libxl: make libxl_device_pci_{add,remove,destroy} interfaces asynchronous

This does not make the implementation fully asynchronous but just
updates the API to support asynchrony in the future.

Currently although these functions do not call hotplug scripts etc and
therefore are not "slow" (per the comment about ao machinery in
libxl_internal.h) they do interact with the device model and so are
not quite "fast" either. We can live with this for now.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Campbell <ian.campbell@citrix.com>

5 files changed, 46 insertions, 29 deletions

diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 5ec2d749f7..cc74e1359f 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -757,10 +757,21 @@ int libxl_device_vfb_destroy(libxl_ctx *ctx, uint32_t domid,
                              LIBXL_EXTERNAL_CALLERS_ONLY;
 
 /* PCI Passthrough */
-int libxl_device_pci_add(libxl_ctx *ctx, uint32_t domid, libxl_device_pci *pcidev);
-int libxl_device_pci_remove(libxl_ctx *ctx, uint32_t domid, libxl_device_pci *pcidev);
-int libxl_device_pci_destroy(libxl_ctx *ctx, uint32_t domid, libxl_device_pci *pcidev);
-libxl_device_pci *libxl_device_pci_list(libxl_ctx *ctx, uint32_t domid, int *num);
+int libxl_device_pci_add(libxl_ctx *ctx, uint32_t domid,
+                         libxl_device_pci *pcidev,
+                         const libxl_asyncop_how *ao_how)
+                         LIBXL_EXTERNAL_CALLERS_ONLY;
+int libxl_device_pci_remove(libxl_ctx *ctx, uint32_t domid,
+                            libxl_device_pci *pcidev,
+                            const libxl_asyncop_how *ao_how)
+                            LIBXL_EXTERNAL_CALLERS_ONLY;
+int libxl_device_pci_destroy(libxl_ctx *ctx, uint32_t domid,
+                             libxl_device_pci *pcidev,
+                             const libxl_asyncop_how *ao_how)
+                             LIBXL_EXTERNAL_CALLERS_ONLY;
+
+libxl_device_pci *libxl_device_pci_list(libxl_ctx *ctx, uint32_t domid,
+                                        int *num);
 
 /*
  * Functions related to making devices assignable -- that is, bound to
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index 9c92ae61a5..48986f3fa8 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -1010,13 +1010,15 @@ int libxl__device_pci_setdefault(libxl__gc *gc, libxl_device_pci *pci)
     return 0;
 }
 
-int libxl_device_pci_add(libxl_ctx *ctx, uint32_t domid, libxl_device_pci *pcidev)
+int libxl_device_pci_add(libxl_ctx *ctx, uint32_t domid,
+                         libxl_device_pci *pcidev,
+                         const libxl_asyncop_how *ao_how)
 {
-    GC_INIT(ctx);
+    AO_CREATE(ctx, domid, ao_how);
     int rc;
     rc = libxl__device_pci_add(gc, domid, pcidev, 0);
-    GC_FREE;
-    return rc;
+    libxl__ao_complete(egc, ao, rc);
+    return AO_INPROGRESS;
 }
 
 static int libxl_pcidev_assignable(libxl_ctx *ctx, libxl_device_pci *pcidev)
@@ -1150,6 +1152,9 @@ static int qemu_pci_remove_xenstore(libxl__gc *gc, uint32_t domid,
     return 0;
 }
 
+static int libxl__device_pci_remove_common(libxl__gc *gc, uint32_t domid,
+                                           libxl_device_pci *pcidev, int force);
+
 static int do_pci_remove(libxl__gc *gc, uint32_t domid,
                          libxl_device_pci *pcidev, int force)
 {
@@ -1263,10 +1268,7 @@ out:
     stubdomid = libxl_get_stubdom_id(ctx, domid);
     if (stubdomid != 0) {
         libxl_device_pci pcidev_s = *pcidev;
-        if (force)
-                libxl_device_pci_destroy(ctx, stubdomid, &pcidev_s);
-        else
-                libxl_device_pci_remove(ctx, stubdomid, &pcidev_s);
+        libxl__device_pci_remove_common(gc, stubdomid, &pcidev_s, force);
     }
 
     libxl__device_pci_remove_xenstore(gc, domid, pcidev);
@@ -1313,27 +1315,31 @@ out:
     return rc;
 }
 
-int libxl_device_pci_remove(libxl_ctx *ctx, uint32_t domid, libxl_device_pci *pcidev)
+int libxl_device_pci_remove(libxl_ctx *ctx, uint32_t domid,
+                            libxl_device_pci *pcidev,
+                            const libxl_asyncop_how *ao_how)
+
 {
-    GC_INIT(ctx);
+    AO_CREATE(ctx, domid, ao_how);
     int rc;
 
     rc = libxl__device_pci_remove_common(gc, domid, pcidev, 0);
 
-    GC_FREE;
-    return rc;
+    libxl__ao_complete(egc, ao, rc);
+    return AO_INPROGRESS;
 }
 
 int libxl_device_pci_destroy(libxl_ctx *ctx, uint32_t domid,
-                                  libxl_device_pci *pcidev)
+                             libxl_device_pci *pcidev,
+                             const libxl_asyncop_how *ao_how)
 {
-    GC_INIT(ctx);
+    AO_CREATE(ctx, domid, ao_how);
     int rc;
 
     rc = libxl__device_pci_remove_common(gc, domid, pcidev, 1);
 
-    GC_FREE;
-    return rc;
+    libxl__ao_complete(egc, ao, rc);
+    return AO_INPROGRESS;
 }
 
 static void libxl__device_pci_from_xs_be(libxl__gc *gc,
@@ -1415,7 +1421,7 @@ int libxl__device_pci_destroy_all(libxl__gc *gc, uint32_t domid)
          * respond to SCI interrupt because the guest kernel has shut down the
          * devices by the time we even get here!
          */
-        if (libxl_device_pci_destroy(ctx, domid, pcidevs + i) < 0)
+        if (libxl__device_pci_remove_common(gc, domid, pcidevs + i, 1) < 0)
             rc = ERROR_FAIL;
     }
 
diff --git a/tools/libxl/xl_cmdimpl.c b/tools/libxl/xl_cmdimpl.c
index a7dc3403d1..138cd72b80 100644
--- a/tools/libxl/xl_cmdimpl.c
+++ b/tools/libxl/xl_cmdimpl.c
@@ -2389,9 +2389,9 @@ static void pcidetach(const char *dom, const char *bdf, int force)
         exit(2);
     }
     if (force)
-        libxl_device_pci_destroy(ctx, domid, &pcidev);
+        libxl_device_pci_destroy(ctx, domid, &pcidev, 0);
     else
-        libxl_device_pci_remove(ctx, domid, &pcidev);
+        libxl_device_pci_remove(ctx, domid, &pcidev, 0);
 
     libxl_device_pci_dispose(&pcidev);
     xlu_cfg_destroy(config);
@@ -2435,7 +2435,7 @@ static void pciattach(const char *dom, const char *bdf, const char *vs)
         fprintf(stderr, "pci-attach: malformed BDF specification \"%s\"\n", bdf);
         exit(2);
     }
-    libxl_device_pci_add(ctx, domid, &pcidev);
+    libxl_device_pci_add(ctx, domid, &pcidev, 0);
 
     libxl_device_pci_dispose(&pcidev);
     xlu_cfg_destroy(config);
diff --git a/tools/ocaml/libs/xl/xenlight_stubs.c b/tools/ocaml/libs/xl/xenlight_stubs.c
index adda67f54f..5f19a82c8b 100644
--- a/tools/ocaml/libs/xl/xenlight_stubs.c
+++ b/tools/ocaml/libs/xl/xenlight_stubs.c
@@ -423,7 +423,7 @@ value stub_xl_device_pci_add(value info, value domid)
 	device_pci_val(&gc, &lg, &c_info, info);
 
 	INIT_CTX();
-	ret = libxl_device_pci_add(ctx, Int_val(domid), &c_info);
+	ret = libxl_device_pci_add(ctx, Int_val(domid), &c_info, 0);
 	if (ret != 0)
 		failwith_xl("pci_add", &lg);
 	FREE_CTX();
@@ -441,7 +441,7 @@ value stub_xl_device_pci_remove(value info, value domid)
 	device_pci_val(&gc, &lg, &c_info, info);
 
 	INIT_CTX();
-	ret = libxl_device_pci_remove(ctx, Int_val(domid), &c_info);
+	ret = libxl_device_pci_remove(ctx, Int_val(domid), &c_info, 0);
 	if (ret != 0)
 		failwith_xl("pci_remove", &lg);
 	FREE_CTX();
diff --git a/tools/python/xen/lowlevel/xl/xl.c b/tools/python/xen/lowlevel/xl/xl.c
index 553fc58871..0551c7636f 100644
--- a/tools/python/xen/lowlevel/xl/xl.c
+++ b/tools/python/xen/lowlevel/xl/xl.c
@@ -497,7 +497,7 @@ static PyObject *pyxl_pci_add(XlObject *self, PyObject *args)
         return NULL;
     }
     pci = (Py_device_pci *)obj;
-    if ( libxl_device_pci_add(self->ctx, domid, &pci->obj) ) {
+    if ( libxl_device_pci_add(self->ctx, domid, &pci->obj, 0) ) {
         PyErr_SetString(xl_error_obj, "cannot add pci device");
         return NULL;
     }
@@ -519,12 +519,12 @@ static PyObject *pyxl_pci_del(XlObject *self, PyObject *args)
     }
     pci = (Py_device_pci *)obj;
     if ( force ) {
-        if ( libxl_device_pci_destroy(self->ctx, domid, &pci->obj) ) {
+        if ( libxl_device_pci_destroy(self->ctx, domid, &pci->obj, 0) ) {
             PyErr_SetString(xl_error_obj, "cannot remove pci device");
             return NULL;
         }
     } else {
-        if ( libxl_device_pci_remove(self->ctx, domid, &pci->obj) ) {
+        if ( libxl_device_pci_remove(self->ctx, domid, &pci->obj, 0) ) {
             PyErr_SetString(xl_error_obj, "cannot remove pci device");
             return NULL;
         }