From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wanpeng Li Subject: Re: [PATCH] KVM: x86: Keep masked bits unmodified on kvm_set_shared_msr Date: Thu, 21 Aug 2014 16:05:36 +0800 Message-ID: <20140821080536.GA30303@kernel> References: <1408536711-32643-1-git-send-email-namit@cs.technion.ac.il> Reply-To: Wanpeng Li Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: pbonzini@redhat.com, kvm@vger.kernel.org To: Nadav Amit Return-path: Received: from mga02.intel.com ([134.134.136.20]:27497 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751962AbaHUIEF (ORCPT ); Thu, 21 Aug 2014 04:04:05 -0400 Content-Disposition: inline In-Reply-To: <1408536711-32643-1-git-send-email-namit@cs.technion.ac.il> Sender: kvm-owner@vger.kernel.org List-ID: Hi Nadav, On Wed, Aug 20, 2014 at 03:11:51PM +0300, Nadav Amit wrote: >Currently, when an msr is updated using kvm_set_shared_msr the masked bits are >zeroed. This behavior is currently valid since the only MSR with partial mask Why zeroed? vmx_vcpu_setup() set all mask to -1ull. >is EFER, in which only SCE might be unmasked. However, using the Do you mean SCE might be masked? >kvm_set_shared_msr for other purposes becomes impossible. > >This patch keeps the masked bits unmodified while setting a shared msr. > Do you mean "keeps the unmasked bits unmodified" instead of "keeps the masked bits unmodified"? Regards, Wanpeng Li >Signed-off-by: Nadav Amit >--- > arch/x86/kvm/x86.c | 1 + > 1 file changed, 1 insertion(+) > >diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >index 5f5edb6..ee42410 100644 >--- a/arch/x86/kvm/x86.c >+++ b/arch/x86/kvm/x86.c >@@ -236,6 +236,7 @@ void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) > > if (((value ^ smsr->values[slot].curr) & mask) == 0) > return; >+ value = (smsr->values[slot].curr & ~mask) | (value & mask); > smsr->values[slot].curr = value; > wrmsrl(shared_msrs_global.msrs[slot], value); > if (!smsr->registered) { >-- >1.9.1 > >-- >To unsubscribe from this list: send the line "unsubscribe kvm" in >the body of a message to majordomo@vger.kernel.org >More majordomo info at http://vger.kernel.org/majordomo-info.html