qemu: support xen hvm direct kernel boot

qemu side patch to support xen HVM direct kernel boot:
if -kernel exists, calls xen_load_linux(), which will read kernel/initrd
and add a linuxboot.bin or multiboot.bin option rom. The
linuxboot.bin/multiboot.bin will load kernel/initrd and jump to execute
kernel directly. It's working when xen uses seabios.

During this work, found the 'kvmvapic' is in option_rom list, it should
not be there in xen case. Set s->vapic_control = 0 in xen_apic_realize()
to handle that.

Signed-off-by: Chunyan Liu <cyliu@suse.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>

hw/i386/pc.c

@@ -1190,6 +1190,31 @@ void pc_acpi_init(const char *default_dsdt)
     }
 }
 
+FWCfgState *xen_load_linux(const char *kernel_filename,
+                           const char *kernel_cmdline,
+                           const char *initrd_filename,
+                           ram_addr_t below_4g_mem_size,
+                           PcGuestInfo *guest_info)
+{
+    int i;
+    FWCfgState *fw_cfg;
+
+    assert(kernel_filename != NULL);
+
+    fw_cfg = fw_cfg_init(BIOS_CFG_IOPORT, BIOS_CFG_IOPORT + 1, 0, 0);
+    rom_set_fw(fw_cfg);
+
+    load_linux(fw_cfg, kernel_filename, initrd_filename,
+               kernel_cmdline, below_4g_mem_size);
+    for (i = 0; i < nb_option_roms; i++) {
+        assert(!strcmp(option_rom[i].name, "linuxboot.bin") ||
+               !strcmp(option_rom[i].name, "multiboot.bin"));
+        rom_add_option(option_rom[i].name, option_rom[i].bootindex);
+    }
+    guest_info->fw_cfg = fw_cfg;
+    return fw_cfg;
+}
+
 FWCfgState *pc_memory_init(MachineState *machine,
                            MemoryRegion *system_memory,
                            ram_addr_t below_4g_mem_size,

hw/i386/pc_piix.c

@@ -182,6 +182,13 @@ static void pc_init1(MachineState *machine,
         fw_cfg = pc_memory_init(machine, system_memory,
                                 below_4g_mem_size, above_4g_mem_size,
                                 rom_memory, &ram_memory, guest_info);
+    } else if (machine->kernel_filename != NULL) {
+        /* For xen HVM direct kernel boot, load linux here */
+        fw_cfg = xen_load_linux(machine->kernel_filename,
+                                machine->kernel_cmdline,
+                                machine->initrd_filename,
+                                below_4g_mem_size,
+                                guest_info);
     }
 
     gsi_state = g_malloc0(sizeof(*gsi_state));

hw/i386/xen/xen_apic.c

@@ -40,6 +40,7 @@ static void xen_apic_realize(DeviceState *dev, Error **errp)
 {
     APICCommonState *s = APIC_COMMON(dev);
 
+    s->vapic_control = 0;
     memory_region_init_io(&s->io_memory, OBJECT(s), &xen_apic_io_ops, s,
                           "xen-apic-msi", APIC_SPACE_SIZE);
 

include/hw/i386/pc.h

@@ -188,6 +188,11 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
 void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
                             MemoryRegion *pci_address_space);
 
+FWCfgState *xen_load_linux(const char *kernel_filename,
+                           const char *kernel_cmdline,
+                           const char *initrd_filename,
+                           ram_addr_t below_4g_mem_size,
+                           PcGuestInfo *guest_info);
 FWCfgState *pc_memory_init(MachineState *machine,
                            MemoryRegion *system_memory,
                            ram_addr_t below_4g_mem_size,