Re: [PATCH v4 1/2] KVM: PPC: Add new capability to control MCE behaviour

[Paul Mackerras <paulus@ozlabs.org>]

On Mon, Jan 09, 2017 at 05:10:35PM +0530, Aravinda Prasad wrote:
> This patch introduces a new KVM capability to control
> how KVM behaves on machine check exception (MCE).
> Without this capability, KVM redirects machine check
> exceptions to guest's 0x200 vector, if the address in
> error belongs to the guest. With this capability KVM
> causes a guest exit with NMI exit reason.
> 
> The new capability is required to avoid problems if
> a new kernel/KVM is used with an old QEMU for guests
> that don't issue "ibm,nmi-register". As old QEMU does
> not understand the NMI exit type, it treats it as a
> fatal error. However, the guest could have handled
> the machine check error if the exception was delivered
> to guest's 0x200 interrupt vector instead of NMI exit
> in case of old QEMU.

You need to add a description of the new capability to
Documentation/virtual/kvm/api.txt.

Paul.