When IGVM is not being used by the confidential guest, the guest firmware has
to be reloaded explictly again into memory. This is because, the memory into
which the firmware was loaded before reset was encrypted and is thus lost
upon reset. When IGVM is used, it is expected that the IGVM will contain the
guest firmware and the execution of the IGVM directives will set up the guest
firmware memory.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 target/i386/kvm/kvm.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index e971f5f8c4..199a224dbf 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -50,6 +50,8 @@
 #include "qemu/config-file.h"
 #include "qemu/error-report.h"
 #include "qemu/memalign.h"
+#include "qemu/datadir.h"
+#include "hw/loader.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/kvm/xen_evtchn.h"
 #include "hw/i386/pc.h"
@@ -3254,6 +3256,22 @@ static int kvm_vm_enable_energy_msrs(KVMState *s)
 
 static int xen_init_wrapper(MachineState *ms, KVMState *s);
 
+static void reload_bios_rom(X86MachineState *x86ms)
+{
+    int bios_size;
+    const char *bios_name;
+    char *filename;
+
+    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);
+}
+
 int kvm_arch_vmfd_change_ops(MachineState *ms, KVMState *s)
 {
     Error *local_err = NULL;
@@ -3272,6 +3290,16 @@ int kvm_arch_vmfd_change_ops(MachineState *ms, KVMState *s)
             error_report_err(local_err);
             return ret;
         }
+        if (object_dynamic_cast(OBJECT(ms), TYPE_X86_MACHINE)) {
+            X86MachineState *x86ms = X86_MACHINE(ms);
+            /*
+             * If an IGVM file is specified then the firmware must be provided
+             * in the IGVM file.
+             */
+            if (!x86ms->igvm) {
+                reload_bios_rom(x86ms);
+            }
+        }
     }
 
     ret = kvm_vm_enable_exception_payload(s);
-- 
2.42.0