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Commit 42124925 authored by Jan Kiszka's avatar Jan Kiszka Committed by Paolo Bonzini
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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: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 8246bf52

arch/x86/kvm/vmx.c

+14 −0
Original line number Diff line number Diff line
@@ -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