create mode 100644 include/hyperv/hvhdk.h
>>  create mode 100644 include/hyperv/hvhdk_mini.h
>>
>> --
>> 2.34.1
>>
>