[Qemu-devel] [PATCH V8 03/14] Add persistent state handling to TPM TIS frontend driver

[Stefan Berger]

This patch adds support for handling of persistent state to the TPM TIS
frontend.

The currently used buffer is determined (can only be in currently active
locality and either be a read or a write buffer) and only that buffer's content
is stored. The reverse is done when the state is restored from disk
where the buffer's content are copied into the currently used buffer.

To keep compatibility with existing Xen implementation the VMStateDescription
was adapted to be compatible with existing state. For that I am adding Andreas
Niederl as an author to the file.

v5:
 - removing qdev.no_user=1

v4:
 - main thread releases the 'state' lock while periodically calling the
   backends function that may request it to write data into block storage.

v3:
 - all functions prefixed with tis_
 - while the main thread is waiting for an outstanding TPM command to finish,
   it periodically does some work (writes data to the block storage)

Signed-off-by: Stefan Berger <address@hidden>

---
 hw/tpm_tis.c |  166 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)

Index: qemu-git/hw/tpm_tis.c
===================================================================
--- qemu-git.orig/hw/tpm_tis.c
+++ qemu-git/hw/tpm_tis.c
@@ -6,6 +6,8 @@
  * Author: Stefan Berger <address@hidden>
  *         David Safford <address@hidden>
  *
+ * Xen 4 support: Andrease Niederl <address@hidden>
+ *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation, version 2 of the
@@ -839,3 +841,167 @@ static int tis_init(ISADevice *dev)
  err_exit:
     return -1;
 }
+
+/* persistent state handling */
+
+static void tis_pre_save(void *opaque)
+{
+    TPMState *s = opaque;
+    uint8_t locty = s->active_locty;
+
+    qemu_mutex_lock(&s->state_lock);
+
+    /* wait for outstanding requests to complete */
+    if (IS_VALID_LOCTY(locty) && s->loc[locty].state == STATE_EXECUTION) {
+        if (!s->be_driver->ops->job_for_main_thread) {
+            qemu_cond_wait(&s->from_tpm_cond, &s->state_lock);
+        } else {
+            while (s->loc[locty].state == STATE_EXECUTION) {
+                qemu_mutex_unlock(&s->state_lock);
+
+                s->be_driver->ops->job_for_main_thread(NULL);
+                usleep(10000);
+
+                qemu_mutex_lock(&s->state_lock);
+            }
+        }
+    }
+
+#ifdef DEBUG_TIS_SR
+    fprintf(stderr,
+            "tpm_tis: suspend: locty 0 : r_offset = %d, w_offset = %d\n",
+            s->loc[0].r_offset, s->loc[0].w_offset);
+    if (s->loc[0].r_offset) {
+        tis_dump_state(opaque, 0);
+    }
+#endif
+
+    qemu_mutex_unlock(&s->state_lock);
+
+    /* copy current active read or write buffer into the buffer
+       written to disk */
+    if (IS_VALID_LOCTY(locty)) {
+        switch (s->loc[locty].state) {
+        case STATE_RECEPTION:
+            memcpy(s->buf,
+                   s->loc[locty].w_buffer.buffer,
+                   MIN(sizeof(s->buf),
+                       s->loc[locty].w_buffer.size));
+            s->offset = s->loc[locty].w_offset;
+        break;
+        case STATE_COMPLETION:
+            memcpy(s->buf,
+                   s->loc[locty].r_buffer.buffer,
+                   MIN(sizeof(s->buf),
+                       s->loc[locty].r_buffer.size));
+            s->offset = s->loc[locty].r_offset;
+        break;
+        default:
+            /* leak nothing */
+            memset(s->buf, 0x0, sizeof(s->buf));
+        break;
+        }
+    }
+
+    s->be_driver->ops->save_volatile_data();
+}
+
+
+static int tis_post_load(void *opaque,
+                         int version_id __attribute__((unused)))
+{
+    TPMState *s = opaque;
+
+    uint8_t locty = s->active_locty;
+
+    if (IS_VALID_LOCTY(locty)) {
+        switch (s->loc[locty].state) {
+        case STATE_RECEPTION:
+            memcpy(s->loc[locty].w_buffer.buffer,
+                   s->buf,
+                   MIN(sizeof(s->buf),
+                       s->loc[locty].w_buffer.size));
+            s->loc[locty].w_offset = s->offset;
+        break;
+        case STATE_COMPLETION:
+            memcpy(s->loc[locty].r_buffer.buffer,
+                   s->buf,
+                   MIN(sizeof(s->buf),
+                       s->loc[locty].r_buffer.size));
+            s->loc[locty].r_offset = s->offset;
+        break;
+        default:
+        break;
+        }
+    }
+
+#ifdef DEBUG_TIS_SR
+    fprintf(stderr,
+            "tpm_tis: resume : locty 0 : r_offset = %d, w_offset = %d\n",
+            s->loc[0].r_offset, s->loc[0].w_offset);
+#endif
+
+    return s->be_driver->ops->load_volatile_data(s);
+}
+
+
+static const VMStateDescription vmstate_locty = {
+    .name = "loc",
+    .version_id = 1,
+    .minimum_version_id = 0,
+    .minimum_version_id_old = 0,
+    .fields      = (VMStateField[]) {
+        VMSTATE_UINT32(state, TPMLocality),
+        VMSTATE_UINT32(inte, TPMLocality),
+        VMSTATE_UINT32(ints, TPMLocality),
+        VMSTATE_UINT8(access, TPMLocality),
+        VMSTATE_UINT8(sts, TPMLocality),
+        VMSTATE_END_OF_LIST(),
+    }
+};
+
+
+static const VMStateDescription vmstate_tis = {
+    .name = "tpm",
+    .version_id = 1,
+    .minimum_version_id = 0,
+    .minimum_version_id_old = 0,
+    .pre_save  = tis_pre_save,
+    .post_load = tis_post_load,
+    .fields = (VMStateField[]) {
+        VMSTATE_UINT32(irq_num, TPMState),
+        VMSTATE_UINT32(offset, TPMState),
+        VMSTATE_BUFFER(buf, TPMState),
+        VMSTATE_UINT8(active_locty, TPMState),
+        VMSTATE_UINT8(aborting_locty, TPMState),
+        VMSTATE_UINT8(next_locty, TPMState),
+
+        VMSTATE_STRUCT_ARRAY(loc, TPMState, NUM_LOCALITIES, 1,
+                             vmstate_locty, TPMLocality),
+
+        VMSTATE_END_OF_LIST()
+    }
+};
+
+
+static ISADeviceInfo tis_device_info = {
+    .init         = tis_init,
+    .qdev.name    = "tpm-tis",
+    .qdev.size    = sizeof(TPMState),
+    .qdev.vmsd    = &vmstate_tis,
+    .qdev.reset   = tis_reset,
+    .qdev.props = (Property[]) {
+        DEFINE_PROP_UINT32("irq", TPMState,
+                           irq_num, TPM_TIS_IRQ),
+        DEFINE_PROP_STRING("tpmdev", TPMState, backend),
+        DEFINE_PROP_END_OF_LIST(),
+    },
+};
+
+
+static void tis_register_device(void)
+{
+    isa_qdev_register(&tis_device_info);
+}
+
+device_init(tis_register_device)