[v3,1/1] Add support for generating OpenSBI domains in the device tree

OpenSBI has support for domains, which are partitions of CPUs and memory into
isolated compartments. Domains can be specified in the device tree according to
a standardized format [1], which OpenSBI parses at boot time to initialize all
system domains. This patch enables simply specifying domains (and their
associated memory regions) on the QEMU command line, from which these are then
rendered into the machine's device tree.

At machine initialization time, a new create_fdt_opensbi_domains() function
walks the peripherals/peripherals-anon containers, identifies all domains and
memregions, and parses them into the relevant device tree structures.

[1] https://github.com/riscv-software-src/opensbi/blob/master/docs/domain_support.md

Signed-off-by: Gregor Haas <gregorhaas1997@gmail.com>
---
 MAINTAINERS                       |   7 +
 hw/riscv/Kconfig                  |   4 +
 hw/riscv/meson.build              |   1 +
 hw/riscv/opensbi_domain.c         | 542 ++++++++++++++++++++++++++++++
 hw/riscv/virt.c                   |   3 +
 include/hw/riscv/opensbi_domain.h |  50 +++
 6 files changed, 607 insertions(+)
 create mode 100644 hw/riscv/opensbi_domain.c
 create mode 100644 include/hw/riscv/opensbi_domain.h

On 8/5/24 6:04 PM, Gregor Haas wrote:
> OpenSBI has support for domains, which are partitions of CPUs and memory into
> isolated compartments. Domains can be specified in the device tree according to
> a standardized format [1], which OpenSBI parses at boot time to initialize all
> system domains. This patch enables simply specifying domains (and their
> associated memory regions) on the QEMU command line, from which these are then
> rendered into the machine's device tree.
> 
> At machine initialization time, a new create_fdt_opensbi_domains() function
> walks the peripherals/peripherals-anon containers, identifies all domains and
> memregions, and parses them into the relevant device tree structures.
> 
> [1] https://github.com/riscv-software-src/opensbi/blob/master/docs/domain_support.md
> 
> Signed-off-by: Gregor Haas <gregorhaas1997@gmail.com>
> ---

Reviewed-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>

>   MAINTAINERS                       |   7 +
>   hw/riscv/Kconfig                  |   4 +
>   hw/riscv/meson.build              |   1 +
>   hw/riscv/opensbi_domain.c         | 542 ++++++++++++++++++++++++++++++
>   hw/riscv/virt.c                   |   3 +
>   include/hw/riscv/opensbi_domain.h |  50 +++
>   6 files changed, 607 insertions(+)
>   create mode 100644 hw/riscv/opensbi_domain.c
>   create mode 100644 include/hw/riscv/opensbi_domain.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 98eddf7ae1..796c023a7b 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -355,6 +355,13 @@ F: target/riscv/XVentanaCondOps.decode
>   F: target/riscv/insn_trans/trans_xventanacondops.c.inc
>   F: disas/riscv-xventana*
>   
> +RISC-V OpenSBI domain support
> +M: Gregor Haas <gregorhaas1997@gmail.com>
> +L: qemu-riscv@nongnu.org
> +S: Maintained
> +F: hw/riscv/opensbi_domain.c
> +F: include/hw/riscv/opensbi_domain.h
> +
>   RENESAS RX CPUs
>   R: Yoshinori Sato <ysato@users.sourceforge.jp>
>   S: Orphan
> diff --git a/hw/riscv/Kconfig b/hw/riscv/Kconfig
> index a2030e3a6f..db3a4d77ad 100644
> --- a/hw/riscv/Kconfig
> +++ b/hw/riscv/Kconfig
> @@ -1,6 +1,9 @@
>   config RISCV_NUMA
>       bool
>   
> +config RISCV_OPENSBI_DOMAIN
> +    bool
> +
>   config IBEX
>       bool
>   
> @@ -40,6 +43,7 @@ config RISCV_VIRT
>       imply TPM_TIS_SYSBUS
>       select DEVICE_TREE
>       select RISCV_NUMA
> +    select RISCV_OPENSBI_DOMAIN
>       select GOLDFISH_RTC
>       select PCI
>       select PCI_EXPRESS_GENERIC_BRIDGE
> diff --git a/hw/riscv/meson.build b/hw/riscv/meson.build
> index f872674093..f47626c164 100644
> --- a/hw/riscv/meson.build
> +++ b/hw/riscv/meson.build
> @@ -1,6 +1,7 @@
>   riscv_ss = ss.source_set()
>   riscv_ss.add(files('boot.c'))
>   riscv_ss.add(when: 'CONFIG_RISCV_NUMA', if_true: files('numa.c'))
> +riscv_ss.add(when: 'CONFIG_RISCV_OPENSBI_DOMAIN', if_true: files('opensbi_domain.c'))
>   riscv_ss.add(files('riscv_hart.c'))
>   riscv_ss.add(when: 'CONFIG_OPENTITAN', if_true: files('opentitan.c'))
>   riscv_ss.add(when: 'CONFIG_RISCV_VIRT', if_true: files('virt.c'))
> diff --git a/hw/riscv/opensbi_domain.c b/hw/riscv/opensbi_domain.c
> new file mode 100644
> index 0000000000..67a6bab538
> --- /dev/null
> +++ b/hw/riscv/opensbi_domain.c
> @@ -0,0 +1,542 @@
> +#include "qemu/osdep.h"
> +#include "hw/riscv/opensbi_domain.h"
> +#include "hw/boards.h"
> +#include "hw/riscv/virt.h"
> +#include "qapi/error.h"
> +#include "qemu/cutils.h"
> +#include "qemu/error-report.h"
> +#include "sysemu/device_tree.h"
> +
> +#include <libfdt.h>
> +
> +static void create_fdt_domain_possible_harts(MachineState *ms,
> +                                             OpenSBIDomainState *s,
> +                                             char *path) {
> +    unsigned long i, cpu;
> +    unsigned long num_cpus;
> +
> +    num_cpus = s->last_possible_hart - s->first_possible_hart + 1;
> +    if (num_cpus) {
> +        g_autofree uint32_t *phandles = g_malloc0_n(num_cpus, sizeof(uint32_t));
> +
> +        for (i = 0, cpu = s->first_possible_hart; i < num_cpus; i++, cpu++) {
> +            g_autofree char *cpu_name = g_strdup_printf("/cpus/cpu@%li", cpu);
> +            phandles[i] = cpu_to_fdt32(qemu_fdt_get_phandle(
> +                    ms->fdt, cpu_name));
> +        }
> +
> +        qemu_fdt_setprop(ms->fdt, path, "possible-harts",
> +                         phandles, num_cpus * 4);
> +    }
> +}
> +
> +static void create_fdt_domain_regions(MachineState *ms,
> +                                      OpenSBIDomainState *s,
> +                                      char *path) {
> +    unsigned long i;
> +    int num_regions = 0;
> +    DeviceState *ds;
> +
> +    for (i = 0; i < OPENSBI_DOMAIN_MEMREGIONS_MAX; i++) {
> +        if (s->regions[i]) {
> +            num_regions++;
> +        }
> +    }
> +
> +    if (num_regions) {
> +        g_autofree uint32_t *regions =
> +                 g_malloc0_n(num_regions, 2 * sizeof(uint32_t));
> +        for (i = 0; i < OPENSBI_DOMAIN_MEMREGIONS_MAX; i++) {
> +            if (s->regions[i]) {
> +                ds = DEVICE(s->regions[i]);
> +                g_autofree char *region_name = g_strdup_printf(
> +                       "/chosen/opensbi-domains/%s", ds->id);
> +                regions[2 * i] = cpu_to_fdt32(qemu_fdt_get_phandle
> +                        (ms->fdt, region_name));
> +                regions[2 * i + 1] = cpu_to_fdt32(s->region_perms[i]);
> +            }
> +        }
> +
> +        qemu_fdt_setprop(ms->fdt, path, "regions",
> +                         regions, num_regions * 8);
> +    }
> +}
> +
> +struct DomainFDTState {
> +    MachineState *ms;
> +    bool regions;
> +};
> +
> +static void create_fdt_one_domain(MachineState *ms, OpenSBIDomainState *s)
> +{
> +    DeviceState *ds = DEVICE(s);
> +    g_autofree char *path, *cpu_name;
> +
> +    if (ds->id) {
> +        path = g_strdup_printf("/chosen/opensbi-domains/%s",
> +                               ds->id);
> +    } else {
> +        path = g_strdup_printf("/chosen/opensbi-domains/domain@%lx",
> +                               s->next_addr);
> +    }
> +
> +    qemu_fdt_add_subnode(ms->fdt, path);
> +    qemu_fdt_setprop_string(ms->fdt, path, "compatible",
> +                            "opensbi,domain,instance");
> +    qemu_fdt_setprop_cells(ms->fdt, path, "phandle",
> +                           qemu_fdt_alloc_phandle(ms->fdt));
> +
> +    create_fdt_domain_possible_harts(ms, s, path);
> +    create_fdt_domain_regions(ms, s, path);
> +
> +    /* Assign boot hart to this domain */
> +    if (s->boot_hart != -1) {
> +        cpu_name = g_strdup_printf("/cpus/cpu@%i", s->boot_hart);
> +        qemu_fdt_setprop_cell(ms->fdt, path, "boot-hart",
> +                              qemu_fdt_get_phandle(ms->fdt, cpu_name));
> +        if (s->assign) {
> +            qemu_fdt_setprop_cell(ms->fdt, cpu_name, "opensbi-domain",
> +                                    qemu_fdt_get_phandle(ms->fdt, path));
> +        }
> +    }
> +
> +    if (s->next_arg1 != -1) {
> +        qemu_fdt_setprop_cells(ms->fdt, path, "next-arg1",
> +                             (uint64_t) s->next_arg1 >> 32, s->next_arg1);
> +    }
> +
> +    if (s->next_addr != -1) {
> +        qemu_fdt_setprop_cells(ms->fdt, path, "next-addr",
> +                             (uint64_t) s->next_addr >> 32, s->next_addr);
> +    }
> +
> +    if (s->next_mode != -1) {
> +        qemu_fdt_setprop_cell(ms->fdt, path, "next-mode",
> +                            s->next_mode);
> +    }
> +
> +    if (s->system_reset_allowed) {
> +        qemu_fdt_setprop(ms->fdt, path, "system-reset-allowed", NULL, 0);
> +    }
> +
> +    if (s->system_suspend_allowed) {
> +        qemu_fdt_setprop(ms->fdt, path, "system-suspend-allowed", NULL, 0);
> +    }
> +}
> +
> +static uint32_t create_fdt_one_device(MachineState *ms, char *device)
> +{
> +    uint32_t phandle;
> +    int offs = fdt_path_offset(ms->fdt, device);
> +
> +    if (offs < 0) {
> +        error_report("%s: Could not find device %s: %s", __func__,
> +                     device, fdt_strerror(offs));
> +        exit(1);
> +    }
> +
> +    phandle = fdt_get_phandle(ms->fdt, offs);
> +    if (!phandle) {
> +        phandle = qemu_fdt_alloc_phandle(ms->fdt);
> +        qemu_fdt_setprop_cell(ms->fdt, device, "phandle", phandle);
> +    }
> +
> +    return phandle;
> +}
> +
> +static void create_fdt_one_memregion(MachineState *ms,
> +                                     OpenSBIMemregionState *s)
> +{
> +    g_autofree char *path;
> +    int i, dev, num_devices;
> +    DeviceState *ds = DEVICE(s);
> +
> +    path = g_strdup_printf("/chosen/opensbi-domains/%s", ds->id);
> +    qemu_fdt_add_subnode(ms->fdt, path);
> +    qemu_fdt_setprop_string(ms->fdt, path, "compatible",
> +                            "opensbi,domain,memregion");
> +    qemu_fdt_setprop_cells(ms->fdt, path, "base",
> +                           (uint64_t) s->base >> 32, s->base);
> +
> +    qemu_fdt_setprop_cell(ms->fdt, path, "order",
> +                          (uint32_t) s->order);
> +
> +    if (s->mmio) {
> +        qemu_fdt_setprop(ms->fdt, path, "mmio", NULL, 0);
> +
> +        /* Get all phandles for related devices */
> +        num_devices = 0;
> +        for (i = 0; i < OPENSBI_MEMREGION_DEVICES_MAX; i++) {
> +            if (s->devices[i]) {
> +                num_devices++;
> +            }
> +        }
> +
> +        if (num_devices) {
> +            g_autofree uint32_t *devices =
> +                g_malloc0_n(num_devices, sizeof(uint32_t));
> +            for (i = 0, dev = 0; i < OPENSBI_MEMREGION_DEVICES_MAX &&
> +                                 dev < num_devices; i++) {
> +                if (s->devices[i]) {
> +                    devices[dev++] = create_fdt_one_device(ms,
> +                                                         s->devices[i]);
> +                }
> +            }
> +
> +            qemu_fdt_setprop(ms->fdt, path, "devices", devices,
> +                             num_devices * 4);
> +        }
> +    }
> +
> +    qemu_fdt_setprop_cells(ms->fdt, path, "phandle",
> +                           qemu_fdt_alloc_phandle(ms->fdt));
> +}
> +
> +static int create_fdt_domains(Object *obj, void *opaque)
> +{
> +    struct DomainFDTState *dfs = opaque;
> +    OpenSBIDomainState *osds;
> +    OpenSBIMemregionState *osms;
> +
> +    osds = (OpenSBIDomainState *)
> +            object_dynamic_cast(obj, TYPE_OPENSBI_DOMAIN);
> +    osms = (OpenSBIMemregionState *)
> +            object_dynamic_cast(obj, TYPE_OPENSBI_MEMREGION);
> +
> +    if (dfs->regions) {
> +        if (osms) {
> +            create_fdt_one_memregion(dfs->ms, osms);
> +        }
> +    } else {
> +        if (osds) {
> +            create_fdt_one_domain(dfs->ms, osds);
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +static const char *containers[] = {
> +        "/peripheral", "/peripheral-anon"
> +};
> +
> +void create_fdt_opensbi_domains(MachineState *s)
> +{
> +    int i;
> +    MachineState *ms = MACHINE(s);
> +    Object *container;
> +
> +    struct DomainFDTState check = {
> +            .ms = ms,
> +            .regions = true
> +    };
> +
> +    /* Make sure that top-level node exists */
> +    qemu_fdt_add_subnode(ms->fdt, "/chosen/opensbi-domains");
> +    qemu_fdt_setprop_string(ms->fdt, "/chosen/opensbi-domains",
> +                            "compatible", "opensbi,domain,config");
> +
> +    /* Do a scan through regions first */
> +    for (i = 0; i < ARRAY_SIZE(containers); i++) {
> +        container = container_get(OBJECT(s), containers[i]);
> +        object_child_foreach(container, create_fdt_domains, &check);
> +    }
> +
> +    /* Then scan through domains */
> +    check.regions = false;
> +    for (i = 0; i < ARRAY_SIZE(containers); i++) {
> +        container = container_get(OBJECT(s), containers[i]);
> +        object_child_foreach(container, create_fdt_domains, &check);
> +    }
> +}
> +
> +/* OpenSBI Memregions */
> +
> +static void set_mmio(Object *obj, bool val, Error **err)
> +{
> +    OpenSBIMemregionState *s = OPENSBI_MEMREGION(obj);
> +    s->mmio = val;
> +}
> +
> +static void set_device(Object *obj, const char *val, Error **err)
> +{
> +    int i;
> +    OpenSBIMemregionState *s = OPENSBI_MEMREGION(obj);
> +
> +    for (i = 0; i < OPENSBI_DOMAIN_MEMREGIONS_MAX; i++) {
> +        if (!s->devices[i]) {
> +            s->devices[i] = g_strdup(val);
> +            break;
> +        }
> +    }
> +}
> +
> +static void opensbi_memregion_instance_init(Object *obj)
> +{
> +    int i;
> +    OpenSBIMemregionState *s = OPENSBI_MEMREGION(obj);
> +
> +    s->base = -1;
> +    object_property_add_uint64_ptr(obj, "base", &s->base,
> +                                   OBJ_PROP_FLAG_WRITE);
> +    object_property_set_description(obj, "base",
> +                                    "The base address of the domain memory region. If \"order\" is also specified, "
> +                                    "this property should be a 2 ^ order aligned 64 bit address");
> +
> +    s->order = -1;
> +    object_property_add_uint32_ptr(obj, "order", &s->order,
> +                                   OBJ_PROP_FLAG_WRITE);
> +    object_property_set_description(obj, "order",
> +                                    "The order of the domain memory region. This property should have a 32 bit value "
> +                                    "(i.e. one DT cell) in the range 3 <= order <= __riscv_xlen.");
> +
> +    s->mmio = false;
> +    object_property_add_bool(obj, "mmio", NULL, set_mmio);
> +    object_property_set_description(obj, "mmio",
> +                                    "A boolean flag representing whether the domain memory region is a "
> +                                    "memory-mapped I/O (MMIO) region.");
> +
> +    for (i = 0; i < OPENSBI_DOMAIN_MEMREGIONS_MAX; i++) {
> +        g_autofree char *propname = g_strdup_printf("device%i", i);
> +        object_property_add_str(obj, propname, NULL, set_device);
> +
> +        g_autofree char *description = g_strdup_printf(
> +                "Device %i (out of %i) for this memregion. This property should be a device tree path to the device.",
> +                i, OPENSBI_DOMAIN_MEMREGIONS_MAX);
> +        object_property_set_description(obj, propname, description);
> +    }
> +}
> +
> +static void opensbi_memregion_realize(DeviceState *ds, Error **errp)
> +{
> +    #if defined(TARGET_RISCV32)
> +    int xlen = 32;
> +    #elif defined(TARGET_RISCV64)
> +    int xlen = 64;
> +    #endif
> +
> +    OpenSBIMemregionState *s = OPENSBI_MEMREGION(ds);
> +
> +    if (s->base == -1) {
> +        error_setg(errp, "must specify base");
> +        return;
> +    }
> +
> +    if (s->order == -1) {
> +        error_setg(errp, "must specify order");
> +        return;
> +    }
> +
> +    /* Check order bounds */
> +    if (s->order < 3 || s->order > xlen) {
> +        error_setg(errp, "order must be between 3 and %d", xlen);
> +        return;
> +    }
> +
> +    /* Check base alignment */
> +    if (s->order < xlen && (s->base & (BIT(s->order) - 1))) {
> +        error_setg(errp, "base not aligned to order");
> +        return;
> +    }
> +}
> +
> +static void opensbi_memregion_class_init(ObjectClass *oc, void *opaque)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +    dc->realize = opensbi_memregion_realize;
> +}
> +
> +static const TypeInfo opensbi_memregion_info = {
> +        .name = TYPE_OPENSBI_MEMREGION,
> +        .parent = TYPE_DEVICE,
> +        .instance_init = opensbi_memregion_instance_init,
> +        .instance_size = sizeof(OpenSBIDomainState),
> +        .class_init = opensbi_memregion_class_init
> +};
> +
> +/* OpenSBI Domains */
> +
> +static void set_sysreset_allowed(Object *obj, bool val, Error **err)
> +{
> +    OpenSBIDomainState *s = OPENSBI_DOMAIN(obj);
> +    s->system_reset_allowed = val;
> +}
> +
> +static void set_suspend_allowed(Object *obj, bool val, Error **err)
> +{
> +    OpenSBIDomainState *s = OPENSBI_DOMAIN(obj);
> +    s->system_suspend_allowed = val;
> +}
> +
> +static void set_assign(Object *obj, bool val, Error **err)
> +{
> +    OpenSBIDomainState *s = OPENSBI_DOMAIN(obj);
> +    s->assign = val;
> +}
> +
> +static void set_possible_harts(Object *obj, const char *str, Error **err)
> +{
> +    OpenSBIDomainState *s = OPENSBI_DOMAIN(obj);
> +    const char *firstcpu,  *firstcpu_end, *lastcpu;
> +
> +    firstcpu = str;
> +    if (qemu_strtoul(firstcpu, &firstcpu_end, 0,
> +                     &s->first_possible_hart) < 0) {
> +        error_setg(err, "could not convert firstcpu");
> +        return;
> +    }
> +
> +    lastcpu = qemu_strchrnul(str, '-');
> +    if (*lastcpu) {
> +        if (lastcpu != firstcpu_end) {
> +            error_setg(err, "could not separate firstcpu and lastcpu");
> +            return;
> +        }
> +
> +        lastcpu++;
> +        if (qemu_strtoul(lastcpu, NULL, 0,
> +                         &s->last_possible_hart) < 0) {
> +            error_setg(err, "could not convert lastcpu");
> +            return;
> +        }
> +    } else {
> +        s->last_possible_hart = s->first_possible_hart;
> +    }
> +}
> +
> +static void opensbi_domain_instance_init(Object *obj)
> +{
> +    int i;
> +    OpenSBIDomainState *s = OPENSBI_DOMAIN(obj);
> +
> +    s->boot_hart = VIRT_CPUS_MAX;
> +    object_property_add_uint32_ptr(obj, "boot-hart", &s->boot_hart,
> +                                   OBJ_PROP_FLAG_WRITE);
> +    object_property_set_description(obj, "boot-hart",
> +                                    "The HART booting the domain instance.");
> +
> +    s->first_possible_hart = -1;
> +    s->last_possible_hart = -1;
> +    object_property_add_str(obj, "possible-harts", NULL, set_possible_harts);
> +    object_property_set_description(obj, "possible-harts",
> +                                    "The contiguous list of CPUs for the domain instance, specified as firstcpu[-lastcpu]");
> +
> +    s->next_arg1 = -1;
> +    object_property_add_uint64_ptr(obj, "next-arg1", &s->next_arg1,
> +                                   OBJ_PROP_FLAG_WRITE);
> +    object_property_set_description(obj, "next-arg1",
> +                                    "The 64 bit next booting stage arg1 for the domain instance.");
> +
> +    s->next_addr = -1;
> +    object_property_add_uint64_ptr(obj, "next-addr", &s->next_addr,
> +                                   OBJ_PROP_FLAG_WRITE);
> +    object_property_set_description(obj, "next-addr",
> +                                    "The 64 bit next booting stage address for the domain instance.");
> +
> +    s->next_mode = -1;
> +    object_property_add_uint32_ptr(obj, "next-mode", &s->next_mode,
> +                                   OBJ_PROP_FLAG_WRITE);
> +    object_property_set_description(obj, "next-mode",
> +                                    "The 32 bit next booting stage mode for the domain instance.");
> +
> +    s->system_reset_allowed = false;
> +    object_property_add_bool(obj, "system-reset-allowed", NULL,
> +                             set_sysreset_allowed);
> +    object_property_set_description(obj, "system-reset-allowed",
> +                                    "Whether the domain instance is allowed to do system reset.");
> +
> +    s->system_suspend_allowed = false;
> +    object_property_add_bool(obj, "system-suspend-allowed", NULL,
> +                             set_suspend_allowed);
> +    object_property_set_description(obj, "system-suspend-allowed",
> +                                    "Whether the domain instance is allowed to do system suspend.");
> +
> +    for (i = 0; i < OPENSBI_DOMAIN_MEMREGIONS_MAX; i++) {
> +        s->regions[i] = NULL;
> +        g_autofree char *reg_propname = g_strdup_printf("region%i", i);
> +        object_property_add_link(obj, reg_propname, TYPE_OPENSBI_MEMREGION,
> +                                 (Object **) &s->regions[i],
> +                                 qdev_prop_allow_set_link_before_realize, 0);
> +
> +        g_autofree char *reg_description = g_strdup_printf(
> +                "Region %i (out of %i) for this domain.",
> +                i, OPENSBI_DOMAIN_MEMREGIONS_MAX);
> +        object_property_set_description(obj, reg_propname, reg_description);
> +
> +        s->region_perms[i] = 0;
> +        g_autofree char *perm_propname = g_strdup_printf("perms%i", i);
> +        object_property_add_uint32_ptr(obj, perm_propname, &s->region_perms[i],
> +                                       OBJ_PROP_FLAG_WRITE);
> +
> +        g_autofree char *perm_description = g_strdup_printf(
> +                "Permissions for region %i for this domain.", i);
> +        object_property_set_description(obj, perm_propname, perm_description);
> +    }
> +
> +    object_property_add_bool(obj, "assign", NULL, set_assign);
> +    object_property_set_description(obj, "assign",
> +                                    "Whether to assign this domain to its boot hart.");
> +}
> +
> +static void opensbi_domain_realize(DeviceState *ds, Error **errp)
> +{
> +    OpenSBIDomainState *s = OPENSBI_DOMAIN(ds);
> +
> +    if (s->boot_hart >= VIRT_CPUS_MAX) {
> +        error_setg(errp, "boot hart larger than maximum number of CPUs (%d)",
> +                 VIRT_CPUS_MAX);
> +        return;
> +    }
> +
> +    if (s->first_possible_hart == -1) {
> +        if (s->last_possible_hart != -1) {
> +            error_setg(errp,
> +                     "last possible hart set when first possible hart unset");
> +            return;
> +        }
> +    } else {
> +        if (s->first_possible_hart >= VIRT_CPUS_MAX) {
> +            error_setg(errp,
> +                     "first possible hart larger than maximum number of CPUs (%d)",
> +                     VIRT_CPUS_MAX);
> +            return;
> +        }
> +
> +        if (s->last_possible_hart != -1) {
> +            if (s->last_possible_hart < s->first_possible_hart) {
> +                error_setg(errp,
> +                         "last possible hart larger than first possible hart");
> +                return;
> +            }
> +
> +            if (s->last_possible_hart >= VIRT_CPUS_MAX) {
> +                error_setg(errp,
> +                         "last possible hart larger than maximum number of CPUS (%d)",
> +                         VIRT_CPUS_MAX);
> +                return;
> +            }
> +        }
> +    }
> +}
> +
> +static void opensbi_domain_class_init(ObjectClass *oc, void *opaque)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +    dc->realize = opensbi_domain_realize;
> +}
> +
> +static const TypeInfo opensbi_domain_info = {
> +        .name = TYPE_OPENSBI_DOMAIN,
> +        .parent = TYPE_DEVICE,
> +        .instance_init = opensbi_domain_instance_init,
> +        .instance_size = sizeof(OpenSBIDomainState),
> +        .class_init = opensbi_domain_class_init
> +};
> +
> +static void opensbi_register_types(void)
> +{
> +    type_register_static(&opensbi_domain_info);
> +    type_register_static(&opensbi_memregion_info);
> +}
> +
> +type_init(opensbi_register_types)
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index 9981e0f6c9..bb4bf3ce5b 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -55,6 +55,7 @@
>   #include "hw/acpi/aml-build.h"
>   #include "qapi/qapi-visit-common.h"
>   #include "hw/virtio/virtio-iommu.h"
> +#include "hw/riscv/opensbi_domain.h"
>   
>   /* KVM AIA only supports APLIC MSI. APLIC Wired is always emulated by QEMU. */
>   static bool virt_use_kvm_aia(RISCVVirtState *s)
> @@ -1051,6 +1052,8 @@ static void finalize_fdt(RISCVVirtState *s)
>       create_fdt_uart(s, virt_memmap, irq_mmio_phandle);
>   
>       create_fdt_rtc(s, virt_memmap, irq_mmio_phandle);
> +
> +    create_fdt_opensbi_domains(MACHINE(s));
>   }
>   
>   static void create_fdt(RISCVVirtState *s, const MemMapEntry *memmap)
> diff --git a/include/hw/riscv/opensbi_domain.h b/include/hw/riscv/opensbi_domain.h
> new file mode 100644
> index 0000000000..bcce16a609
> --- /dev/null
> +++ b/include/hw/riscv/opensbi_domain.h
> @@ -0,0 +1,50 @@
> +
> +#ifndef RISCV_DOMAIN_H
> +#define RISCV_DOMAIN_H
> +
> +#include "hw/sysbus.h"
> +#include "qom/object.h"
> +#include "cpu.h"
> +
> +#define TYPE_OPENSBI_MEMREGION "opensbi-memregion"
> +OBJECT_DECLARE_SIMPLE_TYPE(OpenSBIMemregionState, OPENSBI_MEMREGION)
> +
> +#define OPENSBI_MEMREGION_DEVICES_MAX   16
> +
> +struct OpenSBIMemregionState {
> +    /* public */
> +    DeviceState parent_obj;
> +
> +    /* private */
> +    uint64_t base;
> +    uint32_t order;
> +    bool mmio;
> +    char *devices[OPENSBI_MEMREGION_DEVICES_MAX];
> +};
> +
> +#define TYPE_OPENSBI_DOMAIN "opensbi-domain"
> +OBJECT_DECLARE_SIMPLE_TYPE(OpenSBIDomainState, OPENSBI_DOMAIN)
> +
> +#define OPENSBI_DOMAIN_MEMREGIONS_MAX   16
> +
> +struct OpenSBIDomainState {
> +    /* public */
> +    DeviceState parent_obj;
> +
> +    /* private */
> +    OpenSBIMemregionState *regions[OPENSBI_DOMAIN_MEMREGIONS_MAX];
> +    unsigned int region_perms[OPENSBI_DOMAIN_MEMREGIONS_MAX];
> +    unsigned long first_possible_hart, last_possible_hart;
> +    unsigned int boot_hart;
> +    uint64_t next_arg1;
> +    uint64_t next_addr;
> +    uint32_t next_mode;
> +    bool system_reset_allowed;
> +    bool system_suspend_allowed;
> +
> +    bool assign;
> +};
> +
> +void create_fdt_opensbi_domains(MachineState *s);
> +
> +#endif /* RISCV_DOMAIN_H */