hw/i386: export a new function x86_bios_rom_reload

Confidential guest smust reload their bios rom upon reset. This is because
bios memory is encrypted and upon reset, the contents of the old bios memory
is lost and cannot be re-used. To this end, export a new x86 function
x86_bios_rom_reload() to reload the bios again. This function will be used in
the subsequent patches.

Reviewed-by: Bernhard Beschow <shentey@gmail.com>
Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20260225035000.385950-14-anisinha@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/i386/x86-common.c b/hw/i386/x86-common.c
index c98abaf36895fba515ecac50d1651175586d2dee..a420112666ae5fc53a93e16492883427684bd52c 100644 (file)
--- a/hw/i386/x86-common.c
+++ b/hw/i386/x86-common.c
@@ -1085,6 +1085,27 @@ static void load_bios_from_file(X86MachineState *x86ms, const char *bios_name,
     exit(1);
 }
 
+void x86_bios_rom_reload(X86MachineState *x86ms)
+{
+    int bios_size;
+    const char *bios_name;
+    char *filename;
+
+    if (memory_region_size(&x86ms->bios) == 0) {
+        /* if -bios is not used */
+        return;
+    }
+
+    bios_name = MACHINE(x86ms)->firmware ?: "bios.bin";
+    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
+
+    bios_size = get_bios_size(x86ms, bios_name, filename);
+
+    void *ptr = memory_region_get_ram_ptr(&x86ms->bios);
+    load_image_size(filename, ptr, bios_size);
+    x86_firmware_configure(0x100000000ULL - bios_size, ptr, bios_size);
+}
+
 void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
                        MemoryRegion *rom_memory, bool isapc_ram_fw)
 {

diff --git a/include/hw/i386/x86.h b/include/hw/i386/x86.h
index 23be6274377499c5f9b15fe508283b4a816916e8..a85a5600ce9fd621a4509fe42815550c37cf7abe 100644 (file)
--- a/include/hw/i386/x86.h
+++ b/include/hw/i386/x86.h
@@ -125,6 +125,7 @@ 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,
                        MemoryRegion *rom_memory, bool isapc_ram_fw);
+void x86_bios_rom_reload(X86MachineState *x86ms);
 
 void x86_load_linux(X86MachineState *x86ms,
                     FWCfgState *fw_cfg,