diff mbox

[DOC,v7] PV Calls protocol design

Message ID alpine.DEB.2.10.1610181417420.16441@sstabellini-ThinkPad-X260 (mailing list archive)
State New, archived
Headers show

Commit Message

Stefano Stabellini Oct. 18, 2016, 9:20 p.m. UTC
On Thu, 13 Oct 2016, Stefano Stabellini wrote:
> Hi all,
> 
> This is the design document of the PV Calls protocol. You can find
> prototypes of the Linux frontend and backend drivers here:
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/sstabellini/xen.git pvcalls-7
> 
> To use them, make sure to enable CONFIG_XEN_PVCALLS in your kernel
> config and add "pvcalls=1" to the command line of your DomU Linux
> kernel. You also need the toolstack to create the initial xenstore nodes
> for the protocol. To do that, please apply the attached patch to libxl
> (the patch is based on Xen 4.7.0-rc3) and add "pvcalls=1" to your DomU
> config file.

There is a small mistake in the patch attached to my previous email,
which breaks cases where pvcalls is unspecified. This patch should work
as expected.
diff mbox

Patch

diff --git a/docs/man/xl.cfg.pod.5 b/docs/man/xl.cfg.pod.5
index a4cc1b3..fd67429 100644
--- a/docs/man/xl.cfg.pod.5
+++ b/docs/man/xl.cfg.pod.5
@@ -488,6 +488,11 @@  Specifies the networking provision (both emulated network adapters,
 and Xen virtual interfaces) to provided to the guest.  See
 F<docs/misc/xl-network-configuration.markdown>.
 
+=item B<pvcalls=BOOLEAN>
+
+Enables the paravirtualized function calls protocol. Please see
+F<docs/misc/pvcalls.markdown> for more details.
+
 =item B<vtpm=[ "VTPM_SPEC_STRING", "VTPM_SPEC_STRING", ...]>
 
 Specifies the virtual trusted platform module to be
diff --git a/docs/misc/xenstore-paths.markdown b/docs/misc/xenstore-paths.markdown
index 2a37dae..cea99d5 100644
--- a/docs/misc/xenstore-paths.markdown
+++ b/docs/misc/xenstore-paths.markdown
@@ -275,6 +275,12 @@  A virtual scsi device frontend. Described by
 A virtual usb device frontend. Described by
 [xen/include/public/io/usbif.h][USBIF]
 
+#### ~/device/pvcalls/$DEVID/* []
+
+Paravirtualized POSIX function calls frontend. Described by
+[docs/misc/pvcalls.markdown][PVCALLS]
+
+
 #### ~/console/* []
 
 The primary PV console device. Described in [console.txt](console.txt)
@@ -354,6 +360,10 @@  A PV SCSI backend.
 A PV USB backend. Described by
 [xen/include/public/io/usbif.h][USBIF]
 
+#### ~/backend/pvcalls/$DOMID/$DEVID/* []
+
+A PVCalls backend.
+
 #### ~/backend/console/$DOMID/$DEVID/* []
 
 A PV console backend. Described in [console.txt](console.txt)
diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index c39d745..d784a10 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2299,6 +2299,70 @@  int libxl_devid_to_device_vtpm(libxl_ctx *ctx,
     return rc;
 }
 
+/******************************************************************************/
+
+int libxl__device_pvcalls_setdefault(libxl__gc *gc, libxl_device_pvcalls *pvcalls)
+{
+    int rc;
+
+    rc = libxl__resolve_domid(gc, pvcalls->backend_domname, &pvcalls->backend_domid);
+    return rc;
+}
+
+static int libxl__device_from_pvcalls(libxl__gc *gc, uint32_t domid,
+                                   libxl_device_pvcalls *pvcalls,
+                                   libxl__device *device)
+{
+   device->backend_devid   = pvcalls->devid;
+   device->backend_domid   = pvcalls->backend_domid;
+   device->backend_kind    = LIBXL__DEVICE_KIND_PVCALLS;
+   device->devid           = pvcalls->devid;
+   device->domid           = domid;
+   device->kind            = LIBXL__DEVICE_KIND_PVCALLS;
+
+   return 0;
+}
+
+
+int libxl__device_pvcalls_add(libxl__gc *gc, uint32_t domid,
+                           libxl_device_pvcalls *pvcalls)
+{
+    flexarray_t *front;
+    flexarray_t *back;
+    libxl__device device;
+    int rc;
+
+    rc = libxl__device_pvcalls_setdefault(gc, pvcalls);
+    if (rc) goto out;
+
+    front = flexarray_make(gc, 16, 1);
+    back = flexarray_make(gc, 16, 1);
+
+    if (pvcalls->devid == -1) {
+        if ((pvcalls->devid = libxl__device_nextid(gc, domid, "pvcalls")) < 0) {
+            rc = ERROR_FAIL;
+            goto out;
+        }
+    }
+
+    rc = libxl__device_from_pvcalls(gc, domid, pvcalls, &device);
+    if (rc != 0) goto out;
+
+    flexarray_append_pair(back, "frontend-id", libxl__sprintf(gc, "%d", domid));
+    flexarray_append_pair(back, "online", "1");
+    flexarray_append_pair(back, "state", GCSPRINTF("%d", XenbusStateInitialising));
+    flexarray_append_pair(front, "backend-id",
+                          libxl__sprintf(gc, "%d", pvcalls->backend_domid));
+    flexarray_append_pair(front, "state", GCSPRINTF("%d", XenbusStateInitialising));
+
+    libxl__device_generic_add(gc, XBT_NULL, &device,
+                              libxl__xs_kvs_of_flexarray(gc, back, back->count),
+                              libxl__xs_kvs_of_flexarray(gc, front, front->count),
+                              NULL);
+    rc = 0;
+out:
+    return rc;
+}
 
 /******************************************************************************/
 
@@ -4250,6 +4314,8 @@  out:
  * libxl_device_vfb_destroy
  * libxl_device_usbctrl_remove
  * libxl_device_usbctrl_destroy
+ * libxl_device_pvcalls_remove
+ * libxl_device_pvcalls_destroy
  */
 #define DEFINE_DEVICE_REMOVE_EXT(type, remtype, removedestroy, f)        \
     int libxl_device_##type##_##removedestroy(libxl_ctx *ctx,           \
@@ -4311,6 +4377,11 @@  DEFINE_DEVICE_REMOVE(vtpm, destroy, 1)
 DEFINE_DEVICE_REMOVE_CUSTOM(usbctrl, remove, 0)
 DEFINE_DEVICE_REMOVE_CUSTOM(usbctrl, destroy, 1)
 
+/* pvcalls */
+
+DEFINE_DEVICE_REMOVE(pvcalls, remove, 0)
+DEFINE_DEVICE_REMOVE(pvcalls, destroy, 1)
+
 /* channel/console hotunplug is not implemented. There are 2 possibilities:
  * 1. add support for secondary consoles to xenconsoled
  * 2. dynamically add/remove qemu chardevs via qmp messages. */
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 2c0f868..9358071 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -1753,6 +1753,16 @@  int libxl_device_vfb_destroy(libxl_ctx *ctx, uint32_t domid,
                              const libxl_asyncop_how *ao_how)
                              LIBXL_EXTERNAL_CALLERS_ONLY;
 
+/* pvcalls */
+int libxl_device_pvcalls_remove(libxl_ctx *ctx, uint32_t domid,
+                            libxl_device_pvcalls *pvcalls,
+                            const libxl_asyncop_how *ao_how)
+                             LIBXL_EXTERNAL_CALLERS_ONLY;
+int libxl_device_pvcalls_destroy(libxl_ctx *ctx, uint32_t domid,
+                             libxl_device_pvcalls *pvcalls,
+                             const libxl_asyncop_how *ao_how)
+                             LIBXL_EXTERNAL_CALLERS_ONLY;
+
 /* PCI Passthrough */
 int libxl_device_pci_add(libxl_ctx *ctx, uint32_t domid,
                          libxl_device_pci *pcidev,
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 5000bd0..433fd49 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -1327,6 +1327,9 @@  static void domcreate_launch_dm(libxl__egc *egc, libxl__multidev *multidev,
         libxl__device_console_dispose(&console);
     }
 
+    if (libxl_defbool_val(d_config->pvcalls.enabled))
+        libxl__device_pvcalls_add(gc, domid, &d_config->pvcalls);
+
     switch (d_config->c_info.type) {
     case LIBXL_DOMAIN_TYPE_HVM:
     {
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index c791418..063d926 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1224,6 +1224,7 @@  _hidden int libxl__device_vkb_setdefault(libxl__gc *gc, libxl_device_vkb *vkb);
 _hidden int libxl__device_pci_setdefault(libxl__gc *gc, libxl_device_pci *pci);
 _hidden void libxl__rdm_setdefault(libxl__gc *gc,
                                    libxl_domain_build_info *b_info);
+_hidden int libxl__device_pvcalls_setdefault(libxl__gc *gc, libxl_device_pvcalls *pvcalls);
 
 _hidden const char *libxl__device_nic_devname(libxl__gc *gc,
                                               uint32_t domid,
@@ -2647,6 +2648,10 @@  _hidden int libxl__device_vkb_add(libxl__gc *gc, uint32_t domid,
 _hidden int libxl__device_vfb_add(libxl__gc *gc, uint32_t domid,
                                   libxl_device_vfb *vfb);
 
+/* Internal function to connect a pvcalls device */
+_hidden int libxl__device_pvcalls_add(libxl__gc *gc, uint32_t domid,
+                                  libxl_device_pvcalls *pvcalls);
+
 /* Waits for the passed device to reach state XenbusStateInitWait.
  * This is not really useful by itself, but is important when executing
  * hotplug scripts, since we need to be sure the device is in the correct
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 9840f3b..8131a93 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -685,6 +685,13 @@  libxl_device_vtpm = Struct("device_vtpm", [
     ("uuid",             libxl_uuid),
 ])
 
+libxl_device_pvcalls = Struct("device_pvcalls", [
+    ("backend_domid",    libxl_domid),
+    ("backend_domname",  string),
+    ("devid",            libxl_devid),
+    ("enabled",          libxl_defbool),
+])
+
 libxl_device_channel = Struct("device_channel", [
     ("backend_domid", libxl_domid),
     ("backend_domname", string),
@@ -709,6 +716,7 @@  libxl_domain_config = Struct("domain_config", [
     ("vfbs", Array(libxl_device_vfb, "num_vfbs")),
     ("vkbs", Array(libxl_device_vkb, "num_vkbs")),
     ("vtpms", Array(libxl_device_vtpm, "num_vtpms")),
+    ("pvcalls", libxl_device_pvcalls),
     # a channel manifests as a console with a name,
     # see docs/misc/channels.txt
     ("channels", Array(libxl_device_channel, "num_channels")),
diff --git a/tools/libxl/libxl_types_internal.idl b/tools/libxl/libxl_types_internal.idl
index 177f9b7..b41122b 100644
--- a/tools/libxl/libxl_types_internal.idl
+++ b/tools/libxl/libxl_types_internal.idl
@@ -24,6 +24,7 @@  libxl__device_kind = Enumeration("device_kind", [
     (8, "VTPM"),
     (9, "VUSB"),
     (10, "QUSB"),
+    (11, "PVCALLS"),
     ])
 
 libxl__console_backend = Enumeration("console_backend", [
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index 03ab644..0efe7c1 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -1898,6 +1898,11 @@  static void parse_config_data(const char *config_source,
             free(buf2);
         }
     }
+    
+    if (xlu_cfg_get_defbool(config, "pvcalls", &d_config->pvcalls.enabled, 0))
+        libxl_defbool_set(&d_config->pvcalls.enabled, false);
+    else if (libxl_defbool_val(d_config->pvcalls.enabled))
+        replace_string(&d_config->pvcalls.backend_domname, "0");
 
     if (!xlu_cfg_get_list (config, "channel", &channels, 0, 0)) {
         d_config->num_channels = 0;