[v6,20/60] i386/tdx: Don't initialize pc.rom for TDX VMs

Commit Message

Xiaoyao Li Nov. 5, 2024, 6:23 a.m. UTC

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 <[e-mail]>
---
This is more as a workaround of the issue that for q35 machine type, the
real memslot update (which requires memslot deletion )for pc.rom happens
after tdx_init_memory_region. It leads to the private memory ADD'ed
before get lost. I haven't work out a good solution to resolve the
order issue. So just skip the pc.rom setup to avoid memslot deletion.
---
 hw/i386/pc.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

Patch

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2047633e4cf7..4a23856aed47 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -43,6 +43,7 @@ 
 #include "sysemu/xen.h"
 #include "sysemu/reset.h"
 #include "kvm/kvm_i386.h"
+#include "kvm/tdx.h"
 #include "hw/xen/xen.h"
 #include "qapi/qmp/qlist.h"
 #include "qemu/error-report.h"
@@ -966,21 +967,23 @@  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);