[PATCH v1 23/40] i386/tdx: Don't initialize pc.rom for TDX VMs

Xiaoyao Li
2022-08-02T07:50:08Z

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>
---
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 | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 1f62971759bf..c089dc49485d 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -62,6 +62,7 @@
#include "sysemu/reset.h"
#include "sysemu/runstate.h"
#include "kvm/kvm_i386.h"
+#include "kvm/tdx.h"
#include "hw/xen/xen.h"
#include "hw/xen/start_info.h"
#include "ui/qemu-spice.h"
@@ -1084,16 +1085,18 @@ 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));
- 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));
+ 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);
--
2.27.0