Newer 9.1 machine types will default to using the KVM_SEV_INIT2 API for
creating SEV/SEV-ES going forward. However, this API results in guest
measurement changes which are generally not expected for users of these
older guest types and can cause disruption if they switch to a newer
QEMU/kernel version. Avoid this by continuing to use the older
KVM_SEV_INIT/KVM_SEV_ES_INIT APIs for older machine types.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 hw/i386/pc.c         | 5 +++++
 hw/i386/pc_piix.c    | 1 +
 hw/i386/pc_q35.c     | 1 +
 include/hw/i386/pc.h | 3 +++
 target/i386/sev.c    | 1 +
 5 files changed, 11 insertions(+)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e80f02bef4..96bf90c17e 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -78,6 +78,11 @@
     { "qemu64-" TYPE_X86_CPU, "model-id", "QEMU Virtual CPU version " v, },\
     { "athlon-" TYPE_X86_CPU, "model-id", "QEMU Virtual CPU version " v, },
 
+GlobalProperty pc_compat_9_0[] = {
+    { "sev-guest", "legacy-vm-type", "true" },
+};
+const size_t pc_compat_9_0_len = G_N_ELEMENTS(pc_compat_9_0);
+
 GlobalProperty pc_compat_8_2[] = {};
 const size_t pc_compat_8_2_len = G_N_ELEMENTS(pc_compat_8_2);
 
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 069414a1ac..0b7a9debab 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -528,6 +528,7 @@ static void pc_i440fx_9_0_machine_options(MachineClass *m)
     pc_i440fx_machine_options(m);
     m->alias = NULL;
     m->is_default = false;
+    compat_props_add(m->compat_props, pc_compat_9_0, pc_compat_9_0_len);
 }
 
 DEFINE_I440FX_MACHINE(v9_0, "pc-i440fx-9.0", NULL,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 77d7f700a8..acb55fc787 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -380,6 +380,7 @@ static void pc_q35_9_0_machine_options(MachineClass *m)
 {
     pc_q35_machine_options(m);
     m->alias = NULL;
+    compat_props_add(m->compat_props, pc_compat_9_0, pc_compat_9_0_len);
 }
 
 DEFINE_Q35_MACHINE(v9_0, "pc-q35-9.0", NULL,
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index fb1d4106e5..e52290916c 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -199,6 +199,9 @@ void pc_system_parse_ovmf_flash(uint8_t *flash_ptr, size_t flash_size);
 /* sgx.c */
 void pc_machine_init_sgx_epc(PCMachineState *pcms);
 
+extern GlobalProperty pc_compat_9_0[];
+extern const size_t pc_compat_9_0_len;
+
 extern GlobalProperty pc_compat_8_2[];
 extern const size_t pc_compat_8_2_len;
 
diff --git a/target/i386/sev.c b/target/i386/sev.c
index f4ee317cb0..d30b68c11e 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -1417,6 +1417,7 @@ sev_guest_instance_init(Object *obj)
     object_property_add_uint32_ptr(obj, "reduced-phys-bits",
                                    &sev->reduced_phys_bits,
                                    OBJ_PROP_FLAG_READWRITE);
+    object_apply_compat_props(obj);
 }
 
 /* sev guest info */
-- 
2.25.1