On Tue, 2018-02-20 at 21:24 -0500, Krish Sadhukhan wrote:
> According to Intel SDM 26.2.1.1, the following rules should be enforced
> on vmentry:
>
> * If the "NMI exiting" VM-execution control is 0, "Virtual NMIs"
> VM-execution control must be 0.
> * If the “virtual NMIs” VM-execution control is 0, the “NMI-window
> exiting” VM-execution control must be 0.
>
> This patch enforces these rules when entering an L2 guest.
>
> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
> Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx>
> Reviewed-by: Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
s/^Reviewed-by: Reviewed-by:/Reviewed-by:/
> ---
> arch/x86/kvm/vmx.c | 29 +++++++++++++++++++++++++++--
> 1 file changed, 27 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 8eba631..24b88db 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -1366,6 +1366,16 @@ static inline bool nested_cpu_has_preemption_timer(struct vmcs12 *vmcs12)
> PIN_BASED_VMX_PREEMPTION_TIMER;
> }
>
> +static inline bool nested_cpu_has_nmi_exiting(struct vmcs12 *vmcs12)
> +{
> + return vmcs12->pin_based_vm_exec_control & PIN_BASED_NMI_EXITING;
> +}
> +
> +static inline bool nested_cpu_has_virtual_nmis(struct vmcs12 *vmcs12)
> +{
> + return vmcs12->pin_based_vm_exec_control & PIN_BASED_VIRTUAL_NMIS;
> +}
> +
> static inline int nested_cpu_has_ept(struct vmcs12 *vmcs12)
> {
> return nested_cpu_has2(vmcs12, SECONDARY_EXEC_ENABLE_EPT);
> @@ -5667,8 +5677,7 @@ static bool nested_exit_intr_ack_set(struct kvm_vcpu *vcpu)
>
> static bool nested_exit_on_nmi(struct kvm_vcpu *vcpu)
> {
> - return get_vmcs12(vcpu)->pin_based_vm_exec_control &
> - PIN_BASED_NMI_EXITING;
> + return nested_cpu_has_nmi_exiting(get_vmcs12(vcpu));
> }
>
> static void enable_irq_window(struct kvm_vcpu *vcpu)
> @@ -10752,6 +10761,19 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
> return 0;
> }
>
> +static int nested_vmx_check_nmi_controls(struct vmcs12 *vmcs12)
> +{
> + if (!nested_cpu_has_nmi_exiting(vmcs12) &&
> + nested_cpu_has_virtual_nmis(vmcs12))
> + return -EINVAL;
> +
> + if (!nested_cpu_has_virtual_nmis(vmcs12) &&
> + nested_cpu_has(vmcs12, CPU_BASED_VIRTUAL_NMI_PENDING))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> static int check_vmentry_prereqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> {
> struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -10796,6 +10818,9 @@ static int check_vmentry_prereqs(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
> vmx->nested.nested_vmx_entry_ctls_high))
> return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
>
> + if (nested_vmx_check_nmi_controls(vmcs12))
> + return VMXERR_ENTRY_INVALID_CONTROL_FIELD;
> +
> if (nested_cpu_has_vmfunc(vmcs12)) {
> if (vmcs12->vm_function_control &
> ~vmx->nested.nested_vmx_vmfunc_controls)
On a related note, which VMentry checks do we decide to do in software
and which ones we defer to hardware?
The spec has like a dizillion checks that are enfored by hardware on
VMEntry, which ones do we decide that it makes sense to validate in
software before-hand?
Regards.
Amazon Development Center Germany GmbH
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