From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] Add MCE support to KVM Date: Tue, 21 Apr 2009 11:04:35 -0500 Message-ID: <49EDEE93.30103@codemonkey.ws> References: <1239155601.6384.3.camel@yhuang-dev.sh.intel.com> <49DE195D.1020303@redhat.com> <1239332455.6384.108.camel@yhuang-dev.sh.intel.com> <49E08762.1010206@redhat.com> <1239590499.6384.4016.camel@yhuang-dev.sh.intel.com> <49E337D7.5050502@redhat.com> <49EA515C.9000507@codemonkey.ws> <49EAE1F6.9050205@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Huang Ying , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Andi Kleen To: Avi Kivity Return-path: In-Reply-To: <49EAE1F6.9050205@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Avi Kivity wrote: > Anthony Liguori wrote: >> 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. >> > > Right now everything in the vcpu is emulated in the kernel. > Everything else is emulated either in the kernel (irqchip) or in > userspace. This makes things easier to understand, and is more future > friendly if more cpu features become virtualized by hardware. Except cpuid, which is handled in userspace, sort of :-) I think the same arguments apply here too. Regards, Anthony Liguori