Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753359AbbKCJpf (ORCPT ); Tue, 3 Nov 2015 04:45:35 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54357 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752902AbbKCJpH (ORCPT ); Tue, 3 Nov 2015 04:45:07 -0500 Subject: Re: [PATCH] KVM: VMX: fix SMEP and SMAP without EPT To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org References: <1446499200-17836-1-git-send-email-rkrcmar@redhat.com> Cc: kvm@vger.kernel.org, Feng Wu , Dongxiao Xu , stable From: Paolo Bonzini Message-ID: <5638821D.6070701@redhat.com> Date: Tue, 3 Nov 2015 10:45:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <1446499200-17836-1-git-send-email-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2035 Lines: 59 On 02/11/2015 22:20, Radim Krčmář wrote: > The comment in code had it mostly right, but we enable paging for > emulated real mode regardless of EPT. > > Without EPT (which implies emulated real mode), secondary VCPUs won't > start unless we disable SM[AE]P when the guest doesn't use paging. > > Signed-off-by: Radim Krčmář > --- > arch/x86/kvm/vmx.c | 19 ++++++++++--------- > 1 file changed, 10 insertions(+), 9 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index b680c2e0e8a3..ab598558a7a4 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3788,20 +3788,21 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > if (!is_paging(vcpu)) { > hw_cr4 &= ~X86_CR4_PAE; > hw_cr4 |= X86_CR4_PSE; > - /* > - * SMEP/SMAP is disabled if CPU is in non-paging mode > - * in hardware. However KVM always uses paging mode to > - * emulate guest non-paging mode with TDP. > - * To emulate this behavior, SMEP/SMAP needs to be > - * manually disabled when guest switches to non-paging > - * mode. > - */ > - hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP); > } else if (!(cr4 & X86_CR4_PAE)) { > hw_cr4 &= ~X86_CR4_PAE; > } > } > > + if (!enable_unrestricted_guest && !is_paging(vcpu)) > + /* > + * SMEP/SMAP is disabled if CPU is in non-paging mode in > + * hardware. However KVM always uses paging mode without > + * unrestricted guest. > + * To emulate this behavior, SMEP/SMAP needs to be manually > + * disabled when guest switches to non-paging mode. > + */ > + hw_cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP); > + > vmcs_writel(CR4_READ_SHADOW, cr4); > vmcs_writel(GUEST_CR4, hw_cr4); > return 0; > Applied with Cc: stable@vger.kernel.org. Paolo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/