KVM: x86: Detect and Initialize AVIC support

This patch introduces AVIC-related data structure, and AVIC
initialization code.

There are three main data structures for AVIC:
    * Virtual APIC (vAPIC) backing page (per-VCPU)
    * Physical APIC ID table (per-VM)
    * Logical APIC ID table (per-VM)

Currently, AVIC is disabled by default. Users can manually
enable AVIC via kernel boot option kvm-amd.avic=1 or during
kvm-amd module loading with parameter avic=1.
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
[Avoid extra indentation (Boris). - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -773,6 +773,10 @@ struct kvm_arch {
 	u8 nr_reserved_ioapic_pins;
 
 	bool disabled_lapic_found;
+
+	/* Struct members for AVIC */
+	struct page *avic_logical_id_table_page;
+	struct page *avic_physical_id_table_page;
 };
 
 struct kvm_vm_stat {

arch/x86/include/asm/svm.h

@@ -116,6 +116,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #define V_INTR_MASKING_SHIFT 24
 #define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT)
 
+#define AVIC_ENABLE_SHIFT 31
+#define AVIC_ENABLE_MASK (1 << AVIC_ENABLE_SHIFT)
+
 #define SVM_INTERRUPT_SHADOW_MASK 1
 
 #define SVM_IOIO_STR_SHIFT 2