From 42124925c1f580068661bebd963d7c102175a8a9 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Sat, 4 Jan 2014 18:47:19 +0100 Subject: [PATCH] KVM: nVMX: Leave VMX mode on clearing of feature control MSR 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 Signed-off-by: Paolo Bonzini --- 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 c8eb27ff1a2d..bff55554faec 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; } @@ -8503,6 +8507,16 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu) vmx->nested.sync_shadow_vmcs = true; } +/* + * 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 -- 2.39.2