Re: [PATCH v3 05/18] hw/misc: riscv_worldguard: Add RISC-V WorldGuard global config

[Konstantin Semichastnov <k.semichastnov@syntacore.com>]

On 10/21/25 18:55, Jim Shu wrote:
> Add a device for RISCV WG global config, which contains the number of
> worlds, reset value, and trusted WID ... etc.
> 
> This global config is used by both CPU WG extension and wgChecker devices.
> 
> Signed-off-by: Jim Shu <jim.shu@sifive.com>
> Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
> ---
>   hw/misc/Kconfig                    |   3 +
>   hw/misc/meson.build                |   1 +
>   hw/misc/riscv_worldguard.c         | 182 +++++++++++++++++++++++++++++
>   include/hw/misc/riscv_worldguard.h |  56 +++++++++
>   4 files changed, 242 insertions(+)
>   create mode 100644 hw/misc/riscv_worldguard.c
>   create mode 100644 include/hw/misc/riscv_worldguard.h
> 
> diff --git a/hw/misc/Kconfig b/hw/misc/Kconfig
> index 4e35657468..bee8824868 100644
> --- a/hw/misc/Kconfig
> +++ b/hw/misc/Kconfig
> @@ -235,4 +235,7 @@ config IOSB
>   config XLNX_VERSAL_TRNG
>       bool
>   
> +config RISCV_WORLDGUARD
> +    bool
> +
>   source macio/Kconfig
> diff --git a/hw/misc/meson.build b/hw/misc/meson.build
> index b1d8d8e5d2..200ccc96c0 100644
> --- a/hw/misc/meson.build
> +++ b/hw/misc/meson.build
> @@ -34,6 +34,7 @@ system_ss.add(when: 'CONFIG_SIFIVE_E_PRCI', if_true: files('sifive_e_prci.c'))
>   system_ss.add(when: 'CONFIG_SIFIVE_E_AON', if_true: files('sifive_e_aon.c'))
>   system_ss.add(when: 'CONFIG_SIFIVE_U_OTP', if_true: files('sifive_u_otp.c'))
>   system_ss.add(when: 'CONFIG_SIFIVE_U_PRCI', if_true: files('sifive_u_prci.c'))
> +specific_ss.add(when: 'CONFIG_RISCV_WORLDGUARD', if_true: files('riscv_worldguard.c'))
>   
>   subdir('macio')
>   
> diff --git a/hw/misc/riscv_worldguard.c b/hw/misc/riscv_worldguard.c
> new file mode 100644
> index 0000000000..588c16ae9a
> --- /dev/null
> +++ b/hw/misc/riscv_worldguard.c
> @@ -0,0 +1,182 @@
> +/*
> + * RISC-V WorldGuard Device
> + *
> + * Copyright (c) 2022 SiFive, Inc.
> + *
> + * This provides WorldGuard global config.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2 or later, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "qapi/error.h"
> +#include "qemu/log.h"
> +#include "exec/hwaddr.h"
> +#include "hw/registerfields.h"
> +#include "hw/sysbus.h"
> +#include "hw/hw.h"
> +#include "hw/qdev-properties.h"
> +#include "hw/misc/riscv_worldguard.h"
> +#include "hw/core/cpu.h"
> +#include "target/riscv/cpu.h"
> +#include "trace.h"
> +
> +/*
> + * WorldGuard global config:
> + * List the global setting of WG, like num-of-worlds. It is unique in the machine.
> + * All CPUs with WG extension and wgChecker devices will use it.
> + */
> +struct RISCVWorldGuardState *worldguard_config;
> +
> +static Property riscv_worldguard_properties[] = {
Hi, I believe that this array should also be declared as "const", as 
otherwise it will not compile due to the call of 
device_class_set_props() on line 245. This is because 
device_class_set_props() expects a property array to be constant, as it 
checks for the last element to be non-null at compile time.

> +    DEFINE_PROP_UINT32("nworlds", RISCVWorldGuardState, nworlds, 0),
> +
> +    /* Only Trusted WID could access wgCheckers if it is enabled. */
> +    DEFINE_PROP_UINT32("trustedwid", RISCVWorldGuardState, trustedwid, NO_TRUSTEDWID),
> +
> +    /*
> +     * WG reset value is bypass mode in HW. All WG permission checkings are
> +     * pass by default, so SW could correctly run on the machine w/o any WG
> +     * programming.
> +     */
> +    DEFINE_PROP_BOOL("hw-bypass", RISCVWorldGuardState, hw_bypass, false),
> +
> +    /*
> +     * TrustZone compatible mode:
> +     * This mode is only supported in 2 worlds system. It converts WorldGuard
> +     * WID to TZ NS signal on the bus so WG could be cooperated with
> +     * TZ components. In QEMU, it converts WID to 'MemTxAttrs.secure' bit used
> +     * by TZ.
> +     */
> +    DEFINE_PROP_BOOL("tz-compat", RISCVWorldGuardState, tz_compat, false),
> +};
> +
> +/* WID to MemTxAttrs converter */
> +void wid_to_mem_attrs(MemTxAttrs *attrs, uint32_t wid)
> +{
> +    g_assert(wid < worldguard_config->nworlds);
> +
> +    attrs->unspecified = 0;
> +    if (worldguard_config->tz_compat) {
> +        attrs->secure = wid;
> +    } else {
> +        attrs->world_id = wid;
> +    }
> +}
> +
> +/* MemTxAttrs to WID converter */
> +uint32_t mem_attrs_to_wid(MemTxAttrs attrs)
> +{
> +    if (attrs.unspecified) {
> +        if (worldguard_config->trustedwid != NO_TRUSTEDWID) {
> +            return worldguard_config->trustedwid;
> +        } else {
> +            return worldguard_config->nworlds - 1;
> +        }
> +    }
> +
> +    if (worldguard_config->tz_compat) {
> +        return attrs.secure;
> +    } else {
> +        return attrs.world_id;
> +    }
> +}
> +
> +bool could_access_wgblocks(MemTxAttrs attrs, const char *wgblock)
> +{
> +    uint32_t wid = mem_attrs_to_wid(attrs);
> +    uint32_t trustedwid = worldguard_config->trustedwid;
> +
> +    if ((trustedwid == NO_TRUSTEDWID) || (wid == trustedwid)) {
> +        return true;
> +    } else {
> +        /*
> +         * Only Trusted WID could access WG blocks if having it.
> +         * Access them from other WIDs will get failed.
> +         */
> +        qemu_log_mask(LOG_GUEST_ERROR,
> +                      "%s: Invalid access to %s from non-trusted WID %d\n",
> +                      __func__, wgblock, wid);
> +
> +        return false;
> +    }
> +}
> +
> +static void riscv_worldguard_realize(DeviceState *dev, Error **errp)
> +{
> +    RISCVWorldGuardState *s = RISCV_WORLDGUARD(dev);
> +
> +    if (worldguard_config != NULL) {
> +        error_setg(errp, "Couldn't realize multiple global WorldGuard configs.");
> +        return;
> +    }
> +
> +    if ((s->nworlds) & (s->nworlds - 1)) {
> +        error_setg(errp, "Current implementation only support power-of-2 NWorld.");
> +        return;
> +    }
> +
> +    if ((s->trustedwid != NO_TRUSTEDWID) && (s->trustedwid >= s->nworlds)) {
> +        error_setg(errp, "Trusted WID must be less than the number of world.");
> +        return;
> +    }
> +
> +    if ((s->nworlds != 2) && (s->tz_compat)) {
> +        error_setg(errp, "Only 2 worlds system could use TrustZone compatible mode.");
> +        return;
> +    }
> +
> +    /* Register WG global config */
> +    worldguard_config = s;
> +
> +    /* Initialize global data for wgChecker */
> +    wgc_slot_perm_mask = MAKE_64BIT_MASK(0, 2 * worldguard_config->nworlds);
> +}
> +
> +static void riscv_worldguard_class_init(ObjectClass *klass, const void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +
> +    device_class_set_props(dc, riscv_worldguard_properties);
> +    dc->user_creatable = true;
> +    dc->realize = riscv_worldguard_realize;
> +}
> +
> +static const TypeInfo riscv_worldguard_info = {
> +    .name          = TYPE_RISCV_WORLDGUARD,
> +    .parent        = TYPE_DEVICE,
> +    .instance_size = sizeof(RISCVWorldGuardState),
> +    .class_init    = riscv_worldguard_class_init,
> +};
> +
> +/*
> + * Create WorldGuard global config
> + */
> +DeviceState *riscv_worldguard_create(uint32_t nworlds, uint32_t trustedwid,
> +                                     bool hw_bypass, bool tz_compat)
> +{
> +    DeviceState *dev = qdev_new(TYPE_RISCV_WORLDGUARD);
> +    qdev_prop_set_uint32(dev, "nworlds", nworlds);
> +    qdev_prop_set_uint32(dev, "trustedwid", trustedwid);
> +    qdev_prop_set_bit(dev, "hw-bypass", hw_bypass);
> +    qdev_prop_set_bit(dev, "tz-compat", tz_compat);
> +    qdev_realize(DEVICE(dev), NULL, &error_fatal);
> +    return dev;
> +}
> +
> +static void riscv_worldguard_register_types(void)
> +{
> +    type_register_static(&riscv_worldguard_info);
> +}
> +
> +type_init(riscv_worldguard_register_types)
> diff --git a/include/hw/misc/riscv_worldguard.h b/include/hw/misc/riscv_worldguard.h
> new file mode 100644
> index 0000000000..bb276e59b8
> --- /dev/null
> +++ b/include/hw/misc/riscv_worldguard.h
> @@ -0,0 +1,56 @@
> +/*
> + * RISC-V WorldGuard Devices
> + *
> + * Copyright (c) 2022 RISCV, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2 or later, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#ifndef HW_RISCV_WORLDGUARD_H
> +#define HW_RISCV_WORLDGUARD_H
> +
> +#include "qom/object.h"
> +#include "hw/sysbus.h"
> +#include "exec/hwaddr.h"
> +
> +#define TYPE_RISCV_WORLDGUARD "riscv.worldguard"
> +
> +#define NO_TRUSTEDWID           UINT32_MAX
> +
> +typedef struct RISCVWorldGuardState RISCVWorldGuardState;
> +DECLARE_INSTANCE_CHECKER(RISCVWorldGuardState, RISCV_WORLDGUARD,
> +                         TYPE_RISCV_WORLDGUARD)
> +
> +struct RISCVWorldGuardState {
> +    /*< private >*/
> +    DeviceState parent_obj;
> +
> +    /*< public >*/
> +
> +    /* Property */
> +    uint32_t nworlds;
> +    uint32_t trustedwid;
> +    bool hw_bypass;
> +    bool tz_compat;
> +};
> +
> +extern struct RISCVWorldGuardState *worldguard_config;
> +
> +DeviceState *riscv_worldguard_create(uint32_t nworlds, uint32_t trustedwid,
> +                                     bool hw_bypass, bool tz_compat);
> +
> +void wid_to_mem_attrs(MemTxAttrs *attrs, uint32_t wid);
> +uint32_t mem_attrs_to_wid(MemTxAttrs attrs);
> +bool could_access_wgblocks(MemTxAttrs attrs, const char *wgblock);
> +
> +#endif