KVM: SVM: Add definitions for new bits in VMCB::int_ctrl related to vNMI

Add defines for three new bits in VMVC::int_ctrl that are part of SVM's
Virtual NMI (vNMI) support:

  V_NMI_PENDING_MASK(11)  - Virtual NMI is pending
  V_NMI_BLOCKING_MASK(12) - Virtual NMI is masked
  V_NMI_ENABLE_MASK(26)   - Enable NMI virtualization

To "inject" an NMI, the hypervisor (KVM) sets V_NMI_PENDING.  When the
CPU services the pending vNMI, hardware clears V_NMI_PENDING and sets
V_NMI_BLOCKING, e.g. to indicate that the vCPU is handling an NMI.
Hardware clears V_NMI_BLOCKING upon successful execution of IRET, or if a
VM-Exit occurs while delivering the virtual NMI.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
Link: https://lore.kernel.org/r/20230227084016.3368-10-santosh.shukla@amd.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/include/asm/svm.h

@@ -183,6 +183,12 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define V_GIF_SHIFT 9
 #define V_GIF_MASK (1 << V_GIF_SHIFT)
 
+#define V_NMI_PENDING_SHIFT 11
+#define V_NMI_PENDING_MASK (1 << V_NMI_PENDING_SHIFT)
+
+#define V_NMI_BLOCKING_SHIFT 12
+#define V_NMI_BLOCKING_MASK (1 << V_NMI_BLOCKING_SHIFT)
+
 #define V_INTR_PRIO_SHIFT 16
 #define V_INTR_PRIO_MASK (0x0f << V_INTR_PRIO_SHIFT)
 
@@ -197,6 +203,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define V_GIF_ENABLE_SHIFT 25
 #define V_GIF_ENABLE_MASK (1 << V_GIF_ENABLE_SHIFT)
 
+#define V_NMI_ENABLE_SHIFT 26
+#define V_NMI_ENABLE_MASK (1 << V_NMI_ENABLE_SHIFT)
+
 #define AVIC_ENABLE_SHIFT 31
 #define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)