[HVM] Change VCPU->LAPIC_ID mapping so that VCPU0 has ID0.

This fixes booting of older x86/64 Linux kernels.
Signed-off-by: Keir Fraser <keir@xensource.com>

tools/firmware/hvmloader/acpi/build.c

@@ -110,7 +110,7 @@ int construct_madt(struct acpi_20_madt *madt)
         memset(lapic, 0, sizeof(*lapic));
         lapic->type    = ACPI_PROCESSOR_LOCAL_APIC;
         lapic->length  = sizeof(*lapic);
-        lapic->acpi_processor_id = lapic->apic_id = i + 1;
+        lapic->acpi_processor_id = lapic->apic_id = LAPIC_ID(i);
         lapic->flags   = ACPI_LOCAL_APIC_ENABLED;
         offset += sizeof(*lapic);
         lapic++;

tools/firmware/hvmloader/config.h

@@ -2,10 +2,11 @@
 #define __HVMLOADER_CONFIG_H__
 
 #define IOAPIC_BASE_ADDRESS 0xfec00000
-#define IOAPIC_ID           0x00
+#define IOAPIC_ID           0x01
 #define IOAPIC_VERSION      0x11
 
 #define LAPIC_BASE_ADDRESS  0xfee00000
+#define LAPIC_ID(vcpu_id)   ((vcpu_id) * 2)
 
 #define PCI_ISA_DEVFN       0x08    /* dev 1, fn 0 */
 #define PCI_ISA_IRQ_MASK    0x0c60U /* ISA IRQs 5,6,10,11 are PCI connected */

tools/firmware/hvmloader/mp_tables.c

@@ -222,7 +222,7 @@ void fill_mp_config_table(struct mp_config_table *mpct, int length)
 void fill_mp_proc_entry(struct mp_proc_entry *mppe, int vcpu_id)
 {
     mppe->type = ENTRY_TYPE_PROCESSOR;
-    mppe->lapic_id = vcpu_id + 1;
+    mppe->lapic_id = LAPIC_ID(vcpu_id);
     mppe->lapic_version = 0x11;
     mppe->cpu_flags = CPU_FLAG_ENABLED;
     if ( vcpu_id == 0 )

xen/arch/x86/hvm/vlapic.c

@@ -767,7 +767,7 @@ static int vlapic_reset(struct vlapic *vlapic)
     struct vcpu *v = vlapic_vcpu(vlapic);
     int i;
 
-    vlapic_set_reg(vlapic, APIC_ID,  (v->vcpu_id + 1) << 24);
+    vlapic_set_reg(vlapic, APIC_ID,  (v->vcpu_id * 2) << 24);
     vlapic_set_reg(vlapic, APIC_LVR, VLAPIC_VERSION);
 
     for ( i = 0; i < 8; i++ )