[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

[John Cabaj]

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(-)

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2.43.0