Re: [PATCH v8 12/15] hw/vmapple/cfg: Introduce vmapple cfg region

[Phil Dennis-Jordan]

On Sun, 10 Nov 2024 at 08:15, Akihiko Odaki <akihiko.odaki@daynix.com> wrote:
>
> On 2024/11/08 23:47, 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.
> >
> > v7:
> >
> >   * Changed error messages for overrun of properties with
> >     fixed-length strings to be more useful to users than developers.
> >
> > v8:
> >
> >   * Consistent parenthesising of macro arguments for better safety.
> >
> >   hw/vmapple/Kconfig           |   3 +
> >   hw/vmapple/cfg.c             | 196 +++++++++++++++++++++++++++++++++++
> >   hw/vmapple/meson.build       |   1 +
> >   include/hw/vmapple/vmapple.h |   2 +
> >   4 files changed, 202 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..787e2505d57
> > --- /dev/null
> > +++ b/hw/vmapple/cfg.c
> > @@ -0,0 +1,196 @@
> > +/*
> > + * 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 set_fixlen_property_or_error(char *restrict dst,
> > +                                         const char *restrict src,
> > +                                         size_t dst_size, Error **errp,
> > +                                         const char *property_name)
> > +{
> > +    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,
> > +               "Failed to set property '%s' on VMApple 'cfg' device: 
> > length "
> > +               "(%zu) exceeds maximum of %zu",
>
> Don't print the device name here as it will be automatically printed.

That's not what I'm seeing in tests. With code as-is, and setting an
overly long value from create_cfg() in the vmapple machine type
startup, I get the following output:

qemu-system-aarch64: Failed to set property 'soc_name' on VMApple
'cfg' device: length (50) exceeds maximum of 31

I don't see any redundant mention of an object or property name. Of
course, this error occurs during the cfg device's realize(), not
immediately when setting the property. I can't see a built-in way to
explicitly limit the length of a string property.

> > +               property_name, len, dst_size - 1);
> > +    return false;
> > +}
> > +
> > +#define set_fixlen_property_or_return(dst_array, src, errp, property_name) 
> > \
> > +    do { \
> > +        if (!set_fixlen_property_or_error((dst_array), (src), \
> > +                                          ARRAY_SIZE(dst_array), \
> > +                                          (errp), (property_name))) { \
> > +            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)");
> > +    }
> > +
> > +    set_fixlen_property_or_return(s->cfg.serial, s->serial, errp, 
> > "serial");
> > +    set_fixlen_property_or_return(s->cfg.model, s->model, errp, "model");
> > +    set_fixlen_property_or_return(s->cfg.soc_name, s->soc_name, errp, 
> > "soc_name");
> > +    set_fixlen_property_or_return(s->cfg.unk8, "D/A", errp, "unk8");
> > +    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 */
>
>