xen/tools/libs/light/libxl_virtio.c

/*
 * Setup VirtIO backend. This is intended to interact with a VirtIO
 * backend that is watching xenstore, and create new VirtIO devices
 * with the parameter found in xenstore (VirtIO frontend don't
 * interact with xenstore.)
 *
 * Copyright (C) 2022 Linaro Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published
 * by the Free Software Foundation; version 2.1 only. with the special
 * exception on linking described in file LICENSE.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 */

#include "libxl_internal.h"

static int libxl__device_virtio_setdefault(libxl__gc *gc, uint32_t domid,
                                           libxl_device_virtio *virtio,
                                           bool hotplug)
{
    int rc;

    rc = libxl__resolve_domid(gc, virtio->backend_domname,
                              &virtio->backend_domid);
    if (rc < 0) return rc;

    libxl_defbool_setdefault(&virtio->grant_usage,
                             virtio->backend_domid != LIBXL_TOOLSTACK_DOMID);

    return 0;
}

static int libxl__device_from_virtio(libxl__gc *gc, uint32_t domid,
                                     libxl_device_virtio *virtio,
                                     libxl__device *device)
{
    device->backend_devid   = virtio->devid;
    device->backend_domid   = virtio->backend_domid;
    device->devid           = virtio->devid;
    device->domid           = domid;

    device->backend_kind    = LIBXL__DEVICE_KIND_VIRTIO;
    device->kind            = LIBXL__DEVICE_KIND_VIRTIO;

    return 0;
}

static int libxl__set_xenstore_virtio(libxl__gc *gc, uint32_t domid,
                                      libxl_device_virtio *virtio,
                                      flexarray_t *back, flexarray_t *front,
                                      flexarray_t *ro_front)
{
    const char *transport = libxl_virtio_transport_to_string(virtio->transport);

    flexarray_append_pair(back, "irq", GCSPRINTF("%u", virtio->irq));
    flexarray_append_pair(back, "base", GCSPRINTF("%#"PRIx64, virtio->base));
    flexarray_append_pair(back, "type", GCSPRINTF("%s", virtio->type));
    flexarray_append_pair(back, "transport", GCSPRINTF("%s", transport));
    flexarray_append_pair(back, "grant_usage",
                          libxl_defbool_val(virtio->grant_usage) ? "1" : "0");

    return 0;
}

static int libxl__virtio_from_xenstore(libxl__gc *gc, const char *libxl_path,
                                       libxl_devid devid,
                                       libxl_device_virtio *virtio)
{
    const char *be_path, *tmp = NULL;
    int rc;

    virtio->devid = devid;

    rc = libxl__xs_read_mandatory(gc, XBT_NULL,
                                  GCSPRINTF("%s/backend", libxl_path),
                                  &be_path);
    if (rc) goto out;

    rc = libxl__backendpath_parse_domid(gc, be_path, &virtio->backend_domid);
    if (rc) goto out;

    rc = libxl__xs_read_checked(gc, XBT_NULL,
				GCSPRINTF("%s/irq", be_path), &tmp);
    if (rc) goto out;

    if (tmp) {
        virtio->irq = strtoul(tmp, NULL, 0);
    }

    tmp = NULL;
    rc = libxl__xs_read_checked(gc, XBT_NULL,
				GCSPRINTF("%s/base", be_path), &tmp);
    if (rc) goto out;

    if (tmp) {
        virtio->base = strtoul(tmp, NULL, 0);
    }

    tmp = NULL;
    rc = libxl__xs_read_checked(gc, XBT_NULL,
				GCSPRINTF("%s/transport", be_path), &tmp);
    if (rc) goto out;

    if (tmp) {
        if (!strcmp(tmp, "mmio")) {
            virtio->transport = LIBXL_VIRTIO_TRANSPORT_MMIO;
        } else {
            return ERROR_INVAL;
        }
    }

    tmp = NULL;
    rc = libxl__xs_read_checked(gc, XBT_NULL,
                                GCSPRINTF("%s/grant_usage", be_path), &tmp);
    if (rc) goto out;

    if (tmp) {
        libxl_defbool_set(&virtio->grant_usage, strtoul(tmp, NULL, 0));
    }

    tmp = NULL;
    rc = libxl__xs_read_checked(gc, XBT_NULL,
				GCSPRINTF("%s/type", be_path), &tmp);
    if (rc) goto out;

    if (tmp) {
        int len = sizeof(VIRTIO_DEVICE_TYPE_GENERIC) - 1;

        if (!strncmp(tmp, VIRTIO_DEVICE_TYPE_GENERIC, len)) {
            virtio->type = libxl__strdup(NOGC, tmp);
        } else {
            return ERROR_INVAL;
        }
    }

out:
    return rc;
}

static LIBXL_DEFINE_UPDATE_DEVID(virtio)

#define libxl__add_virtios NULL
#define libxl_device_virtio_compare NULL

DEFINE_DEVICE_TYPE_STRUCT(virtio, VIRTIO, virtios,
    .set_xenstore_config = (device_set_xenstore_config_fn_t)
                           libxl__set_xenstore_virtio,
    .from_xenstore = (device_from_xenstore_fn_t)libxl__virtio_from_xenstore,
    .skip_attach = 1
);

/*
 * Local variables:
 * mode: C
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */