confidential guest support: Rework the "memory-encryption" property

Currently the "memory-encryption" property is only looked at once we
get to kvm_init().  Although protection of guest memory from the
hypervisor isn't something that could really ever work with TCG, it's
not conceptually tied to the KVM accelerator.

In addition, the way the string property is resolved to an object is
almost identical to how a QOM link property is handled.

So, create a new "confidential-guest-support" link property which sets
this QOM interface link directly in the machine.  For compatibility we
keep the "memory-encryption" property, but now implemented in terms of
the new property.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 3526e88b6c5d950abdc4185a8cd1fedf78ed7277..88a6b8c19eb5b31b1667f7e3759c0828cf0881d9 100644 (file)
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2184,8 +2184,9 @@ static int kvm_init(MachineState *ms)
      * if memory encryption object is specified then initialize the memory
      * encryption context.
      */
-    if (ms->memory_encryption) {
-        ret = sev_guest_init(ms->memory_encryption);
+    if (ms->cgs) {
+        /* FIXME handle mechanisms other than SEV */
+        ret = sev_kvm_init(ms->cgs);
         if (ret < 0) {
             goto err;
         }

diff --git a/accel/kvm/sev-stub.c b/accel/kvm/sev-stub.c
index 5db9ab8f0013bcc718e3a754c6774404ee2a4d89..3d4787ae4aab6e816dfed427159470abe29af9fa 100644 (file)
--- a/accel/kvm/sev-stub.c
+++ b/accel/kvm/sev-stub.c
@@ -15,7 +15,8 @@
 #include "qemu-common.h"
 #include "sysemu/sev.h"
 
-int sev_guest_init(const char *id)
+int sev_kvm_init(ConfidentialGuestSupport *cgs)
 {
-    return -1;
+    /* SEV can't be selected if it's not compiled */
+    g_assert_not_reached();
 }

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 919067b5c94c285cac8866a9fadaa07906a479da..f45a795478e06eb44a26e7ed9702b3378c882281 100644 (file)
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -32,6 +32,7 @@
 #include "hw/mem/nvdimm.h"
 #include "migration/global_state.h"
 #include "migration/vmstate.h"
+#include "exec/confidential-guest-support.h"
 
 GlobalProperty hw_compat_5_2[] = {};
 const size_t hw_compat_5_2_len = G_N_ELEMENTS(hw_compat_5_2);
@@ -427,16 +428,37 @@ static char *machine_get_memory_encryption(Object *obj, Error **errp)
 {
     MachineState *ms = MACHINE(obj);
 
-    return g_strdup(ms->memory_encryption);
+    if (ms->cgs) {
+        return g_strdup(object_get_canonical_path_component(OBJECT(ms->cgs)));
+    }
+
+    return NULL;
 }
 
 static void machine_set_memory_encryption(Object *obj, const char *value,
                                         Error **errp)
 {
-    MachineState *ms = MACHINE(obj);
+    Object *cgs =
+        object_resolve_path_component(object_get_objects_root(), value);
+
+    if (!cgs) {
+        error_setg(errp, "No such memory encryption object '%s'", value);
+        return;
+    }
 
-    g_free(ms->memory_encryption);
-    ms->memory_encryption = g_strdup(value);
+    object_property_set_link(obj, "confidential-guest-support", cgs, errp);
+}
+
+static void machine_check_confidential_guest_support(const Object *obj,
+                                                     const char *name,
+                                                     Object *new_target,
+                                                     Error **errp)
+{
+    /*
+     * So far the only constraint is that the target has the
+     * TYPE_CONFIDENTIAL_GUEST_SUPPORT interface, and that's checked
+     * by the QOM core
+     */
 }
 
 static bool machine_get_nvdimm(Object *obj, Error **errp)
@@ -836,6 +858,15 @@ static void machine_class_init(ObjectClass *oc, void *data)
     object_class_property_set_description(oc, "suppress-vmdesc",
         "Set on to disable self-describing migration");
 
+    object_class_property_add_link(oc, "confidential-guest-support",
+                                   TYPE_CONFIDENTIAL_GUEST_SUPPORT,
+                                   offsetof(MachineState, cgs),
+                                   machine_check_confidential_guest_support,
+                                   OBJ_PROP_LINK_STRONG);
+    object_class_property_set_description(oc, "confidential-guest-support",
+                                          "Set confidential guest scheme to support");
+
+    /* For compatibility */
     object_class_property_add_str(oc, "memory-encryption",
         machine_get_memory_encryption, machine_set_memory_encryption);
     object_class_property_set_description(oc, "memory-encryption",
@@ -1158,9 +1189,9 @@ void machine_run_board_init(MachineState *machine)
                     cc->deprecation_note);
     }
 
-    if (machine->memory_encryption) {
+    if (machine->cgs) {
         /*
-         * With memory encryption, the host can't see the real
+         * With confidential guests, the host can't see the real
          * contents of RAM, so there's no point in it trying to merge
          * areas.
          */

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 85af4faf76447adf3533a74d2d730144b0a1576c..a46dfe5d1a6ae23c58dfefa8bdd1c2c9f8147ea2 100644 (file)
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -270,7 +270,7 @@ struct MachineState {
     bool iommu;
     bool suppress_vmdesc;
     bool enable_graphics;
-    char *memory_encryption;
+    ConfidentialGuestSupport *cgs;
     char *ram_memdev_id;
     /*
      * convenience alias to ram_memdev_id backend memory region

diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
index 7335e59867f81775b50d0c7012ca8b757c8de821..3b5b1aacf1bb5c3763e54afe77a3ddaa8e2ea1bd 100644 (file)
--- a/include/sysemu/sev.h
+++ b/include/sysemu/sev.h
@@ -16,7 +16,7 @@
 
 #include "sysemu/kvm.h"
 
-int sev_guest_init(const char *id);
+int sev_kvm_init(ConfidentialGuestSupport *cgs);
 int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp);
 int sev_inject_launch_secret(const char *hdr, const char *secret,
                              uint64_t gpa, Error **errp);

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 8d4e1ea2625321c0218b0cefbe2bba627819ccba..fa962d533c8397795cc029a4a053199bfa2d5112 100644 (file)
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -335,26 +335,6 @@ static const TypeInfo sev_guest_info = {
     }
 };
 
-static SevGuestState *
-lookup_sev_guest_info(const char *id)
-{
-    Object *obj;
-    SevGuestState *info;
-
-    obj = object_resolve_path_component(object_get_objects_root(), id);
-    if (!obj) {
-        return NULL;
-    }
-
-    info = (SevGuestState *)
-            object_dynamic_cast(obj, TYPE_SEV_GUEST);
-    if (!info) {
-        return NULL;
-    }
-
-    return info;
-}
-
 bool
 sev_enabled(void)
 {
@@ -682,10 +662,9 @@ sev_vm_state_change(void *opaque, int running, RunState state)
     }
 }
 
-int
-sev_guest_init(const char *id)
+int sev_kvm_init(ConfidentialGuestSupport *cgs)
 {
-    SevGuestState *sev;
+    SevGuestState *sev = SEV_GUEST(cgs);
     char *devname;
     int ret, fw_error;
     uint32_t ebx;
@@ -698,13 +677,6 @@ sev_guest_init(const char *id)
         return -1;
     }
 
-    sev = lookup_sev_guest_info(id);
-    if (!sev) {
-        error_report("%s: '%s' is not a valid '%s' object",
-                     __func__, id, TYPE_SEV_GUEST);
-        goto err;
-    }
-
     sev_guest = sev;
     sev->state = SEV_STATE_UNINIT;