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>
222 lines
7 KiB
C
222 lines
7 KiB
C
/*
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* Generic Loader
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*
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* Copyright (C) 2014 Li Guang
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* Copyright (C) 2016 Xilinx Inc.
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* Written by Li Guang <lig.fnst@cn.fujitsu.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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*/
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/*
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* Internally inside QEMU this is a device. It is a strange device that
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* provides no hardware interface but allows QEMU to monkey patch memory
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* specified when it is created. To be able to do this it has a reset
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* callback that does the memory operations.
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* This device allows the user to monkey patch memory. To be able to do
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* this it needs a backend to manage the datas, the same as other
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* memory-related devices. In this case as the backend is so trivial we
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* have merged it with the frontend instead of creating and maintaining a
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* separate backend.
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*/
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#include "qemu/osdep.h"
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#include "hw/core/cpu.h"
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#include "hw/sysbus.h"
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#include "sysemu/dma.h"
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#include "sysemu/reset.h"
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#include "hw/loader.h"
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#include "hw/qdev-properties.h"
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#include "qapi/error.h"
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#include "qemu/module.h"
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#include "hw/core/generic-loader.h"
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#define CPU_NONE 0xFFFFFFFF
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static void generic_loader_reset(void *opaque)
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{
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GenericLoaderState *s = GENERIC_LOADER(opaque);
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if (s->set_pc) {
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CPUClass *cc = CPU_GET_CLASS(s->cpu);
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cpu_reset(s->cpu);
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if (cc) {
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cc->set_pc(s->cpu, s->addr);
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}
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}
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if (s->data_len) {
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assert(s->data_len < sizeof(s->data));
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dma_memory_write(s->cpu->as, s->addr, &s->data, s->data_len);
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}
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}
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static void generic_loader_realize(DeviceState *dev, Error **errp)
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{
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GenericLoaderState *s = GENERIC_LOADER(dev);
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hwaddr entry;
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int big_endian;
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int size = 0;
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s->set_pc = false;
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/* Perform some error checking on the user's options */
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if (s->data || s->data_len || s->data_be) {
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/* User is loading memory values */
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if (s->file) {
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error_setg(errp, "Specifying a file is not supported when loading "
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"memory values");
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return;
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} else if (s->force_raw) {
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error_setg(errp, "Specifying force-raw is not supported when "
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"loading memory values");
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return;
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} else if (!s->data_len) {
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/* We can't check for !data here as a value of 0 is still valid. */
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error_setg(errp, "Both data and data-len must be specified");
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return;
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} else if (s->data_len > 8) {
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error_setg(errp, "data-len cannot be greater then 8 bytes");
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return;
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}
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} else if (s->file || s->force_raw) {
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/* User is loading an image */
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if (s->data || s->data_len || s->data_be) {
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error_setg(errp, "data can not be specified when loading an "
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"image");
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return;
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}
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/* The user specified a file, only set the PC if they also specified
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* a CPU to use.
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*/
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if (s->cpu_num != CPU_NONE) {
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s->set_pc = true;
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}
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} else if (s->addr) {
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/* User is setting the PC */
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if (s->data || s->data_len || s->data_be) {
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error_setg(errp, "data can not be specified when setting a "
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"program counter");
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return;
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} else if (s->cpu_num == CPU_NONE) {
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error_setg(errp, "cpu_num must be specified when setting a "
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"program counter");
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return;
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}
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s->set_pc = true;
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} else {
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/* Did the user specify anything? */
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error_setg(errp, "please include valid arguments");
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return;
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}
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qemu_register_reset(generic_loader_reset, dev);
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if (s->cpu_num != CPU_NONE) {
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s->cpu = qemu_get_cpu(s->cpu_num);
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if (!s->cpu) {
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error_setg(errp, "Specified boot CPU#%d is nonexistent",
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s->cpu_num);
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return;
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}
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} else {
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s->cpu = first_cpu;
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}
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big_endian = target_words_bigendian();
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if (s->file) {
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AddressSpace *as = s->cpu ? s->cpu->as : NULL;
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if (!s->force_raw) {
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size = load_elf_as(s->file, NULL, NULL, NULL, &entry, NULL, NULL,
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NULL, big_endian, 0, 0, 0, as);
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if (size < 0) {
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size = load_uimage_as(s->file, &entry, NULL, NULL, NULL, NULL,
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as);
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}
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if (size < 0) {
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size = load_targphys_hex_as(s->file, &entry, as);
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}
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}
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if (size < 0 || s->force_raw) {
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/* Default to the maximum size being the machine's ram size */
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size = load_image_targphys_as(s->file, s->addr, ram_size, as);
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} else {
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s->addr = entry;
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}
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if (size < 0) {
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error_setg(errp, "Cannot load specified image %s", s->file);
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return;
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}
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}
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/* Convert the data endiannes */
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if (s->data_be) {
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s->data = cpu_to_be64(s->data);
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} else {
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s->data = cpu_to_le64(s->data);
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}
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}
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static void generic_loader_unrealize(DeviceState *dev)
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{
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qemu_unregister_reset(generic_loader_reset, dev);
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}
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static Property generic_loader_props[] = {
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DEFINE_PROP_UINT64("addr", GenericLoaderState, addr, 0),
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DEFINE_PROP_UINT64("data", GenericLoaderState, data, 0),
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DEFINE_PROP_UINT8("data-len", GenericLoaderState, data_len, 0),
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DEFINE_PROP_BOOL("data-be", GenericLoaderState, data_be, false),
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DEFINE_PROP_UINT32("cpu-num", GenericLoaderState, cpu_num, CPU_NONE),
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DEFINE_PROP_BOOL("force-raw", GenericLoaderState, force_raw, false),
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DEFINE_PROP_STRING("file", GenericLoaderState, file),
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DEFINE_PROP_END_OF_LIST(),
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};
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static void generic_loader_class_init(ObjectClass *klass, void *data)
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{
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DeviceClass *dc = DEVICE_CLASS(klass);
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/* The reset function is not registered here and is instead registered in
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* the realize function to allow this device to be added via the device_add
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* command in the QEMU monitor.
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* TODO: Improve the device_add functionality to allow resets to be
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* connected
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*/
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dc->realize = generic_loader_realize;
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dc->unrealize = generic_loader_unrealize;
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device_class_set_props(dc, generic_loader_props);
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dc->desc = "Generic Loader";
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set_bit(DEVICE_CATEGORY_MISC, dc->categories);
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}
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static TypeInfo generic_loader_info = {
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.name = TYPE_GENERIC_LOADER,
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.parent = TYPE_DEVICE,
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.instance_size = sizeof(GenericLoaderState),
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.class_init = generic_loader_class_init,
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};
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static void generic_loader_register_type(void)
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{
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type_register_static(&generic_loader_info);
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}
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type_init(generic_loader_register_type)
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