Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

* Speed up AddressSpaceDispatch creation (Alexey)
* Fix kvm.c assert (David)
* Memory fixes and further speedup (me)
* Persistent reservation manager infrastructure (me)
* virtio-serial: add enable_backend callback (Pavel)
* chardev GMainContext fixes (Peter)

# gpg: Signature made Fri 22 Sep 2017 20:07:33 BST
# gpg:                using RSA key 0xBFFBD25F78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg:                 aka "Paolo Bonzini <pbonzini@redhat.com>"
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4  E2F7 7E15 100C CD36 69B1
#      Subkey fingerprint: F133 3857 4B66 2389 866C  7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream: (32 commits)
  chardev: remove context in chr_update_read_handler
  chardev: use per-dev context for io_add_watch_poll
  chardev: add Chardev.gcontext field
  chardev: new qemu_chr_be_update_read_handlers()
  scsi: add persistent reservation manager using qemu-pr-helper
  scsi: add multipath support to qemu-pr-helper
  scsi: build qemu-pr-helper
  scsi, file-posix: add support for persistent reservation management
  memory: Share special empty FlatView
  memory: seek FlatView sharing candidates among children subregions
  memory: trace FlatView creation and destruction
  memory: Create FlatView directly
  memory: Get rid of address_space_init_shareable
  memory: Rework "info mtree" to print flat views and dispatch trees
  memory: Do not allocate FlatView in address_space_init
  memory: Share FlatView's and dispatch trees between address spaces
  memory: Move address_space_update_ioeventfds
  memory: Alloc dispatch tree where topology is generared
  memory: Store physical root MR in FlatView
  memory: Rename mem_begin/mem_commit/mem_add helpers
  ...

# Conflicts:
#	configure

Makefile

@@ -372,6 +372,11 @@ qemu-bridge-helper$(EXESUF): qemu-bridge-helper.o $(COMMON_LDADDS)
 fsdev/virtfs-proxy-helper$(EXESUF): fsdev/virtfs-proxy-helper.o fsdev/9p-marshal.o fsdev/9p-iov-marshal.o $(COMMON_LDADDS)
 fsdev/virtfs-proxy-helper$(EXESUF): LIBS += -lcap
 
+scsi/qemu-pr-helper$(EXESUF): scsi/qemu-pr-helper.o scsi/utils.o $(crypto-obj-y) $(io-obj-y) $(qom-obj-y) $(COMMON_LDADDS)
+ifdef CONFIG_MPATH
+scsi/qemu-pr-helper$(EXESUF): LIBS += -ludev -lmultipath -lmpathpersist
+endif
+
 qemu-img-cmds.h: $(SRC_PATH)/qemu-img-cmds.hx $(SRC_PATH)/scripts/hxtool
 	$(call quiet-command,sh $(SRC_PATH)/scripts/hxtool -h < $< > $@,"GEN","$@")
 
@@ -488,7 +493,7 @@ clean:
 	rm -f *.msi
 	find . \( -name '*.so' -o -name '*.dll' -o -name '*.mo' -o -name '*.[oda]' \) -type f -exec rm {} +
 	rm -f $(filter-out %.tlb,$(TOOLS)) $(HELPERS-y) qemu-ga TAGS cscope.* *.pod *~ */*~
-	rm -f fsdev/*.pod
+	rm -f fsdev/*.pod scsi/*.pod
 	rm -f qemu-img-cmds.h
 	rm -f ui/shader/*-vert.h ui/shader/*-frag.h
 	@# May not be present in GENERATED_FILES

Makefile.objs

@@ -171,6 +171,7 @@ trace-events-subdirs += qapi
 trace-events-subdirs += accel/tcg
 trace-events-subdirs += accel/kvm
 trace-events-subdirs += nbd
+trace-events-subdirs += scsi
 
 trace-events-files = $(SRC_PATH)/trace-events $(trace-events-subdirs:%=$(SRC_PATH)/%/trace-events)
 

accel/kvm/kvm-all.c

@@ -722,7 +722,6 @@ static void kvm_set_phys_mem(KVMMemoryListener *kml,
     mem = kvm_lookup_matching_slot(kml, start_addr, size);
     if (!add) {
         if (!mem) {
-            g_assert(!memory_region_is_ram(mr) && !writeable && !mr->romd_mode);
             return;
         }
         if (mem->flags & KVM_MEM_LOG_DIRTY_PAGES) {

block/file-posix.c

@@ -33,6 +33,9 @@
 #include "block/raw-aio.h"
 #include "qapi/qmp/qstring.h"
 
+#include "scsi/pr-manager.h"
+#include "scsi/constants.h"
+
 #if defined(__APPLE__) && (__MACH__)
 #include <paths.h>
 #include <sys/param.h>
@@ -155,6 +158,8 @@ typedef struct BDRVRawState {
     bool page_cache_inconsistent:1;
     bool has_fallocate;
     bool needs_alignment;
+
+    PRManager *pr_mgr;
 } BDRVRawState;
 
 typedef struct BDRVRawReopenState {
@@ -402,6 +407,11 @@ static QemuOptsList raw_runtime_opts = {
             .type = QEMU_OPT_STRING,
             .help = "file locking mode (on/off/auto, default: auto)",
         },
+        {
+            .name = "pr-manager",
+            .type = QEMU_OPT_STRING,
+            .help = "id of persistent reservation manager object (default: none)",
+        },
         { /* end of list */ }
     },
 };
@@ -413,6 +423,7 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
     QemuOpts *opts;
     Error *local_err = NULL;
     const char *filename = NULL;
+    const char *str;
     BlockdevAioOptions aio, aio_default;
     int fd, ret;
     struct stat st;
@@ -476,6 +487,16 @@ static int raw_open_common(BlockDriverState *bs, QDict *options,
         abort();
     }
 
+    str = qemu_opt_get(opts, "pr-manager");
+    if (str) {
+        s->pr_mgr = pr_manager_lookup(str, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            ret = -EINVAL;
+            goto fail;
+        }
+    }
+
     s->open_flags = open_flags;
     raw_parse_flags(bdrv_flags, &s->open_flags);
 
@@ -2597,6 +2618,15 @@ static BlockAIOCB *hdev_aio_ioctl(BlockDriverState *bs,
     if (fd_open(bs) < 0)
         return NULL;
 
+    if (req == SG_IO && s->pr_mgr) {
+        struct sg_io_hdr *io_hdr = buf;
+        if (io_hdr->cmdp[0] == PERSISTENT_RESERVE_OUT ||
+            io_hdr->cmdp[0] == PERSISTENT_RESERVE_IN) {
+            return pr_manager_execute(s->pr_mgr, bdrv_get_aio_context(bs),
+                                      s->fd, io_hdr, cb, opaque);
+        }
+    }
+
     acb = g_new(RawPosixAIOData, 1);
     acb->bs = bs;
     acb->aio_type = QEMU_AIO_IOCTL;

chardev/char-fd.c

@@ -84,8 +84,7 @@ static GSource *fd_chr_add_watch(Chardev *chr, GIOCondition cond)
     return qio_channel_create_watch(s->ioc_out, cond);
 }
 
-static void fd_chr_update_read_handler(Chardev *chr,
-                                       GMainContext *context)
+static void fd_chr_update_read_handler(Chardev *chr)
 {
     FDChardev *s = FD_CHARDEV(chr);
 
@@ -94,7 +93,7 @@ static void fd_chr_update_read_handler(Chardev *chr,
         chr->gsource = io_add_watch_poll(chr, s->ioc_in,
                                            fd_chr_read_poll,
                                            fd_chr_read, chr,
-                                           context);
+                                           chr->gcontext);
     }
 }
 

chardev/char-fe.c

@@ -253,7 +253,6 @@ void qemu_chr_fe_set_handlers(CharBackend *b,
                               bool set_open)
 {
     Chardev *s;
-    ChardevClass *cc;
     int fe_open;
 
     s = b->chr;
@@ -261,7 +260,6 @@ void qemu_chr_fe_set_handlers(CharBackend *b,
         return;
     }
 
-    cc = CHARDEV_GET_CLASS(s);
     if (!opaque && !fd_can_read && !fd_read && !fd_event) {
         fe_open = 0;
         remove_fd_in_watch(s);
@@ -273,9 +271,8 @@ void qemu_chr_fe_set_handlers(CharBackend *b,
     b->chr_event = fd_event;
     b->chr_be_change = be_change;
     b->opaque = opaque;
-    if (cc->chr_update_read_handler) {
-        cc->chr_update_read_handler(s, context);
-    }
+
+    qemu_chr_be_update_read_handlers(s, context);
 
     if (set_open) {
         qemu_chr_fe_set_open(b, fe_open);

chardev/char-pty.c

@@ -112,8 +112,7 @@ static void pty_chr_update_read_handler_locked(Chardev *chr)
     }
 }
 
-static void pty_chr_update_read_handler(Chardev *chr,
-                                        GMainContext *context)
+static void pty_chr_update_read_handler(Chardev *chr)
 {
     qemu_mutex_lock(&chr->chr_write_lock);
     pty_chr_update_read_handler_locked(chr);
@@ -219,7 +218,7 @@ static void pty_chr_state(Chardev *chr, int connected)
             chr->gsource = io_add_watch_poll(chr, s->ioc,
                                                pty_chr_read_poll,
                                                pty_chr_read,
-                                               chr, NULL);
+                                               chr, chr->gcontext);
         }
     }
 }

chardev/char-socket.c

@@ -516,13 +516,12 @@ static void tcp_chr_connect(void *opaque)
         chr->gsource = io_add_watch_poll(chr, s->ioc,
                                            tcp_chr_read_poll,
                                            tcp_chr_read,
-                                           chr, NULL);
+                                           chr, chr->gcontext);
     }
     qemu_chr_be_event(chr, CHR_EVENT_OPENED);
 }
 
-static void tcp_chr_update_read_handler(Chardev *chr,
-                                        GMainContext *context)
+static void tcp_chr_update_read_handler(Chardev *chr)
 {
     SocketChardev *s = SOCKET_CHARDEV(chr);
 
@@ -535,7 +534,7 @@ static void tcp_chr_update_read_handler(Chardev *chr,
         chr->gsource = io_add_watch_poll(chr, s->ioc,
                                            tcp_chr_read_poll,
                                            tcp_chr_read, chr,
-                                           context);
+                                           chr->gcontext);
     }
 }
 

chardev/char-udp.c

@@ -100,8 +100,7 @@ static gboolean udp_chr_read(QIOChannel *chan, GIOCondition cond, void *opaque)
     return TRUE;
 }
 
-static void udp_chr_update_read_handler(Chardev *chr,
-                                        GMainContext *context)
+static void udp_chr_update_read_handler(Chardev *chr)
 {
     UdpChardev *s = UDP_CHARDEV(chr);
 
@@ -110,7 +109,7 @@ static void udp_chr_update_read_handler(Chardev *chr,
         chr->gsource = io_add_watch_poll(chr, s->ioc,
                                            udp_chr_read_poll,
                                            udp_chr_read, chr,
-                                           context);
+                                           chr->gcontext);
     }
 }
 

chardev/char.c

@@ -180,6 +180,17 @@ void qemu_chr_be_write(Chardev *s, uint8_t *buf, int len)
     }
 }
 
+void qemu_chr_be_update_read_handlers(Chardev *s,
+                                      GMainContext *context)
+{
+    ChardevClass *cc = CHARDEV_GET_CLASS(s);
+
+    s->gcontext = context;
+    if (cc->chr_update_read_handler) {
+        cc->chr_update_read_handler(s);
+    }
+}
+
 int qemu_chr_add_client(Chardev *s, int fd)
 {
     return CHARDEV_GET_CLASS(s)->chr_add_client ?

configure

@@ -290,6 +290,7 @@ netmap="no"
 sdl=""
 sdlabi=""
 virtfs=""
+mpath=""
 vnc="yes"
 sparse="no"
 vde=""
@@ -936,6 +937,10 @@ for opt do
   ;;
   --enable-virtfs) virtfs="yes"
   ;;
+  --disable-mpath) mpath="no"
+  ;;
+  --enable-mpath) mpath="yes"
+  ;;
   --disable-vnc) vnc="no"
   ;;
   --enable-vnc) vnc="yes"
@@ -1479,6 +1484,7 @@ disabled with --disable-FEATURE, default is enabled if available:
   vnc-png         PNG compression for VNC server
   cocoa           Cocoa UI (Mac OS X only)
   virtfs          VirtFS
+  mpath           Multipath persistent reservation passthrough
   xen             xen backend driver support
   xen-pci-passthrough
   brlapi          BrlAPI (Braile)
@@ -3294,6 +3300,30 @@ else
       "Please install the pixman devel package."
 fi
 
+##########################################
+# libmpathpersist probe
+
+if test "$mpath" != "no" ; then
+  cat > $TMPC <<EOF
+#include <libudev.h>
+#include <mpath_persist.h>
+unsigned mpath_mx_alloc_len = 1024;
+int logsink;
+int main(void) {
+    struct udev *udev = udev_new();
+    mpath_lib_init(udev);
+    return 0;
+}
+EOF
+  if compile_prog "" "-ludev -lmultipath -lmpathpersist" ; then
+    mpathpersist=yes
+  else
+    mpathpersist=no
+  fi
+else
+  mpathpersist=no
+fi
+
 ##########################################
 # libcap probe
 
@@ -5023,16 +5053,34 @@ if test "$want_tools" = "yes" ; then
   fi
 fi
 if test "$softmmu" = yes ; then
-  if test "$virtfs" != no ; then
-    if test "$cap" = yes && test "$linux" = yes && test "$attr" = yes ; then
+  if test "$linux" = yes; then
+    if test "$virtfs" != no && test "$cap" = yes && test "$attr" = yes ; then
       virtfs=yes
       tools="$tools fsdev/virtfs-proxy-helper\$(EXESUF)"
     else
       if test "$virtfs" = yes; then
-        error_exit "VirtFS is supported only on Linux and requires libcap devel and libattr devel"
+        error_exit "VirtFS requires libcap devel and libattr devel"
       fi
       virtfs=no
     fi
+    if test "$mpath" != no && test "$mpathpersist" = yes ; then
+      mpath=yes
+    else
+      if test "$mpath" = yes; then
+        error_exit "Multipath requires libmpathpersist devel"
+      fi
+      mpath=no
+    fi
+    tools="$tools scsi/qemu-pr-helper\$(EXESUF)"
+  else
+    if test "$virtfs" = yes; then
+      error_exit "VirtFS is supported only on Linux"
+    fi
+    virtfs=no
+    if test "$mpath" = yes; then
+      error_exit "Multipath is supported only on Linux"
+    fi
+    mpath=no
   fi
 fi
 
@@ -5278,6 +5326,7 @@ echo "Audio drivers     $audio_drv_list"
 echo "Block whitelist (rw) $block_drv_rw_whitelist"
 echo "Block whitelist (ro) $block_drv_ro_whitelist"
 echo "VirtFS support    $virtfs"
+echo "Multipath support $mpath"
 echo "VNC support       $vnc"
 if test "$vnc" = "yes" ; then
     echo "VNC SASL support  $vnc_sasl"
@@ -5729,6 +5778,9 @@ fi
 if test "$virtfs" = "yes" ; then
   echo "CONFIG_VIRTFS=y" >> $config_host_mak
 fi
+if test "$mpath" = "yes" ; then
+  echo "CONFIG_MPATH=y" >> $config_host_mak
+fi
 if test "$vhost_scsi" = "yes" ; then
   echo "CONFIG_VHOST_SCSI=y" >> $config_host_mak
 fi
@@ -6510,7 +6562,7 @@ fi
 
 # build tree in object directory in case the source is not in the current directory
 DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos tests/qapi-schema tests/tcg/xtensa tests/qemu-iotests tests/vm"
-DIRS="$DIRS docs docs/interop fsdev"
+DIRS="$DIRS docs docs/interop fsdev scsi"
 DIRS="$DIRS pc-bios/optionrom pc-bios/spapr-rtas pc-bios/s390-ccw"
 DIRS="$DIRS roms/seabios roms/vgabios"
 DIRS="$DIRS qapi-generated"

cpus.c

@@ -1764,8 +1764,9 @@ void qemu_init_vcpu(CPUState *cpu)
         /* If the target cpu hasn't set up any address spaces itself,
          * give it the default one.
          */
-        AddressSpace *as = address_space_init_shareable(cpu->memory,
-                                                        "cpu-memory");
+        AddressSpace *as = g_new0(AddressSpace, 1);
+
+        address_space_init(as, cpu->memory, "cpu-memory");
         cpu->num_ases = 1;
         cpu_address_space_init(cpu, as, 0);
     }

docs/devel/atomics.txt

@@ -63,11 +63,23 @@ operations:
     typeof(*ptr) atomic_fetch_sub(ptr, val)
     typeof(*ptr) atomic_fetch_and(ptr, val)
     typeof(*ptr) atomic_fetch_or(ptr, val)
+    typeof(*ptr) atomic_fetch_xor(ptr, val)
+    typeof(*ptr) atomic_fetch_inc_nonzero(ptr)
     typeof(*ptr) atomic_xchg(ptr, val)
     typeof(*ptr) atomic_cmpxchg(ptr, old, new)
 
 all of which return the old value of *ptr.  These operations are
-polymorphic; they operate on any type that is as wide as an int.
+polymorphic; they operate on any type that is as wide as a pointer.
+
+Similar operations return the new value of *ptr:
+
+    typeof(*ptr) atomic_inc_fetch(ptr)
+    typeof(*ptr) atomic_dec_fetch(ptr)
+    typeof(*ptr) atomic_add_fetch(ptr, val)
+    typeof(*ptr) atomic_sub_fetch(ptr, val)
+    typeof(*ptr) atomic_and_fetch(ptr, val)
+    typeof(*ptr) atomic_or_fetch(ptr, val)
+    typeof(*ptr) atomic_xor_fetch(ptr, val)
 
 Sequentially consistent loads and stores can be done using:
 

docs/interop/pr-helper.rst

@@ -0,0 +1,83 @@
+..
+
+======================================
+Persistent reservation helper protocol
+======================================
+
+QEMU's SCSI passthrough devices, ``scsi-block`` and ``scsi-generic``,
+can delegate implementation of persistent reservations to an external
+(and typically privileged) program.  Persistent Reservations allow
+restricting access to block devices to specific initiators in a shared
+storage setup.
+
+For a more detailed reference please refer the the SCSI Primary
+Commands standard, specifically the section on Reservations and the
+"PERSISTENT RESERVE IN" and "PERSISTENT RESERVE OUT" commands.
+
+This document describes the socket protocol used between QEMU's
+``pr-manager-helper`` object and the external program.
+
+.. contents::
+
+Connection and initialization
+-----------------------------
+
+All data transmitted on the socket is big-endian.
+
+After connecting to the helper program's socket, the helper starts a simple
+feature negotiation process by writing four bytes corresponding to
+the features it exposes (``supported_features``).  QEMU reads it,
+then writes four bytes corresponding to the desired features of the
+helper program (``requested_features``).
+
+If a bit is 1 in ``requested_features`` and 0 in ``supported_features``,
+the corresponding feature is not supported by the helper and the connection
+is closed.  On the other hand, it is acceptable for a bit to be 0 in
+``requested_features`` and 1 in ``supported_features``; in this case,
+the helper will not enable the feature.
+
+Right now no feature is defined, so the two parties always write four
+zero bytes.
+
+Command format
+--------------
+
+It is invalid to send multiple commands concurrently on the same
+socket.  It is however possible to connect multiple sockets to the
+helper and send multiple commands to the helper for one or more
+file descriptors.
+
+A command consists of a request and a response.  A request consists
+of a 16-byte SCSI CDB.  A file descriptor must be passed to the helper
+together with the SCSI CDB using ancillary data.
+
+The CDB has the following limitations:
+
+- the command (stored in the first byte) must be one of 0x5E
+  (PERSISTENT RESERVE IN) or 0x5F (PERSISTENT RESERVE OUT).
+
+- the allocation length (stored in bytes 7-8 of the CDB for PERSISTENT
+  RESERVE IN) or parameter list length (stored in bytes 5-8 of the CDB
+  for PERSISTENT RESERVE OUT) is limited to 8 KiB.
+
+For PERSISTENT RESERVE OUT, the parameter list is sent right after the
+CDB.  The length of the parameter list is taken from the CDB itself.
+
+The helper's reply has the following structure:
+
+- 4 bytes for the SCSI status
+
+- 4 bytes for the payload size (nonzero only for PERSISTENT RESERVE IN
+  and only if the SCSI status is 0x00, i.e. GOOD)
+
+- 96 bytes for the SCSI sense data
+
+- if the size is nonzero, the payload follows
+
+The sense data is always sent to keep the protocol simple, even though
+it is only valid if the SCSI status is CHECK CONDITION (0x02).
+
+The payload size is always less than or equal to the allocation length
+specified in the CDB for the PERSISTENT RESERVE IN command.
+
+If the protocol is violated, the helper closes the socket.

docs/pr-manager.rst

@@ -0,0 +1,111 @@
+======================================
+Persistent reservation managers
+======================================
+
+SCSI persistent Reservations allow restricting access to block devices
+to specific initiators in a shared storage setup.  When implementing
+clustering of virtual machines, it is a common requirement for virtual
+machines to send persistent reservation SCSI commands.  However,
+the operating system restricts sending these commands to unprivileged
+programs because incorrect usage can disrupt regular operation of the
+storage fabric.
+
+For this reason, QEMU's SCSI passthrough devices, ``scsi-block``
+and ``scsi-generic`` (both are only available on Linux) can delegate
+implementation of persistent reservations to a separate object,
+the "persistent reservation manager".  Only PERSISTENT RESERVE OUT and
+PERSISTENT RESERVE IN commands are passed to the persistent reservation
+manager object; other commands are processed by QEMU as usual.
+
+-----------------------------------------
+Defining a persistent reservation manager
+-----------------------------------------
+
+A persistent reservation manager is an instance of a subclass of the
+"pr-manager" QOM class.
+
+Right now only one subclass is defined, ``pr-manager-helper``, which
+forwards the commands to an external privileged helper program
+over Unix sockets.  The helper program only allows sending persistent
+reservation commands to devices for which QEMU has a file descriptor,
+so that QEMU will not be able to effect persistent reservations
+unless it has access to both the socket and the device.
+
+``pr-manager-helper`` has a single string property, ``path``, which
+accepts the path to the helper program's Unix socket.  For example,
+the following command line defines a ``pr-manager-helper`` object and
+attaches it to a SCSI passthrough device::
+
+      $ qemu-system-x86_64
+          -device virtio-scsi \
+          -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock
+          -drive if=none,id=hd,driver=raw,file.filename=/dev/sdb,file.pr-manager=helper0
+          -device scsi-block,drive=hd
+
+Alternatively, using ``-blockdev``::
+
+      $ qemu-system-x86_64
+          -device virtio-scsi \
+          -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock
+          -blockdev node-name=hd,driver=raw,file.driver=host_device,file.filename=/dev/sdb,file.pr-manager=helper0
+          -device scsi-block,drive=hd
+
+----------------------------------
+Invoking :program:`qemu-pr-helper`
+----------------------------------
+
+QEMU provides an implementation of the persistent reservation helper,
+called :program:`qemu-pr-helper`.  The helper should be started as a
+system service and supports the following option:
+
+-d, --daemon              run in the background
+-q, --quiet               decrease verbosity
+-v, --verbose             increase verbosity
+-f, --pidfile=path        PID file when running as a daemon
+-k, --socket=path         path to the socket
+-T, --trace=trace-opts    tracing options
+
+By default, the socket and PID file are placed in the runtime state
+directory, for example :file:`/var/run/qemu-pr-helper.sock` and
+:file:`/var/run/qemu-pr-helper.pid`.  The PID file is not created
+unless :option:`-d` is passed too.
+
+:program:`qemu-pr-helper` can also use the systemd socket activation
+protocol.  In this case, the systemd socket unit should specify a
+Unix stream socket, like this::
+
+    [Socket]
+    ListenStream=/var/run/qemu-pr-helper.sock
+
+After connecting to the socket, :program:`qemu-pr-helper`` can optionally drop
+root privileges, except for those capabilities that are needed for
+its operation.  To do this, add the following options:
+
+-u, --user=user           user to drop privileges to
+-g, --group=group         group to drop privileges to
+
+---------------------------------------------
+Multipath devices and persistent reservations
+---------------------------------------------
+
+Proper support of persistent reservation for multipath devices requires
+communication with the multipath daemon, so that the reservation is
+registered and applied when a path is newly discovered or becomes online
+again.  :command:`qemu-pr-helper` can do this if the ``libmpathpersist``
+library was available on the system at build time.
+
+As of August 2017, a reservation key must be specified in ``multipath.conf``
+for ``multipathd`` to check for persistent reservation for newly
+discovered paths or reinstated paths.  The attribute can be added
+to the ``defaults`` section or the ``multipaths`` section; for example::
+
+    multipaths {
+        multipath {
+            wwid   XXXXXXXXXXXXXXXX
+            alias      yellow
+            reservation_key  0x123abc
+        }
+    }
+
+Linking :program:`qemu-pr-helper` to ``libmpathpersist`` does not impede
+its usage on regular SCSI devices.

hmp-commands-info.hx

@@ -250,9 +250,10 @@ ETEXI
 
     {
         .name       = "mtree",
-        .args_type  = "flatview:-f",
-        .params     = "[-f]",
-        .help       = "show memory tree (-f: dump flat view for address spaces)",
+        .args_type  = "flatview:-f,dispatch_tree:-d",
+        .params     = "[-f][-d]",
+        .help       = "show memory tree (-f: dump flat view for address spaces;"
+                      "-d: dump dispatch tree, valid with -f only)",
         .cmd        = hmp_info_mtree,
     },
 

hw/arm/armv7m.c

@@ -41,7 +41,7 @@ static MemTxResult bitband_read(void *opaque, hwaddr offset,
 
     /* Find address in underlying memory and round down to multiple of size */
     addr = bitband_addr(s, offset) & (-size);
-    res = address_space_read(s->source_as, addr, attrs, buf, size);
+    res = address_space_read(&s->source_as, addr, attrs, buf, size);
     if (res) {
         return res;
     }
@@ -66,7 +66,7 @@ static MemTxResult bitband_write(void *opaque, hwaddr offset, uint64_t value,
 
     /* Find address in underlying memory and round down to multiple of size */
     addr = bitband_addr(s, offset) & (-size);
-    res = address_space_read(s->source_as, addr, attrs, buf, size);
+    res = address_space_read(&s->source_as, addr, attrs, buf, size);
     if (res) {
         return res;
     }
@@ -79,7 +79,7 @@ static MemTxResult bitband_write(void *opaque, hwaddr offset, uint64_t value,
     } else {
         buf[bitpos >> 3] &= ~bit;
     }
-    return address_space_write(s->source_as, addr, attrs, buf, size);
+    return address_space_write(&s->source_as, addr, attrs, buf, size);
 }
 
 static const MemoryRegionOps bitband_ops = {
@@ -111,8 +111,7 @@ static void bitband_realize(DeviceState *dev, Error **errp)
         return;
     }
 
-    s->source_as = address_space_init_shareable(s->source_memory,
-                                                "bitband-source");
+    address_space_init(&s->source_as, s->source_memory, "bitband-source");
 }
 
 /* Board init.  */

hw/char/virtio-console.c

@@ -187,6 +187,26 @@ static int chr_be_change(void *opaque)
     return 0;
 }
 
+static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable)
+{
+    VirtConsole *vcon = VIRTIO_CONSOLE(port);
+
+    if (!qemu_chr_fe_backend_connected(&vcon->chr)) {
+        return;
+    }
+
+    if (enable) {
+        VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
+
+        qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
+                                 k->is_console ? NULL : chr_event,
+                                 chr_be_change, vcon, NULL, false);
+    } else {
+        qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL,
+                                 NULL, NULL, NULL, false);
+    }
+}
+
 static void virtconsole_realize(DeviceState *dev, Error **errp)
 {
     VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(dev);
@@ -258,6 +278,7 @@ static void virtserialport_class_init(ObjectClass *klass, void *data)
     k->unrealize = virtconsole_unrealize;
     k->have_data = flush_buf;
     k->set_guest_connected = set_guest_connected;
+    k->enable_backend = virtconsole_enable_backend;
     k->guest_writable = guest_writable;
     dc->props = virtserialport_properties;
 }

hw/char/virtio-serial-bus.c

@@ -637,6 +637,13 @@ static void set_status(VirtIODevice *vdev, uint8_t status)
     if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
         guest_reset(vser);
     }
+
+    QTAILQ_FOREACH(port, &vser->ports, next) {
+        VirtIOSerialPortClass *vsc = VIRTIO_SERIAL_PORT_GET_CLASS(port);
+        if (vsc->enable_backend) {
+            vsc->enable_backend(port, vdev->vm_running);
+        }
+    }
 }
 
 static void vser_reset(VirtIODevice *vdev)