[PATCH 0/3] x86: clear vmcss on all cpus when doing kdump if necessary

Avi Kivity avi at redhat.com
Mon Oct 15 11:43:20 EDT 2012

On 10/12/2012 08:40 AM, Zhang Yanfei wrote:
> Currently, kdump just makes all the logical processors leave VMX operation by
> executing VMXOFF instruction, so any VMCSs active on the logical processors may
> be corrupted. But, sometimes, we need the VMCSs to debug guest images contained
> in the host vmcore. To prevent the corruption, we should VMCLEAR the VMCSs before
> executing the VMXOFF instruction.

How have you verified that VMXOFF doesn't flush cached VMCSs already?

> The patch set provides an alternative way to clear VMCSs related to guests
> on all cpus when host is doing kdump.

I'm not sure the sysctl is really necessary.  The only reason to turn if
off is if the corruption is so severe that the loaded vmcs list itself
causes a crash.  I think it should be rare enough that we can do it

error compiling committee.c: too many arguments to function

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