From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752079AbeBZJ03 (ORCPT ); Mon, 26 Feb 2018 04:26:29 -0500 Received: from userp2130.oracle.com ([156.151.31.86]:37794 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751563AbeBZJ0Z (ORCPT ); Mon, 26 Feb 2018 04:26:25 -0500 MIME-Version: 1.0 Message-ID: <1f6d0e8e-6d76-4262-9e8b-f8b1f23d8248@default> Date: Mon, 26 Feb 2018 01:26:19 -0800 (PST) From: Liran Alon To: Cc: , , , Subject: Re: [PATCH] KVM: X86: Allow userspace to define the microcode version X-Mailer: Zimbra on Oracle Beehive Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=8815 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=1 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1802260128 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id w1Q9QX9r025219 ----- kernellwp@gmail.com wrote: > From: Wanpeng Li > > Linux (among the others) has checks to make sure that certain features > > aren't enabled on a certain family/model/stepping if the microcode > version > isn't greater than or equal to a known good version. > > By exposing the real microcode version, we're preventing buggy guests > that > don't check that they are running virtualized (i.e., they should trust > the > hypervisor) from disabling features that are effectively not buggy. > > Suggested-by: Filippo Sironi > Cc: Paolo Bonzini > Cc: Radim Krčmář > Signed-off-by: Wanpeng Li > --- > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/x86.c | 8 ++++++-- > 2 files changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h > b/arch/x86/include/asm/kvm_host.h > index 938d453..6e13f2f 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -507,6 +507,7 @@ struct kvm_vcpu_arch { > u64 smi_count; > bool tpr_access_reporting; > u64 ia32_xss; > + u32 microcode_version; > > /* > * Paging state of the vcpu > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 1a3ed81..cc51c61 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2247,7 +2247,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, > struct msr_data *msr_info) > > switch (msr) { > case MSR_AMD64_NB_CFG: > - case MSR_IA32_UCODE_REV: > case MSR_IA32_UCODE_WRITE: > case MSR_VM_HSAVE_PA: > case MSR_AMD64_PATCH_LOADER: > @@ -2255,6 +2254,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, > struct msr_data *msr_info) > case MSR_AMD64_DC_CFG: > break; > > + case MSR_IA32_UCODE_REV: > + if (msr_info->host_initiated) > + vcpu->arch.microcode_version = data >> 32; > + break; > case MSR_EFER: > return set_efer(vcpu, data); > case MSR_K7_HWCR: > @@ -2550,7 +2553,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, > struct msr_data *msr_info) > msr_info->data = 0; > break; > case MSR_IA32_UCODE_REV: > - msr_info->data = 0x100000000ULL; > + msr_info->data = (u64)vcpu->arch.microcode_version << 32; > break; > case MSR_MTRRcap: > case 0x200 ... 0x2ff: > @@ -8232,6 +8235,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool > init_event) > vcpu->arch.regs_dirty = ~0; > > vcpu->arch.ia32_xss = 0; > + vcpu->arch.microcode_version = 0x1; > > kvm_x86_ops->vcpu_reset(vcpu, init_event); > } > -- > 2.7.4 I think you need to add MSR_IA32_UCODE_REV to emulated_msrs[] to allow for proper live-migration of this MSR value. The rest seems fine to me. :) Regards, -Liran