Merge remote-tracking branch 'remotes/berrange-gitlab/tags/misc-fixes-pull-request' into staging

Merge misc patches

# gpg: Signature made Mon 14 Jun 2021 15:14:48 BST
# gpg:                using RSA key DAF3A6FDB26B62912D0E8E3FBE86EBB415104FDF
# gpg: Good signature from "Daniel P. Berrange <dan@berrange.com>" [full]
# gpg:                 aka "Daniel P. Berrange <berrange@redhat.com>" [full]
# Primary key fingerprint: DAF3 A6FD B26B 6291 2D0E  8E3F BE86 EBB4 1510 4FDF

* remotes/berrange-gitlab/tags/misc-fixes-pull-request:
  usb/dev-mtp: use GDateTime for formatting timestamp for objects
  block: use GDateTime for formatting timestamp when dumping snapshot info
  migration: use GDateTime for formatting timestamp in snapshot names
  block: remove duplicate trace.h include
  block: add trace point when fdatasync fails
  block: preserve errno from fdatasync failures
  softmmu: add trace point when bdrv_flush_all fails
  migration: add trace point when vm_stop_force_state fails
  sasl: remove comment about obsolete kerberos versions
  docs: recommend SCRAM-SHA-256 SASL mech instead of SHA-1 variant
  docs: document usage of the authorization framework
  docs: document how to pass secret data to QEMU
  docs: add table of contents to QAPI references

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

block/file-posix.c

@@ -106,8 +106,6 @@
 #include <xfs/xfs.h>
 #endif
 
-#include "trace.h"
-
 /* OS X does not have O_DSYNC */
 #ifndef O_DSYNC
 #ifdef O_SYNC
@@ -160,7 +158,7 @@ typedef struct BDRVRawState {
     bool discard_zeroes:1;
     bool use_linux_aio:1;
     bool use_linux_io_uring:1;
-    bool page_cache_inconsistent:1;
+    int page_cache_inconsistent; /* errno from fdatasync failure */
     bool has_fallocate;
     bool needs_alignment;
     bool drop_cache;
@@ -1333,11 +1331,13 @@ static int handle_aiocb_flush(void *opaque)
     int ret;
 
     if (s->page_cache_inconsistent) {
-        return -EIO;
+        return -s->page_cache_inconsistent;
     }
 
     ret = qemu_fdatasync(aiocb->aio_fildes);
     if (ret == -1) {
+        trace_file_flush_fdatasync_failed(errno);
+
         /* There is no clear definition of the semantics of a failing fsync(),
          * so we may have to assume the worst. The sad truth is that this
          * assumption is correct for Linux. Some pages are now probably marked
@@ -1352,7 +1352,7 @@ static int handle_aiocb_flush(void *opaque)
          * Obviously, this doesn't affect O_DIRECT, which bypasses the page
          * cache. */
         if ((s->open_flags & O_DIRECT) == 0) {
-            s->page_cache_inconsistent = true;
+            s->page_cache_inconsistent = errno;
         }
         return -errno;
     }

block/qapi.c

@@ -663,10 +663,8 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes,
 
 void bdrv_snapshot_dump(QEMUSnapshotInfo *sn)
 {
-    char date_buf[128], clock_buf[128];
+    char clock_buf[128];
     char icount_buf[128] = {0};
-    struct tm tm;
-    time_t ti;
     int64_t secs;
     char *sizing = NULL;
 
@@ -674,10 +672,9 @@ void bdrv_snapshot_dump(QEMUSnapshotInfo *sn)
         qemu_printf("%-10s%-17s%8s%20s%13s%11s",
                     "ID", "TAG", "VM SIZE", "DATE", "VM CLOCK", "ICOUNT");
     } else {
-        ti = sn->date_sec;
-        localtime_r(&ti, &tm);
-        strftime(date_buf, sizeof(date_buf),
-                 "%Y-%m-%d %H:%M:%S", &tm);
+        g_autoptr(GDateTime) date = g_date_time_new_from_unix_local(sn->date_sec);
+        g_autofree char *date_buf = g_date_time_format(date, "%Y-%m-%d %H:%M:%S");
+
         secs = sn->vm_clock_nsec / 1000000000;
         snprintf(clock_buf, sizeof(clock_buf),
                  "%02d:%02d:%02d.%03d",

block/trace-events

@@ -206,6 +206,7 @@ file_copy_file_range(void *bs, int src, int64_t src_off, int dst, int64_t dst_of
 file_FindEjectableOpticalMedia(const char *media) "Matching using %s"
 file_setup_cdrom(const char *partition) "Using %s as optical disc"
 file_hdev_is_sg(int type, int version) "SG device found: type=%d, version=%d"
+file_flush_fdatasync_failed(int err) "errno %d"
 
 # ssh.c
 sftp_error(const char *op, const char *ssh_err, int ssh_err_code, int sftp_err_code) "%s failed: %s (libssh error code: %d, sftp error code: %d)"

docs/interop/qemu-ga-ref.rst

@@ -10,4 +10,7 @@ QEMU Guest Agent Protocol Reference
    TODO: display the QEMU version, both here and in our Sphinx manuals
    more generally.
 
+.. contents::
+   :depth: 3
+
 .. qapi-doc:: qga/qapi-schema.json

docs/interop/qemu-qmp-ref.rst

@@ -10,4 +10,7 @@ QEMU QMP Reference Manual
    TODO: display the QEMU version, both here and in our Sphinx manuals
    more generally.
 
+.. contents::
+   :depth: 3
+
 .. qapi-doc:: qapi/qapi-schema.json

docs/interop/qemu-storage-daemon-qmp-ref.rst

@@ -10,4 +10,7 @@ QEMU Storage Daemon QMP Reference Manual
    TODO: display the QEMU version, both here and in our Sphinx manuals
    more generally.
 
+.. contents::
+   :depth: 3
+
 .. qapi-doc:: storage-daemon/qapi/qapi-schema.json

docs/system/authz.rst

@@ -0,0 +1,263 @@
+.. _client authorization:
+
+Client authorization
+--------------------
+
+When configuring a QEMU network backend with either TLS certificates or SASL
+authentication, access will be granted if the client successfully proves
+their identity. If the authorization identity database is scoped to the QEMU
+client this may be sufficient. It is common, however, for the identity database
+to be much broader and thus authentication alone does not enable sufficient
+access control. In this case QEMU provides a flexible system for enforcing
+finer grained authorization on clients post-authentication.
+
+Identity providers
+~~~~~~~~~~~~~~~~~~
+
+At the time of writing there are two authentication frameworks used by QEMU
+that emit an identity upon completion.
+
+ * TLS x509 certificate distinguished name.
+
+   When configuring the QEMU backend as a network server with TLS, there
+   are a choice of credentials to use. The most common scenario is to utilize
+   x509 certificates. The simplest configuration only involves issuing
+   certificates to the servers, allowing the client to avoid a MITM attack
+   against their intended server.
+
+   It is possible, however, to enable mutual verification by requiring that
+   the client provide a certificate to the server to prove its own identity.
+   This is done by setting the property ``verify-peer=yes`` on the
+   ``tls-creds-x509`` object, which is in fact the default.
+
+   When peer verification is enabled, client will need to be issued with a
+   certificate by the same certificate authority as the server. If this is
+   still not sufficiently strong access control the Distinguished Name of
+   the certificate can be used as an identity in the QEMU authorization
+   framework.
+
+ * SASL username.
+
+   When configuring the QEMU backend as a network server with SASL, upon
+   completion of the SASL authentication mechanism, a username will be
+   provided. The format of this username will vary depending on the choice
+   of mechanism configured for SASL. It might be a simple UNIX style user
+   ``joebloggs``, while if using Kerberos/GSSAPI it can have a realm
+   attached ``joebloggs@QEMU.ORG``.  Whatever format the username is presented
+   in, it can be used with the QEMU authorization framework.
+
+Authorization drivers
+~~~~~~~~~~~~~~~~~~~~~
+
+The QEMU authorization framework is a general purpose design with choice of
+user customizable drivers. These are provided as objects that can be
+created at startup using the ``-object`` argument, or at runtime using the
+``object_add`` monitor command.
+
+Simple
+^^^^^^
+
+This authorization driver provides a simple mechanism for granting access
+based on an exact match against a single identity. This is useful when it is
+known that only a single client is to be allowed access.
+
+A possible use case would be when configuring QEMU for an incoming live
+migration. It is known exactly which source QEMU the migration is expected
+to arrive from. The x509 certificate associated with this source QEMU would
+thus be used as the identity to match against. Alternatively if the virtual
+machine is dedicated to a specific tenant, then the VNC server would be
+configured with SASL and the username of only that tenant listed.
+
+To create an instance of this driver via QMP:
+
+::
+
+   {
+     "execute": "object-add",
+     "arguments": {
+       "qom-type": "authz-simple",
+       "id": "authz0",
+       "props": {
+         "identity": "fred"
+       }
+     }
+   }
+
+
+Or via the command line
+
+::
+
+   -object authz-simple,id=authz0,identity=fred
+
+
+List
+^^^^
+
+In some network backends it will be desirable to grant access to a range of
+clients. This authorization driver provides a list mechanism for granting
+access by matching identities against a list of permitted one. Each match
+rule has an associated policy and a catch all policy applies if no rule
+matches. The match can either be done as an exact string comparison, or can
+use the shell-like glob syntax, which allows for use of wildcards.
+
+To create an instance of this class via QMP:
+
+::
+
+   {
+     "execute": "object-add",
+     "arguments": {
+       "qom-type": "authz-list",
+       "id": "authz0",
+       "props": {
+         "rules": [
+            { "match": "fred", "policy": "allow", "format": "exact" },
+            { "match": "bob", "policy": "allow", "format": "exact" },
+            { "match": "danb", "policy": "deny", "format": "exact" },
+            { "match": "dan*", "policy": "allow", "format": "glob" }
+         ],
+         "policy": "deny"
+       }
+     }
+   }
+
+
+Due to the way this driver requires setting nested properties, creating
+it on the command line will require use of the JSON syntax for ``-object``.
+In most cases, however, the next driver will be more suitable.
+
+List file
+^^^^^^^^^
+
+This is a variant on the previous driver that allows for a more dynamic
+access control policy by storing the match rules in a standalone file
+that can be reloaded automatically upon change.
+
+To create an instance of this class via QMP:
+
+::
+
+   {
+     "execute": "object-add",
+     "arguments": {
+       "qom-type": "authz-list-file",
+       "id": "authz0",
+       "props": {
+         "filename": "/etc/qemu/myvm-vnc.acl",
+         "refresh": true
+       }
+     }
+   }
+
+
+If ``refresh`` is ``yes``, inotify is used to monitor for changes
+to the file and auto-reload the rules.
+
+The ``myvm-vnc.acl`` file should contain the match rules in a format that
+closely matches the previous driver:
+
+::
+
+   {
+     "rules": [
+       { "match": "fred", "policy": "allow", "format": "exact" },
+       { "match": "bob", "policy": "allow", "format": "exact" },
+       { "match": "danb", "policy": "deny", "format": "exact" },
+       { "match": "dan*", "policy": "allow", "format": "glob" }
+     ],
+     "policy": "deny"
+   }
+
+
+The object can be created on the command line using
+
+::
+
+   -object authz-list-file,id=authz0,\
+           filename=/etc/qemu/myvm-vnc.acl,refresh=on
+
+
+PAM
+^^^
+
+In some scenarios it might be desirable to integrate with authorization
+mechanisms that are implemented outside of QEMU. In order to allow maximum
+flexibility, QEMU provides a driver that uses the ``PAM`` framework.
+
+To create an instance of this class via QMP:
+
+::
+
+   {
+     "execute": "object-add",
+     "arguments": {
+       "qom-type": "authz-pam",
+       "id": "authz0",
+       "parameters": {
+         "service": "qemu-vnc-tls"
+       }
+     }
+   }
+
+
+The driver only uses the PAM "account" verification
+subsystem. The above config would require a config
+file /etc/pam.d/qemu-vnc-tls. For a simple file
+lookup it would contain
+
+::
+
+   account requisite  pam_listfile.so item=user sense=allow \
+           file=/etc/qemu/vnc.allow
+
+
+The external file would then contain a list of usernames.
+If x509 cert was being used as the username, a suitable
+entry would match the distinguished name:
+
+::
+
+   CN=laptop.berrange.com,O=Berrange Home,L=London,ST=London,C=GB
+
+
+On the command line it can be created using
+
+::
+
+   -object authz-pam,id=authz0,service=qemu-vnc-tls
+
+
+There are a variety of PAM plugins that can be used which are not illustrated
+here, and it is possible to implement brand new plugins using the PAM API.
+
+
+Connecting backends
+~~~~~~~~~~~~~~~~~~~
+
+The authorization driver is created using the ``-object`` argument and then
+needs to be associated with a network service. The authorization driver object
+will be given a unique ID that needs to be referenced.
+
+The property to set in the network service will vary depending on the type of
+identity to verify. By convention, any network server backend that uses TLS
+will provide ``tls-authz`` property, while any server using SASL will provide
+a ``sasl-authz`` property.
+
+Thus an example using SASL and authorization for the VNC server would look
+like:
+
+::
+
+   $QEMU --object authz-simple,id=authz0,identity=fred \
+         --vnc 0.0.0.0:1,sasl,sasl-authz=authz0
+
+While to validate both the x509 certificate and SASL username:
+
+::
+
+   echo "CN=laptop.qemu.org,O=QEMU Project,L=London,ST=London,C=GB" >> tls.acl
+   $QEMU --object authz-simple,id=authz0,identity=fred \
+         --object authz-list-file,id=authz1,filename=tls.acl \
+	 --object tls-creds-x509,id=tls0,dir=/etc/qemu/tls,verify-peer=yes \
+         --vnc 0.0.0.0:1,sasl,sasl-authz=auth0,tls-creds=tls0,tls-authz=authz1

docs/system/index.rst

@@ -30,6 +30,8 @@ Contents:
    guest-loader
    vnc-security
    tls
+   secrets
+   authz
    gdb
    managed-startup
    cpu-hotplug

docs/system/secrets.rst

@@ -0,0 +1,162 @@
+.. _secret data:
+
+Providing secret data to QEMU
+-----------------------------
+
+There are a variety of objects in QEMU which require secret data to be provided
+by the administrator or management application. For example, network block
+devices often require a password, LUKS block devices require a passphrase to
+unlock key material, remote desktop services require an access password.
+QEMU has a general purpose mechanism for providing secret data to QEMU in a
+secure manner, using the ``secret`` object type.
+
+At startup this can be done using the ``-object secret,...`` command line
+argument. At runtime this can be done using the ``object_add`` QMP / HMP
+monitor commands. The examples that follow will illustrate use of ``-object``
+command lines, but they all apply equivalentely in QMP / HMP. When creating
+a ``secret`` object it must be given a unique ID string. This ID is then
+used to identify the object when configuring the thing which need the data.
+
+
+INSECURE: Passing secrets as clear text inline
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+**The following should never be done in a production environment or on a
+multi-user host. Command line arguments are usually visible in the process
+listings and are often collected in log files by system monitoring agents
+or bug reporting tools. QMP/HMP commands and their arguments are also often
+logged and attached to bug reports. This all risks compromising secrets that
+are passed inline.**
+
+For the convenience of people debugging / developing with QEMU, it is possible
+to pass secret data inline on the command line.
+
+::
+
+   -object secret,id=secvnc0,data=87539319
+
+
+Again it is possible to provide the data in base64 encoded format, which is
+particularly useful if the data contains binary characters that would clash
+with argument parsing.
+
+::
+
+   -object secret,id=secvnc0,data=ODc1MzkzMTk=,format=base64
+
+
+**Note: base64 encoding does not provide any security benefit.**
+
+Passing secrets as clear text via a file
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The simplest approach to providing data securely is to use a file to store
+the secret:
+
+::
+
+   -object secret,id=secvnc0,file=vnc-password.txt
+
+
+In this example the file ``vnc-password.txt`` contains the plain text secret
+data. It is important to note that the contents of the file are treated as an
+opaque blob. The entire raw file contents is used as the value, thus it is
+important not to mistakenly add any trailing newline character in the file if
+this newline is not intended to be part of the secret data.
+
+In some cases it might be more convenient to pass the secret data in base64
+format and have QEMU decode to get the raw bytes before use:
+
+::
+
+   -object secret,id=sec0,file=vnc-password.txt,format=base64
+
+
+The file should generally be given mode ``0600`` or ``0400`` permissions, and
+have its user/group ownership set to the same account that the QEMU process
+will be launched under. If using mandatory access control such as SELinux, then
+the file should be labelled to only grant access to the specific QEMU process
+that needs access. This will prevent other processes/users from compromising the
+secret data.
+
+
+Passing secrets as cipher text inline
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+To address the insecurity of passing secrets inline as clear text, it is
+possible to configure a second secret as an AES key to use for decrypting
+the data.
+
+The secret used as the AES key must always be configured using the file based
+storage mechanism:
+
+::
+
+   -object secret,id=secmaster,file=masterkey.data,format=base64
+
+
+In this case the ``masterkey.data`` file would be initialized with 32
+cryptographically secure random bytes, which are then base64 encoded.
+The contents of this file will by used as an AES-256 key to encrypt the
+real secret that can now be safely passed to QEMU inline as cipher text
+
+::
+
+   -object secret,id=secvnc0,keyid=secmaster,data=BASE64-CIPHERTEXT,iv=BASE64-IV,format=base64
+
+
+In this example ``BASE64-CIPHERTEXT`` is the result of AES-256-CBC encrypting
+the secret with ``masterkey.data`` and then base64 encoding the ciphertext.
+The ``BASE64-IV`` data is 16 random bytes which have been base64 encrypted.
+These bytes are used as the initialization vector for the AES-256-CBC value.
+
+A single master key can be used to encrypt all subsequent secrets, **but it is
+critical that a different initialization vector is used for every secret**.
+
+Passing secrets via the Linux keyring
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The earlier mechanisms described are platform agnostic. If using QEMU on a Linux
+host, it is further possible to pass secrets to QEMU using the Linux keyring:
+
+::
+
+   -object secret_keyring,id=secvnc0,serial=1729
+
+
+This instructs QEMU to load data from the Linux keyring secret identified by
+the serial number ``1729``. It is possible to combine use of the keyring with
+other features mentioned earlier such as base64 encoding:
+
+::
+
+   -object secret_keyring,id=secvnc0,serial=1729,format=base64
+
+
+and also encryption with a master key:
+
+::
+
+   -object secret_keyring,id=secvnc0,keyid=secmaster,serial=1729,iv=BASE64-IV
+
+
+Best practice
+~~~~~~~~~~~~~
+
+It is recommended for production deployments to use a master key secret, and
+then pass all subsequent inline secrets encrypted with the master key.
+
+Each QEMU instance must have a distinct master key, and that must be generated
+from a cryptographically secure random data source. The master key should be
+deleted immediately upon QEMU shutdown. If passing the master key as a file,
+the key file must have access control rules applied that restrict access to
+just the one QEMU process that is intended to use it. Alternatively the Linux
+keyring can be used to pass the master key to QEMU.
+
+The secrets for individual QEMU device backends must all then be encrypted
+with this master key.
+
+This procedure helps ensure that the individual secrets for QEMU backends will
+not be compromised, even if ``-object`` CLI args or ``object_add`` monitor
+commands are collected in log files and attached to public bug support tickets.
+The only item that needs strongly protecting is the master key file.

docs/system/vnc-security.rst

@@ -168,7 +168,7 @@ used is drastically reduced. In fact only the GSSAPI SASL mechanism
 provides an acceptable level of security by modern standards. Previous
 versions of QEMU referred to the DIGEST-MD5 mechanism, however, it has
 multiple serious flaws described in detail in RFC 6331 and thus should
-never be used any more. The SCRAM-SHA-1 mechanism provides a simple
+never be used any more. The SCRAM-SHA-256 mechanism provides a simple
 username/password auth facility similar to DIGEST-MD5, but does not
 support session encryption, so can only be used in combination with TLS.
 
@@ -191,11 +191,12 @@ reasonable configuration is
 
 ::
 
-   mech_list: scram-sha-1
+   mech_list: scram-sha-256
    sasldb_path: /etc/qemu/passwd.db
 
 The ``saslpasswd2`` program can be used to populate the ``passwd.db``
-file with accounts.
+file with accounts. Note that the ``passwd.db`` file stores passwords
+in clear text.
 
 Other SASL configurations will be left as an exercise for the reader.
 Note that all mechanisms, except GSSAPI, should be combined with use of

hw/usb/dev-mtp.c

@@ -772,12 +772,9 @@ static void usb_mtp_add_str(MTPData *data, const char *str)
 
 static void usb_mtp_add_time(MTPData *data, time_t time)
 {
-    char buf[16];
-    struct tm tm;
-
-    gmtime_r(&time, &tm);
-    strftime(buf, sizeof(buf), "%Y%m%dT%H%M%S", &tm);
-    usb_mtp_add_str(data, buf);
+    g_autoptr(GDateTime) then = g_date_time_new_from_unix_utc(time);
+    g_autofree char *thenstr = g_date_time_format(then, "%Y%m%dT%H%M%S");
+    usb_mtp_add_str(data, thenstr);
 }
 
 /* ----------------------------------------------------------------------- */

migration/migration.c

@@ -3115,6 +3115,7 @@ static void migration_completion(MigrationState *s)
         if (!ret) {
             bool inactivate = !migrate_colo_enabled();
             ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
+            trace_migration_completion_vm_stop(ret);
             if (ret >= 0) {
                 ret = migration_maybe_pause(s, &current_active_state,
                                             MIGRATION_STATUS_DEVICE);

migration/savevm.c

@@ -2775,8 +2775,7 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
     QEMUFile *f;
     int saved_vm_running;
     uint64_t vm_state_size;
-    qemu_timeval tv;
-    struct tm tm;
+    g_autoptr(GDateTime) now = g_date_time_new_now_local();
     AioContext *aio_context;
 
     if (migration_is_blocked(errp)) {
@@ -2836,9 +2835,8 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
     memset(sn, 0, sizeof(*sn));
 
     /* fill auxiliary fields */
-    qemu_gettimeofday(&tv);
-    sn->date_sec = tv.tv_sec;
-    sn->date_nsec = tv.tv_usec * 1000;
+    sn->date_sec = g_date_time_to_unix(now);
+    sn->date_nsec = g_date_time_get_microsecond(now) * 1000;
     sn->vm_clock_nsec = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
     if (replay_mode != REPLAY_MODE_NONE) {
         sn->icount = replay_get_current_icount();
@@ -2849,9 +2847,8 @@ bool save_snapshot(const char *name, bool overwrite, const char *vmstate,
     if (name) {
         pstrcpy(sn->name, sizeof(sn->name), name);
     } else {
-        /* cast below needed for OpenBSD where tv_sec is still 'long' */
-        localtime_r((const time_t *)&tv.tv_sec, &tm);
-        strftime(sn->name, sizeof(sn->name), "vm-%Y%m%d%H%M%S", &tm);
+        g_autofree char *autoname = g_date_time_format(now,  "vm-%Y%m%d%H%M%S");
+        pstrcpy(sn->name, sizeof(sn->name), autoname);
     }
 
     /* save the VM state */

migration/trace-events

@@ -149,6 +149,7 @@ migrate_pending(uint64_t size, uint64_t max, uint64_t pre, uint64_t compat, uint
 migrate_send_rp_message(int msg_type, uint16_t len) "%d: len %d"
 migrate_send_rp_recv_bitmap(char *name, int64_t size) "block '%s' size 0x%"PRIi64
 migration_completion_file_err(void) ""
+migration_completion_vm_stop(int ret) "ret %d"
 migration_completion_postcopy_end(void) ""
 migration_completion_postcopy_end_after_complete(void) ""
 migration_rate_limit_pre(int ms) "%d ms"

qemu.sasl

@@ -19,26 +19,23 @@ mech_list: gssapi
 
 # If using TLS with VNC, or a UNIX socket only, it is possible to
 # enable plugins which don't provide session encryption. The
-# 'scram-sha-1' plugin allows plain username/password authentication
+# 'scram-sha-256' plugin allows plain username/password authentication
 # to be performed
 #
-#mech_list: scram-sha-1
+#mech_list: scram-sha-256
 
 # You can also list many mechanisms at once, and the VNC server will
 # negotiate which to use by considering the list enabled on the VNC
 # client.
-#mech_list: scram-sha-1 gssapi
+#mech_list: scram-sha-256 gssapi
 
-# Some older builds of MIT kerberos on Linux ignore this option &
-# instead need KRB5_KTNAME env var.
-# For modern Linux, and other OS, this should be sufficient
-#
 # This file needs to be populated with the service principal that
 # was created on the Kerberos v5 server. If switching to a non-gssapi
 # mechanism this can be commented out.
 keytab: /etc/qemu/krb5.tab
 
-# If using scram-sha-1 for username/passwds, then this is the file
+# If using scram-sha-256 for username/passwds, then this is the file
 # containing the passwds. Use 'saslpasswd2 -a qemu [username]'
-# to add entries, and 'sasldblistusers2 -f [sasldb_path]' to browse it
+# to add entries, and 'sasldblistusers2 -f [sasldb_path]' to browse it.
+# Note that this file stores passwords in clear text.
 #sasldb_path: /etc/qemu/passwd.db

softmmu/cpus.c

@@ -44,6 +44,7 @@
 #include "sysemu/whpx.h"
 #include "hw/boards.h"
 #include "hw/hw.h"
+#include "trace.h"
 
 #ifdef CONFIG_LINUX
 
@@ -266,6 +267,7 @@ static int do_vm_stop(RunState state, bool send_stop)
 
     bdrv_drain_all();
     ret = bdrv_flush_all();
+    trace_vm_stop_flush_all(ret);
 
     return ret;
 }
@@ -704,12 +706,15 @@ int vm_stop_force_state(RunState state)
     if (runstate_is_running()) {
         return vm_stop(state);
     } else {
+        int ret;
         runstate_set(state);
 
         bdrv_drain_all();
         /* Make sure to return an error if the flush in a previous vm_stop()
          * failed. */
-        return bdrv_flush_all();
+        ret = bdrv_flush_all();
+        trace_vm_stop_flush_all(ret);
+        return ret;
     }
 }
 

softmmu/trace-events

@@ -19,6 +19,9 @@ flatview_new(void *view, void *root) "%p (root %p)"
 flatview_destroy(void *view, void *root) "%p (root %p)"
 flatview_destroy_rcu(void *view, void *root) "%p (root %p)"
 
+# softmmu.c
+vm_stop_flush_all(int ret) "ret %d"
+
 # vl.c
 vm_state_notify(int running, int reason, const char *reason_str) "running %d reason %d (%s)"
 load_file(const char *name, const char *path) "name %s location %s"