[PATCH v1 08/28] hw/i386: refactor x86_bios_rom_init for reuse in confidential guest reset

[Ani Sinha <anisinha@redhat.com>]

For confidential guests, bios image must be reinitialized upon reset. This
is because bios memory is encrypted and hence once the old confidential
kvm context is destroyed, it cannot be decrypted. It needs to be reinitilized.
In order to do that, this change refactors x86_bios_rom_init() code so that
parts of it can be called during confidential guest reset.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 hw/i386/x86-common.c  | 50 ++++++++++++++++++++++++++++++++-----------
 include/hw/i386/x86.h |  5 ++++-
 2 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c
index c844749900..81fa4f47fb 100644
--- a/hw/i386/x86-common.c
+++ b/hw/i386/x86-common.c
@@ -1024,17 +1024,11 @@ void x86_isa_bios_init(MemoryRegion *isa_bios, MemoryRegion *isa_memory,
     memory_region_set_readonly(isa_bios, read_only);
 }
 
-void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
-                       MemoryRegion *rom_memory, bool isapc_ram_fw)
+int get_bios_size(X86MachineState *x86ms,
+                  const char *bios_name, char *filename)
 {
-    const char *bios_name;
-    char *filename;
     int bios_size;
-    ssize_t ret;
 
-    /* BIOS load */
-    bios_name = MACHINE(x86ms)->firmware ?: default_firmware;
-    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
     if (filename) {
         bios_size = get_image_size(filename, NULL);
     } else {
@@ -1044,6 +1038,20 @@ void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
         (bios_size % 65536) != 0) {
         goto bios_error;
     }
+
+    return bios_size;
+
+ bios_error:
+    fprintf(stderr, "qemu: could not load PC BIOS '%s'\n", bios_name);
+    exit(1);
+}
+
+void load_bios_from_file(X86MachineState *x86ms, const char *bios_name,
+                         char *filename, int bios_size, bool isapc_ram_fw)
+{
+    ssize_t ret;
+
+    /* BIOS load */
     if (machine_require_guest_memfd(MACHINE(x86ms))) {
         memory_region_init_ram_guest_memfd(&x86ms->bios, NULL, "pc.bios",
                                            bios_size, &error_fatal);
@@ -1072,7 +1080,26 @@ void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
             goto bios_error;
         }
     }
-    g_free(filename);
+
+    return;
+
+ bios_error:
+    fprintf(stderr, "qemu: could not load PC BIOS '%s'\n", bios_name);
+    exit(1);
+}
+
+void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
+                       MemoryRegion *rom_memory, bool isapc_ram_fw)
+{
+    int bios_size;
+    const char *bios_name;
+    char *filename;
+
+    bios_name = MACHINE(x86ms)->firmware ?: default_firmware;
+    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
+
+    bios_size = get_bios_size(x86ms, bios_name, filename);
+    load_bios_from_file(x86ms, bios_name, filename, bios_size, isapc_ram_fw);
 
     if (!machine_require_guest_memfd(MACHINE(x86ms))) {
         /* map the last 128KB of the BIOS in ISA space */
@@ -1084,9 +1111,6 @@ void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
     memory_region_add_subregion(rom_memory,
                                 (uint32_t)(-bios_size),
                                 &x86ms->bios);
+    g_free(filename);
     return;
-
-bios_error:
-    fprintf(stderr, "qemu: could not load PC BIOS '%s'\n", bios_name);
-    exit(1);
 }
diff --git a/include/hw/i386/x86.h b/include/hw/i386/x86.h
index 8755cad50a..8871f95891 100644
--- a/include/hw/i386/x86.h
+++ b/include/hw/i386/x86.h
@@ -122,7 +122,10 @@ void x86_cpu_unplug_request_cb(HotplugHandler *hotplug_dev,
                                DeviceState *dev, Error **errp);
 void x86_cpu_unplug_cb(HotplugHandler *hotplug_dev,
                        DeviceState *dev, Error **errp);
-
+int get_bios_size(X86MachineState *x86ms,
+                  const char *bios_name, char *filename);
+void load_bios_from_file(X86MachineState *x86ms, const char *bios_name,
+                         char *filename, int bios_size, bool isapc_ram_fw);
 void x86_isa_bios_init(MemoryRegion *isa_bios, MemoryRegion *isa_memory,
                        MemoryRegion *bios, bool read_only);
 void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
-- 
2.42.0