From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753039AbeAaRRS (ORCPT ); Wed, 31 Jan 2018 12:17:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48584 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752172AbeAaRRR (ORCPT ); Wed, 31 Jan 2018 12:17:17 -0500 Subject: Re: [PATCH] KVM: nVMX: preserve SECONDARY_EXEC_DESC without UMIP To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org, kvm@vger.kernel.org References: <20180131171250.29568-1-rkrcmar@redhat.com> From: Paolo Bonzini Message-ID: <9a4039a3-9352-15f7-1917-0bef13e2f085@redhat.com> Date: Wed, 31 Jan 2018 12:17:13 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 MIME-Version: 1.0 In-Reply-To: <20180131171250.29568-1-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 31/01/2018 12:12, Radim Krčmář wrote: > L1 might want to use SECONDARY_EXEC_DESC, so we must not clear the VMCS > bit if UMIP is not being emulated. > > We must still set the bit when emulating UMIP as the feature can be > passed to L2 where L0 will do the emulation and because L2 can change > CR4 without a VM exit, we should clear the bit if UMIP is disabled. > > Fixes: 0367f205a3b7 ("KVM: vmx: add support for emulating UMIP") > Signed-off-by: Radim Krčmář > --- > I haven't tested emulated UMIP (yet) nor machines with UMIP, but at > least kvm-unit-tests don't throw an error anymore. > > arch/x86/kvm/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 438802d0b01d..b1e554a74b34 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -4379,7 +4379,8 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) > vmcs_set_bits(SECONDARY_VM_EXEC_CONTROL, > SECONDARY_EXEC_DESC); > hw_cr4 &= ~X86_CR4_UMIP; > - } else > + } else if (!is_guest_mode(vcpu) || > + !nested_cpu_has2(get_vmcs12(vcpu), SECONDARY_EXEC_DESC)) > vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL, > SECONDARY_EXEC_DESC); > > Reviewed-by: Paolo Bonzini