diff mbox series

[v3,4/9] host trust limitation: Rework the "memory-encryption" property

Message ID 20200619020602.118306-5-david@gibson.dropbear.id.au (mailing list archive)
State New, archived
Headers show
Series Generalize memory encryption models | expand

Commit Message

David Gibson June 19, 2020, 2:05 a.m. UTC
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 "host-trust-limitation" 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>
---
 accel/kvm/kvm-all.c | 23 +++++++----------------
 hw/core/machine.c   | 41 ++++++++++++++++++++++++++++++++++++-----
 include/hw/boards.h |  2 +-
 3 files changed, 44 insertions(+), 22 deletions(-)

Comments

Richard Henderson July 14, 2020, 7:36 p.m. UTC | #1
On 6/18/20 7:05 PM, David Gibson wrote:
> 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 "host-trust-limitation" 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>
> ---
>  accel/kvm/kvm-all.c | 23 +++++++----------------
>  hw/core/machine.c   | 41 ++++++++++++++++++++++++++++++++++++-----
>  include/hw/boards.h |  2 +-
>  3 files changed, 44 insertions(+), 22 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~
diff mbox series

Patch

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 1e43e27f45..d8e8fa345e 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2180,25 +2180,16 @@  static int kvm_init(MachineState *ms)
      * if memory encryption object is specified then initialize the memory
      * encryption context.
      */
-    if (ms->memory_encryption) {
-        Object *obj = object_resolve_path_component(object_get_objects_root(),
-                                                    ms->memory_encryption);
-
-        if (object_dynamic_cast(obj, TYPE_HOST_TRUST_LIMITATION)) {
-            HostTrustLimitation *htl = HOST_TRUST_LIMITATION(obj);
-            HostTrustLimitationClass *htlc
-                = HOST_TRUST_LIMITATION_GET_CLASS(htl);
-
-            ret = htlc->kvm_init(htl);
-            if (ret < 0) {
-                goto err;
-            }
+    if (ms->htl) {
+        HostTrustLimitationClass *htlc =
+            HOST_TRUST_LIMITATION_GET_CLASS(ms->htl);
 
-            kvm_state->htl = htl;
-        } else {
-            ret = -1;
+        ret = htlc->kvm_init(ms->htl);
+        if (ret < 0) {
             goto err;
         }
+
+        kvm_state->htl = ms->htl;
     }
 
     ret = kvm_arch_init(ms, s);
diff --git a/hw/core/machine.c b/hw/core/machine.c
index fdc0c7e038..a71792bc16 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -27,6 +27,7 @@ 
 #include "hw/pci/pci.h"
 #include "hw/mem/nvdimm.h"
 #include "migration/vmstate.h"
+#include "exec/host-trust-limitation.h"
 
 GlobalProperty hw_compat_5_0[] = {
     { "virtio-balloon-device", "page-poison", "false" },
@@ -425,16 +426,37 @@  static char *machine_get_memory_encryption(Object *obj, Error **errp)
 {
     MachineState *ms = MACHINE(obj);
 
-    return g_strdup(ms->memory_encryption);
+    if (ms->htl) {
+        return object_get_canonical_path_component(OBJECT(ms->htl));
+    }
+
+    return NULL;
 }
 
 static void machine_set_memory_encryption(Object *obj, const char *value,
                                         Error **errp)
 {
-    MachineState *ms = MACHINE(obj);
+    Object *htl =
+        object_resolve_path_component(object_get_objects_root(), value);
+
+    if (!htl) {
+        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, htl, "host-trust-limitation", errp);
+}
+
+static void machine_check_host_trust_limitation(const Object *obj,
+                                                const char *name,
+                                                Object *new_target,
+                                                Error **errp)
+{
+    /*
+     * So far the only constraint is that the target has the
+     * TYPE_HOST_TRUST_LIMITATION interface, and that's checked by the
+     * QOM core
+     */
 }
 
 static bool machine_get_nvdimm(Object *obj, Error **errp)
@@ -855,6 +877,15 @@  static void machine_class_init(ObjectClass *oc, void *data)
     object_class_property_set_description(oc, "enforce-config-section",
         "Set on to enforce configuration section migration");
 
+    object_class_property_add_link(oc, "host-trust-limitation",
+                                   TYPE_HOST_TRUST_LIMITATION,
+                                   offsetof(MachineState, htl),
+                                   machine_check_host_trust_limitation,
+                                   OBJ_PROP_LINK_STRONG);
+    object_class_property_set_description(oc, "host-trust-limitation",
+        "Set host trust limitation object to use");
+
+    /* 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",
@@ -1127,7 +1158,7 @@  void machine_run_board_init(MachineState *machine)
         }
     }
 
-    if (machine->memory_encryption) {
+    if (machine->htl) {
         /*
          * With host trust limitation, the host can't see the real
          * contents of RAM, so there's no point in it trying to merge
diff --git a/include/hw/boards.h b/include/hw/boards.h
index 18815d9be2..a9f8444729 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -277,7 +277,7 @@  struct MachineState {
     bool suppress_vmdesc;
     bool enforce_config_section;
     bool enable_graphics;
-    char *memory_encryption;
+    HostTrustLimitation *htl;
     char *ram_memdev_id;
     /*
      * convenience alias to ram_memdev_id backend memory region