On Fri, 19 Jun 2026 19:11:27 +0800 fanhuang <[email protected]> wrote:
> Introduce a TYPE_MEMORY_DEVICE subclass `sp-mem` for boot-time > SOFT_RESERVED memory exposed to the guest with a per-device NUMA > proximity domain. > > The device targets accelerator memory (HBM and similar) that the > firmware hands to the guest OS as SOFT_RESERVED memory, so a driver > in the guest -- rather than the kernel's general allocator -- owns > the range. > > Usage: > > -object memory-backend-ram,id=spm0,size=$SIZE > -numa node,nodeid=$N > -device sp-mem,id=dev0,memdev=spm0,node=$N[,addr=$GPA] > > The device is boot-time only (no hotplug). > > Signed-off-by: FangSheng Huang <[email protected]> Reviewed-by: Igor Mammedov <[email protected]> > --- > include/hw/mem/sp-mem.h | 33 ++++++++++++ > hw/mem/sp-mem.c | 109 ++++++++++++++++++++++++++++++++++++++++ > hw/mem/Kconfig | 4 ++ > hw/mem/meson.build | 1 + > 4 files changed, 147 insertions(+) > create mode 100644 include/hw/mem/sp-mem.h > create mode 100644 hw/mem/sp-mem.c > > diff --git a/include/hw/mem/sp-mem.h b/include/hw/mem/sp-mem.h > new file mode 100644 > index 0000000000..a8951b49e6 > --- /dev/null > +++ b/include/hw/mem/sp-mem.h > @@ -0,0 +1,33 @@ > +/* > + * Specific Purpose Memory (SPM) device > + * > + * TYPE_MEMORY_DEVICE subclass for boot-time-only memory exposed to the > + * guest as an E820 SOFT_RESERVED range with a SRAT memory-affinity entry. > + * > + * Copyright (c) 2026 Advanced Micro Devices, Inc. > + * > + * Authors: > + * FangSheng Huang <[email protected]> > + * > + * SPDX-License-Identifier: GPL-2.0-or-later > + */ > + > +#ifndef QEMU_SP_MEM_H > +#define QEMU_SP_MEM_H > + > +#include "hw/core/qdev.h" > +#include "qom/object.h" > + > +#define TYPE_SP_MEM "sp-mem" > + > +OBJECT_DECLARE_SIMPLE_TYPE(SpMemDevice, SP_MEM) > + > +struct SpMemDevice { > + DeviceState parent_obj; > + > + HostMemoryBackend *hostmem; > + uint32_t node; > + uint64_t addr; > +}; > + > +#endif /* QEMU_SP_MEM_H */ > diff --git a/hw/mem/sp-mem.c b/hw/mem/sp-mem.c > new file mode 100644 > index 0000000000..d088222f54 > --- /dev/null > +++ b/hw/mem/sp-mem.c > @@ -0,0 +1,109 @@ > +/* > + * Specific Purpose Memory (SPM) device > + * > + * Copyright (c) 2026 Advanced Micro Devices, Inc. > + * > + * Authors: > + * FangSheng Huang <[email protected]> > + * > + * SPDX-License-Identifier: GPL-2.0-or-later > + */ > + > +#include "qemu/osdep.h" > +#include "qemu/module.h" > +#include "qapi/error.h" > +#include "hw/core/qdev-properties.h" > +#include "hw/core/qdev.h" > +#include "hw/mem/sp-mem.h" > +#include "hw/mem/memory-device.h" > +#include "system/hostmem.h" > + > +#define SP_MEM_MEMDEV_PROP "memdev" > +#define SP_MEM_NODE_PROP "node" > +#define SP_MEM_ADDR_PROP "addr" > + > +static const Property sp_mem_properties[] = { > + DEFINE_PROP_LINK(SP_MEM_MEMDEV_PROP, SpMemDevice, hostmem, > + TYPE_MEMORY_BACKEND, HostMemoryBackend *), > + DEFINE_PROP_UINT32(SP_MEM_NODE_PROP, SpMemDevice, node, 0), > + DEFINE_PROP_UINT64(SP_MEM_ADDR_PROP, SpMemDevice, addr, 0), > +}; > + > +static uint64_t sp_mem_get_addr(const MemoryDeviceState *md) > +{ > + return object_property_get_uint(OBJECT(md), SP_MEM_ADDR_PROP, > + &error_abort); > +} > + > +static void sp_mem_set_addr(MemoryDeviceState *md, uint64_t addr, > + Error **errp) > +{ > + object_property_set_uint(OBJECT(md), SP_MEM_ADDR_PROP, addr, errp); > +} > + > +static MemoryRegion *sp_mem_get_memory_region(MemoryDeviceState *md, > + Error **errp) > +{ > + SpMemDevice *spm = SP_MEM(md); > + > + if (!spm->hostmem) { > + error_setg(errp, "'%s' property must be set", SP_MEM_MEMDEV_PROP); > + return NULL; > + } > + return host_memory_backend_get_memory(spm->hostmem); > +} > + > +static void sp_mem_realize(DeviceState *dev, Error **errp) > +{ > + SpMemDevice *spm = SP_MEM(dev); > + > + if (!spm->hostmem) { > + error_setg(errp, "'%s' property is required", SP_MEM_MEMDEV_PROP); > + return; > + } > + if (host_memory_backend_is_mapped(spm->hostmem)) { > + error_setg(errp, "memory backend '%s' is already in use", > + > object_get_canonical_path_component(OBJECT(spm->hostmem))); > + return; > + } > + host_memory_backend_set_mapped(spm->hostmem, true); > +} > + > +static void sp_mem_unrealize(DeviceState *dev) > +{ > + SpMemDevice *spm = SP_MEM(dev); > + > + host_memory_backend_set_mapped(spm->hostmem, false); > +} > + > +static void sp_mem_class_init(ObjectClass *oc, const void *data) > +{ > + DeviceClass *dc = DEVICE_CLASS(oc); > + MemoryDeviceClass *mdc = MEMORY_DEVICE_CLASS(oc); > + > + dc->desc = "SPM (Specific Purpose Memory) device"; > + dc->hotpluggable = false; > + dc->realize = sp_mem_realize; > + dc->unrealize = sp_mem_unrealize; > + device_class_set_props(dc, sp_mem_properties); > + > + mdc->get_addr = sp_mem_get_addr; > + mdc->set_addr = sp_mem_set_addr; > + mdc->get_memory_region = sp_mem_get_memory_region; > + mdc->get_plugged_size = memory_device_get_region_size; > +} > + > +static const TypeInfo sp_mem_types[] = { > + { > + .name = TYPE_SP_MEM, > + .parent = TYPE_DEVICE, > + .class_init = sp_mem_class_init, > + .instance_size = sizeof(SpMemDevice), > + .interfaces = (InterfaceInfo[]) { > + { TYPE_MEMORY_DEVICE }, > + { } > + }, > + }, > +}; > + > +DEFINE_TYPES(sp_mem_types) > diff --git a/hw/mem/Kconfig b/hw/mem/Kconfig > index 73c5ae8ad9..39ddb36710 100644 > --- a/hw/mem/Kconfig > +++ b/hw/mem/Kconfig > @@ -16,3 +16,7 @@ config CXL_MEM_DEVICE > bool > default y if CXL > select MEM_DEVICE > + > +config SP_MEM > + bool > + select MEM_DEVICE > diff --git a/hw/mem/meson.build b/hw/mem/meson.build > index 8c2beeb7d4..f410d75475 100644 > --- a/hw/mem/meson.build > +++ b/hw/mem/meson.build > @@ -4,6 +4,7 @@ mem_ss.add(when: 'CONFIG_DIMM', if_true: files('pc-dimm.c')) > mem_ss.add(when: 'CONFIG_NPCM7XX', if_true: files('npcm7xx_mc.c')) > mem_ss.add(when: 'CONFIG_NVDIMM', if_true: files('nvdimm.c')) > mem_ss.add(when: 'CONFIG_CXL_MEM_DEVICE', if_true: files('cxl_type3.c')) > +mem_ss.add(when: 'CONFIG_SP_MEM', if_true: files('sp-mem.c')) > stub_ss.add(files('cxl_type3_stubs.c')) > > stub_ss.add(files('memory-device-stubs.c'))
