From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: [PATCH 05/12] KVM: nVMX: Leave VMX mode on clearing of feature control MSR Date: Sat, 4 Jan 2014 18:47:19 +0100 Message-ID: References: Cc: kvm To: Paolo Bonzini , Gleb Natapov , Marcelo Tosatti Return-path: Received: from mout.web.de ([212.227.15.3]:62721 "EHLO mout.web.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754828AbaADRrn (ORCPT ); Sat, 4 Jan 2014 12:47:43 -0500 Received: from mchn199C.home ([95.157.58.223]) by smtp.web.de (mrweb003) with ESMTPSA (Nemesis) id 0Ljahc-1VOEh402AK-00bYui for ; Sat, 04 Jan 2014 18:47:42 +0100 In-Reply-To: In-Reply-To: References: Sender: kvm-owner@vger.kernel.org List-ID: From: Jan Kiszka When userspace sets MSR_IA32_FEATURE_CONTROL to 0, make sure we leave root and non-root mode, fully disabling VMX. The register state of the VCPU is undefined after this step, so userspace has to set it to a proper state afterward. This enables to reboot a VM while it is running some hypervisor code. Signed-off-by: Jan Kiszka --- arch/x86/kvm/vmx.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 9fa8a1c..3edf08f 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2455,6 +2455,8 @@ static int vmx_get_vmx_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata) return 1; } +static void vmx_leave_nested(struct kvm_vcpu *vcpu); + static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) { u32 msr_index = msr_info->index; @@ -2470,6 +2472,8 @@ static int vmx_set_vmx_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) & FEATURE_CONTROL_LOCKED) return 0; to_vmx(vcpu)->nested.msr_ia32_feature_control = data; + if (host_initialized && data == 0) + vmx_leave_nested(vcpu); return 1; } @@ -8507,6 +8511,16 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu) } /* + * Forcibly leave nested mode in order to be able to reset the VCPU later on. + */ +static void vmx_leave_nested(struct kvm_vcpu *vcpu) +{ + if (is_guest_mode(vcpu)) + nested_vmx_vmexit(vcpu); + free_nested(to_vmx(vcpu)); +} + +/* * L1's failure to enter L2 is a subset of a normal exit, as explained in * 23.7 "VM-entry failures during or after loading guest state" (this also * lists the acceptable exit-reason and exit-qualification parameters). -- 1.8.1.1.298.ge7eed54