vl: Add sgx compound properties to expose SGX EPC sections to guest

Because SGX EPC is enumerated through CPUID, EPC "devices" need to be
realized prior to realizing the vCPUs themselves, i.e. long before
generic devices are parsed and realized.  From a virtualization
perspective, the CPUID aspect also means that EPC sections cannot be
hotplugged without paravirtualizing the guest kernel (hardware does
not support hotplugging as EPC sections must be locked down during
pre-boot to provide EPC's security properties).

So even though EPC sections could be realized through the generic
-devices command, they need to be created much earlier for them to
actually be usable by the guest.  Place all EPC sections in a
contiguous block, somewhat arbitrarily starting after RAM above 4g.
Ensuring EPC is in a contiguous region simplifies calculations, e.g.
device memory base, PCI hole, etc..., allows dynamic calculation of the
total EPC size, e.g. exposing EPC to guests does not require -maxmem,
and last but not least allows all of EPC to be enumerated in a single
ACPI entry, which is expected by some kernels, e.g. Windows 7 and 8.

The new compound properties command for sgx like below:
 ......
 -object memory-backend-epc,id=mem1,size=28M,prealloc=on \
 -object memory-backend-epc,id=mem2,size=10M \
 -M sgx-epc.0.memdev=mem1,sgx-epc.1.memdev=mem2

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Yang Zhong <yang.zhong@intel.com>
Message-Id: <20210719112136.57018-6-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/hw/i386/x86.c b/hw/i386/x86.c
index 00448ed..41ef9a8 100644
--- a/hw/i386/x86.c
+++ b/hw/i386/x86.c
@@ -30,6 +30,8 @@
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/qapi-visit-common.h"
+#include "qapi/clone-visitor.h"
+#include "qapi/qapi-visit-machine.h"
 #include "qapi/visitor.h"
 #include "sysemu/qtest.h"
 #include "sysemu/whpx.h"
@@ -1263,6 +1265,27 @@ static void x86_machine_set_bus_lock_ratelimit(Object *obj, Visitor *v,
     visit_type_uint64(v, name, &x86ms->bus_lock_ratelimit, errp);
 }
 
+static void machine_get_sgx_epc(Object *obj, Visitor *v, const char *name,
+                                void *opaque, Error **errp)
+{
+    X86MachineState *x86ms = X86_MACHINE(obj);
+    SgxEPCList *list = x86ms->sgx_epc_list;
+
+    visit_type_SgxEPCList(v, name, &list, errp);
+}
+
+static void machine_set_sgx_epc(Object *obj, Visitor *v, const char *name,
+                                void *opaque, Error **errp)
+{
+    X86MachineState *x86ms = X86_MACHINE(obj);
+    SgxEPCList *list;
+
+    list = x86ms->sgx_epc_list;
+    visit_type_SgxEPCList(v, name, &x86ms->sgx_epc_list, errp);
+
+    qapi_free_SgxEPCList(list);
+}
+
 static void x86_machine_initfn(Object *obj)
 {
     X86MachineState *x86ms = X86_MACHINE(obj);
@@ -1322,6 +1345,12 @@ static void x86_machine_class_init(ObjectClass *oc, void *data)
                                 x86_machine_set_bus_lock_ratelimit, NULL, NULL);
     object_class_property_set_description(oc, X86_MACHINE_BUS_LOCK_RATELIMIT,
             "Set the ratelimit for the bus locks acquired in VMs");
+
+    object_class_property_add(oc, "sgx-epc", "SgxEPC",
+        machine_get_sgx_epc, machine_set_sgx_epc,
+        NULL, NULL);
+    object_class_property_set_description(oc, "sgx-epc",
+        "SGX EPC device");
 }
 
 static const TypeInfo x86_machine_info = {