[RFC PATCH 2/2] qemu: support xen hvm direct kernel boot

[Chunyan Liu <cyliu@suse.com>]

[support xen HVM direct kernel boot]
qemu side patch: 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.

Signed-off-by: Chunyan Liu <cyliu@suse.com>
---
 hw/i386/pc.c         | 29 +++++++++++++++++++++++++++++
 hw/i386/pc_piix.c    |  7 +++++++
 include/hw/i386/pc.h |  5 +++++
 3 files changed, 41 insertions(+)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e6369d5..dcd5d48 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1187,6 +1187,35 @@ 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++) {
+        /* For xen, we only want to add the linuxboot.bin/multiboot.bin option rom.
+         * But in option_rom, there is still kvmvapic.bin. We don't want to add it.
+         */
+        if (strcmp(option_rom[i].name, "linuxboot.bin") &&
+            strcmp(option_rom[i].name, "multiboot.bin")) {
+            continue;
+        }
+        rom_add_option(option_rom[i].name, option_rom[i].bootindex);
+    }
+    guest_info->fw_cfg = fw_cfg;
+    return fw_cfg;
+}
+
 FWCfgState *pc_memory_init(MemoryRegion *system_memory,
                            const char *kernel_filename,
                            const char *kernel_cmdline,
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index eaf3e61..14d4164 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -157,6 +157,13 @@ static void pc_init1(QEMUMachineInitArgs *args,
                        args->initrd_filename,
                        below_4g_mem_size, above_4g_mem_size,
                        rom_memory, &ram_memory, guest_info);
+    } else if (args->kernel_filename != NULL) {
+        /* For xen HVM direct kernel boot, load linux here */
+        fw_cfg = xen_load_linux(args->kernel_filename,
+                                args->kernel_cmdline,
+                                args->initrd_filename,
+                                below_4g_mem_size,
+                                guest_info);
     }
 
     gsi_state = g_malloc0(sizeof(*gsi_state));
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 32a7687..e472184 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -134,6 +134,11 @@ 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(MemoryRegion *system_memory,
                            const char *kernel_filename,
                            const char *kernel_cmdline,
-- 
1.8.4.5