linux-kernel - Re: [PATCH] Add MCE support to KVM

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Message-ID: <49EA515C.9000507@codemonkey.ws>
Date:	Sat, 18 Apr 2009 17:17:00 -0500
From:	Anthony Liguori <anthony@...emonkey.ws>
To:	Avi Kivity <avi@...hat.com>
CC:	Huang Ying <ying.huang@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH] Add MCE support to KVM

Avi Kivity wrote: 
>
> Then we would need to tell which read-only MSRs are setup writeable 
> and which aren't...
>
> I'm okay with an ioctl to setup MCE, but just make sure userspace has 
> all the information to know what the kernel can do rather than the 
> try-and-see-if-it-works approach.  We can publish this information via 
> KVM_CAP things, or via another ioctl (see KVM_GET_SUPPORTED_CPUID2 for 
> an example).

Why not introduce a new exit type for MSR reads/writes that aren't 
handled by the kernel?  You just need a bit on the return that indicates 
whether to GPF because of an invalid MSR access.

KVM_SET_MSRs should be reserved for MSRs that are performance 
sensitive.  Not all of them will be.

Regards,

Anthony Liguori

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