Re: [Qemu-devel] [PATCH 4/4] target-ppc: Handle NMI guest exit

From: Paul Mackerras <paulus@ozlabs.org>
To: Thomas Huth <thuth@redhat.com>
Cc: benh@au1.ibm.com, aik@ozlabs.ru, agraf@suse.de,
	qemu-devel@nongnu.org, qemu-ppc@nongnu.org,
	Aravinda Prasad <aravinda@linux.vnet.ibm.com>,
	sam.bobroff@au1.ibm.com, david@gibson.dropbear.id.au
Subject: Re: [Qemu-devel] [PATCH 4/4] target-ppc: Handle NMI guest exit
Date: Mon, 16 Nov 2015 14:50:46 +1100	[thread overview]
Message-ID: <20151116035046.GA19340@iris.ozlabs.ibm.com> (raw)
In-Reply-To: <56444957.9080003@redhat.com>

On Thu, Nov 12, 2015 at 09:09:59AM +0100, Thomas Huth wrote:
> 
> Shouldn't you also check MSR_ME here first and enter checkstop when
> machine checks are disabled?

MSR_ME is a hypervisor resource and is not able to be controlled by HV
KVM guests, or in fact by the OS running on the pseries machine target
regardless of how it's accelerated or emulated.

What you say would only apply if we had a powernv machine target and
we were emulating the whole system, and in that case we wouldn't be
using any hcalls, and we wouldn't be doing FWNMI (or at least not at
this level).

So the answer is no, MSR_ME will always be set when running in a
guest, and we don't ever need to checkstop the virtual machine.

> Also I think you have to set up some more registers for machine check
> interrupts, like SRR0 and SRR1?

They are already set up by the process of taking the machine check in
the first place.

Paul.