From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Nadav Har'El" Subject: Re: [PATCH 6/24] Implement reading and writing of VMX MSRs Date: Wed, 23 Jun 2010 11:13:18 +0300 Message-ID: <20100623081318.GA23957@fermat.math.technion.ac.il> References: <1276431753-nyh@il.ibm.com> <201006131225.o5DCPctX012929@rice.haifa.ibm.com> <4C15EB93.6040101@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mailgw11.technion.ac.il ([132.68.225.11]:44532 "EHLO mailgw11.technion.ac.il" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751209Ab0FWINW (ORCPT ); Wed, 23 Jun 2010 04:13:22 -0400 Content-Disposition: inline In-Reply-To: <4C15EB93.6040101@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Mon, Jun 14, 2010, Avi Kivity wrote about "Re: [PATCH 6/24] Implement reading and writing of VMX MSRs": > On 06/13/2010 03:25 PM, Nadav Har'El wrote: > >When the guest can use VMX instructions (when the "nested" module option is > >on), it should also be able to read and write VMX MSRs, e.g., to query > >about > >VMX capabilities. This patch adds this support. >... > >@@ -702,7 +702,11 @@ static u32 msrs_to_save[] = { >... > >+ MSR_IA32_FEATURE_CONTROL, MSR_IA32_VMX_BASIC, >... > These are read only from the guest point of view, but we need write > support from the host to allow for tuning the features exposed to the guest. Hi, I'm afraid I did not understand what you meant. There is a KVM_SET_MSRS ioctl, but it appears to do the same thing that a guest's WRMSR would do, i.e., eventually call nested_vmx_set_msr(). In some of these MSRs (like VMX_BASIC) there's no point, if I understand correctly, for the guest or the host to change anything (e.g., what would it mean to change the VMCS length or revision id?). In others like VMX_PROCBASED_CTLS I guess that we can allow it to be set if it doesn't try to enable something not supported - is that what you had in mind? Or did you mean something else? Thanks, Nadav. -- Nadav Har'El | Wednesday, Jun 23 2010, 11 Tammuz 5770 nyh@math.technion.ac.il |----------------------------------------- Phone +972-523-790466, ICQ 13349191 |AAAAA: the American Association for the http://nadav.harel.org.il |Abolition of Abbreviations and Acronyms