[Bug 1921082] Re: VM crash when process broadcast MCE

[Thomas Huth <1921082@bugs.launchpad.net>]

The QEMU project is currently moving its bug tracking to another system.
For this we need to know which bugs are still valid and which could be
closed already. Thus we are setting the bug state to "Incomplete" now.

If the bug has already been fixed in the latest upstream version of QEMU,
then please close this ticket as "Fix released".

If it is not fixed yet and you think that this bug report here is still
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for this problem in our new tracker here:

    https://gitlab.com/qemu-project/qemu/-/issues

and then close this ticket here on Launchpad (or let it expire auto-
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the state back to "New" or "Confirmed" within the next 60 days (other-
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anymore).

Thank you and sorry for the inconvenience.


** Changed in: qemu
       Status: New => Incomplete

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https://bugs.launchpad.net/bugs/1921082

Title:
  VM crash when process broadcast MCE

Status in QEMU:
  Incomplete

Bug description:
  When i do memory SRAR test for VM, I meet the following issue:

  My VM has 16 vCPU, I will inject one UE error to memory which is accessed by VM, Then host MCE is raised and SIGBUS is send to VM, and qemu take control.
  Qemu will check the broadcast attribute by following  cpu_x86_support_mca_broadcast();  

  Then Qemu may inject MCE to all vCPU, as vCPU is just one process for
  HOST, we can't guarantee all the vCPUs will enter MCE hander in 1S
  sync time, and the VM may panic.

  This issue will be easily fixed by expand monarch_timeout
  configuration, but the exact monarch_timeout can't be easily got, as
  it will depand on the num of vCPUs and current system schedule status.

  I am wondering why VM need broadcast attribute for MCE, When qeme
  process MCE event form host, it will always be signaled for one vCPU?
  If so, why does qemu need boradcast the MCE event to all vCPUs?

  Can weu just deliver LMCE to one specifc vCPU and make this behavior
  default?

  If anything wrong, Please point out.

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