[Qemu-devel] [Minios-devel] [PATCH v7 0/<VARIOUS>] Begin to disentangle libxenctrl and provide some stable libraries

[Qemu-devel] [Minios-devel] [PATCH v7 0/<VARIOUS>] Begin to disentangle libxenctrl and provide some stable libraries

[Ian Campbell]

In <1431963008.4944.80.camel@citrix.com> I proposed stabilising some
parts of the libxenctrl API/ABI by disaggregating into separate
libraries.

This is v7 of that set of series against:
    xen
    qemu-xen
    qemu-xen-traditional
    mini-os

NB: Samuel+minios-devel will only get the mini-os side and Stefano+qemu
-devel the qemu-xen side.

The code for all repos can be found in:

git://xenbits.xen.org/people/ianc/libxenctrl-split/xen.git                  v7
git://xenbits.xen.org/people/ianc/libxenctrl-split/qemu-xen.git             v7
git://xenbits.xen.org/people/ianc/libxenctrl-split/qemu-xen-traditional.git v7
git://xenbits.xen.org/people/ianc/libxenctrl-split/mini-os.git              v7

The tip of the xen.git branch contains an extra patch hacking Config.mk
to point to all the others above, which should get the correct things for
the HEAD of the branch, but not further back in time.

The new libraries here are:

 * libxentoollog: Common logging infrastructure
 * libxenevtchn: Userspace access to evtchns (via /dev/xen/evtchn etc)
 * libxengnttab: Userspace access to grant tables (via /dev/xen/gnt??? etc)
 * libxencall: Making hypercalls (i.e. the IOCTL_PRIVCMD_HYPERCALL type
   functionality)
 * libxenforeignmemory: Privileged mappings of foreign memory
   (IOCTL_PRIVCMD_MMAP et al)

The first three were actually pretty distinct within libxenctrl already and
have not changed in quite some time.

Although the other two are somewhat new they are based on top of long
standing stable ioctls, which gives me some confidence.

Nonetheless I would appreciate extra review of at least the interface
headers of all of these with a particular eye to the suitability of these
interfaces being maintained in an ABI (_B_, not _P_) stable way going
forward.

Still to come would be libraries for specific out of tree purposes
(device model, kexec), which would be adding new library at the same
level as libxc I think, rather than underneath, i.e. also using the
libraries split out here, but hopefully not libxenctrl itself.

The new libraries use linker version-scripts to hopefully make future
ABI changes be possible in a compatible way.

Since last time:

 * Lots more docs updates based on feedback given and especially the
   discussion around the semantics of the libraries wrt forking without
   exec.
 * s/gnttab_munmap/gnttab_unmap/ and s/gntshr_munmap/gntshr_unshare/      
    in the libxengnttab API.
 * Use O_CLOEXEC on Linux and FreeBSD unconditionally.
 * Fixed a stubdom/Makefile build race issue
 * Dropped -pedantic from headers check, the headers in xen/include/public
   are not -pedantic clean, and the libraries can include headers from
   there (and then the check breaks).
 * Dropped libxencall atform madvise thing, in favour of simpler solution
   of touching the pages to uncow them.
 * The xentoollog patch went in but was reverted, that patch now refers to
   the revisions of qemu and mini-os with the corresponding changes.

Even with the dropped acks mini-os and qemu-xen-trad are fully acked, while
qemu-xen and xen are mostly acked (but had a few dropped acks since last
time).

The whole thing has been build tested on Linux (incl stubdoms), and on
FreeBSD. I have runtime tested on Linux with qemu-xen, qemu-xen-trad and
stubdoms.

Neither NetBSD nor Solaris have been tested at all. It's certainly not
impossible that I've not got the #includes in the new files quite right.

http://xenbits.xen.org/people/ianc/libxenctrl-split/v7.html is the document
I've been using to try and track what I'm doing. It may not be all that
useful. The history of it is in the v6-with-doc branch of the xen.git
linked to above.

A few of the initial patches went in, but in the meantime I discovered a
wrinkle in the changes to the stubdom build changes, so now there are some
new ones.

    tools: Refactor "xentoollog" into its own library

went in but then came out again and is now blocking on a libvirt patch,
which is in libvirt.git#master waiting to get through our libvirt push
gate.

Ian.

[Qemu-devel] [PATCH QEMU-XEN v7 0/8] Begin to disentangle libxenctrl and provide some stable libraries

[Ian Campbell]

We intend to stabilise some parts of the libxenctrl interface by
splitting out some functionality into separate stable libraries.

This is the qemu-xen part of the first phase of that change.

This mail is (or is intended to be) a reply to a "0/<VARIOUS>"
super-intro mail covering all of the related patch series and which
contains more details.

Ian Campbell (8):
  xen_console: correctly cleanup primary console on teardown.
  xen: Switch to libxenevtchn interface for compat shims.
  xen: Switch to libxengnttab interface for compat shims.
  xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages
  xen: Switch uses of xc_map_foreign_{pages,bulk} to use
    libxenforeignmemory API.
  xen: Use stable library interfaces when they are available.
  xen: domainbuild: reopen libxenctrl interface after forking for domain
    watcher.
  xen: make it possible to build without the Xen PV domain builder

 configure                    |  57 ++++++++++++++++-
 hw/block/xen_disk.c          |  38 +++++------
 hw/char/xen_console.c        |  19 +++---
 hw/display/xenfb.c           |  28 +++++----
 hw/net/xen_nic.c             |  18 +++---
 hw/xen/xen_backend.c         |  44 ++++++-------
 hw/xenpv/Makefile.objs       |   4 +-
 hw/xenpv/xen_domainbuild.c   |   9 ++-
 hw/xenpv/xen_machine_pv.c    |  15 +++--
 include/hw/xen/xen_backend.h |   5 +-
 include/hw/xen/xen_common.h  | 147 ++++++++++++++++++++++++++++++++++---------
 xen-common.c                 |   6 ++
 xen-hvm.c                    |  39 ++++++------
 xen-mapcache.c               |   6 +-
 14 files changed, 299 insertions(+), 136 deletions(-)

-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 1/8] xen_console: correctly cleanup primary console on teardown.

[Ian Campbell]

All of the work in con_disconnect applies to the primary console case
(when xendev->dev is NULL). Therefore remove the early check and bail
and allow it to fall through. All of the existing code is correctly
conditional already.

The ->dev and ->gnttabdev handles are either both set or neither. For
consistency with con_initialise() with to the former here too.

With this con_initialise and con_disconnect now mirror each other.

Fix up a hard tab in the function while editing.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

---
v4: New patch based on feedback to "xen: Switch uses of
xc_map_foreign_bulk to use libxenforeignmemory API."
---
 hw/char/xen_console.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index eb7f450..63ade33 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -265,9 +265,6 @@ static void con_disconnect(struct XenDevice *xendev)
 {
     struct XenConsole *con = container_of(xendev, struct XenConsole, xendev);
 
-    if (!xendev->dev) {
-        return;
-    }
     if (con->chr) {
         qemu_chr_add_handlers(con->chr, NULL, NULL, NULL, NULL);
         qemu_chr_fe_release(con->chr);
@@ -275,12 +272,12 @@ static void con_disconnect(struct XenDevice *xendev)
     xen_be_unbind_evtchn(&con->xendev);
 
     if (con->sring) {
-        if (!xendev->gnttabdev) {
+        if (!xendev->dev) {
             munmap(con->sring, XC_PAGE_SIZE);
         } else {
             xc_gnttab_munmap(xendev->gnttabdev, con->sring, 1);
         }
-	con->sring = NULL;
+        con->sring = NULL;
     }
 }
 
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 2/8] xen: Switch to libxenevtchn interface for compat shims.

[Ian Campbell]

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxenevtchn which provides access to event
channels.

In preparation for this switch the compatibility layer in xen_common.h
(which support building with older versions of Xen) to use what will
be the new library API. This means that the evtchn shim will disappear
for versions of Xen which include libxenevtchn.

To simplify things for the <= 4.0.0 support we wrap the int fd in a
malloc(sizeof int) such that the handle is always a pointer. This
leads to less typedef headaches and the need for
XC_HANDLER_INITIAL_VALUE etc for these interfaces.

Note that this patch does not add any support for actually using
libxenevtchn, it just adjusts the existing shims.

Note that xc_evtchn_alloc_unbound functionality remains in libxenctrl,
since that functionality is not exposed by /dev/xen/evtchn.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
v4: Ran checkpatch, fixed all errors
    Allocate correct size for handle (i.e. not size of the ptr)
---
 hw/xen/xen_backend.c         | 31 ++++++++++++++++---------------
 include/hw/xen/xen_backend.h |  2 +-
 include/hw/xen/xen_common.h  | 44 ++++++++++++++++++++++++++++++++++----------
 xen-hvm.c                    | 25 +++++++++++++------------
 4 files changed, 64 insertions(+), 38 deletions(-)

diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index 2510e2e..ae2a1f0 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -243,19 +243,19 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
     xendev->debug      = debug;
     xendev->local_port = -1;
 
-    xendev->evtchndev = xen_xc_evtchn_open(NULL, 0);
-    if (xendev->evtchndev == XC_HANDLER_INITIAL_VALUE) {
+    xendev->evtchndev = xenevtchn_open(NULL, 0);
+    if (xendev->evtchndev == NULL) {
         xen_be_printf(NULL, 0, "can't open evtchn device\n");
         g_free(xendev);
         return NULL;
     }
-    fcntl(xc_evtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
+    fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 
     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
         xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
         if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
             xen_be_printf(NULL, 0, "can't open gnttab device\n");
-            xc_evtchn_close(xendev->evtchndev);
+            xenevtchn_close(xendev->evtchndev);
             g_free(xendev);
             return NULL;
         }
@@ -306,8 +306,8 @@ static struct XenDevice *xen_be_del_xendev(int dom, int dev)
             g_free(xendev->fe);
         }
 
-        if (xendev->evtchndev != XC_HANDLER_INITIAL_VALUE) {
-            xc_evtchn_close(xendev->evtchndev);
+        if (xendev->evtchndev != NULL) {
+            xenevtchn_close(xendev->evtchndev);
         }
         if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
             xc_gnttab_close(xendev->gnttabdev);
@@ -691,13 +691,14 @@ static void xen_be_evtchn_event(void *opaque)
     struct XenDevice *xendev = opaque;
     evtchn_port_t port;
 
-    port = xc_evtchn_pending(xendev->evtchndev);
+    port = xenevtchn_pending(xendev->evtchndev);
     if (port != xendev->local_port) {
-        xen_be_printf(xendev, 0, "xc_evtchn_pending returned %d (expected %d)\n",
+        xen_be_printf(xendev, 0,
+                      "xenevtchn_pending returned %d (expected %d)\n",
                       port, xendev->local_port);
         return;
     }
-    xc_evtchn_unmask(xendev->evtchndev, port);
+    xenevtchn_unmask(xendev->evtchndev, port);
 
     if (xendev->ops->event) {
         xendev->ops->event(xendev);
@@ -740,14 +741,14 @@ int xen_be_bind_evtchn(struct XenDevice *xendev)
     if (xendev->local_port != -1) {
         return 0;
     }
-    xendev->local_port = xc_evtchn_bind_interdomain
+    xendev->local_port = xenevtchn_bind_interdomain
         (xendev->evtchndev, xendev->dom, xendev->remote_port);
     if (xendev->local_port == -1) {
-        xen_be_printf(xendev, 0, "xc_evtchn_bind_interdomain failed\n");
+        xen_be_printf(xendev, 0, "xenevtchn_bind_interdomain failed\n");
         return -1;
     }
     xen_be_printf(xendev, 2, "bind evtchn port %d\n", xendev->local_port);
-    qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev),
+    qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev),
                         xen_be_evtchn_event, NULL, xendev);
     return 0;
 }
@@ -757,15 +758,15 @@ void xen_be_unbind_evtchn(struct XenDevice *xendev)
     if (xendev->local_port == -1) {
         return;
     }
-    qemu_set_fd_handler(xc_evtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
-    xc_evtchn_unbind(xendev->evtchndev, xendev->local_port);
+    qemu_set_fd_handler(xenevtchn_fd(xendev->evtchndev), NULL, NULL, NULL);
+    xenevtchn_unbind(xendev->evtchndev, xendev->local_port);
     xen_be_printf(xendev, 2, "unbind evtchn port %d\n", xendev->local_port);
     xendev->local_port = -1;
 }
 
 int xen_be_send_notify(struct XenDevice *xendev)
 {
-    return xc_evtchn_notify(xendev->evtchndev, xendev->local_port);
+    return xenevtchn_notify(xendev->evtchndev, xendev->local_port);
 }
 
 /*
diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
index 3b4125e..a90314f 100644
--- a/include/hw/xen/xen_backend.h
+++ b/include/hw/xen/xen_backend.h
@@ -46,7 +46,7 @@ struct XenDevice {
     int                remote_port;
     int                local_port;
 
-    XenEvtchn          evtchndev;
+    xenevtchn_handle   *evtchndev;
     XenGnttab          gnttabdev;
 
     struct XenDevOps   *ops;
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 4ac0c6f..5c51b44 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -39,17 +39,38 @@ static inline void *xc_map_foreign_bulk(int xc_handle, uint32_t dom, int prot,
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 410
 
 typedef int XenXC;
-typedef int XenEvtchn;
+typedef int xenevtchn_handle;
 typedef int XenGnttab;
 
 #  define XC_INTERFACE_FMT "%i"
 #  define XC_HANDLER_INITIAL_VALUE    -1
 
-static inline XenEvtchn xen_xc_evtchn_open(void *logger,
-                                           unsigned int open_flags)
+static inline xenevtchn_handle *xenevtchn_open(void *logger,
+                                               unsigned int open_flags)
 {
-    return xc_evtchn_open();
+    xenevtchn_handle *h = malloc(sizeof(*h));
+    if (!h) {
+        return NULL;
+    }
+    *h = xc_evtchn_open();
+    if (*h == -1) {
+        free(h);
+        h = NULL;
+    }
+    return h;
 }
+static inline int xenevtchn_close(xenevtchn_handle *h)
+{
+    int rc = xc_evtchn_close(*h);
+    free(h);
+    return rc;
+}
+#define xenevtchn_fd(h) xc_evtchn_fd(*h)
+#define xenevtchn_pending(h) xc_evtchn_pending(*h)
+#define xenevtchn_notify(h, p) xc_evtchn_notify(*h, p)
+#define xenevtchn_bind_interdomain(h, d, p) xc_evtchn_bind_interdomain(*h, d, p)
+#define xenevtchn_unmask(h, p) xc_evtchn_unmask(*h, p)
+#define xenevtchn_unbind(h, p) xc_evtchn_unmask(*h, p)
 
 static inline XenGnttab xen_xc_gnttab_open(void *logger,
                                            unsigned int open_flags)
@@ -108,17 +129,20 @@ static inline void xs_close(struct xs_handle *xsh)
 #else
 
 typedef xc_interface *XenXC;
-typedef xc_evtchn *XenEvtchn;
+typedef xc_evtchn xenevtchn_handle;
 typedef xc_gnttab *XenGnttab;
 
 #  define XC_INTERFACE_FMT "%p"
 #  define XC_HANDLER_INITIAL_VALUE    NULL
 
-static inline XenEvtchn xen_xc_evtchn_open(void *logger,
-                                           unsigned int open_flags)
-{
-    return xc_evtchn_open(logger, open_flags);
-}
+#define xenevtchn_open(l, f) xc_evtchn_open(l, f);
+#define xenevtchn_close(h) xc_evtchn_close(h)
+#define xenevtchn_fd(h) xc_evtchn_fd(h)
+#define xenevtchn_pending(h) xc_evtchn_pending(h)
+#define xenevtchn_notify(h, p) xc_evtchn_notify(h, p)
+#define xenevtchn_bind_interdomain(h, d, p) xc_evtchn_bind_interdomain(h, d, p)
+#define xenevtchn_unmask(h, p) xc_evtchn_unmask(h, p)
+#define xenevtchn_unbind(h, p) xc_evtchn_unbind(h, p)
 
 static inline XenGnttab xen_xc_gnttab_open(void *logger,
                                            unsigned int open_flags)
diff --git a/xen-hvm.c b/xen-hvm.c
index 3d78a0c..6680782 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -109,7 +109,7 @@ typedef struct XenIOState {
     /* evtchn local port for buffered io */
     evtchn_port_t bufioreq_local_port;
     /* the evtchn fd for polling */
-    XenEvtchn xce_handle;
+    xenevtchn_handle *xce_handle;
     /* which vcpu we are serving */
     int send_vcpu;
 
@@ -714,7 +714,7 @@ static ioreq_t *cpu_get_ioreq(XenIOState *state)
     int i;
     evtchn_port_t port;
 
-    port = xc_evtchn_pending(state->xce_handle);
+    port = xenevtchn_pending(state->xce_handle);
     if (port == state->bufioreq_local_port) {
         timer_mod(state->buffered_io_timer,
                 BUFFER_IO_MAX_DELAY + qemu_clock_get_ms(QEMU_CLOCK_REALTIME));
@@ -733,7 +733,7 @@ static ioreq_t *cpu_get_ioreq(XenIOState *state)
         }
 
         /* unmask the wanted port again */
-        xc_evtchn_unmask(state->xce_handle, port);
+        xenevtchn_unmask(state->xce_handle, port);
 
         /* get the io packet from shared memory */
         state->send_vcpu = i;
@@ -1040,7 +1040,7 @@ static void handle_buffered_io(void *opaque)
                 BUFFER_IO_MAX_DELAY + qemu_clock_get_ms(QEMU_CLOCK_REALTIME));
     } else {
         timer_del(state->buffered_io_timer);
-        xc_evtchn_unmask(state->xce_handle, state->bufioreq_local_port);
+        xenevtchn_unmask(state->xce_handle, state->bufioreq_local_port);
     }
 }
 
@@ -1084,7 +1084,8 @@ static void cpu_handle_ioreq(void *opaque)
         }
 
         req->state = STATE_IORESP_READY;
-        xc_evtchn_notify(state->xce_handle, state->ioreq_local_port[state->send_vcpu]);
+        xenevtchn_notify(state->xce_handle,
+                         state->ioreq_local_port[state->send_vcpu]);
     }
 }
 
@@ -1092,8 +1093,8 @@ static void xen_main_loop_prepare(XenIOState *state)
 {
     int evtchn_fd = -1;
 
-    if (state->xce_handle != XC_HANDLER_INITIAL_VALUE) {
-        evtchn_fd = xc_evtchn_fd(state->xce_handle);
+    if (state->xce_handle != NULL) {
+        evtchn_fd = xenevtchn_fd(state->xce_handle);
     }
 
     state->buffered_io_timer = timer_new_ms(QEMU_CLOCK_REALTIME, handle_buffered_io,
@@ -1131,7 +1132,7 @@ static void xen_exit_notifier(Notifier *n, void *data)
 {
     XenIOState *state = container_of(n, XenIOState, exit);
 
-    xc_evtchn_close(state->xce_handle);
+    xenevtchn_close(state->xce_handle);
     xs_daemon_close(state->xenstore);
 }
 
@@ -1200,8 +1201,8 @@ int xen_hvm_init(PCMachineState *pcms,
 
     state = g_malloc0(sizeof (XenIOState));
 
-    state->xce_handle = xen_xc_evtchn_open(NULL, 0);
-    if (state->xce_handle == XC_HANDLER_INITIAL_VALUE) {
+    state->xce_handle = xenevtchn_open(NULL, 0);
+    if (state->xce_handle == NULL) {
         perror("xen: event channel open");
         return -1;
     }
@@ -1281,7 +1282,7 @@ int xen_hvm_init(PCMachineState *pcms,
 
     /* FIXME: how about if we overflow the page here? */
     for (i = 0; i < max_cpus; i++) {
-        rc = xc_evtchn_bind_interdomain(state->xce_handle, xen_domid,
+        rc = xenevtchn_bind_interdomain(state->xce_handle, xen_domid,
                                         xen_vcpu_eport(state->shared_page, i));
         if (rc == -1) {
             fprintf(stderr, "shared evtchn %d bind error %d\n", i, errno);
@@ -1290,7 +1291,7 @@ int xen_hvm_init(PCMachineState *pcms,
         state->ioreq_local_port[i] = rc;
     }
 
-    rc = xc_evtchn_bind_interdomain(state->xce_handle, xen_domid,
+    rc = xenevtchn_bind_interdomain(state->xce_handle, xen_domid,
                                     bufioreq_evtchn);
     if (rc == -1) {
         fprintf(stderr, "buffered evtchn bind error %d\n", errno);
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 3/8] xen: Switch to libxengnttab interface for compat shims.

[Ian Campbell]

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxengnttab which provides access to grant
tables.

In preparation for this switch the compatibility layer in xen_common.h
(which support building with older versions of Xen) to use what will
be the new library API. This means that the gnttab shim will disappear
for versions of Xen which include libxengnttab.

To simplify things for the <= 4.0.0 support we wrap the int fd in a
malloc(sizeof int) such that the handle is always a pointer. This
leads to less typedef headaches and the need for
XC_HANDLER_INITIAL_VALUE etc for these interfaces.

Note that this patch does not add any support for actually using
libxengnttab, it just adjusts the existing shims.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
v4: Ran checkpatch, fixed all errors
    Allocate correct size for handle (i.e. not size of the ptr)
    Rebase onto "xen_console: correctly cleanup primary console on
    teardown."

v5: Rebase over b4f72e31b924 "hw/net/xen_nic.c: Free 'netdev->txs'
when map 'netdev->rxs' fails" which added a new gnttab_munmap.

v7: s/gnttab_munmap/gnttab_unmap/ to reflect change in the library.
---
 hw/block/xen_disk.c          | 38 ++++++++++++++++++++------------------
 hw/char/xen_console.c        |  4 ++--
 hw/net/xen_nic.c             | 18 +++++++++---------
 hw/xen/xen_backend.c         | 10 +++++-----
 include/hw/xen/xen_backend.h |  2 +-
 include/hw/xen/xen_common.h  | 42 ++++++++++++++++++++++++++++++++----------
 6 files changed, 69 insertions(+), 45 deletions(-)

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 8146650..e1f8dd4 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -171,11 +171,11 @@ static gint int_cmp(gconstpointer a, gconstpointer b, gpointer user_data)
 static void destroy_grant(gpointer pgnt)
 {
     PersistentGrant *grant = pgnt;
-    XenGnttab gnt = grant->blkdev->xendev.gnttabdev;
+    xengnttab_handle *gnt = grant->blkdev->xendev.gnttabdev;
 
-    if (xc_gnttab_munmap(gnt, grant->page, 1) != 0) {
+    if (xengnttab_unmap(gnt, grant->page, 1) != 0) {
         xen_be_printf(&grant->blkdev->xendev, 0,
-                      "xc_gnttab_munmap failed: %s\n",
+                      "xengnttab_unmap failed: %s\n",
                       strerror(errno));
     }
     grant->blkdev->persistent_gnt_count--;
@@ -188,11 +188,11 @@ static void remove_persistent_region(gpointer data, gpointer dev)
 {
     PersistentRegion *region = data;
     struct XenBlkDev *blkdev = dev;
-    XenGnttab gnt = blkdev->xendev.gnttabdev;
+    xengnttab_handle *gnt = blkdev->xendev.gnttabdev;
 
-    if (xc_gnttab_munmap(gnt, region->addr, region->num) != 0) {
+    if (xengnttab_unmap(gnt, region->addr, region->num) != 0) {
         xen_be_printf(&blkdev->xendev, 0,
-                      "xc_gnttab_munmap region %p failed: %s\n",
+                      "xengnttab_unmap region %p failed: %s\n",
                       region->addr, strerror(errno));
     }
     xen_be_printf(&blkdev->xendev, 3,
@@ -327,7 +327,7 @@ err:
 
 static void ioreq_unmap(struct ioreq *ioreq)
 {
-    XenGnttab gnt = ioreq->blkdev->xendev.gnttabdev;
+    xengnttab_handle *gnt = ioreq->blkdev->xendev.gnttabdev;
     int i;
 
     if (ioreq->num_unmap == 0 || ioreq->mapped == 0) {
@@ -337,8 +337,9 @@ static void ioreq_unmap(struct ioreq *ioreq)
         if (!ioreq->pages) {
             return;
         }
-        if (xc_gnttab_munmap(gnt, ioreq->pages, ioreq->num_unmap) != 0) {
-            xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed: %s\n",
+        if (xengnttab_unmap(gnt, ioreq->pages, ioreq->num_unmap) != 0) {
+            xen_be_printf(&ioreq->blkdev->xendev, 0,
+                          "xengnttab_unmap failed: %s\n",
                           strerror(errno));
         }
         ioreq->blkdev->cnt_map -= ioreq->num_unmap;
@@ -348,8 +349,9 @@ static void ioreq_unmap(struct ioreq *ioreq)
             if (!ioreq->page[i]) {
                 continue;
             }
-            if (xc_gnttab_munmap(gnt, ioreq->page[i], 1) != 0) {
-                xen_be_printf(&ioreq->blkdev->xendev, 0, "xc_gnttab_munmap failed: %s\n",
+            if (xengnttab_unmap(gnt, ioreq->page[i], 1) != 0) {
+                xen_be_printf(&ioreq->blkdev->xendev, 0,
+                              "xengnttab_unmap failed: %s\n",
                               strerror(errno));
             }
             ioreq->blkdev->cnt_map--;
@@ -361,7 +363,7 @@ static void ioreq_unmap(struct ioreq *ioreq)
 
 static int ioreq_map(struct ioreq *ioreq)
 {
-    XenGnttab gnt = ioreq->blkdev->xendev.gnttabdev;
+    xengnttab_handle *gnt = ioreq->blkdev->xendev.gnttabdev;
     uint32_t domids[BLKIF_MAX_SEGMENTS_PER_REQUEST];
     uint32_t refs[BLKIF_MAX_SEGMENTS_PER_REQUEST];
     void *page[BLKIF_MAX_SEGMENTS_PER_REQUEST];
@@ -412,7 +414,7 @@ static int ioreq_map(struct ioreq *ioreq)
     }
 
     if (batch_maps && new_maps) {
-        ioreq->pages = xc_gnttab_map_grant_refs
+        ioreq->pages = xengnttab_map_grant_refs
             (gnt, new_maps, domids, refs, ioreq->prot);
         if (ioreq->pages == NULL) {
             xen_be_printf(&ioreq->blkdev->xendev, 0,
@@ -428,7 +430,7 @@ static int ioreq_map(struct ioreq *ioreq)
         ioreq->blkdev->cnt_map += new_maps;
     } else if (new_maps)  {
         for (i = 0; i < new_maps; i++) {
-            ioreq->page[i] = xc_gnttab_map_grant_ref
+            ioreq->page[i] = xengnttab_map_grant_ref
                 (gnt, domids[i], refs[i], ioreq->prot);
             if (ioreq->page[i] == NULL) {
                 xen_be_printf(&ioreq->blkdev->xendev, 0,
@@ -778,9 +780,9 @@ static void blk_alloc(struct XenDevice *xendev)
     if (xen_mode != XEN_EMULATE) {
         batch_maps = 1;
     }
-    if (xc_gnttab_set_max_grants(xendev->gnttabdev,
+    if (xengnttab_set_max_grants(xendev->gnttabdev,
             MAX_GRANTS(max_requests, BLKIF_MAX_SEGMENTS_PER_REQUEST)) < 0) {
-        xen_be_printf(xendev, 0, "xc_gnttab_set_max_grants failed: %s\n",
+        xen_be_printf(xendev, 0, "xengnttab_set_max_grants failed: %s\n",
                       strerror(errno));
     }
 }
@@ -987,7 +989,7 @@ static int blk_connect(struct XenDevice *xendev)
         }
     }
 
-    blkdev->sring = xc_gnttab_map_grant_ref(blkdev->xendev.gnttabdev,
+    blkdev->sring = xengnttab_map_grant_ref(blkdev->xendev.gnttabdev,
                                             blkdev->xendev.dom,
                                             blkdev->ring_ref,
                                             PROT_READ | PROT_WRITE);
@@ -1052,7 +1054,7 @@ static void blk_disconnect(struct XenDevice *xendev)
     xen_be_unbind_evtchn(&blkdev->xendev);
 
     if (blkdev->sring) {
-        xc_gnttab_munmap(blkdev->xendev.gnttabdev, blkdev->sring, 1);
+        xengnttab_unmap(blkdev->xendev.gnttabdev, blkdev->sring, 1);
         blkdev->cnt_map--;
         blkdev->sring = NULL;
     }
diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index 63ade33..ac1b324 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -233,7 +233,7 @@ static int con_initialise(struct XenDevice *xendev)
                                           PROT_READ|PROT_WRITE,
                                           con->ring_ref);
     } else {
-        con->sring = xc_gnttab_map_grant_ref(xendev->gnttabdev, con->xendev.dom,
+        con->sring = xengnttab_map_grant_ref(xendev->gnttabdev, con->xendev.dom,
                                              con->ring_ref,
                                              PROT_READ|PROT_WRITE);
     }
@@ -275,7 +275,7 @@ static void con_disconnect(struct XenDevice *xendev)
         if (!xendev->dev) {
             munmap(con->sring, XC_PAGE_SIZE);
         } else {
-            xc_gnttab_munmap(xendev->gnttabdev, con->sring, 1);
+            xengnttab_unmap(xendev->gnttabdev, con->sring, 1);
         }
         con->sring = NULL;
     }
diff --git a/hw/net/xen_nic.c b/hw/net/xen_nic.c
index 0da16b4..3ffb07d 100644
--- a/hw/net/xen_nic.c
+++ b/hw/net/xen_nic.c
@@ -168,7 +168,7 @@ static void net_tx_packets(struct XenNetDev *netdev)
                           (txreq.flags & NETTXF_more_data)      ? " more_data"      : "",
                           (txreq.flags & NETTXF_extra_info)     ? " extra_info"     : "");
 
-            page = xc_gnttab_map_grant_ref(netdev->xendev.gnttabdev,
+            page = xengnttab_map_grant_ref(netdev->xendev.gnttabdev,
                                            netdev->xendev.dom,
                                            txreq.gref, PROT_READ);
             if (page == NULL) {
@@ -190,7 +190,7 @@ static void net_tx_packets(struct XenNetDev *netdev)
                 qemu_send_packet(qemu_get_queue(netdev->nic),
                                  page + txreq.offset, txreq.size);
             }
-            xc_gnttab_munmap(netdev->xendev.gnttabdev, page, 1);
+            xengnttab_unmap(netdev->xendev.gnttabdev, page, 1);
             net_tx_response(netdev, &txreq, NETIF_RSP_OKAY);
         }
         if (!netdev->tx_work) {
@@ -260,7 +260,7 @@ static ssize_t net_rx_packet(NetClientState *nc, const uint8_t *buf, size_t size
     memcpy(&rxreq, RING_GET_REQUEST(&netdev->rx_ring, rc), sizeof(rxreq));
     netdev->rx_ring.req_cons = ++rc;
 
-    page = xc_gnttab_map_grant_ref(netdev->xendev.gnttabdev,
+    page = xengnttab_map_grant_ref(netdev->xendev.gnttabdev,
                                    netdev->xendev.dom,
                                    rxreq.gref, PROT_WRITE);
     if (page == NULL) {
@@ -270,7 +270,7 @@ static ssize_t net_rx_packet(NetClientState *nc, const uint8_t *buf, size_t size
         return -1;
     }
     memcpy(page + NET_IP_ALIGN, buf, size);
-    xc_gnttab_munmap(netdev->xendev.gnttabdev, page, 1);
+    xengnttab_unmap(netdev->xendev.gnttabdev, page, 1);
     net_rx_response(netdev, &rxreq, NETIF_RSP_OKAY, NET_IP_ALIGN, size, 0);
 
     return size;
@@ -342,19 +342,19 @@ static int net_connect(struct XenDevice *xendev)
         return -1;
     }
 
-    netdev->txs = xc_gnttab_map_grant_ref(netdev->xendev.gnttabdev,
+    netdev->txs = xengnttab_map_grant_ref(netdev->xendev.gnttabdev,
                                           netdev->xendev.dom,
                                           netdev->tx_ring_ref,
                                           PROT_READ | PROT_WRITE);
     if (!netdev->txs) {
         return -1;
     }
-    netdev->rxs = xc_gnttab_map_grant_ref(netdev->xendev.gnttabdev,
+    netdev->rxs = xengnttab_map_grant_ref(netdev->xendev.gnttabdev,
                                           netdev->xendev.dom,
                                           netdev->rx_ring_ref,
                                           PROT_READ | PROT_WRITE);
     if (!netdev->rxs) {
-        xc_gnttab_munmap(netdev->xendev.gnttabdev, netdev->txs, 1);
+        xengnttab_unmap(netdev->xendev.gnttabdev, netdev->txs, 1);
         netdev->txs = NULL;
         return -1;
     }
@@ -379,11 +379,11 @@ static void net_disconnect(struct XenDevice *xendev)
     xen_be_unbind_evtchn(&netdev->xendev);
 
     if (netdev->txs) {
-        xc_gnttab_munmap(netdev->xendev.gnttabdev, netdev->txs, 1);
+        xengnttab_unmap(netdev->xendev.gnttabdev, netdev->txs, 1);
         netdev->txs = NULL;
     }
     if (netdev->rxs) {
-        xc_gnttab_munmap(netdev->xendev.gnttabdev, netdev->rxs, 1);
+        xengnttab_unmap(netdev->xendev.gnttabdev, netdev->rxs, 1);
         netdev->rxs = NULL;
     }
 }
diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index ae2a1f0..966e34f 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -252,15 +252,15 @@ static struct XenDevice *xen_be_get_xendev(const char *type, int dom, int dev,
     fcntl(xenevtchn_fd(xendev->evtchndev), F_SETFD, FD_CLOEXEC);
 
     if (ops->flags & DEVOPS_FLAG_NEED_GNTDEV) {
-        xendev->gnttabdev = xen_xc_gnttab_open(NULL, 0);
-        if (xendev->gnttabdev == XC_HANDLER_INITIAL_VALUE) {
+        xendev->gnttabdev = xengnttab_open(NULL, 0);
+        if (xendev->gnttabdev == NULL) {
             xen_be_printf(NULL, 0, "can't open gnttab device\n");
             xenevtchn_close(xendev->evtchndev);
             g_free(xendev);
             return NULL;
         }
     } else {
-        xendev->gnttabdev = XC_HANDLER_INITIAL_VALUE;
+        xendev->gnttabdev = NULL;
     }
 
     QTAILQ_INSERT_TAIL(&xendevs, xendev, next);
@@ -309,8 +309,8 @@ static struct XenDevice *xen_be_del_xendev(int dom, int dev)
         if (xendev->evtchndev != NULL) {
             xenevtchn_close(xendev->evtchndev);
         }
-        if (xendev->gnttabdev != XC_HANDLER_INITIAL_VALUE) {
-            xc_gnttab_close(xendev->gnttabdev);
+        if (xendev->gnttabdev != NULL) {
+            xengnttab_close(xendev->gnttabdev);
         }
 
         QTAILQ_REMOVE(&xendevs, xendev, next);
diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
index a90314f..8e8857b 100644
--- a/include/hw/xen/xen_backend.h
+++ b/include/hw/xen/xen_backend.h
@@ -47,7 +47,7 @@ struct XenDevice {
     int                local_port;
 
     xenevtchn_handle   *evtchndev;
-    XenGnttab          gnttabdev;
+    xengnttab_handle   *gnttabdev;
 
     struct XenDevOps   *ops;
     QTAILQ_ENTRY(XenDevice) next;
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 5c51b44..8f38310 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -40,7 +40,7 @@ static inline void *xc_map_foreign_bulk(int xc_handle, uint32_t dom, int prot,
 
 typedef int XenXC;
 typedef int xenevtchn_handle;
-typedef int XenGnttab;
+typedef int xengnttab_handle;
 
 #  define XC_INTERFACE_FMT "%i"
 #  define XC_HANDLER_INITIAL_VALUE    -1
@@ -72,11 +72,31 @@ static inline int xenevtchn_close(xenevtchn_handle *h)
 #define xenevtchn_unmask(h, p) xc_evtchn_unmask(*h, p)
 #define xenevtchn_unbind(h, p) xc_evtchn_unmask(*h, p)
 
-static inline XenGnttab xen_xc_gnttab_open(void *logger,
-                                           unsigned int open_flags)
+static inline xengnttab_handle *xengnttab_open(void *logger,
+                                               unsigned int open_flags)
 {
-    return xc_gnttab_open();
+    xengnttab_handle *h = malloc(sizeof(*h));
+    if (!h) {
+        return NULL;
+    }
+    *h = xc_gnttab_open();
+    if (*h == -1) {
+        free(h);
+        h = NULL;
+    }
+    return h;
 }
+static inline int xengnttab_close(xengnttab_handle *h)
+{
+    int rc = xc_gnttab_close(*h);
+    free(h);
+    return rc;
+}
+#define xengnttab_set_max_grants(h, n) xc_gnttab_set_max_grants(*h, n)
+#define xengnttab_map_grant_ref(h, d, r, p) xc_gnttab_map_grant_ref(*h, d, r, p)
+#define xengnttab_map_grant_refs(h, c, d, r, p) \
+    xc_gnttab_map_grant_refs(*h, c, d, r, p)
+#define xengnttab_unmap(h, a, n) xc_gnttab_munmap(*h, a, n)
 
 static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
                                           unsigned int open_flags)
@@ -130,7 +150,7 @@ static inline void xs_close(struct xs_handle *xsh)
 
 typedef xc_interface *XenXC;
 typedef xc_evtchn xenevtchn_handle;
-typedef xc_gnttab *XenGnttab;
+typedef xc_gnttab xengnttab_handle;
 
 #  define XC_INTERFACE_FMT "%p"
 #  define XC_HANDLER_INITIAL_VALUE    NULL
@@ -144,11 +164,13 @@ typedef xc_gnttab *XenGnttab;
 #define xenevtchn_unmask(h, p) xc_evtchn_unmask(h, p)
 #define xenevtchn_unbind(h, p) xc_evtchn_unbind(h, p)
 
-static inline XenGnttab xen_xc_gnttab_open(void *logger,
-                                           unsigned int open_flags)
-{
-    return xc_gnttab_open(logger, open_flags);
-}
+#define xengnttab_open(l, f) xc_gnttab_open(l, f)
+#define xengnttab_close(h) xc_gnttab_close(h)
+#define xengnttab_set_max_grants(h, n) xc_gnttab_set_max_grants(h, n)
+#define xengnttab_map_grant_ref(h, d, r, p) xc_gnttab_map_grant_ref(h, d, r, p)
+#define xengnttab_unmap(h, a, n) xc_gnttab_munmap(h, a, n)
+#define xengnttab_map_grant_refs(h, c, d, r, p) \
+    xc_gnttab_map_grant_refs(h, c, d, r, p)
 
 static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
                                           unsigned int open_flags)
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 4/8] xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages

[Ian Campbell]

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxenforeignmemory which provides access to
privileged foreign mappings and which will provide an interface
equivalent to xc_map_foreign_{pages,bulk}.

In preparation for this switch all uses of xc_map_foreign_range to
xc_map_foreign_pages. This is trivial because size was always
XC_PAGE_SIZE so the necessary adjustments are trivial:

  * Pass &mfn (an array of length 1) instead of mfn. The function
    takes a pointer to const, so there is no possibily of mfn changing
    due to this change.
  * Pass nr_pages=1 instead of size=XC_PAGE_SIZE

There is one wrinkle in xen_console.c:con_initialise() where
con->ring_ref is an int but can in some code paths (when !xendev->dev)
be treated as an mfn. I think this is an existing latent truncation
hazard on platforms where xen_pfn_t is 64-bit and int is 32-bit (e.g.
amd64, both arm* variants). I'm unsure under what circumstances
xendev->dev can be NULL or if anything elsewhere ensures the value
fits into an int. For now I just use a temporary xen_pfn_t to in
effect upcast the pointer from int* to xen_pfn_t*.

In xenfb.c:common_bind we now explicitly launder the mfn into a
xen_pfn_t, so it has the correct type to be passed to
xc_map_foreign_pages and doesn't provoke warnings on 32-bit x86.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
v7: Correct type mismatch (int64 vs xen_pfn_t) on 32 bit x86 in
    xenfb.c, by explicitly laundering via a xen_pfn_t variable.

v6: Switch to xc_map_foreign_pages rather than _bulk. Switching to
    _bulk without checking the value of err[0] risked missing errors.
    The new xenforeignmemory_map coming later in this series will
    DTRT with err==NULL.

    Dropped Stefano's Reviewed-by due to this change.

v4: Ran checkpatch, fixed all errors
    Mention the const-ness of the mfn array in the commit log

fixup!xen: Switch uses of xc_map_foreign_range into xc_map_foreign_pages
---
 hw/char/xen_console.c |  8 ++++----
 hw/display/xenfb.c    | 15 ++++++++-------
 xen-hvm.c             | 14 +++++++-------
 3 files changed, 19 insertions(+), 18 deletions(-)

diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index ac1b324..3e8a57b 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -228,10 +228,10 @@ static int con_initialise(struct XenDevice *xendev)
 	con->buffer.max_capacity = limit;
 
     if (!xendev->dev) {
-        con->sring = xc_map_foreign_range(xen_xc, con->xendev.dom,
-                                          XC_PAGE_SIZE,
-                                          PROT_READ|PROT_WRITE,
-                                          con->ring_ref);
+        xen_pfn_t mfn = con->ring_ref;
+        con->sring = xc_map_foreign_pages(xen_xc, con->xendev.dom,
+                                         PROT_READ|PROT_WRITE,
+                                         &mfn, 1);
     } else {
         con->sring = xengnttab_map_grant_ref(xendev->gnttabdev, con->xendev.dom,
                                              con->ring_ref,
diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index 5e324ef..4a597d7 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -95,23 +95,24 @@ struct XenFB {
 
 static int common_bind(struct common *c)
 {
-    uint64_t mfn;
+    uint64_t val;
+    xen_pfn_t mfn;
 
-    if (xenstore_read_fe_uint64(&c->xendev, "page-ref", &mfn) == -1)
+    if (xenstore_read_fe_uint64(&c->xendev, "page-ref", &val) == -1)
 	return -1;
-    assert(mfn == (xen_pfn_t)mfn);
+    mfn = (xen_pfn_t)val;
+    assert(val == mfn);
 
     if (xenstore_read_fe_int(&c->xendev, "event-channel", &c->xendev.remote_port) == -1)
 	return -1;
 
-    c->page = xc_map_foreign_range(xen_xc, c->xendev.dom,
-				   XC_PAGE_SIZE,
-				   PROT_READ | PROT_WRITE, mfn);
+    c->page = xc_map_foreign_pages(xen_xc, c->xendev.dom,
+                                   PROT_READ | PROT_WRITE, &mfn, 1);
     if (c->page == NULL)
 	return -1;
 
     xen_be_bind_evtchn(&c->xendev);
-    xen_be_printf(&c->xendev, 1, "ring mfn %"PRIx64", remote-port %d, local-port %d\n",
+    xen_be_printf(&c->xendev, 1, "ring mfn %"PRI_xen_pfn", remote-port %d, local-port %d\n",
 		  mfn, c->xendev.remote_port, c->xendev.local_port);
 
     return 0;
diff --git a/xen-hvm.c b/xen-hvm.c
index 6680782..2f4e109 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -1240,8 +1240,9 @@ int xen_hvm_init(PCMachineState *pcms,
     DPRINTF("buffered io page at pfn %lx\n", bufioreq_pfn);
     DPRINTF("buffered io evtchn is %x\n", bufioreq_evtchn);
 
-    state->shared_page = xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
-                                              PROT_READ|PROT_WRITE, ioreq_pfn);
+    state->shared_page = xc_map_foreign_pages(xen_xc, xen_domid,
+                                              PROT_READ|PROT_WRITE,
+                                              &ioreq_pfn, 1);
     if (state->shared_page == NULL) {
         hw_error("map shared IO page returned error %d handle=" XC_INTERFACE_FMT,
                  errno, xen_xc);
@@ -1251,8 +1252,8 @@ int xen_hvm_init(PCMachineState *pcms,
     if (!rc) {
         DPRINTF("shared vmport page at pfn %lx\n", ioreq_pfn);
         state->shared_vmport_page =
-            xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
-                                 PROT_READ|PROT_WRITE, ioreq_pfn);
+            xc_map_foreign_pages(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
+                                 &ioreq_pfn, 1);
         if (state->shared_vmport_page == NULL) {
             hw_error("map shared vmport IO page returned error %d handle="
                      XC_INTERFACE_FMT, errno, xen_xc);
@@ -1261,10 +1262,9 @@ int xen_hvm_init(PCMachineState *pcms,
         hw_error("get vmport regs pfn returned error %d, rc=%d", errno, rc);
     }
 
-    state->buffered_io_page = xc_map_foreign_range(xen_xc, xen_domid,
-                                                   XC_PAGE_SIZE,
+    state->buffered_io_page = xc_map_foreign_pages(xen_xc, xen_domid,
                                                    PROT_READ|PROT_WRITE,
-                                                   bufioreq_pfn);
+                                                   &bufioreq_pfn, 1);
     if (state->buffered_io_page == NULL) {
         hw_error("map buffered IO page returned error %d", errno);
     }
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 5/8] xen: Switch uses of xc_map_foreign_{pages, bulk} to use libxenforeignmemory API.

[Ian Campbell]

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

One such library will be libxenforeignmemory which provides access to
privileged foreign mappings and which will provide an interface
equivalent to xc_map_foreign_{pages,bulk}.

The new xenforeignmemory_map() function behaves like
xc_map_foreign_pages() when the err argument is NULL and like
xc_map_foreign_bulk() when err is non-NULL, which maps into the shim
here onto checking err == NULL and calling the appropriate old
function.

Note that xenforeignmemory_map() takes the number of pages before the
arrays themselves, in order to support potentially future use of
variable-length-arrays in the prototype (in the future, when Xen's
baseline toolchain requirements are new enough to ensure VLAs are
supported).

In preparation for adding support for libxenforeignmemory add support
to the <=4.0 and <=4.6 compat code in xen_common.h to allow us to
switch to using the new API. These shims will disappear for versions
of Xen which include libxenforeignmemory.

Since libxenforeignmemory will have its own handle type but for <= 4.6
the functionality is provided by using a libxenctrl handle we
introduce a new global xen_fmem alongside the existing xen_xc. In fact
we make xen_fmem a pointer to the existing xen_xc, which then works
correctly with both <=4.0 (xc handle is an int) and <=4.6 (xc handle
is a pointer). In the latter case xen_fmem is actually a double
indirect pointer, but it all falls out in the wash.

Unlike libxenctrl libxenforeignmemory has an explicit unmap function,
rather than just specifying that munmap should be used, so the unmap
paths are updated to use xenforeignmemory_unmap, which is a shim for
munmap on these versions of xen. The mappings in xen-hvm.c do not
appear to be unmapped (which makes sense for a qemu-dm process)

In fb_disconnect this results in a change from simply mmap over the
existing mapping (with an implicit munmap) to expliclty unmapping with
xenforeignmemory_unmap and then mapping the required anonymous memory
in the same hole. I don't think this is a problem since any other
thread which was racily touching this region would already be running
the risk of hitting the mapping halfway through the call. If this is
thought to be a problem then we could consider adding an extra API to
the libxenforeignmemory interface to replace a foreign mapping with
anonymous shared memory, but I'd prefer not to.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
v7: Move two copies of compat xenforeignmemory_map to a common location.
    Note that the existing xen_domain_create #ifdef will be covered by
    a CONFIG_XEN_PV_DOMAIN_BUILD in a later patch, and so is not a
    suitable place to put this function.
v6: Handle _pages as well as _bulk, due to changes in the previous
    patches, including the dropping of "xen: Switch uses of
    xc_map_foreign_pages into xc_map_foreign_bulk" which previous preceded
    this patch and the change of "xen: Switch uses of
    xc_map_foreign_range into xc_map_foreign_bulk" into "xen: Switch
    uses of xc_map_foreign_range into xc_map_foreign_pages".

    Handle reordering of arguments to xenforeignmemory_map().

    Dropped Stefano's Reviewed-by due to these changes.

v4: Rebase onto "xen_console: correctly cleanup primary console on
    teardown."

    xenforeignmemory_unmap takes pages not bytes

    Compat wrapper for xenforeignmemory_open instead of ifdef in code.

    Run check patch and fix most issues. I did not fix:

ERROR: do not initialise globals to 0 or NULL
+xenforeignmemory_handle *xen_fmem = NULL;

=> This is consistent with all of the existing declarations.

ERROR: need consistent spacing around '*' (ctx:WxV)
+typedef xc_interface *xenforeignmemory_handle;

=> I think this is a false +ve since this is a pointer "*" not a multiple "*".

reorder args to xenforeignmemory_map
---
 hw/char/xen_console.c        |  8 ++++----
 hw/display/xenfb.c           | 17 +++++++++--------
 hw/xen/xen_backend.c         |  3 ++-
 include/hw/xen/xen_backend.h |  1 +
 include/hw/xen/xen_common.h  | 23 +++++++++++++++++++++++
 xen-common.c                 |  6 ++++++
 xen-hvm.c                    | 12 ++++++------
 xen-mapcache.c               |  6 +++---
 8 files changed, 54 insertions(+), 22 deletions(-)

diff --git a/hw/char/xen_console.c b/hw/char/xen_console.c
index 3e8a57b..b92d0c6 100644
--- a/hw/char/xen_console.c
+++ b/hw/char/xen_console.c
@@ -229,9 +229,9 @@ static int con_initialise(struct XenDevice *xendev)
 
     if (!xendev->dev) {
         xen_pfn_t mfn = con->ring_ref;
-        con->sring = xc_map_foreign_pages(xen_xc, con->xendev.dom,
-                                         PROT_READ|PROT_WRITE,
-                                         &mfn, 1);
+        con->sring = xenforeignmemory_map(xen_fmem, con->xendev.dom,
+                                          PROT_READ|PROT_WRITE,
+                                          1, &mfn, NULL);
     } else {
         con->sring = xengnttab_map_grant_ref(xendev->gnttabdev, con->xendev.dom,
                                              con->ring_ref,
@@ -273,7 +273,7 @@ static void con_disconnect(struct XenDevice *xendev)
 
     if (con->sring) {
         if (!xendev->dev) {
-            munmap(con->sring, XC_PAGE_SIZE);
+            xenforeignmemory_unmap(xen_fmem, con->sring, 1);
         } else {
             xengnttab_unmap(xendev->gnttabdev, con->sring, 1);
         }
diff --git a/hw/display/xenfb.c b/hw/display/xenfb.c
index 4a597d7..55258b8 100644
--- a/hw/display/xenfb.c
+++ b/hw/display/xenfb.c
@@ -106,8 +106,8 @@ static int common_bind(struct common *c)
     if (xenstore_read_fe_int(&c->xendev, "event-channel", &c->xendev.remote_port) == -1)
 	return -1;
 
-    c->page = xc_map_foreign_pages(xen_xc, c->xendev.dom,
-                                   PROT_READ | PROT_WRITE, &mfn, 1);
+    c->page = xenforeignmemory_map(xen_fmem, c->xendev.dom,
+                                   PROT_READ | PROT_WRITE, 1, &mfn, NULL);
     if (c->page == NULL)
 	return -1;
 
@@ -122,7 +122,7 @@ static void common_unbind(struct common *c)
 {
     xen_be_unbind_evtchn(&c->xendev);
     if (c->page) {
-	munmap(c->page, XC_PAGE_SIZE);
+        xenforeignmemory_unmap(xen_fmem, c->page, 1);
 	c->page = NULL;
     }
 }
@@ -495,15 +495,15 @@ static int xenfb_map_fb(struct XenFB *xenfb)
     fbmfns = g_malloc0(sizeof(xen_pfn_t) * xenfb->fbpages);
 
     xenfb_copy_mfns(mode, n_fbdirs, pgmfns, pd);
-    map = xc_map_foreign_pages(xen_xc, xenfb->c.xendev.dom,
-			       PROT_READ, pgmfns, n_fbdirs);
+    map = xenforeignmemory_map(xen_fmem, xenfb->c.xendev.dom,
+                               PROT_READ, n_fbdirs, pgmfns, NULL);
     if (map == NULL)
 	goto out;
     xenfb_copy_mfns(mode, xenfb->fbpages, fbmfns, map);
-    munmap(map, n_fbdirs * XC_PAGE_SIZE);
+    xenforeignmemory_unmap(xen_fmem, map, n_fbdirs);
 
-    xenfb->pixels = xc_map_foreign_pages(xen_xc, xenfb->c.xendev.dom,
-            PROT_READ, fbmfns, xenfb->fbpages);
+    xenfb->pixels = xenforeignmemory_map(xen_fmem, xenfb->c.xendev.dom,
+            PROT_READ, xenfb->fbpages, fbmfns, NULL);
     if (xenfb->pixels == NULL)
 	goto out;
 
@@ -910,6 +910,7 @@ static void fb_disconnect(struct XenDevice *xendev)
      *   Replacing the framebuffer with anonymous shared memory
      *   instead.  This releases the guest pages and keeps qemu happy.
      */
+    xenforeignmemory_unmap(xen_fmem, fb->pixels, fb->fbpages);
     fb->pixels = mmap(fb->pixels, fb->fbpages * XC_PAGE_SIZE,
                       PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANON,
                       -1, 0);
diff --git a/hw/xen/xen_backend.c b/hw/xen/xen_backend.c
index 966e34f..caa459c 100644
--- a/hw/xen/xen_backend.c
+++ b/hw/xen/xen_backend.c
@@ -45,6 +45,7 @@
 
 /* public */
 XenXC xen_xc = XC_HANDLER_INITIAL_VALUE;
+xenforeignmemory_handle *xen_fmem = NULL;
 struct xs_handle *xenstore = NULL;
 const char *xen_protocol;
 
@@ -717,7 +718,7 @@ int xen_be_init(void)
 
     qemu_set_fd_handler(xs_fileno(xenstore), xenstore_update, NULL, NULL);
 
-    if (xen_xc == XC_HANDLER_INITIAL_VALUE) {
+    if (xen_xc == XC_HANDLER_INITIAL_VALUE || xen_fmem == NULL) {
         /* Check if xen_init() have been called */
         goto err;
     }
diff --git a/include/hw/xen/xen_backend.h b/include/hw/xen/xen_backend.h
index 8e8857b..e0d52ee 100644
--- a/include/hw/xen/xen_backend.h
+++ b/include/hw/xen/xen_backend.h
@@ -57,6 +57,7 @@ struct XenDevice {
 
 /* variables */
 extern XenXC xen_xc;
+extern xenforeignmemory_handle *xen_fmem;
 extern struct xs_handle *xenstore;
 extern const char *xen_protocol;
 
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 8f38310..55809b4 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -41,6 +41,7 @@ static inline void *xc_map_foreign_bulk(int xc_handle, uint32_t dom, int prot,
 typedef int XenXC;
 typedef int xenevtchn_handle;
 typedef int xengnttab_handle;
+typedef int xenforeignmemory_handle;
 
 #  define XC_INTERFACE_FMT "%i"
 #  define XC_HANDLER_INITIAL_VALUE    -1
@@ -104,6 +105,10 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
     return xc_interface_open();
 }
 
+#define xenforeignmemory_open(l, f) &xen_xc
+/* See below for xenforeignmemory_map */
+#define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
+
 static inline int xc_fd(int xen_xc)
 {
     return xen_xc;
@@ -149,6 +154,7 @@ static inline void xs_close(struct xs_handle *xsh)
 #else
 
 typedef xc_interface *XenXC;
+typedef xc_interface *xenforeignmemory_handle;
 typedef xc_evtchn xenevtchn_handle;
 typedef xc_gnttab xengnttab_handle;
 
@@ -178,6 +184,10 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
     return xc_interface_open(logger, dombuild_logger, open_flags);
 }
 
+#define xenforeignmemory_open(l, f) &xen_xc
+/* See below for xenforeignmemory_map */
+#define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
+
 /* FIXME There is now way to have the xen fd */
 static inline int xc_fd(xc_interface *xen_xc)
 {
@@ -501,4 +511,17 @@ static inline int xen_domain_create(XenXC xc, uint32_t ssidref,
 }
 #endif
 
+#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 470
+static inline void *xenforeignmemory_map(XenXC *h, uint32_t dom,
+                                         int prot, size_t pages,
+                                         const xen_pfn_t arr[/*pages*/],
+                                         int err[/*pages*/])
+{
+    if (err)
+        return xc_map_foreign_bulk(*h, dom, prot, arr, err, pages);
+    else
+        return xc_map_foreign_pages(*h, dom, prot, arr, pages);
+}
+#endif
+
 #endif /* QEMU_HW_XEN_COMMON_H */
diff --git a/xen-common.c b/xen-common.c
index 0dcdbc3..6cd2959 100644
--- a/xen-common.c
+++ b/xen-common.c
@@ -118,6 +118,12 @@ static int xen_init(MachineState *ms)
         xen_be_printf(NULL, 0, "can't open xen interface\n");
         return -1;
     }
+    xen_fmem = xenforeignmemory_open(0, 0);
+    if (xen_fmem == NULL) {
+        xen_be_printf(NULL, 0, "can't open xen fmem interface\n");
+        xc_interface_close(xen_xc);
+        return -1;
+    }
     qemu_add_vm_change_state_handler(xen_change_state_handler, NULL);
 
     global_state_set_optional();
diff --git a/xen-hvm.c b/xen-hvm.c
index 2f4e109..c64f4b0 100644
--- a/xen-hvm.c
+++ b/xen-hvm.c
@@ -1240,9 +1240,9 @@ int xen_hvm_init(PCMachineState *pcms,
     DPRINTF("buffered io page at pfn %lx\n", bufioreq_pfn);
     DPRINTF("buffered io evtchn is %x\n", bufioreq_evtchn);
 
-    state->shared_page = xc_map_foreign_pages(xen_xc, xen_domid,
+    state->shared_page = xenforeignmemory_map(xen_fmem, xen_domid,
                                               PROT_READ|PROT_WRITE,
-                                              &ioreq_pfn, 1);
+                                              1, &ioreq_pfn, NULL);
     if (state->shared_page == NULL) {
         hw_error("map shared IO page returned error %d handle=" XC_INTERFACE_FMT,
                  errno, xen_xc);
@@ -1252,8 +1252,8 @@ int xen_hvm_init(PCMachineState *pcms,
     if (!rc) {
         DPRINTF("shared vmport page at pfn %lx\n", ioreq_pfn);
         state->shared_vmport_page =
-            xc_map_foreign_pages(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
-                                 &ioreq_pfn, 1);
+            xenforeignmemory_map(xen_fmem, xen_domid, PROT_READ|PROT_WRITE,
+                                 1, &ioreq_pfn, NULL);
         if (state->shared_vmport_page == NULL) {
             hw_error("map shared vmport IO page returned error %d handle="
                      XC_INTERFACE_FMT, errno, xen_xc);
@@ -1262,9 +1262,9 @@ int xen_hvm_init(PCMachineState *pcms,
         hw_error("get vmport regs pfn returned error %d, rc=%d", errno, rc);
     }
 
-    state->buffered_io_page = xc_map_foreign_pages(xen_xc, xen_domid,
+    state->buffered_io_page = xenforeignmemory_map(xen_fmem, xen_domid,
                                                    PROT_READ|PROT_WRITE,
-                                                   &bufioreq_pfn, 1);
+                                                   1, &bufioreq_pfn, NULL);
     if (state->buffered_io_page == NULL) {
         hw_error("map buffered IO page returned error %d", errno);
     }
diff --git a/xen-mapcache.c b/xen-mapcache.c
index 97fece2..4a04378 100644
--- a/xen-mapcache.c
+++ b/xen-mapcache.c
@@ -176,10 +176,10 @@ static void xen_remap_bucket(MapCacheEntry *entry,
         pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
     }
 
-    vaddr_base = xc_map_foreign_bulk(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
-                                     pfns, err, nb_pfn);
+    vaddr_base = xenforeignmemory_map(xen_fmem, xen_domid, PROT_READ|PROT_WRITE,
+                                      nb_pfn, pfns, err);
     if (vaddr_base == NULL) {
-        perror("xc_map_foreign_bulk");
+        perror("xenforeignmemory_map");
         exit(-1);
     }
 
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 6/8] xen: Use stable library interfaces when they are available.

[Ian Campbell]

In Xen 4.7 we are refactoring parts libxenctrl into a number of
separate libraries which will provide backward and forward API and ABI
compatiblity.

Specifically libxenevtchn, libxengnttab and libxenforeignmemory.

Previous patches have already laid the groundwork for using these by
switching the existing compatibility shims to reflect the intefaces to
these libraries.

So all which remains is to update configure to detect the libraries
and enable their use. Although they are notionally independent we take
an all or nothing approach to the three libraries since they were
added at the same time.

The only non-obvious bit is that we now open a proper xenforeignmemory
handle for xen_fmem instead of reusing the xen_xc handle.

Build tested with 4.0 .. 4.6 (inclusive) and the patches targetting
4.7 which adds these libraries.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
v6: Two minor formatting things.
    Rebase onto "xen: fix usage of xc_domain_create in domain
    builder", required adjusting the configure script changes.

    The rebase wasn't entirely trivial (semantically), so dropped
    Stefano's reviwed by.

v5: Remove ifdef check when undeffing the compat stuff.
    s/now way/no way/

v4: xenforeignmemory_open is now a compat wrapper, so no ifdef.

    Simplify configury by asserting that interface version 470 will
    always have the libraries (lack of them makes it 460).

    Ran checkpatch and fixed everything except:

ERROR: need consistent spacing around '*' (ctx:WxV)
+typedef xc_interface *XenXC;

Which I think is a false +ve.

Simpler configure stuff
---
 configure                   | 42 +++++++++++++++++++++++++++++++++++++++++-
 include/hw/xen/xen_common.h | 35 +++++++++++++++++++++++++++++++++--
 2 files changed, 74 insertions(+), 3 deletions(-)

diff --git a/configure b/configure
index b9552fd..162aa16 100755
--- a/configure
+++ b/configure
@@ -1938,6 +1938,7 @@ fi
 
 if test "$xen" != "no" ; then
   xen_libs="-lxenstore -lxenctrl -lxenguest"
+  xen_stable_libs="-lxenforeignmemory -lxengnttab -lxenevtchn"
 
   # First we test whether Xen headers and libraries are available.
   # If no, we are done and there is no Xen support.
@@ -1960,16 +1961,52 @@ EOF
   # Xen unstable
   elif
       cat > $TMPC <<EOF &&
+/*
+ * If we have stable libs the we don't want the libxc compat
+ * layers, regardless of what CFLAGS we may have been given.
+ */
+#undef XC_WANT_COMPAT_EVTCHN_API
+#undef XC_WANT_COMPAT_GNTTAB_API
+#undef XC_WANT_COMPAT_MAP_FOREIGN_API
 #include <xenctrl.h>
+#include <xenstore.h>
+#include <xenevtchn.h>
+#include <xengnttab.h>
+#include <xenforeignmemory.h>
 #include <stdint.h>
+#include <xen/hvm/hvm_info_table.h>
+#if !defined(HVM_MAX_VCPUS)
+# error HVM_MAX_VCPUS not defined
+#endif
 int main(void) {
   xc_interface *xc = NULL;
+  xenforeignmemory_handle *xfmem;
+  xenevtchn_handle *xe;
+  xengnttab_handle *xg;
   xen_domain_handle_t handle;
+
+  xs_daemon_open();
+
+  xc = xc_interface_open(0, 0, 0);
+  xc_hvm_set_mem_type(0, 0, HVMMEM_ram_ro, 0, 0);
+  xc_domain_add_to_physmap(0, 0, XENMAPSPACE_gmfn, 0, 0);
+  xc_hvm_inject_msi(xc, 0, 0xf0000000, 0x00000000);
+  xc_hvm_create_ioreq_server(xc, 0, HVM_IOREQSRV_BUFIOREQ_ATOMIC, NULL);
   xc_domain_create(xc, 0, handle, 0, NULL, NULL);
+
+  xfmem = xenforeignmemory_open(0, 0);
+  xenforeignmemory_map(xfmem, 0, 0, 0, 0, 0);
+
+  xe = xenevtchn_open(0, 0);
+  xenevtchn_fd(xe);
+
+  xg = xengnttab_open(0, 0);
+  xengnttab_map_grant_ref(xg, 0, 0, 0);
+
   return 0;
 }
 EOF
-      compile_prog "" "$xen_libs"
+      compile_prog "" "$xen_libs $xen_stable_libs"
     then
     xen_ctrl_version=470
     xen=yes
@@ -2153,6 +2190,9 @@ EOF
   fi
 
   if test "$xen" = yes; then
+    if test $xen_ctrl_version -ge 470  ; then
+      libs_softmmu="$xen_stable_libs $libs_softmmu"
+    fi
     libs_softmmu="$xen_libs $libs_softmmu"
   fi
 fi
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 55809b4..310d6ef 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -6,6 +6,15 @@
 #include <stddef.h>
 #include <inttypes.h>
 
+/*
+ * If we have new enough libxenctrl then we do not want/need these compat
+ * interfaces, despite what the user supplied cflags might say. They
+ * must be undefined before including xenctrl.h
+ */
+#undef XC_WANT_COMPAT_EVTCHN_API
+#undef XC_WANT_COMPAT_GNTTAB_API
+#undef XC_WANT_COMPAT_MAP_FOREIGN_API
+
 #include <xenctrl.h>
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 420
 #  include <xs.h>
@@ -150,8 +159,8 @@ static inline void xs_close(struct xs_handle *xsh)
 }
 
 
-/* Xen 4.1 */
-#else
+/* Xen 4.1 thru 4.6 */
+#elif CONFIG_XEN_CTRL_INTERFACE_VERSION < 470
 
 typedef xc_interface *XenXC;
 typedef xc_interface *xenforeignmemory_handle;
@@ -188,6 +197,28 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
 /* See below for xenforeignmemory_map */
 #define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
 
+/* FIXME There is no way to have the xen fd */
+static inline int xc_fd(xc_interface *xen_xc)
+{
+    return -1;
+}
+#else /* CONFIG_XEN_CTRL_INTERFACE_VERSION >= 470 */
+
+typedef xc_interface *XenXC;
+
+#  define XC_INTERFACE_FMT "%p"
+#  define XC_HANDLER_INITIAL_VALUE    NULL
+
+#include <xenevtchn.h>
+#include <xengnttab.h>
+#include <xenforeignmemory.h>
+
+static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
+                                          unsigned int open_flags)
+{
+    return xc_interface_open(logger, dombuild_logger, open_flags);
+}
+
 /* FIXME There is now way to have the xen fd */
 static inline int xc_fd(xc_interface *xen_xc)
 {
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 7/8] xen: domainbuild: reopen libxenctrl interface after forking for domain watcher.

[Ian Campbell]

Using an existing libxenctrl handle after a fork was never
particularly safe (especially if foreign mappings existed at the time
of the fork) and the xc fd has been unavailable for many releases.

Reopen the handle after fork and therefore do away with xc_fd().

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
The fact that xc_fd hasn't been useful since at least Xen 4.1 makes me
question the utility of this domainbuild in QEMU. Perhaps we should
just nuke it?
---
 hw/xenpv/xen_domainbuild.c  |  9 ++++++---
 include/hw/xen/xen_common.h | 17 -----------------
 2 files changed, 6 insertions(+), 20 deletions(-)

diff --git a/hw/xenpv/xen_domainbuild.c b/hw/xenpv/xen_domainbuild.c
index ac0e5ac..f9be029 100644
--- a/hw/xenpv/xen_domainbuild.c
+++ b/hw/xenpv/xen_domainbuild.c
@@ -174,12 +174,15 @@ static int xen_domain_watcher(void)
     for (i = 3; i < n; i++) {
         if (i == fd[0])
             continue;
-        if (i == xc_fd(xen_xc)) {
-            continue;
-        }
         close(i);
     }
 
+    /*
+     * Reopen xc interface, since the original is unsafe after fork
+     * and was closed above.
+     */
+    xen_xc = xc_interface_open(0, 0, 0);
+
     /* ignore term signals */
     signal(SIGINT,  SIG_IGN);
     signal(SIGTERM, SIG_IGN);
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 310d6ef..8c4fc42 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -118,12 +118,6 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
 /* See below for xenforeignmemory_map */
 #define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
 
-static inline int xc_fd(int xen_xc)
-{
-    return xen_xc;
-}
-
-
 static inline int xc_domain_populate_physmap_exact
     (XenXC xc_handle, uint32_t domid, unsigned long nr_extents,
      unsigned int extent_order, unsigned int mem_flags, xen_pfn_t *extent_start)
@@ -197,11 +191,6 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
 /* See below for xenforeignmemory_map */
 #define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
 
-/* FIXME There is no way to have the xen fd */
-static inline int xc_fd(xc_interface *xen_xc)
-{
-    return -1;
-}
 #else /* CONFIG_XEN_CTRL_INTERFACE_VERSION >= 470 */
 
 typedef xc_interface *XenXC;
@@ -218,12 +207,6 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
 {
     return xc_interface_open(logger, dombuild_logger, open_flags);
 }
-
-/* FIXME There is now way to have the xen fd */
-static inline int xc_fd(xc_interface *xen_xc)
-{
-    return -1;
-}
 #endif
 
 /* Xen before 4.2 */
-- 
2.1.4

[Qemu-devel] [PATCH QEMU-XEN v7 8/8] xen: make it possible to build without the Xen PV domain builder

[Ian Campbell]

Until the previous patch this relied on xc_fd(), which was only
implemented for Xen 4.0 and earlier.

Given this wasn't working since Xen 4.0 I have marked this as disabled
by default.

Removing this support drops the use of a bunch of symbols from
libxenctrl, specifically:

  - xc_domain_create
  - xc_domain_destroy
  - xc_domain_getinfo
  - xc_domain_max_vcpus
  - xc_domain_setmaxmem
  - xc_domain_unpause
  - xc_evtchn_alloc_unbound
  - xc_linux_build

This is another step towards only using Xen libraries which provide a
stable inteface.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
v6: Rebase onto "xen: fix usage of xc_domain_create in domain
    builder" (trivial, Reviewed-by retained)

v5: XEN_CREATE entirely wihtin CONFIG_XEN_PV_DOMAIN_BUILD ifdef.
    Simplify configure'ry.

v4: Fixed all checkpatch errors.
    Disabled by default.
---
 configure                   | 15 +++++++++++++++
 hw/xenpv/Makefile.objs      |  4 +++-
 hw/xenpv/xen_machine_pv.c   | 15 +++++++++++----
 include/hw/xen/xen_common.h |  2 ++
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/configure b/configure
index 162aa16..0d157e7 100755
--- a/configure
+++ b/configure
@@ -250,6 +250,7 @@ vnc_jpeg=""
 vnc_png=""
 xen=""
 xen_ctrl_version=""
+xen_pv_domain_build="no"
 xen_pci_passthrough=""
 linux_aio=""
 cap_ng=""
@@ -927,6 +928,10 @@ for opt do
   ;;
   --enable-xen-pci-passthrough) xen_pci_passthrough="yes"
   ;;
+  --disable-xen-pv-domain-build) xen_pv_domain_build="no"
+  ;;
+  --enable-xen-pv-domain-build) xen_pv_domain_build="yes"
+  ;;
   --disable-brlapi) brlapi="no"
   ;;
   --enable-brlapi) brlapi="yes"
@@ -2214,6 +2219,12 @@ if test "$xen_pci_passthrough" != "no"; then
   fi
 fi
 
+if test "$xen_pv_domain_build" = "yes" &&
+   test "$xen" != "yes"; then
+    error_exit "User requested Xen PV domain builder support" \
+	       "which requires Xen support."
+fi
+
 ##########################################
 # libtool probe
 
@@ -4821,6 +4832,7 @@ fi
 echo "xen support       $xen"
 if test "$xen" = "yes" ; then
   echo "xen ctrl version  $xen_ctrl_version"
+  echo "pv dom build      $xen_pv_domain_build"
 fi
 echo "brlapi support    $brlapi"
 echo "bluez  support    $bluez"
@@ -5189,6 +5201,9 @@ fi
 if test "$xen" = "yes" ; then
   echo "CONFIG_XEN_BACKEND=y" >> $config_host_mak
   echo "CONFIG_XEN_CTRL_INTERFACE_VERSION=$xen_ctrl_version" >> $config_host_mak
+  if test "$xen_pv_domain_build" = "yes" ; then
+    echo "CONFIG_XEN_PV_DOMAIN_BUILD=y" >> $config_host_mak
+  fi
 fi
 if test "$linux_aio" = "yes" ; then
   echo "CONFIG_LINUX_AIO=y" >> $config_host_mak
diff --git a/hw/xenpv/Makefile.objs b/hw/xenpv/Makefile.objs
index 49f6e9e..bbf5873 100644
--- a/hw/xenpv/Makefile.objs
+++ b/hw/xenpv/Makefile.objs
@@ -1,2 +1,4 @@
 # Xen PV machine support
-obj-$(CONFIG_XEN) += xen_domainbuild.o xen_machine_pv.o
+obj-$(CONFIG_XEN) += xen_machine_pv.o
+# Xen PV machine builder support
+obj-$(CONFIG_XEN_PV_DOMAIN_BUILD) += xen_domainbuild.o
diff --git a/hw/xenpv/xen_machine_pv.c b/hw/xenpv/xen_machine_pv.c
index 23d6ef0..3250b94 100644
--- a/hw/xenpv/xen_machine_pv.c
+++ b/hw/xenpv/xen_machine_pv.c
@@ -30,9 +30,6 @@
 
 static void xen_init_pv(MachineState *machine)
 {
-    const char *kernel_filename = machine->kernel_filename;
-    const char *kernel_cmdline = machine->kernel_cmdline;
-    const char *initrd_filename = machine->initrd_filename;
     DriveInfo *dinfo;
     int i;
 
@@ -46,17 +43,27 @@ static void xen_init_pv(MachineState *machine)
     case XEN_ATTACH:
         /* nothing to do, xend handles everything */
         break;
-    case XEN_CREATE:
+#ifdef CONFIG_XEN_PV_DOMAIN_BUILD
+    case XEN_CREATE: {
+        const char *kernel_filename = machine->kernel_filename;
+        const char *kernel_cmdline = machine->kernel_cmdline;
+        const char *initrd_filename = machine->initrd_filename;
         if (xen_domain_build_pv(kernel_filename, initrd_filename,
                                 kernel_cmdline) < 0) {
             fprintf(stderr, "xen pv domain creation failed\n");
             exit(1);
         }
         break;
+    }
+#endif
     case XEN_EMULATE:
         fprintf(stderr, "xen emulation not implemented (yet)\n");
         exit(1);
         break;
+    default:
+        fprintf(stderr, "unhandled xen_mode %d\n", xen_mode);
+        exit(1);
+        break;
     }
 
     xen_be_register("console", &xen_console_ops);
diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
index 8c4fc42..0d19816 100644
--- a/include/hw/xen/xen_common.h
+++ b/include/hw/xen/xen_common.h
@@ -509,6 +509,7 @@ static inline int xen_xc_domain_add_to_physmap(XenXC xch, uint32_t domid,
 }
 #endif
 
+#ifdef CONFIG_XEN_PV_DOMAIN_BUILD
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 470
 static inline int xen_domain_create(XenXC xc, uint32_t ssidref,
                                     xen_domain_handle_t handle, uint32_t flags,
@@ -524,6 +525,7 @@ static inline int xen_domain_create(XenXC xc, uint32_t ssidref,
     return xc_domain_create(xc, ssidref, handle, flags, pdomid, NULL);
 }
 #endif
+#endif
 
 #if CONFIG_XEN_CTRL_INTERFACE_VERSION < 470
 static inline void *xenforeignmemory_map(XenXC *h, uint32_t dom,
-- 
2.1.4

Re: [Qemu-devel] [PATCH QEMU-XEN v7 5/8] xen: Switch uses of xc_map_foreign_{pages, bulk} to use libxenforeignmemory API.

[Stefano Stabellini]

On Wed, 16 Dec 2015, Ian Campbell wrote:
> In Xen 4.7 we are refactoring parts libxenctrl into a number of
> separate libraries which will provide backward and forward API and ABI
> compatiblity.
> 
> One such library will be libxenforeignmemory which provides access to
> privileged foreign mappings and which will provide an interface
> equivalent to xc_map_foreign_{pages,bulk}.
> 
> The new xenforeignmemory_map() function behaves like
> xc_map_foreign_pages() when the err argument is NULL and like
> xc_map_foreign_bulk() when err is non-NULL, which maps into the shim
> here onto checking err == NULL and calling the appropriate old
> function.
> 
> Note that xenforeignmemory_map() takes the number of pages before the
> arrays themselves, in order to support potentially future use of
> variable-length-arrays in the prototype (in the future, when Xen's
> baseline toolchain requirements are new enough to ensure VLAs are
> supported).
> 
> In preparation for adding support for libxenforeignmemory add support
> to the <=4.0 and <=4.6 compat code in xen_common.h to allow us to
> switch to using the new API. These shims will disappear for versions
> of Xen which include libxenforeignmemory.
> 
> Since libxenforeignmemory will have its own handle type but for <= 4.6
> the functionality is provided by using a libxenctrl handle we
> introduce a new global xen_fmem alongside the existing xen_xc. In fact
> we make xen_fmem a pointer to the existing xen_xc, which then works
> correctly with both <=4.0 (xc handle is an int) and <=4.6 (xc handle
> is a pointer). In the latter case xen_fmem is actually a double
> indirect pointer, but it all falls out in the wash.
> 
> Unlike libxenctrl libxenforeignmemory has an explicit unmap function,
> rather than just specifying that munmap should be used, so the unmap
> paths are updated to use xenforeignmemory_unmap, which is a shim for
> munmap on these versions of xen. The mappings in xen-hvm.c do not
> appear to be unmapped (which makes sense for a qemu-dm process)
> 
> In fb_disconnect this results in a change from simply mmap over the
> existing mapping (with an implicit munmap) to expliclty unmapping with
> xenforeignmemory_unmap and then mapping the required anonymous memory
> in the same hole. I don't think this is a problem since any other
> thread which was racily touching this region would already be running
> the risk of hitting the mapping halfway through the call. If this is
> thought to be a problem then we could consider adding an extra API to
> the libxenforeignmemory interface to replace a foreign mapping with
> anonymous shared memory, but I'd prefer not to.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
>  
> diff --git a/include/hw/xen/xen_common.h b/include/hw/xen/xen_common.h
> index 8f38310..55809b4 100644
> --- a/include/hw/xen/xen_common.h
> +++ b/include/hw/xen/xen_common.h
> @@ -41,6 +41,7 @@ static inline void *xc_map_foreign_bulk(int xc_handle, uint32_t dom, int prot,
>  typedef int XenXC;
>  typedef int xenevtchn_handle;
>  typedef int xengnttab_handle;
> +typedef int xenforeignmemory_handle;
>  
>  #  define XC_INTERFACE_FMT "%i"
>  #  define XC_HANDLER_INITIAL_VALUE    -1
> @@ -104,6 +105,10 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
>      return xc_interface_open();
>  }
>  
> +#define xenforeignmemory_open(l, f) &xen_xc
> +/* See below for xenforeignmemory_map */
> +#define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
> +
>  static inline int xc_fd(int xen_xc)
>  {
>      return xen_xc;
> @@ -149,6 +154,7 @@ static inline void xs_close(struct xs_handle *xsh)
>  #else
>  
>  typedef xc_interface *XenXC;
> +typedef xc_interface *xenforeignmemory_handle;
>  typedef xc_evtchn xenevtchn_handle;
>  typedef xc_gnttab xengnttab_handle;
>  
> @@ -178,6 +184,10 @@ static inline XenXC xen_xc_interface_open(void *logger, void *dombuild_logger,
>      return xc_interface_open(logger, dombuild_logger, open_flags);
>  }
>  
> +#define xenforeignmemory_open(l, f) &xen_xc
> +/* See below for xenforeignmemory_map */
> +#define xenforeignmemory_unmap(h, p, s) munmap(p, s * XC_PAGE_SIZE)
> +
>  /* FIXME There is now way to have the xen fd */
>  static inline int xc_fd(xc_interface *xen_xc)
>  {
 @@ -501,4 +511,17 @@ static inline int xen_domain_create(XenXC xc, uint32_t ssidref,
>  }
>  #endif
>  
> +#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 470
> +static inline void *xenforeignmemory_map(XenXC *h, uint32_t dom,
> +                                         int prot, size_t pages,
> +                                         const xen_pfn_t arr[/*pages*/],
> +                                         int err[/*pages*/])
> +{
> +    if (err)
> +        return xc_map_foreign_bulk(*h, dom, prot, arr, err, pages);
> +    else
> +        return xc_map_foreign_pages(*h, dom, prot, arr, pages);
> +}
> +#endif

Why not move the definition of xenforeignmemory_open and
xenforeignmemory_unmap here too?

Re: [Qemu-devel] [PATCH QEMU-XEN v7 5/8] xen: Switch uses of xc_map_foreign_{pages, bulk} to use libxenforeignmemory API.

[Ian Campbell]

On Wed, 2015-12-16 at 14:39 +0000, Stefano Stabellini wrote:
> 
> Why not move the definition of xenforeignmemory_open and
> xenforeignmemory_unmap here too?

I failed to spot they were also the same. Will do.

Ian.