i386/tdx: Don't initialize pc.rom for TDX VMs

For TDX, the address below 1MB are entirely general RAM. No need to
initialize pc.rom memory region for TDs.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Reviewed-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250508150002.689633-20-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 70656157ca0af038cb3991a04efce55b15d5863e..a403987a6422b02598798b5450099ac1932e5097 100644 (file)
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -44,6 +44,7 @@
 #include "system/xen.h"
 #include "system/reset.h"
 #include "kvm/kvm_i386.h"
+#include "kvm/tdx.h"
 #include "hw/xen/xen.h"
 #include "qobject/qlist.h"
 #include "qemu/error-report.h"
@@ -976,21 +977,23 @@ void pc_memory_init(PCMachineState *pcms,
     /* Initialize PC system firmware */
     pc_system_firmware_init(pcms, rom_memory);
 
-    option_rom_mr = g_malloc(sizeof(*option_rom_mr));
-    if (machine_require_guest_memfd(machine)) {
-        memory_region_init_ram_guest_memfd(option_rom_mr, NULL, "pc.rom",
-                                           PC_ROM_SIZE, &error_fatal);
-    } else {
-        memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE,
-                               &error_fatal);
-        if (pcmc->pci_enabled) {
-            memory_region_set_readonly(option_rom_mr, true);
+    if (!is_tdx_vm()) {
+        option_rom_mr = g_malloc(sizeof(*option_rom_mr));
+        if (machine_require_guest_memfd(machine)) {
+            memory_region_init_ram_guest_memfd(option_rom_mr, NULL, "pc.rom",
+                                            PC_ROM_SIZE, &error_fatal);
+        } else {
+            memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE,
+                                &error_fatal);
+            if (pcmc->pci_enabled) {
+                memory_region_set_readonly(option_rom_mr, true);
+            }
         }
+        memory_region_add_subregion_overlap(rom_memory,
+                                            PC_ROM_MIN_VGA,
+                                            option_rom_mr,
+                                            1);
     }
-    memory_region_add_subregion_overlap(rom_memory,
-                                        PC_ROM_MIN_VGA,
-                                        option_rom_mr,
-                                        1);
 
     fw_cfg = fw_cfg_arch_create(machine,
                                 x86ms->boot_cpus, x86ms->apic_id_limit);