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-rw-r--r--migration/vmstate.c168
1 files changed, 134 insertions, 34 deletions
diff --git a/migration/vmstate.c b/migration/vmstate.c
index ff5d589..5feaa32 100644
--- a/migration/vmstate.c
+++ b/migration/vmstate.c
@@ -15,14 +15,15 @@
#include "migration/vmstate.h"
#include "savevm.h"
#include "qapi/error.h"
-#include "qapi/qmp/json-writer.h"
+#include "qobject/json-writer.h"
#include "qemu-file.h"
#include "qemu/bitops.h"
#include "qemu/error-report.h"
#include "trace.h"
static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
- void *opaque, JSONWriter *vmdesc);
+ void *opaque, JSONWriter *vmdesc,
+ Error **errp);
static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
void *opaque);
@@ -50,6 +51,36 @@ vmstate_field_exists(const VMStateDescription *vmsd, const VMStateField *field,
return result;
}
+/*
+ * Create a fake nullptr field when there's a NULL pointer detected in the
+ * array of a VMS_ARRAY_OF_POINTER VMSD field. It's needed because we
+ * can't dereference the NULL pointer.
+ */
+static const VMStateField *
+vmsd_create_fake_nullptr_field(const VMStateField *field)
+{
+ VMStateField *fake = g_new0(VMStateField, 1);
+
+ /* It can only happen on an array of pointers! */
+ assert(field->flags & VMS_ARRAY_OF_POINTER);
+
+ /* Some of fake's properties should match the original's */
+ fake->name = field->name;
+ fake->version_id = field->version_id;
+
+ /* Do not need "field_exists" check as it always exists (which is null) */
+ fake->field_exists = NULL;
+
+ /* See vmstate_info_nullptr - use 1 byte to represent nullptr */
+ fake->size = 1;
+ fake->info = &vmstate_info_nullptr;
+ fake->flags = VMS_SINGLE;
+
+ /* All the rest fields shouldn't matter.. */
+
+ return (const VMStateField *)fake;
+}
+
static int vmstate_n_elems(void *opaque, const VMStateField *field)
{
int n_elems = 1;
@@ -142,23 +173,39 @@ int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
}
for (i = 0; i < n_elems; i++) {
void *curr_elem = first_elem + size * i;
+ const VMStateField *inner_field;
if (field->flags & VMS_ARRAY_OF_POINTER) {
curr_elem = *(void **)curr_elem;
}
+
if (!curr_elem && size) {
- /* if null pointer check placeholder and do not follow */
- assert(field->flags & VMS_ARRAY_OF_POINTER);
- ret = vmstate_info_nullptr.get(f, curr_elem, size, NULL);
- } else if (field->flags & VMS_STRUCT) {
- ret = vmstate_load_state(f, field->vmsd, curr_elem,
- field->vmsd->version_id);
- } else if (field->flags & VMS_VSTRUCT) {
- ret = vmstate_load_state(f, field->vmsd, curr_elem,
- field->struct_version_id);
+ /*
+ * If null pointer found (which should only happen in
+ * an array of pointers), use null placeholder and do
+ * not follow.
+ */
+ inner_field = vmsd_create_fake_nullptr_field(field);
+ } else {
+ inner_field = field;
+ }
+
+ if (inner_field->flags & VMS_STRUCT) {
+ ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
+ inner_field->vmsd->version_id);
+ } else if (inner_field->flags & VMS_VSTRUCT) {
+ ret = vmstate_load_state(f, inner_field->vmsd, curr_elem,
+ inner_field->struct_version_id);
} else {
- ret = field->info->get(f, curr_elem, size, field);
+ ret = inner_field->info->get(f, curr_elem, size,
+ inner_field);
+ }
+
+ /* If we used a fake temp field.. free it now */
+ if (inner_field != field) {
+ g_clear_pointer((gpointer *)&inner_field, g_free);
}
+
if (ret >= 0) {
ret = qemu_file_get_error(f);
}
@@ -310,7 +357,7 @@ static void vmsd_desc_field_start(const VMStateDescription *vmsd,
static void vmsd_desc_field_end(const VMStateDescription *vmsd,
JSONWriter *vmdesc,
- const VMStateField *field, size_t size, int i)
+ const VMStateField *field, size_t size)
{
if (!vmdesc) {
return;
@@ -378,37 +425,91 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
int size = vmstate_size(opaque, field);
uint64_t old_offset, written_bytes;
JSONWriter *vmdesc_loop = vmdesc;
+ bool is_prev_null = false;
trace_vmstate_save_state_loop(vmsd->name, field->name, n_elems);
if (field->flags & VMS_POINTER) {
first_elem = *(void **)first_elem;
assert(first_elem || !n_elems || !size);
}
+
for (i = 0; i < n_elems; i++) {
void *curr_elem = first_elem + size * i;
+ const VMStateField *inner_field;
+ bool is_null;
+ int max_elems = n_elems - i;
- vmsd_desc_field_start(vmsd, vmdesc_loop, field, i, n_elems);
old_offset = qemu_file_transferred(f);
if (field->flags & VMS_ARRAY_OF_POINTER) {
assert(curr_elem);
curr_elem = *(void **)curr_elem;
}
+
if (!curr_elem && size) {
- /* if null pointer write placeholder and do not follow */
- assert(field->flags & VMS_ARRAY_OF_POINTER);
- ret = vmstate_info_nullptr.put(f, curr_elem, size, NULL,
- NULL);
- } else if (field->flags & VMS_STRUCT) {
- ret = vmstate_save_state(f, field->vmsd, curr_elem,
- vmdesc_loop);
- } else if (field->flags & VMS_VSTRUCT) {
- ret = vmstate_save_state_v(f, field->vmsd, curr_elem,
- vmdesc_loop,
- field->struct_version_id, errp);
+ /*
+ * If null pointer found (which should only happen in
+ * an array of pointers), use null placeholder and do
+ * not follow.
+ */
+ inner_field = vmsd_create_fake_nullptr_field(field);
+ is_null = true;
+ } else {
+ inner_field = field;
+ is_null = false;
+ }
+
+ /*
+ * This logic only matters when dumping VM Desc.
+ *
+ * Due to the fake nullptr handling above, if there's mixed
+ * null/non-null data, it doesn't make sense to emit a
+ * compressed array representation spanning the entire array
+ * because the field types will be different (e.g. struct
+ * vs. nullptr). Search ahead for the next null/non-null element
+ * and start a new compressed array if found.
+ */
+ if (vmdesc && (field->flags & VMS_ARRAY_OF_POINTER) &&
+ is_null != is_prev_null) {
+
+ is_prev_null = is_null;
+ vmdesc_loop = vmdesc;
+
+ for (int j = i + 1; j < n_elems; j++) {
+ void *elem = *(void **)(first_elem + size * j);
+ bool elem_is_null = !elem && size;
+
+ if (is_null != elem_is_null) {
+ max_elems = j - i;
+ break;
+ }
+ }
+ }
+
+ vmsd_desc_field_start(vmsd, vmdesc_loop, inner_field,
+ i, max_elems);
+
+ if (inner_field->flags & VMS_STRUCT) {
+ ret = vmstate_save_state(f, inner_field->vmsd,
+ curr_elem, vmdesc_loop);
+ } else if (inner_field->flags & VMS_VSTRUCT) {
+ ret = vmstate_save_state_v(f, inner_field->vmsd,
+ curr_elem, vmdesc_loop,
+ inner_field->struct_version_id,
+ errp);
} else {
- ret = field->info->put(f, curr_elem, size, field,
- vmdesc_loop);
+ ret = inner_field->info->put(f, curr_elem, size,
+ inner_field, vmdesc_loop);
+ }
+
+ written_bytes = qemu_file_transferred(f) - old_offset;
+ vmsd_desc_field_end(vmsd, vmdesc_loop, inner_field,
+ written_bytes);
+
+ /* If we used a fake temp field.. free it now */
+ if (is_null) {
+ g_clear_pointer((gpointer *)&inner_field, g_free);
}
+
if (ret) {
error_setg(errp, "Save of field %s/%s failed",
vmsd->name, field->name);
@@ -418,9 +519,6 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
return ret;
}
- written_bytes = qemu_file_transferred(f) - old_offset;
- vmsd_desc_field_end(vmsd, vmdesc_loop, field, written_bytes, i);
-
/* Compressed arrays only care about the first element */
if (vmdesc_loop && vmsd_can_compress(field)) {
vmdesc_loop = NULL;
@@ -441,12 +539,13 @@ int vmstate_save_state_v(QEMUFile *f, const VMStateDescription *vmsd,
json_writer_end_array(vmdesc);
}
- ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc);
+ ret = vmstate_subsection_save(f, vmsd, opaque, vmdesc, errp);
if (vmsd->post_save) {
int ps_ret = vmsd->post_save(opaque);
- if (!ret) {
+ if (!ret && ps_ret) {
ret = ps_ret;
+ error_setg(errp, "post-save failed: %s", vmsd->name);
}
}
return ret;
@@ -518,7 +617,8 @@ static int vmstate_subsection_load(QEMUFile *f, const VMStateDescription *vmsd,
}
static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
- void *opaque, JSONWriter *vmdesc)
+ void *opaque, JSONWriter *vmdesc,
+ Error **errp)
{
const VMStateDescription * const *sub = vmsd->subsections;
bool vmdesc_has_subsections = false;
@@ -546,7 +646,7 @@ static int vmstate_subsection_save(QEMUFile *f, const VMStateDescription *vmsd,
qemu_put_byte(f, len);
qemu_put_buffer(f, (uint8_t *)vmsdsub->name, len);
qemu_put_be32(f, vmsdsub->version_id);
- ret = vmstate_save_state(f, vmsdsub, opaque, vmdesc);
+ ret = vmstate_save_state_with_err(f, vmsdsub, opaque, vmdesc, errp);
if (ret) {
return ret;
}
generated by cgit v1.1 at 2025-07-02 07:37:36 +0000