hw/misc: add vmcoreinfo device

=================

VMCoreInfo device

=================

The `-device vmcoreinfo` will create a fw_cfg entry for a guest to

store dump details.

etc/vmcoreinfo

**************

A guest may use this fw_cfg entry to add information details to qemu

dumps.

The entry of 16 bytes has the following layout, in little-endian::

#define VMCOREINFO_FORMAT_NONE 0x0

#define VMCOREINFO_FORMAT_ELF 0x1

    struct FWCfgVMCoreInfo {

        uint16_t host_format;  /* formats host supports */

        uint16_t guest_format; /* format guest supplies */

        uint32_t size;         /* size of vmcoreinfo region */

        uint64_t paddr;        /* physical address of vmcoreinfo region */

    };

Only full write (of 16 bytes) are considered valid for further

processing of entry values.

A write of 0 in guest_format will disable further processing of

vmcoreinfo entry values & content.

Format & content

****************

As of qemu 2.11, only VMCOREINFO_FORMAT_ELF is supported.

The entry gives location and size of an ELF note that is appended in

qemu dumps.

The note format/class must be of the target bitness and the size must

be less than 1Mb.

common-obj-$(CONFIG_EDU) += edu.o

common-obj-y += unimp.o

common-obj-y += vmcoreinfo.o

obj-$(CONFIG_VMPORT) += vmport.o

/*

 * Virtual Machine coreinfo device

 *

 * Copyright (C) 2017 Red Hat, Inc.

 *

 * Authors: Marc-André Lureau <marcandre.lureau@redhat.com>

 *

 * 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 "qapi/error.h"

#include "hw/nvram/fw_cfg.h"

#include "hw/misc/vmcoreinfo.h"

static void fw_cfg_vmci_write(void *dev, off_t offset, size_t len)

{

    VMCoreInfoState *s = VMCOREINFO(dev);

    s->has_vmcoreinfo = offset == 0 && len == sizeof(s->vmcoreinfo)

        && s->vmcoreinfo.guest_format != VMCOREINFO_FORMAT_NONE;

}

static void vmcoreinfo_reset(void *dev)

{

    VMCoreInfoState *s = VMCOREINFO(dev);

    s->has_vmcoreinfo = false;

    memset(&s->vmcoreinfo, 0, sizeof(s->vmcoreinfo));

    s->vmcoreinfo.host_format = cpu_to_le16(VMCOREINFO_FORMAT_ELF);

}

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

{

    VMCoreInfoState *s = VMCOREINFO(dev);

    FWCfgState *fw_cfg = fw_cfg_find();

    /* Given that this function is executing, there is at least one VMCOREINFO

     * device. Check if there are several.

     */

    if (!vmcoreinfo_find()) {

        error_setg(errp, "at most one %s device is permitted",

                   VMCOREINFO_DEVICE);

        return;

    }

    if (!fw_cfg || !fw_cfg->dma_enabled) {

        error_setg(errp, "%s device requires fw_cfg with DMA",

                   VMCOREINFO_DEVICE);

        return;

    }

    fw_cfg_add_file_callback(fw_cfg, "etc/vmcoreinfo",

                             NULL, fw_cfg_vmci_write, s,

                             &s->vmcoreinfo, sizeof(s->vmcoreinfo), false);

    qemu_register_reset(vmcoreinfo_reset, dev);

}

static const VMStateDescription vmstate_vmcoreinfo = {

    .name = "vmcoreinfo",

    .version_id = 1,

    .minimum_version_id = 1,

    .fields = (VMStateField[]) {

        VMSTATE_BOOL(has_vmcoreinfo, VMCoreInfoState),

        VMSTATE_UINT16(vmcoreinfo.host_format, VMCoreInfoState),

        VMSTATE_UINT16(vmcoreinfo.guest_format, VMCoreInfoState),

        VMSTATE_UINT32(vmcoreinfo.size, VMCoreInfoState),

        VMSTATE_UINT64(vmcoreinfo.paddr, VMCoreInfoState),

        VMSTATE_END_OF_LIST()

    },

};

static void vmcoreinfo_device_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    dc->vmsd = &vmstate_vmcoreinfo;

    dc->realize = vmcoreinfo_realize;

    dc->hotpluggable = false;

}

static const TypeInfo vmcoreinfo_device_info = {

    .name          = VMCOREINFO_DEVICE,

    .parent        = TYPE_DEVICE,

    .instance_size = sizeof(VMCoreInfoState),

    .class_init    = vmcoreinfo_device_class_init,

};

static void vmcoreinfo_register_types(void)

{

    type_register_static(&vmcoreinfo_device_info);

}

type_init(vmcoreinfo_register_types)

/*

 * Virtual Machine coreinfo device

 *

 * Copyright (C) 2017 Red Hat, Inc.

 *

 * Authors: Marc-André Lureau <marcandre.lureau@redhat.com>

 *

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

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

 *

 */

#ifndef VMCOREINFO_H

#define VMCOREINFO_H

#include "hw/qdev.h"

#define VMCOREINFO_DEVICE "vmcoreinfo"

#define VMCOREINFO(obj) OBJECT_CHECK(VMCoreInfoState, (obj), VMCOREINFO_DEVICE)

#define VMCOREINFO_FORMAT_NONE 0x0

#define VMCOREINFO_FORMAT_ELF 0x1

/* all fields are little-endian */

typedef struct FWCfgVMCoreInfo {

    uint16_t host_format; /* set on reset */

    uint16_t guest_format;

    uint32_t size;

    uint64_t paddr;

} QEMU_PACKED FWCfgVMCoreInfo;

typedef struct VMCoreInfoState {

    DeviceClass parent_obj;

    bool has_vmcoreinfo;

    FWCfgVMCoreInfo vmcoreinfo;

} VMCoreInfoState;

/* returns NULL unless there is exactly one device */

static inline VMCoreInfoState *vmcoreinfo_find(void)

{

    Object *o = object_resolve_path_type("", VMCOREINFO_DEVICE, NULL);

    return o ? VMCOREINFO(o) : NULL;

}

#endif