Commit 094a2239 authored by Paul Durrant's avatar Paul Durrant Committed by Anthony PERARD
Browse files

xen: create xenstore areas for XenDevice-s 



This patch adds a new source module, xen-bus-helper.c, which builds on
basic libxenstore primitives to provide functions to create (setting
permissions appropriately) and destroy xenstore areas, and functions to
'printf' and 'scanf' nodes therein. The main xen-bus code then uses
these primitives [1] to initialize and destroy the frontend and backend
areas for a XenDevice during realize and unrealize respectively.

The 'xen-block' implementation is extended with a 'get_name' method that
returns the VBD number. This number is required to 'name' the xenstore
areas.

NOTE: An exit handler is also added to make sure the xenstore areas are
      cleaned up if QEMU terminates without devices being unrealized.

[1] The 'scanf' functions are actually not yet needed, but they will be
    needed by code delivered in subsequent patches.

Signed-off-by: default avatarPaul Durrant <paul.durrant@citrix.com>
Reviewed-by: default avatarAnthony Perard <anthony.perard@citrix.com>
Signed-off-by: default avatarAnthony PERARD <anthony.perard@citrix.com>
parent 1a72d9ae

hw/block/xen-block.c

+9 −0
Original line number Diff line number Diff line
@@ -13,6 +13,14 @@ 
#include "hw/xen/xen-block.h"

#include "trace.h"



static char *xen_block_get_name(XenDevice *xendev, Error **errp)

{

    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);

    XenBlockVdev *vdev = &blockdev->props.vdev;



    return g_strdup_printf("%lu", vdev->number);

}



static void xen_block_unrealize(XenDevice *xendev, Error **errp)

{

    XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
@@ -262,6 +270,7 @@ static void xen_block_class_init(ObjectClass *class, void *data) 
    DeviceClass *dev_class = DEVICE_CLASS(class);

    XenDeviceClass *xendev_class = XEN_DEVICE_CLASS(class);



    xendev_class->get_name = xen_block_get_name;

    xendev_class->realize = xen_block_realize;

    xendev_class->unrealize = xen_block_unrealize;

hw/xen/Makefile.objs

+1 −1
Original line number Diff line number Diff line 
# xen backend driver support

common-obj-$(CONFIG_XEN) += xen-legacy-backend.o xen_devconfig.o xen_pvdev.o xen-common.o xen-bus.o

common-obj-$(CONFIG_XEN) += xen-legacy-backend.o xen_devconfig.o xen_pvdev.o xen-common.o xen-bus.o xen-bus-helper.o



obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o

obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o xen_pt_graphics.o xen_pt_msi.o

hw/xen/trace-events

+10 −2
Original line number Diff line number Diff line
@@ -16,5 +16,13 @@ xen_domid_restrict(int err) "err: %u" 
# include/hw/xen/xen-bus.c

xen_bus_realize(void) ""

xen_bus_unrealize(void) ""

xen_device_realize(const char *type) "type: %s"

xen_device_unrealize(const char *type) "type: %s"
 
xen_device_realize(const char *type, char *name) "type: %s name: %s"

xen_device_unrealize(const char *type, char *name) "type: %s name: %s"

xen_device_backend_state(const char *type, char *name, const char *state) "type: %s name: %s -> %s"

xen_device_frontend_state(const char *type, char *name, const char *state) "type: %s name: %s -> %s"



# include/hw/xen/xen-bus-helper.c

xs_node_create(const char *node) "%s"

xs_node_destroy(const char *node) "%s"

xs_node_vprintf(char *path, char *value) "%s %s"

xs_node_vscanf(char *path, char *value) "%s %s"

hw/xen/xen-bus-helper.c

0 → 100644
+150 −0
Original line number Diff line number Diff line 
/*

 * Copyright (c) 2018  Citrix Systems Inc.

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 */



#include "qemu/osdep.h"

#include "hw/hw.h"

#include "hw/sysbus.h"

#include "hw/xen/xen.h"

#include "hw/xen/xen-bus.h"

#include "hw/xen/xen-bus-helper.h"

#include "qapi/error.h"



#include <glib/gprintf.h>



struct xs_state {

    enum xenbus_state statenum;

    const char *statestr;

};

#define XS_STATE(state) { state, #state }



static struct xs_state xs_state[] = {

    XS_STATE(XenbusStateUnknown),

    XS_STATE(XenbusStateInitialising),

    XS_STATE(XenbusStateInitWait),

    XS_STATE(XenbusStateInitialised),

    XS_STATE(XenbusStateConnected),

    XS_STATE(XenbusStateClosing),

    XS_STATE(XenbusStateClosed),

    XS_STATE(XenbusStateReconfiguring),

    XS_STATE(XenbusStateReconfigured),

};



#undef XS_STATE



const char *xs_strstate(enum xenbus_state state)

{

    unsigned int i;



   for (i = 0; i < ARRAY_SIZE(xs_state); i++) {

        if (xs_state[i].statenum == state) {

            return xs_state[i].statestr;

        }

    }



    return "INVALID";

}



void xs_node_create(struct xs_handle *xsh, xs_transaction_t tid,

                    const char *node, struct xs_permissions perms[],

                    unsigned int nr_perms, Error **errp)

{

    trace_xs_node_create(node);



    if (!xs_write(xsh, tid, node, "", 0)) {

        error_setg_errno(errp, errno, "failed to create node '%s'", node);

        return;

    }



    if (!xs_set_permissions(xsh, tid, node, perms, nr_perms)) {

        error_setg_errno(errp, errno, "failed to set node '%s' permissions",

                         node);

    }

}



void xs_node_destroy(struct xs_handle *xsh, xs_transaction_t tid,

                     const char *node, Error **errp)

{

    trace_xs_node_destroy(node);



    if (!xs_rm(xsh, tid, node)) {

        error_setg_errno(errp, errno, "failed to destroy node '%s'", node);

    }

}



void xs_node_vprintf(struct xs_handle *xsh, xs_transaction_t tid,

                     const char *node, const char *key, Error **errp,

                     const char *fmt, va_list ap)

{

    char *path, *value;

    int len;



    path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :

        g_strdup(key);

    len = g_vasprintf(&value, fmt, ap);



    trace_xs_node_vprintf(path, value);



    if (!xs_write(xsh, tid, path, value, len)) {

        error_setg_errno(errp, errno, "failed to write '%s' to '%s'",

                         value, path);

    }



    g_free(value);

    g_free(path);

}



void xs_node_printf(struct xs_handle *xsh,  xs_transaction_t tid,

                    const char *node, const char *key, Error **errp,

                    const char *fmt, ...)

{

    va_list ap;



    va_start(ap, fmt);

    xs_node_vprintf(xsh, tid, node, key, errp, fmt, ap);

    va_end(ap);

}



int xs_node_vscanf(struct xs_handle *xsh,  xs_transaction_t tid,

                   const char *node, const char *key, Error **errp,

                   const char *fmt, va_list ap)

{

    char *path, *value;

    int rc;



    path = (strlen(node) != 0) ? g_strdup_printf("%s/%s", node, key) :

        g_strdup(key);

    value = xs_read(xsh, tid, path, NULL);



    trace_xs_node_vscanf(path, value);



    if (value) {

        rc = vsscanf(value, fmt, ap);

    } else {

        error_setg_errno(errp, errno, "failed to read from '%s'",

                         path);

        rc = EOF;

    }



    free(value);

    g_free(path);



    return rc;

}



int xs_node_scanf(struct xs_handle *xsh,  xs_transaction_t tid,

                  const char *node, const char *key, Error **errp,

                  const char *fmt, ...)

{

    va_list ap;

    int rc;



    va_start(ap, fmt);

    rc = xs_node_vscanf(xsh, tid, node, key, errp, fmt, ap);

    va_end(ap);



    return rc;

}

hw/xen/xen-bus.c

+319 −2
Original line number Diff line number Diff line
@@ -8,24 +8,102 @@ 
#include "qemu/osdep.h"

#include "hw/hw.h"

#include "hw/sysbus.h"

#include "hw/xen/xen.h"

#include "hw/xen/xen-bus.h"

#include "hw/xen/xen-bus-helper.h"

#include "monitor/monitor.h"

#include "qapi/error.h"

#include "sysemu/sysemu.h"

#include "trace.h"



static char *xen_device_get_backend_path(XenDevice *xendev)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);

    const char *type = object_get_typename(OBJECT(xendev));

    const char *backend = xendev_class->backend;



    if (!backend) {

        backend = type;

    }



    return g_strdup_printf("/local/domain/%u/backend/%s/%u/%s",

                           xenbus->backend_id, backend, xendev->frontend_id,

                           xendev->name);

}



static char *xen_device_get_frontend_path(XenDevice *xendev)

{

    XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);

    const char *type = object_get_typename(OBJECT(xendev));

    const char *device = xendev_class->device;



    if (!device) {

        device = type;

    }



    return g_strdup_printf("/local/domain/%u/device/%s/%s",

                           xendev->frontend_id, device, xendev->name);

}



static void xen_bus_print_dev(Monitor *mon, DeviceState *dev, int indent)

{

    XenDevice *xendev = XEN_DEVICE(dev);



    monitor_printf(mon, "%*sname = '%s' frontend_id = %u\n",

                   indent, "", xendev->name, xendev->frontend_id);

}



static char *xen_bus_get_dev_path(DeviceState *dev)

{

    return xen_device_get_backend_path(XEN_DEVICE(dev));

}



static void xen_bus_unrealize(BusState *bus, Error **errp)

{

    XenBus *xenbus = XEN_BUS(bus);



    trace_xen_bus_unrealize();



    if (!xenbus->xsh) {

        return;

    }



    xs_close(xenbus->xsh);

}



static void xen_bus_realize(BusState *bus, Error **errp)

{

    XenBus *xenbus = XEN_BUS(bus);

    unsigned int domid;



    trace_xen_bus_realize();



    xenbus->xsh = xs_open(0);

    if (!xenbus->xsh) {

        error_setg_errno(errp, errno, "failed xs_open");

        goto fail;

    }



    if (xs_node_scanf(xenbus->xsh, XBT_NULL, "", /* domain root node */

                      "domid", NULL, "%u", &domid) == 1) {

        xenbus->backend_id = domid;

    } else {

        xenbus->backend_id = 0; /* Assume lack of node means dom0 */

    }



    return;



fail:

    xen_bus_unrealize(bus, &error_abort);

}



static void xen_bus_class_init(ObjectClass *class, void *data)

{

    BusClass *bus_class = BUS_CLASS(class);



    bus_class->print_dev = xen_bus_print_dev;

    bus_class->get_dev_path = xen_bus_get_dev_path;

    bus_class->realize = xen_bus_realize;

    bus_class->unrealize = xen_bus_unrealize;

}
@@ -42,27 +120,241 @@ static const TypeInfo xen_bus_type_info = { 
    },

};



static void xen_device_backend_printf(XenDevice *xendev, const char *key,

                                      const char *fmt, ...)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    Error *local_err = NULL;

    va_list ap;



    g_assert(xenbus->xsh);



    va_start(ap, fmt);

    xs_node_vprintf(xenbus->xsh, XBT_NULL, xendev->backend_path, key,

                    &local_err, fmt, ap);

    va_end(ap);



    if (local_err) {

        error_report_err(local_err);

    }

}



static void xen_device_backend_set_state(XenDevice *xendev,

                                         enum xenbus_state state)

{

    const char *type = object_get_typename(OBJECT(xendev));



    if (xendev->backend_state == state) {

        return;

    }



    trace_xen_device_backend_state(type, xendev->name,

                                   xs_strstate(state));



    xendev->backend_state = state;

    xen_device_backend_printf(xendev, "state", "%u", state);

}



static void xen_device_backend_create(XenDevice *xendev, Error **errp)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    struct xs_permissions perms[2];

    Error *local_err = NULL;



    xendev->backend_path = xen_device_get_backend_path(xendev);



    perms[0].id = xenbus->backend_id;

    perms[0].perms = XS_PERM_NONE;

    perms[1].id = xendev->frontend_id;

    perms[1].perms = XS_PERM_READ;



    g_assert(xenbus->xsh);



    xs_node_create(xenbus->xsh, XBT_NULL, xendev->backend_path, perms,

                   ARRAY_SIZE(perms), &local_err);

    if (local_err) {

        error_propagate_prepend(errp, local_err,

                                "failed to create backend: ");

    }

}



static void xen_device_backend_destroy(XenDevice *xendev)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    Error *local_err = NULL;



    if (!xendev->backend_path) {

        return;

    }



    g_assert(xenbus->xsh);



    xs_node_destroy(xenbus->xsh, XBT_NULL, xendev->backend_path,

                    &local_err);

    g_free(xendev->backend_path);

    xendev->backend_path = NULL;



    if (local_err) {

        error_report_err(local_err);

    }

}



static void xen_device_frontend_printf(XenDevice *xendev, const char *key,

                                       const char *fmt, ...)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    Error *local_err = NULL;

    va_list ap;



    g_assert(xenbus->xsh);



    va_start(ap, fmt);

    xs_node_vprintf(xenbus->xsh, XBT_NULL, xendev->frontend_path, key,

                    &local_err, fmt, ap);

    va_end(ap);



    if (local_err) {

        error_report_err(local_err);

    }

}



static void xen_device_frontend_set_state(XenDevice *xendev,

                                          enum xenbus_state state)

{

    const char *type = object_get_typename(OBJECT(xendev));



    if (xendev->frontend_state == state) {

        return;

    }



    trace_xen_device_frontend_state(type, xendev->name,

                                    xs_strstate(state));



    xendev->frontend_state = state;

    xen_device_frontend_printf(xendev, "state", "%u", state);

}



static void xen_device_frontend_create(XenDevice *xendev, Error **errp)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    struct xs_permissions perms[2];

    Error *local_err = NULL;



    xendev->frontend_path = xen_device_get_frontend_path(xendev);



    perms[0].id = xendev->frontend_id;

    perms[0].perms = XS_PERM_NONE;

    perms[1].id = xenbus->backend_id;

    perms[1].perms = XS_PERM_READ | XS_PERM_WRITE;



    g_assert(xenbus->xsh);



    xs_node_create(xenbus->xsh, XBT_NULL, xendev->frontend_path, perms,

                   ARRAY_SIZE(perms), &local_err);

    if (local_err) {

        error_propagate_prepend(errp, local_err,

                                "failed to create frontend: ");

    }

}



static void xen_device_frontend_destroy(XenDevice *xendev)

{

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    Error *local_err = NULL;



    if (!xendev->frontend_path) {

        return;

    }



    g_assert(xenbus->xsh);



    xs_node_destroy(xenbus->xsh, XBT_NULL, xendev->frontend_path,

                    &local_err);

    g_free(xendev->frontend_path);

    xendev->frontend_path = NULL;



    if (local_err) {

        error_report_err(local_err);

    }

}



static void xen_device_unrealize(DeviceState *dev, Error **errp)

{

    XenDevice *xendev = XEN_DEVICE(dev);

    XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);

    const char *type = object_get_typename(OBJECT(xendev));



    trace_xen_device_unrealize(type);

    if (!xendev->name) {

        return;

    }



    trace_xen_device_unrealize(type, xendev->name);



    if (xendev->exit.notify) {

        qemu_remove_exit_notifier(&xendev->exit);

        xendev->exit.notify = NULL;

    }



    if (xendev_class->unrealize) {

        xendev_class->unrealize(xendev, errp);

    }



    xen_device_frontend_destroy(xendev);

    xen_device_backend_destroy(xendev);



    g_free(xendev->name);

    xendev->name = NULL;

}



static void xen_device_exit(Notifier *n, void *data)

{

    XenDevice *xendev = container_of(n, XenDevice, exit);



    xen_device_unrealize(DEVICE(xendev), &error_abort);

}



static void xen_device_realize(DeviceState *dev, Error **errp)

{

    XenDevice *xendev = XEN_DEVICE(dev);

    XenDeviceClass *xendev_class = XEN_DEVICE_GET_CLASS(xendev);

    XenBus *xenbus = XEN_BUS(qdev_get_parent_bus(DEVICE(xendev)));

    const char *type = object_get_typename(OBJECT(xendev));

    Error *local_err = NULL;



    trace_xen_device_realize(type);

    if (xendev->frontend_id == DOMID_INVALID) {

        xendev->frontend_id = xen_domid;

    }



    if (xendev->frontend_id >= DOMID_FIRST_RESERVED) {

        error_setg(errp, "invalid frontend-id");

        goto unrealize;

    }



    if (!xendev_class->get_name) {

        error_setg(errp, "get_name method not implemented");

        goto unrealize;

    }



    xendev->name = xendev_class->get_name(xendev, &local_err);

    if (local_err) {

        error_propagate_prepend(errp, local_err,

                                "failed to get device name: ");

        goto unrealize;

    }



    trace_xen_device_realize(type, xendev->name);



    xen_device_backend_create(xendev, &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        goto unrealize;

    }



    xen_device_frontend_create(xendev, &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        goto unrealize;

    }



    if (xendev_class->realize) {

        xendev_class->realize(xendev, &local_err);
@@ -72,18 +364,43 @@ static void xen_device_realize(DeviceState *dev, Error **errp) 
        }

    }



    xen_device_backend_printf(xendev, "frontend", "%s",

                              xendev->frontend_path);

    xen_device_backend_printf(xendev, "frontend-id", "%u",

                              xendev->frontend_id);

    xen_device_backend_printf(xendev, "online", "%u", 1);

    xen_device_backend_printf(xendev, "hotplug-status", "connected");



    xen_device_backend_set_state(xendev, XenbusStateInitWait);



    xen_device_frontend_printf(xendev, "backend", "%s",

                               xendev->backend_path);

    xen_device_frontend_printf(xendev, "backend-id", "%u",

                               xenbus->backend_id);



    xen_device_frontend_set_state(xendev, XenbusStateInitialising);



    xendev->exit.notify = xen_device_exit;

    qemu_add_exit_notifier(&xendev->exit);

    return;



unrealize:

    xen_device_unrealize(dev, &error_abort);

}



static Property xen_device_props[] = {

    DEFINE_PROP_UINT16("frontend-id", XenDevice, frontend_id,

                       DOMID_INVALID),

    DEFINE_PROP_END_OF_LIST()

};



static void xen_device_class_init(ObjectClass *class, void *data)

{

    DeviceClass *dev_class = DEVICE_CLASS(class);



    dev_class->realize = xen_device_realize;

    dev_class->unrealize = xen_device_unrealize;

    dev_class->props = xen_device_props;

    dev_class->bus_type = TYPE_XEN_BUS;

}