Re: [PATCH v6 12/15] hw/vmapple/cfg: Introduce vmapple cfg region

[Akihiko Odaki <akihiko.odaki@daynix.com>]

On 2024/11/04 0:00, Phil Dennis-Jordan wrote:
> From: Alexander Graf <graf@amazon.com>
> 
> Instead of device tree or other more standardized means, VMApple passes
> platform configuration to the first stage boot loader in a binary encoded
> format that resides at a dedicated RAM region in physical address space.
> 
> This patch models this configuration space as a qdev device which we can
> then map at the fixed location in the address space. That way, we can
> influence and annotate all configuration fields easily.
> 
> Signed-off-by: Alexander Graf <graf@amazon.com>
> Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
> ---
> 
> v3:
> 
>   * Replaced legacy device reset method with Resettable method
> 
> v4:
> 
>   * Fixed initialisation of default values for properties
>   * Dropped superfluous endianness conversions
>   * Moved most header code to .c, device name #define goes in vmapple.h
> 
> v5:
> 
>   * Improved error reporting in case of string property buffer overflow.
> 
>   hw/vmapple/Kconfig           |   3 +
>   hw/vmapple/cfg.c             | 203 +++++++++++++++++++++++++++++++++++
>   hw/vmapple/meson.build       |   1 +
>   include/hw/vmapple/vmapple.h |   2 +
>   4 files changed, 209 insertions(+)
>   create mode 100644 hw/vmapple/cfg.c
> 
> diff --git a/hw/vmapple/Kconfig b/hw/vmapple/Kconfig
> index 68f88876eb9..8bbeb9a9237 100644
> --- a/hw/vmapple/Kconfig
> +++ b/hw/vmapple/Kconfig
> @@ -4,3 +4,6 @@ config VMAPPLE_AES
>   config VMAPPLE_BDIF
>       bool
>   
> +config VMAPPLE_CFG
> +    bool
> +
> diff --git a/hw/vmapple/cfg.c b/hw/vmapple/cfg.c
> new file mode 100644
> index 00000000000..91c57239f86
> --- /dev/null
> +++ b/hw/vmapple/cfg.c
> @@ -0,0 +1,203 @@
> +/*
> + * VMApple Configuration Region
> + *
> + * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights Reserved.
> + *
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + * 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/vmapple/vmapple.h"
> +#include "hw/sysbus.h"
> +#include "qemu/log.h"
> +#include "qemu/module.h"
> +#include "qapi/error.h"
> +#include "net/net.h"
> +
> +OBJECT_DECLARE_SIMPLE_TYPE(VMAppleCfgState, VMAPPLE_CFG)
> +
> +#define VMAPPLE_CFG_SIZE 0x00010000
> +
> +typedef struct VMAppleCfg {
> +    uint32_t version;         /* 0x000 */
> +    uint32_t nr_cpus;         /* 0x004 */
> +    uint32_t unk1;            /* 0x008 */
> +    uint32_t unk2;            /* 0x00c */
> +    uint32_t unk3;            /* 0x010 */
> +    uint32_t unk4;            /* 0x014 */
> +    uint64_t ecid;            /* 0x018 */
> +    uint64_t ram_size;        /* 0x020 */
> +    uint32_t run_installer1;  /* 0x028 */
> +    uint32_t unk5;            /* 0x02c */
> +    uint32_t unk6;            /* 0x030 */
> +    uint32_t run_installer2;  /* 0x034 */
> +    uint32_t rnd;             /* 0x038 */
> +    uint32_t unk7;            /* 0x03c */
> +    MACAddr mac_en0;          /* 0x040 */
> +    uint8_t pad1[2];
> +    MACAddr mac_en1;          /* 0x048 */
> +    uint8_t pad2[2];
> +    MACAddr mac_wifi0;        /* 0x050 */
> +    uint8_t pad3[2];
> +    MACAddr mac_bt0;          /* 0x058 */
> +    uint8_t pad4[2];
> +    uint8_t reserved[0xa0];   /* 0x060 */
> +    uint32_t cpu_ids[0x80];   /* 0x100 */
> +    uint8_t scratch[0x200];   /* 0x180 */
> +    char serial[32];          /* 0x380 */
> +    char unk8[32];            /* 0x3a0 */
> +    char model[32];           /* 0x3c0 */
> +    uint8_t unk9[32];         /* 0x3e0 */
> +    uint32_t unk10;           /* 0x400 */
> +    char soc_name[32];        /* 0x404 */
> +} VMAppleCfg;
> +
> +struct VMAppleCfgState {
> +    SysBusDevice parent_obj;
> +    VMAppleCfg cfg;
> +
> +    MemoryRegion mem;
> +    char *serial;
> +    char *model;
> +    char *soc_name;
> +};
> +
> +static void vmapple_cfg_reset(Object *obj, ResetType type)
> +{
> +    VMAppleCfgState *s = VMAPPLE_CFG(obj);
> +    VMAppleCfg *cfg;
> +
> +    cfg = memory_region_get_ram_ptr(&s->mem);
> +    memset(cfg, 0, VMAPPLE_CFG_SIZE);
> +    *cfg = s->cfg;
> +}
> +
> +static bool strlcpy_set_error(char *restrict dst, const char *restrict src,
> +                              size_t dst_size, Error **errp,
> +                              const char *parent_func, const char *location,
> +                              const char *buffer_name, const char *extra_info)
> +{
> +    size_t len;
> +
> +    len = g_strlcpy(dst, src, dst_size);
> +    if (len < dst_size) { /* len does not count nul terminator */
> +        return true;
> +    }
> +
> +    error_setg(errp,
> +               "%s (%s) strlcpy error: Destination buffer %s too small "
> +               "(need %zu, have %zu) %s",
> +               parent_func, location, buffer_name, len + 1, dst_size, extra_info);

Let's avoid printing source locations. This is a user-facing error 
message so it should focus on pointing out what's wrong with the user input.

> +    return false;
> +}
> +
> +/*
> + * String copying wrapper that returns and reports a runtime error in
> + * case of truncation due to insufficient destination buffer space.
> + */
> +#define strlcpy_array_return_error(dst_array, src, errp, extra_info) \
> +    do { \
> +        if (!strlcpy_set_error((dst_array), (src), ARRAY_SIZE(dst_array), \
> +                               (errp), __func__, stringify(__LINE__), \
> +                               # dst_array, extra_info)) { \
> +            return; \
> +        } \
> +    } while (0)
> +
> +static void vmapple_cfg_realize(DeviceState *dev, Error **errp)
> +{
> +    VMAppleCfgState *s = VMAPPLE_CFG(dev);
> +    uint32_t i;
> +
> +    if (!s->serial) {
> +        s->serial = g_strdup("1234");
> +    }
> +    if (!s->model) {
> +        s->model = g_strdup("VM0001");
> +    }
> +    if (!s->soc_name) {
> +        s->soc_name = g_strdup("Apple M1 (Virtual)");
> +    }
> +
> +    strlcpy_array_return_error(s->cfg.serial, s->serial, errp,
> +                               "setting 'serial' property on VMApple cfg device");
> +    strlcpy_array_return_error(s->cfg.model, s->model, errp,
> +                               "setting 'model' property on VMApple cfg device");
> +    strlcpy_array_return_error(s->cfg.soc_name, s->soc_name, errp,
> +                               "setting 'soc_name' property on VMApple cfg device");
> +    strlcpy_array_return_error(s->cfg.unk8, "D/A", errp, "");
> +    s->cfg.version = 2;
> +    s->cfg.unk1 = 1;
> +    s->cfg.unk2 = 1;
> +    s->cfg.unk3 = 0x20;
> +    s->cfg.unk4 = 0;
> +    s->cfg.unk5 = 1;
> +    s->cfg.unk6 = 1;
> +    s->cfg.unk7 = 0;
> +    s->cfg.unk10 = 1;
> +
> +    if (s->cfg.nr_cpus > ARRAY_SIZE(s->cfg.cpu_ids)) {
> +        error_setg(errp,
> +                   "Failed to create %u CPUs, vmapple machine supports %zu max",
> +                   s->cfg.nr_cpus, ARRAY_SIZE(s->cfg.cpu_ids));
> +        return;
> +    }
> +    for (i = 0; i < s->cfg.nr_cpus; i++) {
> +        s->cfg.cpu_ids[i] = i;
> +    }
> +}
> +
> +static void vmapple_cfg_init(Object *obj)
> +{
> +    VMAppleCfgState *s = VMAPPLE_CFG(obj);
> +
> +    memory_region_init_ram(&s->mem, obj, "VMApple Config", VMAPPLE_CFG_SIZE,
> +                           &error_fatal);
> +    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mem);
> +}
> +
> +static Property vmapple_cfg_properties[] = {
> +    DEFINE_PROP_UINT32("nr-cpus", VMAppleCfgState, cfg.nr_cpus, 1),
> +    DEFINE_PROP_UINT64("ecid", VMAppleCfgState, cfg.ecid, 0),
> +    DEFINE_PROP_UINT64("ram-size", VMAppleCfgState, cfg.ram_size, 0),
> +    DEFINE_PROP_UINT32("run_installer1", VMAppleCfgState, cfg.run_installer1, 0),
> +    DEFINE_PROP_UINT32("run_installer2", VMAppleCfgState, cfg.run_installer2, 0),
> +    DEFINE_PROP_UINT32("rnd", VMAppleCfgState, cfg.rnd, 0),
> +    DEFINE_PROP_MACADDR("mac-en0", VMAppleCfgState, cfg.mac_en0),
> +    DEFINE_PROP_MACADDR("mac-en1", VMAppleCfgState, cfg.mac_en1),
> +    DEFINE_PROP_MACADDR("mac-wifi0", VMAppleCfgState, cfg.mac_wifi0),
> +    DEFINE_PROP_MACADDR("mac-bt0", VMAppleCfgState, cfg.mac_bt0),
> +    DEFINE_PROP_STRING("serial", VMAppleCfgState, serial),
> +    DEFINE_PROP_STRING("model", VMAppleCfgState, model),
> +    DEFINE_PROP_STRING("soc_name", VMAppleCfgState, soc_name),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void vmapple_cfg_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    ResettableClass *rc = RESETTABLE_CLASS(klass);
> +
> +    dc->realize = vmapple_cfg_realize;
> +    dc->desc = "VMApple Configuration Region";
> +    device_class_set_props(dc, vmapple_cfg_properties);
> +    rc->phases.hold = vmapple_cfg_reset;
> +}
> +
> +static const TypeInfo vmapple_cfg_info = {
> +    .name          = TYPE_VMAPPLE_CFG,
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(VMAppleCfgState),
> +    .instance_init = vmapple_cfg_init,
> +    .class_init    = vmapple_cfg_class_init,
> +};
> +
> +static void vmapple_cfg_register_types(void)
> +{
> +    type_register_static(&vmapple_cfg_info);
> +}
> +
> +type_init(vmapple_cfg_register_types)
> diff --git a/hw/vmapple/meson.build b/hw/vmapple/meson.build
> index d4624713deb..64b78693a31 100644
> --- a/hw/vmapple/meson.build
> +++ b/hw/vmapple/meson.build
> @@ -1,2 +1,3 @@
>   system_ss.add(when: 'CONFIG_VMAPPLE_AES',  if_true: files('aes.c'))
>   system_ss.add(when: 'CONFIG_VMAPPLE_BDIF', if_true: files('bdif.c'))
> +system_ss.add(when: 'CONFIG_VMAPPLE_CFG',  if_true: files('cfg.c'))
> diff --git a/include/hw/vmapple/vmapple.h b/include/hw/vmapple/vmapple.h
> index 9090e9c5ac8..3bba59f5ec7 100644
> --- a/include/hw/vmapple/vmapple.h
> +++ b/include/hw/vmapple/vmapple.h
> @@ -16,4 +16,6 @@
>   
>   #define TYPE_VMAPPLE_BDIF "vmapple-bdif"
>   
> +#define TYPE_VMAPPLE_CFG "vmapple-cfg"
> +
>   #endif /* HW_VMAPPLE_VMAPPLE_H */