ACK: [SRU][S:linux-azure/R:linux-azure/N:linux-azure/J:linux-azure][PATCH 0/2] Revert SAUCE: AMDv4 VMs may get no timer interrupts or suffer from timer interrupt storms

[Andrei Gherzan]

On 2026/09/22 03:53PM, John Cabaj via kernel-team wrote:
> BugLink: https://bugs.launchpad.net/bugs/2167893
> 
> SRU Justification
> 
> [Impact]
> 
> * Microsoft requested patches to work around intermittent deployment failures on AMDv4 VM sizes due to issues with large values of Hyper-V timer as part of LP: #2137674. Fixes in the hypervisor have been rolled out, so the SAUCE patches can be reverted.
> 
> [Fix]
> Revert the following SAUCE patches
>   - "UBUNTU: SAUCE: clocksource: hyper-v: do not use an insanely big TSC in hv_read_tsc_page_tsc()"
>   - "UBUNTU: SAUCE: clocksource: hyper-v: use the APIC timer if the Hyper-V timer is unreliable on some CPUs"
> 
> [Test Plan]
> 
> * Compile tested
> * Microsoft tested
> 
> [Regression potential]
> 
> * Upstream changes are largely localized to time and clock source functions, and have been upstream for some time. Regression likliehood is slim.
> * Possible regressions could result in unexpected behavior of Hyper-V driver.
> 
> [Other info]
> 
> * SF#00422328
> 
> John Cabaj (2):
>   Revert "UBUNTU: SAUCE: clocksource: hyper-v: use the APIC timer if the
>     Hyper-V timer is unreliable on some CPUs"
>   Revert "UBUNTU: SAUCE: clocksource: hyper-v: do not use an insanely
>     big TSC in hv_read_tsc_page_tsc()"
> 
>  arch/x86/kernel/cpu/mshyperv.c     | 43 ------------------------------
>  drivers/clocksource/hyperv_timer.c |  4 +--
>  include/clocksource/hyperv_timer.h |  4 ---
>  3 files changed, 1 insertion(+), 50 deletions(-)

Acked-by: Andrei Gherzan <andrei.gherzan at canonical.com>

-- 
Andrei Gherzan
gpg: rsa4096/D4D94F67AD0E9640
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