[PATCH] hw/i386: Add unaccepted memory configuration

[Dionna Glaze]

For SEV-SNP, an OS is "SEV-SNP capable" without supporting this UEFI
v2.9 memory type. In order for OVMF to be able to avoid pre-validating
potentially hundreds of gibibytes of data before booting, it needs to
know if the guest OS can support its use of the new type of memory in
the memory map.

Cc: Xu, Min M <min.m.xu@intel.com>
Cc: Xiaoyao Li <xiaoyao.li@intel.com>
Cc: Thomas Lendacky <Thomas.Lendacky@amd.com>
Cc: Gerd Hoffman <kraxel@redhat.com>
Signed-off-by: Dionna Glaze <dionnaglaze@google.com>
---
 hw/core/machine.c   | 33 +++++++++++++++++++++++++++++++++
 hw/i386/fw_cfg.c    |  5 +++++
 include/hw/boards.h |  1 +
 3 files changed, 39 insertions(+)

diff --git a/hw/core/machine.c b/hw/core/machine.c
index c53548d0b1..d2b9513951 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -263,6 +263,15 @@ GlobalProperty hw_compat_2_1[] = {
 };
 const size_t hw_compat_2_1_len = G_N_ELEMENTS(hw_compat_2_1);
 
+static QEnumLookup memory_acceptance_lookup = {
+    .array = (const char *const[]) {
+        "default",
+        "true",
+        "false",
+    },
+    .size = 3,
+};
+
 MachineState *current_machine;
 
 static char *machine_get_kernel(Object *obj, Error **errp)
@@ -502,6 +511,20 @@ static void machine_check_confidential_guest_support(const 
Object *obj,
      */
 }
 
+static int machine_get_accept_all_memory(Object *obj, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    return ms->accept_all_memory;
+}
+
+static void machine_set_accept_all_memory(Object *obj, int value, Error **errp)
+{
+    MachineState *ms = MACHINE(obj);
+
+    ms->accept_all_memory = value;
+}
+
 static bool machine_get_nvdimm(Object *obj, Error **errp)
 {
     MachineState *ms = MACHINE(obj);
@@ -1022,6 +1045,15 @@ static void machine_class_init(ObjectClass *oc, void 
*data)
     object_class_property_set_description(oc, "confidential-guest-support",
                                           "Set confidential guest scheme to 
support");
 
+    object_class_property_add_enum(oc, "accept-all-memory",
+                                   "MemoryAcceptance",
+                                   &memory_acceptance_lookup,
+        machine_get_accept_all_memory, machine_set_accept_all_memory);
+    object_class_property_set_description(
+        oc, "accept-all-memory",
+        "false: Accept all memory, true: Accept up to 4G and leave the rest 
unaccepted (UEFI"
+        " v2.9 memory type), default: default firmware behavior.");
+
     /* For compatibility */
     object_class_property_add_str(oc, "memory-encryption",
         machine_get_memory_encryption, machine_set_memory_encryption);
@@ -1072,6 +1104,7 @@ static void machine_initfn(Object *obj)
     ms->kernel_cmdline = g_strdup("");
     ms->ram_size = mc->default_ram_size;
     ms->maxram_size = mc->default_ram_size;
+    ms->accept_all_memory = 0;
 
     if (mc->nvdimm_supported) {
         Object *obj = OBJECT(ms);
diff --git a/hw/i386/fw_cfg.c b/hw/i386/fw_cfg.c
index a283785a8d..96164994f8 100644
--- a/hw/i386/fw_cfg.c
+++ b/hw/i386/fw_cfg.c
@@ -131,6 +131,11 @@ FWCfgState *fw_cfg_arch_create(MachineState *ms,
                      &e820_reserve, sizeof(e820_reserve));
     fw_cfg_add_file(fw_cfg, "etc/e820", e820_table,
                     sizeof(struct e820_entry) * e820_get_num_entries());
+    if (ms->accept_all_memory) {
+        bool accept_all = ms->accept_all_memory == 1;
+        fw_cfg_add_file(fw_cfg, "opt/ovmf/AcceptAllMemory",
+                        &accept_all, sizeof(accept_all));
+    }
 
     fw_cfg_add_bytes(fw_cfg, FW_CFG_HPET, &hpet_cfg, sizeof(hpet_cfg));
     /* allocate memory for the NUMA channel: one (64bit) word for the number
diff --git a/include/hw/boards.h b/include/hw/boards.h
index fa57bac4fb..eaf73498c4 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -362,6 +362,7 @@ struct MachineState {
     struct NVDIMMState *nvdimms_state;
     struct CXLState *cxl_devices_state;
     struct NumaState *numa_state;
+    int accept_all_memory;
 };
 
 #define DEFINE_MACHINE(namestr, machine_initfn) \
-- 
2.37.0.rc0.104.g0611611a94-goog