hostmem: detect host backend memory is being used properly

Currently, we use memory_region_is_mapped() to detect if the host
backend memory is being used. This works if the memory is directly
mapped into guest's address space, however, it is not true for
nvdimm as it uses aliased memory region to map the memory. This is
why this bug can happen:
   https://bugzilla.redhat.com/show_bug.cgi?id=1352769

Fix it by introduce a new filed, is_mapped, to HostMemoryBackend,
we set/clear this filed accordingly when the device link/unlink to
host backend memory

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 8dede4db2e61c729004b2da3c696b4e4fcb6bdc6..ac802570a8f0b1742a0934f637e279c55f585ff0 100644 (file)
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -264,6 +264,16 @@ host_memory_backend_get_memory(HostMemoryBackend *backend, Error **errp)
     return memory_region_size(&backend->mr) ? &backend->mr : NULL;
 }
 
+void host_memory_backend_set_mapped(HostMemoryBackend *backend, bool mapped)
+{
+    backend->is_mapped = mapped;
+}
+
+bool host_memory_backend_is_mapped(HostMemoryBackend *backend)
+{
+    return backend->is_mapped;
+}
+
 static void
 host_memory_backend_memory_complete(UserCreatable *uc, Error **errp)
 {
@@ -341,10 +351,7 @@ host_memory_backend_memory_complete(UserCreatable *uc, Error **errp)
 static bool
 host_memory_backend_can_be_deleted(UserCreatable *uc, Error **errp)
 {
-    MemoryRegion *mr;
-
-    mr = host_memory_backend_get_memory(MEMORY_BACKEND(uc), errp);
-    if (memory_region_is_mapped(mr)) {
+    if (host_memory_backend_is_mapped(MEMORY_BACKEND(uc))) {
         return false;
     } else {
         return true;

diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index 249193a54358d5b93f4e053e0380e6684c7975c9..9e8dab0e89fd33c1d6f2efd6def860f69d94ca37 100644 (file)
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -369,14 +369,9 @@ static void pc_dimm_get_size(Object *obj, Visitor *v, const char *name,
 static void pc_dimm_check_memdev_is_busy(Object *obj, const char *name,
                                       Object *val, Error **errp)
 {
-    MemoryRegion *mr;
     Error *local_err = NULL;
 
-    mr = host_memory_backend_get_memory(MEMORY_BACKEND(val), &local_err);
-    if (local_err) {
-        goto out;
-    }
-    if (memory_region_is_mapped(mr)) {
+    if (host_memory_backend_is_mapped(MEMORY_BACKEND(val))) {
         char *path = object_get_canonical_path_component(val);
         error_setg(&local_err, "can't use already busy memdev: %s", path);
         g_free(path);
@@ -384,7 +379,6 @@ static void pc_dimm_check_memdev_is_busy(Object *obj, const char *name,
         qdev_prop_allow_set_link_before_realize(obj, name, val, &local_err);
     }
 
-out:
     error_propagate(errp, local_err);
 }
 
@@ -421,6 +415,15 @@ static void pc_dimm_realize(DeviceState *dev, Error **errp)
     if (ddc->realize) {
         ddc->realize(dimm, errp);
     }
+
+    host_memory_backend_set_mapped(dimm->hostmem, true);
+}
+
+static void pc_dimm_unrealize(DeviceState *dev, Error **errp)
+{
+    PCDIMMDevice *dimm = PC_DIMM(dev);
+
+    host_memory_backend_set_mapped(dimm->hostmem, false);
 }
 
 static MemoryRegion *pc_dimm_get_memory_region(PCDIMMDevice *dimm)
@@ -439,6 +442,7 @@ static void pc_dimm_class_init(ObjectClass *oc, void *data)
     PCDIMMDeviceClass *ddc = PC_DIMM_CLASS(oc);
 
     dc->realize = pc_dimm_realize;
+    dc->unrealize = pc_dimm_unrealize;
     dc->props = pc_dimm_properties;
     dc->desc = "DIMM memory module";
 

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index c4dde3a52e7fd8d7eef472bbdc4d9316b70cb33a..7e7c843b32d63edb3bbd30973c943a9d0d14a85e 100644 (file)
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -1008,10 +1008,7 @@ static const TypeInfo ivshmem_common_info = {
 static void ivshmem_check_memdev_is_busy(Object *obj, const char *name,
                                          Object *val, Error **errp)
 {
-    MemoryRegion *mr;
-
-    mr = host_memory_backend_get_memory(MEMORY_BACKEND(val), &error_abort);
-    if (memory_region_is_mapped(mr)) {
+    if (host_memory_backend_is_mapped(MEMORY_BACKEND(val))) {
         char *path = object_get_canonical_path_component(val);
         error_setg(errp, "can't use already busy memdev: %s", path);
         g_free(path);
@@ -1060,6 +1057,14 @@ static void ivshmem_plain_realize(PCIDevice *dev, Error **errp)
     }
 
     ivshmem_common_realize(dev, errp);
+    host_memory_backend_set_mapped(s->hostmem, true);
+}
+
+static void ivshmem_plain_exit(PCIDevice *pci_dev)
+{
+    IVShmemState *s = IVSHMEM_COMMON(pci_dev);
+
+    host_memory_backend_set_mapped(s->hostmem, false);
 }
 
 static void ivshmem_plain_class_init(ObjectClass *klass, void *data)
@@ -1068,6 +1073,7 @@ static void ivshmem_plain_class_init(ObjectClass *klass, void *data)
     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
 
     k->realize = ivshmem_plain_realize;
+    k->exit = ivshmem_plain_exit;
     dc->props = ivshmem_plain_properties;
     dc->vmsd = &ivshmem_plain_vmsd;
 }

diff --git a/include/sysemu/hostmem.h b/include/sysemu/hostmem.h
index 4d6617eab76dbc45eae49506c02931a9b8fd852e..c903404308cc5f80a164b01f98053d1e0b2439a6 100644 (file)
--- a/include/sysemu/hostmem.h
+++ b/include/sysemu/hostmem.h
@@ -53,7 +53,7 @@ struct HostMemoryBackend {
     /* protected */
     uint64_t size;
     bool merge, dump;
-    bool prealloc, force_prealloc;
+    bool prealloc, force_prealloc, is_mapped;
     DECLARE_BITMAP(host_nodes, MAX_NODES + 1);
     HostMemPolicy policy;
 
@@ -63,4 +63,6 @@ struct HostMemoryBackend {
 MemoryRegion *host_memory_backend_get_memory(HostMemoryBackend *backend,
                                              Error **errp);
 
+void host_memory_backend_set_mapped(HostMemoryBackend *backend, bool mapped);
+bool host_memory_backend_is_mapped(HostMemoryBackend *backend);
 #endif