[SRU][Q/N/J:linux-azure][PATCH 0/2] [Azure] AMDv4 VMs may get no timer interrupts or suffer from timer interrupt storms

[John Cabaj]

BugLink: https://bugs.launchpad.net/bugs/2137674

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

[Fix]

* Questing and Noble:
- cherry-picks of the following SAUCE patches from Microsoft (https://github.com/dcui/linux/tree/decui/Ubuntu-azure-6.8-6.8.0-1043.49_22.04.1-V2):
  - 28b18cb: "UBUNTU: SAUCE: clocksource: hyper-v: do not use an insanely big TSC in hv_read_tsc_page_tsc()"
  - f796530: "UBUNTU: SAUCE: clocksource: hyper-v: use the APIC timer if the Hyper-V timer is unreliable on some CPUs"
* Jammy:
- cherry-pick of the following SAUCE patch from Microsoft (https://github.com/dcui/linux/tree/decui/Ubuntu-azure-6.8-6.8.0-1043.49_22.04.1-V2):
  - 28b18cb: "UBUNTU: SAUCE: clocksource: hyper-v: do not use an insanely big TSC in hv_read_tsc_page_tsc()"
- backport of the following SAUCE patch from Microsoft (https://github.com/dcui/linux/tree/decui/Ubuntu-azure-6.8-6.8.0-1043.49_22.04.1-V2):
  - f796530: "UBUNTU: SAUCE: clocksource: hyper-v: use the APIC timer if the Hyper-V timer is unreliable on some CPUs"
- cherry-pick of the following upstream patches
  - fd0c6b0: "x86/vdso: Fix gettimeofday masking"
  - 4b52223: "clocksource: hyper-v: Provide noinstr sched_clock()"
- backports of the following upstream patches
  - 9dfb6bf: "clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX"
  - 47a2a14: "clocksource: hyper-v: Introduce a pointer to TSC page"

[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

Dexuan Cui (2):
  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

 arch/x86/kernel/cpu/mshyperv.c     | 43 ++++++++++++++++++++++++++++++
 drivers/clocksource/hyperv_timer.c |  4 ++-
 include/clocksource/hyperv_timer.h |  4 +++
 3 files changed, 50 insertions(+), 1 deletion(-)

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2.43.0