arm/kvm: add support for MTE

Extend the 'mte' property for the virt machine to cover KVM as
well. For KVM, we don't allocate tag memory, but instead enable the
capability.

If MTE has been enabled, we need to disable migration, as we do not
yet have a way to migrate the tags as well. Therefore, MTE will stay
off with KVM unless requested explicitly.

Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230428095533.21747-2-cohuck@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 39 insertions, 30 deletions

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index b99ae18501..06b514b25c 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -2146,7 +2146,7 @@ static void machvirt_init(MachineState *machine)
         exit(1);
     }
 
-    if (vms->mte && (kvm_enabled() || hvf_enabled())) {
+    if (vms->mte && hvf_enabled()) {
         error_report("mach-virt: %s does not support providing "
                      "MTE to the guest CPU",
                      current_accel_name());
@@ -2216,39 +2216,48 @@ static void machvirt_init(MachineState *machine)
         }
 
         if (vms->mte) {
-            /* Create the memory region only once, but link to all cpus. */
-            if (!tag_sysmem) {
-                /*
-                 * The property exists only if MemTag is supported.
-                 * If it is, we must allocate the ram to back that up.
-                 */
-                if (!object_property_find(cpuobj, "tag-memory")) {
-                    error_report("MTE requested, but not supported "
-                                 "by the guest CPU");
-                    exit(1);
+            if (tcg_enabled()) {
+                /* Create the memory region only once, but link to all cpus. */
+                if (!tag_sysmem) {
+                    /*
+                     * The property exists only if MemTag is supported.
+                     * If it is, we must allocate the ram to back that up.
+                     */
+                    if (!object_property_find(cpuobj, "tag-memory")) {
+                        error_report("MTE requested, but not supported "
+                                     "by the guest CPU");
+                        exit(1);
+                    }
+
+                    tag_sysmem = g_new(MemoryRegion, 1);
+                    memory_region_init(tag_sysmem, OBJECT(machine),
+                                       "tag-memory", UINT64_MAX / 32);
+
+                    if (vms->secure) {
+                        secure_tag_sysmem = g_new(MemoryRegion, 1);
+                        memory_region_init(secure_tag_sysmem, OBJECT(machine),
+                                           "secure-tag-memory",
+                                           UINT64_MAX / 32);
+
+                        /* As with ram, secure-tag takes precedence over tag. */
+                        memory_region_add_subregion_overlap(secure_tag_sysmem,
+                                                            0, tag_sysmem, -1);
+                    }
                 }
 
-                tag_sysmem = g_new(MemoryRegion, 1);
-                memory_region_init(tag_sysmem, OBJECT(machine),
-                                   "tag-memory", UINT64_MAX / 32);
-
+                object_property_set_link(cpuobj, "tag-memory",
+                                         OBJECT(tag_sysmem), &error_abort);
                 if (vms->secure) {
-                    secure_tag_sysmem = g_new(MemoryRegion, 1);
-                    memory_region_init(secure_tag_sysmem, OBJECT(machine),
-                                       "secure-tag-memory", UINT64_MAX / 32);
-
-                    /* As with ram, secure-tag takes precedence over tag.  */
-                    memory_region_add_subregion_overlap(secure_tag_sysmem, 0,
-                                                        tag_sysmem, -1);
+                    object_property_set_link(cpuobj, "secure-tag-memory",
+                                             OBJECT(secure_tag_sysmem),
+                                             &error_abort);
                 }
-            }
-
-            object_property_set_link(cpuobj, "tag-memory", OBJECT(tag_sysmem),
-                                     &error_abort);
-            if (vms->secure) {
-                object_property_set_link(cpuobj, "secure-tag-memory",
-                                         OBJECT(secure_tag_sysmem),
-                                         &error_abort);
+            } else if (kvm_enabled()) {
+                if (!kvm_arm_mte_supported()) {
+                    error_report("MTE requested, but not supported by KVM");
+                    exit(1);
+                }
+                kvm_arm_enable_mte(cpuobj, &error_abort);
             }
         }