[SRU][F/aws][PATCH v3 0/6] aws: proper fix for c5.18xlarge hibernation issues

[Andrea Righi]

BugLink: https://bugs.launchpad.net/bugs/1920944

[Impact]

In LP: #1918694 we applied a fix and a workaround to solve the
hibernation issues on c5.18xlarge. The workaround was in the form of a
SAUCE patch:

  "UBUNTU: SAUCE: aws: kvm: double the size of hv_clock_boot"

It looks like we can replace this workaround with a proper fix, by
applying this patch:

http://next.patchew.org/Linux/20210414123544.1060604-1-vkuznets@redhat.com/

[Test plan]

Create a c5.18xlarge instance, run the memory stress test script (the
same test script that we are using to stress test hibernation), trigger
the hibernate event, trigger the resume event. Repeat a couple of times
and the problem is very likely to happen.

[Fix]

Replace "UBUNTU: SAUCE: aws: kvm: double the size of hv_clock_boot"
with:

http://next.patchew.org/Linux/20210414123544.1060604-1-vkuznets@redhat.com/

The fix has been tested extensively in the AWS infrastructure with
positive results.

[Where problems could occur]

This new code introduced by the fix can be executed also when a CPU is
put offline, so we may see potential regressions in the KVM CPU
hotplugging.

----------------------------------------------------------------
Changelog (v2 -> v3):
 - updated backported / signed-off lines with the right upstream info
   (thanks Guilherme!)

NOTE: backport activity was minimal, it only required some context
adjustments to properly apply the changes.

Andrea Righi (1):
      Revert "UBUNTU: SAUCE: aws: kvm: double the size of hv_clock_boot"

Vitaly Kuznetsov (5):
      x86/kvm: Fix pr_info() for async PF setup/teardown
      x86/kvm: Teardown PV features on boot CPU as well
      x86/kvm: Disable kvmclock on all CPUs on shutdown
      x86/kvm: Disable all PV features on crash
      x86/kvm: Unify kvm_pv_guest_cpu_reboot() with kvm_guest_cpu_offline()

 arch/x86/include/asm/kvm_para.h |   9 ++----
 arch/x86/kernel/kvm.c           | 113 ++++++++++++++++++++++++++++++++++++++++++++----------------------
 arch/x86/kernel/kvmclock.c      |  28 ++---------------
 3 files changed, 79 insertions(+), 71 deletions(-)