Devices may have component devices and buses. Device realization may fail. Realization is recursive: a device's realize() method realizes its components, and device_set_realized() realizes its buses (which should in turn realize the devices on that bus, except bus_set_realized() doesn't implement that, yet). When realization of a component or bus fails, we need to roll back: unrealize everything we realized so far. If any of these unrealizes failed, the device would be left in an inconsistent state. Must not happen. device_set_realized() lets it happen: it ignores errors in the roll back code starting at label child_realize_fail. Since realization is recursive, unrealization must be recursive, too. But how could a partly failed unrealize be rolled back? We'd have to re-realize, which can fail. This design is fundamentally broken. device_set_realized() does not roll back at all. Instead, it keeps unrealizing, ignoring further errors. It can screw up even for a device with no buses: if the lone dc->unrealize() fails, it still unregisters vmstate, and calls listeners' unrealize() callback. bus_set_realized() does not roll back either. Instead, it stops unrealizing. Fortunately, no unrealize method can fail, as we'll see below. To fix the design error, drop parameter @errp from all the unrealize methods. Any unrealize method that uses @errp now needs an update. This leads us to unrealize() methods that can fail. Merely passing it to another unrealize method cannot cause failure, though. Here are the ones that do other things with @errp: * virtio_serial_device_unrealize() Fails when qbus_set_hotplug_handler() fails, but still does all the other work. On failure, the device would stay realized with its resources completely gone. Oops. Can't happen, because qbus_set_hotplug_handler() can't actually fail here. Pass &error_abort to qbus_set_hotplug_handler() instead. * hw/ppc/spapr_drc.c's unrealize() Fails when object_property_del() fails, but all the other work is already done. On failure, the device would stay realized with its vmstate registration gone. Oops. Can't happen, because object_property_del() can't actually fail here. Pass &error_abort to object_property_del() instead. * spapr_phb_unrealize() Fails and bails out when remove_drcs() fails, but other work is already done. On failure, the device would stay realized with some of its resources gone. Oops. remove_drcs() fails only when chassis_from_bus()'s object_property_get_uint() fails, and it can't here. Pass &error_abort to remove_drcs() instead. Therefore, no unrealize method can fail before this patch. device_set_realized()'s recursive unrealization via bus uses object_property_set_bool(). Can't drop @errp there, so pass &error_abort. We similarly unrealize with object_property_set_bool() elsewhere, always ignoring errors. Pass &error_abort instead. Several unrealize methods no longer handle errors from other unrealize methods: virtio_9p_device_unrealize(), virtio_input_device_unrealize(), scsi_qdev_unrealize(), ... Much of the deleted error handling looks wrong anyway. One unrealize methods no longer ignore such errors: usb_ehci_pci_exit(). Several realize methods no longer ignore errors when rolling back: v9fs_device_realize_common(), pci_qdev_unrealize(), spapr_phb_realize(), usb_qdev_realize(), vfio_ccw_realize(), virtio_device_realize(). Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200505152926.18877-17-armbru@redhat.com>
272 lines
7.6 KiB
C
272 lines
7.6 KiB
C
/*
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* Virtio 9p backend
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*
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* Copyright IBM, Corp. 2010
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*
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* Authors:
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* Anthony Liguori <aliguori@us.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#include "qemu/osdep.h"
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#include "hw/virtio/virtio.h"
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#include "qemu/sockets.h"
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#include "virtio-9p.h"
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#include "fsdev/qemu-fsdev.h"
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#include "coth.h"
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#include "hw/qdev-properties.h"
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#include "hw/virtio/virtio-access.h"
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#include "qemu/iov.h"
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#include "qemu/module.h"
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static void virtio_9p_push_and_notify(V9fsPDU *pdu)
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{
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V9fsState *s = pdu->s;
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V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
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VirtQueueElement *elem = v->elems[pdu->idx];
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/* push onto queue and notify */
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virtqueue_push(v->vq, elem, pdu->size);
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g_free(elem);
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v->elems[pdu->idx] = NULL;
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/* FIXME: we should batch these completions */
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virtio_notify(VIRTIO_DEVICE(v), v->vq);
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}
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static void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq)
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{
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V9fsVirtioState *v = (V9fsVirtioState *)vdev;
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V9fsState *s = &v->state;
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V9fsPDU *pdu;
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ssize_t len;
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VirtQueueElement *elem;
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while ((pdu = pdu_alloc(s))) {
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P9MsgHeader out;
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elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
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if (!elem) {
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goto out_free_pdu;
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}
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if (iov_size(elem->in_sg, elem->in_num) < 7) {
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virtio_error(vdev,
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"The guest sent a VirtFS request without space for "
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"the reply");
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goto out_free_req;
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}
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len = iov_to_buf(elem->out_sg, elem->out_num, 0, &out, 7);
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if (len != 7) {
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virtio_error(vdev, "The guest sent a malformed VirtFS request: "
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"header size is %zd, should be 7", len);
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goto out_free_req;
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}
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v->elems[pdu->idx] = elem;
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pdu_submit(pdu, &out);
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}
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return;
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out_free_req:
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virtqueue_detach_element(vq, elem, 0);
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g_free(elem);
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out_free_pdu:
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pdu_free(pdu);
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}
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static uint64_t virtio_9p_get_features(VirtIODevice *vdev, uint64_t features,
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Error **errp)
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{
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virtio_add_feature(&features, VIRTIO_9P_MOUNT_TAG);
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return features;
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}
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static void virtio_9p_get_config(VirtIODevice *vdev, uint8_t *config)
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{
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int len;
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struct virtio_9p_config *cfg;
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V9fsVirtioState *v = VIRTIO_9P(vdev);
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V9fsState *s = &v->state;
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len = strlen(s->tag);
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cfg = g_malloc0(sizeof(struct virtio_9p_config) + len);
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virtio_stw_p(vdev, &cfg->tag_len, len);
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/* We don't copy the terminating null to config space */
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memcpy(cfg->tag, s->tag, len);
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memcpy(config, cfg, v->config_size);
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g_free(cfg);
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}
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static void virtio_9p_reset(VirtIODevice *vdev)
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{
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V9fsVirtioState *v = (V9fsVirtioState *)vdev;
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v9fs_reset(&v->state);
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}
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static ssize_t virtio_pdu_vmarshal(V9fsPDU *pdu, size_t offset,
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const char *fmt, va_list ap)
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{
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V9fsState *s = pdu->s;
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V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
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VirtQueueElement *elem = v->elems[pdu->idx];
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ssize_t ret;
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ret = v9fs_iov_vmarshal(elem->in_sg, elem->in_num, offset, 1, fmt, ap);
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if (ret < 0) {
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VirtIODevice *vdev = VIRTIO_DEVICE(v);
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virtio_error(vdev, "Failed to encode VirtFS reply type %d",
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pdu->id + 1);
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}
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return ret;
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}
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static ssize_t virtio_pdu_vunmarshal(V9fsPDU *pdu, size_t offset,
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const char *fmt, va_list ap)
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{
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V9fsState *s = pdu->s;
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V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
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VirtQueueElement *elem = v->elems[pdu->idx];
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ssize_t ret;
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ret = v9fs_iov_vunmarshal(elem->out_sg, elem->out_num, offset, 1, fmt, ap);
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if (ret < 0) {
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VirtIODevice *vdev = VIRTIO_DEVICE(v);
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virtio_error(vdev, "Failed to decode VirtFS request type %d", pdu->id);
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}
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return ret;
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}
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static void virtio_init_in_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
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unsigned int *pniov, size_t *size)
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{
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V9fsState *s = pdu->s;
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V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
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VirtQueueElement *elem = v->elems[pdu->idx];
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size_t buf_size = iov_size(elem->in_sg, elem->in_num);
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if (buf_size < P9_IOHDRSZ) {
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VirtIODevice *vdev = VIRTIO_DEVICE(v);
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virtio_error(vdev,
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"VirtFS reply type %d needs %zu bytes, buffer has %zu, less than minimum",
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pdu->id + 1, *size, buf_size);
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}
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if (buf_size < *size) {
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*size = buf_size;
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}
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*piov = elem->in_sg;
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*pniov = elem->in_num;
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}
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static void virtio_init_out_iov_from_pdu(V9fsPDU *pdu, struct iovec **piov,
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unsigned int *pniov, size_t size)
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{
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V9fsState *s = pdu->s;
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V9fsVirtioState *v = container_of(s, V9fsVirtioState, state);
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VirtQueueElement *elem = v->elems[pdu->idx];
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size_t buf_size = iov_size(elem->out_sg, elem->out_num);
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if (buf_size < size) {
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VirtIODevice *vdev = VIRTIO_DEVICE(v);
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virtio_error(vdev,
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"VirtFS request type %d needs %zu bytes, buffer has %zu",
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pdu->id, size, buf_size);
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}
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*piov = elem->out_sg;
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*pniov = elem->out_num;
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}
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static const V9fsTransport virtio_9p_transport = {
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.pdu_vmarshal = virtio_pdu_vmarshal,
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.pdu_vunmarshal = virtio_pdu_vunmarshal,
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.init_in_iov_from_pdu = virtio_init_in_iov_from_pdu,
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.init_out_iov_from_pdu = virtio_init_out_iov_from_pdu,
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.push_and_notify = virtio_9p_push_and_notify,
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};
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static void virtio_9p_device_realize(DeviceState *dev, Error **errp)
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{
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VirtIODevice *vdev = VIRTIO_DEVICE(dev);
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V9fsVirtioState *v = VIRTIO_9P(dev);
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V9fsState *s = &v->state;
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if (v9fs_device_realize_common(s, &virtio_9p_transport, errp)) {
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return;
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}
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v->config_size = sizeof(struct virtio_9p_config) + strlen(s->fsconf.tag);
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virtio_init(vdev, "virtio-9p", VIRTIO_ID_9P, v->config_size);
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v->vq = virtio_add_queue(vdev, MAX_REQ, handle_9p_output);
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}
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static void virtio_9p_device_unrealize(DeviceState *dev)
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{
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VirtIODevice *vdev = VIRTIO_DEVICE(dev);
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V9fsVirtioState *v = VIRTIO_9P(dev);
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V9fsState *s = &v->state;
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virtio_delete_queue(v->vq);
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virtio_cleanup(vdev);
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v9fs_device_unrealize_common(s);
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}
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/* virtio-9p device */
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static const VMStateDescription vmstate_virtio_9p = {
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.name = "virtio-9p",
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.minimum_version_id = 1,
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.version_id = 1,
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.fields = (VMStateField[]) {
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VMSTATE_VIRTIO_DEVICE,
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VMSTATE_END_OF_LIST()
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},
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};
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static Property virtio_9p_properties[] = {
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DEFINE_PROP_STRING("mount_tag", V9fsVirtioState, state.fsconf.tag),
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DEFINE_PROP_STRING("fsdev", V9fsVirtioState, state.fsconf.fsdev_id),
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DEFINE_PROP_END_OF_LIST(),
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};
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static void virtio_9p_class_init(ObjectClass *klass, void *data)
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{
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DeviceClass *dc = DEVICE_CLASS(klass);
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VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
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device_class_set_props(dc, virtio_9p_properties);
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dc->vmsd = &vmstate_virtio_9p;
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set_bit(DEVICE_CATEGORY_STORAGE, dc->categories);
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vdc->realize = virtio_9p_device_realize;
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vdc->unrealize = virtio_9p_device_unrealize;
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vdc->get_features = virtio_9p_get_features;
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vdc->get_config = virtio_9p_get_config;
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vdc->reset = virtio_9p_reset;
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}
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static const TypeInfo virtio_device_info = {
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.name = TYPE_VIRTIO_9P,
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.parent = TYPE_VIRTIO_DEVICE,
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.instance_size = sizeof(V9fsVirtioState),
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.class_init = virtio_9p_class_init,
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};
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static void virtio_9p_register_types(void)
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{
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type_register_static(&virtio_device_info);
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}
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type_init(virtio_9p_register_types)
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