linux-kernel - RE: [PATCH hyperv-next 0/2] arch/x86, x86/hyperv: Few fixes for the AP startup

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Date: Thu, 8 May 2025 04:22:54 +0000
From: Michael Kelley <mhklinux@...look.com>
To: Roman Kisel <romank@...ux.microsoft.com>, "ardb@...nel.org"
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Subject: RE: [PATCH hyperv-next 0/2] arch/x86, x86/hyperv: Few fixes for the
 AP startup

From: Roman Kisel <romank@...ux.microsoft.com> Sent: Wednesday, May 7, 2025 11:22 AM
> 
> This patchset combines two patches that depend on each other and were not applying
> cleanly:
>   1. Fix APIC ID and VP index confusion in hv_snp_boot_ap():
>     https://lore.kernel.org/linux-hyperv/20250430204720.108962-1-romank@linux.microsoft.com/ 
>   2. Provide the CPU number in the wakeup AP callback:
>     https://lore.kernel.org/linux-hyperv/20250430204720.108962-1-romank@linux.microsoft.com/ 
> 
> I rebased the patches on top of the latest hyperv-next tree and updated the second patch
> that broke the linux-next build. That fix that, I made one non-functional change:
> updated the signature of numachip_wakeup_secondary() to match the parameter list of
> wakeup_secondary_cpu().
> 
> Roman Kisel (2):
>   x86/hyperv: Fix APIC ID and VP index confusion in hv_snp_boot_ap()
>   arch/x86: Provide the CPU number in the wakeup AP callback

I think this works. It's unfortunate that Patch 1 adds 11 lines of code/comments that
Patch 2 then deletes, which seems like undesirable churn. I was expecting adding the
"cpu" parameter to come first, which then makes fixing the hv_snp_boot_ap() problem
more straightforward. But looking more closely, hv_snp_boot_ap() already has a
parameter erroneously named "cpu", so adding the correct "cpu" parameter isn't
transparent. Hence the order you've chosen is probably the best resolution for a
messy situation. :-)

Michael

> 
>  arch/x86/coco/sev/core.c             | 13 ++-----
>  arch/x86/hyperv/hv_init.c            | 33 +++++++++++++++++
>  arch/x86/hyperv/hv_vtl.c             | 54 ++++------------------------
>  arch/x86/hyperv/ivm.c                | 11 ++++--
>  arch/x86/include/asm/apic.h          |  8 ++---
>  arch/x86/include/asm/mshyperv.h      |  7 ++--
>  arch/x86/kernel/acpi/madt_wakeup.c   |  2 +-
>  arch/x86/kernel/apic/apic_noop.c     |  8 ++++-
>  arch/x86/kernel/apic/apic_numachip.c |  2 +-
>  arch/x86/kernel/apic/x2apic_uv_x.c   |  2 +-
>  arch/x86/kernel/smpboot.c            | 10 +++---
>  include/hyperv/hvgdk_mini.h          |  2 +-
>  12 files changed, 76 insertions(+), 76 deletions(-)
> 
> 
> base-commit: 9b0844d87b1407681b78130429f798beb366f43f
> --
> 2.43.0