[PATCH v1 0/3] memory-device: Some cleanups

[PATCH v1 0/3] memory-device: Some cleanups

[David Hildenbrand]

Working on adding multi-memslot support for virtio-mem (teaching memory
device code about memory devices that can consume multiple memslots), I
have some preparatory cleanups in my queue that make sense independent of
the actual memory-device/virtio-mem extensions.

Most CCed people are most probably interested in patch #2.

Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Xiao Guangrong <xiaoguangrong.eric@gmail.com>
Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Eduardo Habkost <eduardo@habkost.net>
Cc: Xiaojuan Yang <yangxiaojuan@loongson.cn>
Cc: Song Gao <gaosong@loongson.cn>
Cc: Daniel Henrique Barboza <danielhb413@gmail.com>
Cc: "Cédric Le Goater" <clg@kaod.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Greg Kurz <groug@kaod.org>
Cc: Harsh Prateek Bora <harshpb@linux.ibm.com>
Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
Cc: Yanan Wang <wangyanan55@huawei.com>

David Hildenbrand (3):
  memory-device: Refactor memory_device_pre_plug()
  memory-device: Factor out device memory initialization into
    memory_devices_init()
  memory-device: Track used region size in DeviceMemoryState

 hw/arm/virt.c                  |  9 +---
 hw/i386/pc.c                   | 17 +++-----
 hw/loongarch/virt.c            | 14 ++----
 hw/mem/memory-device.c         | 80 ++++++++++++++++++----------------
 hw/ppc/spapr.c                 | 15 +++----
 include/hw/boards.h            |  2 +
 include/hw/mem/memory-device.h |  2 +
 7 files changed, 63 insertions(+), 76 deletions(-)

-- 
2.40.1

[PATCH v1 1/3] memory-device: Refactor memory_device_pre_plug()

[David Hildenbrand]

Let's move memory_device_check_addable() and basic checks out of
memory_device_get_free_addr() directly into memory_device_pre_plug().

Separating basic checks from address assignment is cleaner and
prepares for further changes.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/mem/memory-device.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 1636db9679..6c025b02c1 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -68,9 +68,10 @@ static int memory_device_used_region_size(Object *obj, void *opaque)
     return 0;
 }
 
-static void memory_device_check_addable(MachineState *ms, uint64_t size,
+static void memory_device_check_addable(MachineState *ms, MemoryRegion *mr,
                                         Error **errp)
 {
+    const uint64_t size = memory_region_size(mr);
     uint64_t used_region_size = 0;
 
     /* we will need a new memory slot for kvm and vhost */
@@ -100,21 +101,9 @@ static uint64_t memory_device_get_free_addr(MachineState *ms,
                                             uint64_t align, uint64_t size,
                                             Error **errp)
 {
-    Error *err = NULL;
     GSList *list = NULL, *item;
     Range as, new = range_empty;
 
-    if (!ms->device_memory) {
-        error_setg(errp, "memory devices (e.g. for memory hotplug) are not "
-                         "supported by the machine");
-        return 0;
-    }
-
-    if (!memory_region_size(&ms->device_memory->mr)) {
-        error_setg(errp, "memory devices (e.g. for memory hotplug) are not "
-                         "enabled, please specify the maxmem option");
-        return 0;
-    }
     range_init_nofail(&as, ms->device_memory->base,
                       memory_region_size(&ms->device_memory->mr));
 
@@ -126,12 +115,6 @@ static uint64_t memory_device_get_free_addr(MachineState *ms,
                     align);
     }
 
-    memory_device_check_addable(ms, size, &err);
-    if (err) {
-        error_propagate(errp, err);
-        return 0;
-    }
-
     if (hint && !QEMU_IS_ALIGNED(*hint, align)) {
         error_setg(errp, "address must be aligned to 0x%" PRIx64 " bytes",
                    align);
@@ -255,11 +238,28 @@ void memory_device_pre_plug(MemoryDeviceState *md, MachineState *ms,
     uint64_t addr, align = 0;
     MemoryRegion *mr;
 
+    if (!ms->device_memory) {
+        error_setg(errp, "memory devices (e.g. for memory hotplug) are not "
+                         "supported by the machine");
+        return;
+    }
+
+    if (!memory_region_size(&ms->device_memory->mr)) {
+        error_setg(errp, "memory devices (e.g. for memory hotplug) are not "
+                         "enabled, please specify the maxmem option");
+        return;
+    }
+
     mr = mdc->get_memory_region(md, &local_err);
     if (local_err) {
         goto out;
     }
 
+    memory_device_check_addable(ms, mr, &local_err);
+    if (local_err) {
+        goto out;
+    }
+
     if (legacy_align) {
         align = *legacy_align;
     } else {
-- 
2.40.1

[PATCH v1 2/3] memory-device: Factor out device memory initialization into memory_devices_init()

[David Hildenbrand]

Let's factor the common setup out, to prepare for further changes.

On arm64, we'll add the subregion to system RAM now earlier -- which
shouldn't matter, because the system RAM memory region should already be
alive at that point.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/arm/virt.c                  |  9 +--------
 hw/i386/pc.c                   | 17 ++++++-----------
 hw/loongarch/virt.c            | 14 ++++----------
 hw/mem/memory-device.c         | 20 ++++++++++++++++++++
 hw/ppc/spapr.c                 | 15 ++++++---------
 include/hw/mem/memory-device.h |  2 ++
 6 files changed, 39 insertions(+), 38 deletions(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index b99ae18501..284f45d998 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1816,10 +1816,7 @@ static void virt_set_memmap(VirtMachineState *vms, int pa_bits)
     virt_set_high_memmap(vms, base, pa_bits);
 
     if (device_memory_size > 0) {
-        ms->device_memory = g_malloc0(sizeof(*ms->device_memory));
-        ms->device_memory->base = device_memory_base;
-        memory_region_init(&ms->device_memory->mr, OBJECT(vms),
-                           "device-memory", device_memory_size);
+        memory_devices_init(ms, device_memory_base, device_memory_size);
     }
 }
 
@@ -2260,10 +2257,6 @@ static void machvirt_init(MachineState *machine)
 
     memory_region_add_subregion(sysmem, vms->memmap[VIRT_MEM].base,
                                 machine->ram);
-    if (machine->device_memory) {
-        memory_region_add_subregion(sysmem, machine->device_memory->base,
-                                    &machine->device_memory->mr);
-    }
 
     virt_flash_fdt(vms, sysmem, secure_sysmem ?: sysmem);
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index bb62c994fa..9d215df92e 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1039,13 +1039,11 @@ void pc_memory_init(PCMachineState *pcms,
         exit(EXIT_FAILURE);
     }
 
-    /* always allocate the device memory information */
-    machine->device_memory = g_malloc0(sizeof(*machine->device_memory));
-
     /* initialize device memory address space */
     if (pcmc->has_reserved_memory &&
         (machine->ram_size < machine->maxram_size)) {
         ram_addr_t device_mem_size;
+        hwaddr device_mem_base;
 
         if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
             error_report("unsupported amount of memory slots: %"PRIu64,
@@ -1060,19 +1058,16 @@ void pc_memory_init(PCMachineState *pcms,
             exit(EXIT_FAILURE);
         }
 
-        pc_get_device_memory_range(pcms, &machine->device_memory->base, &device_mem_size);
+        pc_get_device_memory_range(pcms, &device_mem_base, &device_mem_size);
 
-        if ((machine->device_memory->base + device_mem_size) <
-            device_mem_size) {
+        if (device_mem_base + device_mem_size < device_mem_size) {
             error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
                          machine->maxram_size);
             exit(EXIT_FAILURE);
         }
-
-        memory_region_init(&machine->device_memory->mr, OBJECT(pcms),
-                           "device-memory", device_mem_size);
-        memory_region_add_subregion(system_memory, machine->device_memory->base,
-                                    &machine->device_memory->mr);
+        memory_devices_init(machine, device_mem_base, device_mem_size);
+    } else {
+        memory_devices_init(machine, 0, 0);
     }
 
     if (pcms->cxl_devices_state.is_enabled) {
diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 2b7588e32a..2ccc90feb4 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -45,7 +45,7 @@
 #include "sysemu/block-backend.h"
 #include "hw/block/flash.h"
 #include "qemu/error-report.h"
-
+#include "hw/mem/memory-device.h"
 
 static void virt_flash_create(LoongArchMachineState *lams)
 {
@@ -804,8 +804,8 @@ static void loongarch_init(MachineState *machine)
 
     /* initialize device memory address space */
     if (machine->ram_size < machine->maxram_size) {
-        machine->device_memory = g_malloc0(sizeof(*machine->device_memory));
         ram_addr_t device_mem_size = machine->maxram_size - machine->ram_size;
+        hwaddr device_mem_base;
 
         if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
             error_report("unsupported amount of memory slots: %"PRIu64,
@@ -820,14 +820,8 @@ static void loongarch_init(MachineState *machine)
             exit(EXIT_FAILURE);
         }
         /* device memory base is the top of high memory address. */
-        machine->device_memory->base = 0x90000000 + highram_size;
-        machine->device_memory->base =
-            ROUND_UP(machine->device_memory->base, 1 * GiB);
-
-        memory_region_init(&machine->device_memory->mr, OBJECT(lams),
-                           "device-memory", device_mem_size);
-        memory_region_add_subregion(address_space_mem, machine->device_memory->base,
-                                    &machine->device_memory->mr);
+        device_mem_base = ROUND_UP(0x90000000 + highram_size, 1 * GiB);
+        memory_devices_init(machine, device_mem_base, device_mem_size);
     }
 
     /* Add isa io region */
diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index 6c025b02c1..d99ceb621a 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -17,6 +17,7 @@
 #include "qemu/range.h"
 #include "hw/virtio/vhost.h"
 #include "sysemu/kvm.h"
+#include "exec/address-spaces.h"
 #include "trace.h"
 
 static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
@@ -333,6 +334,25 @@ uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
     return memory_region_size(mr);
 }
 
+void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size)
+{
+    g_assert(!ms->device_memory);
+    ms->device_memory = g_new0(DeviceMemoryState, 1);
+    ms->device_memory->base = base;
+
+    /*
+     * See memory_device_get_free_addr(): An empty device memory region
+     * means "this machine supports memory devices, but they are not enabled".
+     */
+    if (size > 0) {
+        memory_region_init(&ms->device_memory->mr, OBJECT(ms), "device-memory",
+                           size);
+        memory_region_add_subregion(get_system_memory(),
+                                    ms->device_memory->base,
+                                    &ms->device_memory->mr);
+    }
+}
+
 static const TypeInfo memory_device_info = {
     .name          = TYPE_MEMORY_DEVICE,
     .parent        = TYPE_INTERFACE,
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 1baea16c96..d66dc00ea5 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2866,12 +2866,11 @@ static void spapr_machine_init(MachineState *machine)
     /* map RAM */
     memory_region_add_subregion(sysmem, 0, machine->ram);
 
-    /* always allocate the device memory information */
-    machine->device_memory = g_malloc0(sizeof(*machine->device_memory));
-
     /* initialize hotplug memory address space */
     if (machine->ram_size < machine->maxram_size) {
         ram_addr_t device_mem_size = machine->maxram_size - machine->ram_size;
+        hwaddr device_mem_base;
+
         /*
          * Limit the number of hotpluggable memory slots to half the number
          * slots that KVM supports, leaving the other half for PCI and other
@@ -2890,12 +2889,10 @@ static void spapr_machine_init(MachineState *machine)
             exit(1);
         }
 
-        machine->device_memory->base = ROUND_UP(machine->ram_size,
-                                                SPAPR_DEVICE_MEM_ALIGN);
-        memory_region_init(&machine->device_memory->mr, OBJECT(spapr),
-                           "device-memory", device_mem_size);
-        memory_region_add_subregion(sysmem, machine->device_memory->base,
-                                    &machine->device_memory->mr);
+        device_mem_base = ROUND_UP(machine->ram_size, SPAPR_DEVICE_MEM_ALIGN);
+        memory_devices_init(machine, device_mem_base, device_mem_size);
+    } else {
+        memory_devices_init(machine, 0, 0);
     }
 
     if (smc->dr_lmb_enabled) {
diff --git a/include/hw/mem/memory-device.h b/include/hw/mem/memory-device.h
index 48d2611fc5..6e8a10e2f5 100644
--- a/include/hw/mem/memory-device.h
+++ b/include/hw/mem/memory-device.h
@@ -16,6 +16,7 @@
 #include "hw/qdev-core.h"
 #include "qapi/qapi-types-machine.h"
 #include "qom/object.h"
+#include "exec/hwaddr.h"
 
 #define TYPE_MEMORY_DEVICE "memory-device"
 
@@ -113,5 +114,6 @@ void memory_device_plug(MemoryDeviceState *md, MachineState *ms);
 void memory_device_unplug(MemoryDeviceState *md, MachineState *ms);
 uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
                                        Error **errp);
+void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size);
 
 #endif
-- 
2.40.1

[PATCH v1 3/3] memory-device: Track used region size in DeviceMemoryState

[David Hildenbrand]

Let's avoid iterating over all devices and simply track it in the
DeviceMemoryState.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/mem/memory-device.c | 22 +++-------------------
 include/hw/boards.h    |  2 ++
 2 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index d99ceb621a..675ceeff55 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -52,28 +52,11 @@ static int memory_device_build_list(Object *obj, void *opaque)
     return 0;
 }
 
-static int memory_device_used_region_size(Object *obj, void *opaque)
-{
-    uint64_t *size = opaque;
-
-    if (object_dynamic_cast(obj, TYPE_MEMORY_DEVICE)) {
-        const DeviceState *dev = DEVICE(obj);
-        const MemoryDeviceState *md = MEMORY_DEVICE(obj);
-
-        if (dev->realized) {
-            *size += memory_device_get_region_size(md, &error_abort);
-        }
-    }
-
-    object_child_foreach(obj, memory_device_used_region_size, opaque);
-    return 0;
-}
-
 static void memory_device_check_addable(MachineState *ms, MemoryRegion *mr,
                                         Error **errp)
 {
+    const uint64_t used_region_size = ms->device_memory->used_region_size;
     const uint64_t size = memory_region_size(mr);
-    uint64_t used_region_size = 0;
 
     /* we will need a new memory slot for kvm and vhost */
     if (kvm_enabled() && !kvm_has_free_slot(ms)) {
@@ -86,7 +69,6 @@ static void memory_device_check_addable(MachineState *ms, MemoryRegion *mr,
     }
 
     /* will we exceed the total amount of memory specified */
-    memory_device_used_region_size(OBJECT(ms), &used_region_size);
     if (used_region_size + size < used_region_size ||
         used_region_size + size > ms->maxram_size - ms->ram_size) {
         error_setg(errp, "not enough space, currently 0x%" PRIx64
@@ -297,6 +279,7 @@ void memory_device_plug(MemoryDeviceState *md, MachineState *ms)
     mr = mdc->get_memory_region(md, &error_abort);
     g_assert(ms->device_memory);
 
+    ms->device_memory->used_region_size += memory_region_size(mr);
     memory_region_add_subregion(&ms->device_memory->mr,
                                 addr - ms->device_memory->base, mr);
     trace_memory_device_plug(DEVICE(md)->id ? DEVICE(md)->id : "", addr);
@@ -315,6 +298,7 @@ void memory_device_unplug(MemoryDeviceState *md, MachineState *ms)
     g_assert(ms->device_memory);
 
     memory_region_del_subregion(&ms->device_memory->mr, mr);
+    ms->device_memory->used_region_size -= memory_region_size(mr);
     trace_memory_device_unplug(DEVICE(md)->id ? DEVICE(md)->id : "",
                                mdc->get_addr(md));
 }
diff --git a/include/hw/boards.h b/include/hw/boards.h
index a385010909..9d48c73edb 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -294,11 +294,13 @@ struct MachineClass {
  * address space for memory devices starts
  * @mr: address space container for memory devices
  * @dimm_size: the sum of plugged DIMMs' sizes
+ * @used_region_size: the part of @mr already used by memory devices
  */
 typedef struct DeviceMemoryState {
     hwaddr base;
     MemoryRegion mr;
     uint64_t dimm_size;
+    uint64_t used_region_size;
 } DeviceMemoryState;
 
 /**
-- 
2.40.1

Re: [PATCH v1 2/3] memory-device: Factor out device memory initialization into memory_devices_init()

[Song Gao]

在 2023/5/24 上午2:51, David Hildenbrand 写道:
> Let's factor the common setup out, to prepare for further changes.
>
> On arm64, we'll add the subregion to system RAM now earlier -- which
> shouldn't matter, because the system RAM memory region should already be
> alive at that point.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>   hw/arm/virt.c                  |  9 +--------
>   hw/i386/pc.c                   | 17 ++++++-----------
>   hw/loongarch/virt.c            | 14 ++++----------
>   hw/mem/memory-device.c         | 20 ++++++++++++++++++++
>   hw/ppc/spapr.c                 | 15 ++++++---------
>   include/hw/mem/memory-device.h |  2 ++
>   6 files changed, 39 insertions(+), 38 deletions(-)
For LoongArch

Tested-by: Song Gao <gaosong@loongson.cn>

Thanks.
Song Gao
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index b99ae18501..284f45d998 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -1816,10 +1816,7 @@ static void virt_set_memmap(VirtMachineState *vms, int pa_bits)
>       virt_set_high_memmap(vms, base, pa_bits);
>   
>       if (device_memory_size > 0) {
> -        ms->device_memory = g_malloc0(sizeof(*ms->device_memory));
> -        ms->device_memory->base = device_memory_base;
> -        memory_region_init(&ms->device_memory->mr, OBJECT(vms),
> -                           "device-memory", device_memory_size);
> +        memory_devices_init(ms, device_memory_base, device_memory_size);
>       }
>   }
>   
> @@ -2260,10 +2257,6 @@ static void machvirt_init(MachineState *machine)
>   
>       memory_region_add_subregion(sysmem, vms->memmap[VIRT_MEM].base,
>                                   machine->ram);
> -    if (machine->device_memory) {
> -        memory_region_add_subregion(sysmem, machine->device_memory->base,
> -                                    &machine->device_memory->mr);
> -    }
>   
>       virt_flash_fdt(vms, sysmem, secure_sysmem ?: sysmem);
>   
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index bb62c994fa..9d215df92e 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1039,13 +1039,11 @@ void pc_memory_init(PCMachineState *pcms,
>           exit(EXIT_FAILURE);
>       }
>   
> -    /* always allocate the device memory information */
> -    machine->device_memory = g_malloc0(sizeof(*machine->device_memory));
> -
>       /* initialize device memory address space */
>       if (pcmc->has_reserved_memory &&
>           (machine->ram_size < machine->maxram_size)) {
>           ram_addr_t device_mem_size;
> +        hwaddr device_mem_base;
>   
>           if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
>               error_report("unsupported amount of memory slots: %"PRIu64,
> @@ -1060,19 +1058,16 @@ void pc_memory_init(PCMachineState *pcms,
>               exit(EXIT_FAILURE);
>           }
>   
> -        pc_get_device_memory_range(pcms, &machine->device_memory->base, &device_mem_size);
> +        pc_get_device_memory_range(pcms, &device_mem_base, &device_mem_size);
>   
> -        if ((machine->device_memory->base + device_mem_size) <
> -            device_mem_size) {
> +        if (device_mem_base + device_mem_size < device_mem_size) {
>               error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
>                            machine->maxram_size);
>               exit(EXIT_FAILURE);
>           }
> -
> -        memory_region_init(&machine->device_memory->mr, OBJECT(pcms),
> -                           "device-memory", device_mem_size);
> -        memory_region_add_subregion(system_memory, machine->device_memory->base,
> -                                    &machine->device_memory->mr);
> +        memory_devices_init(machine, device_mem_base, device_mem_size);
> +    } else {
> +        memory_devices_init(machine, 0, 0);
>       }
>   
>       if (pcms->cxl_devices_state.is_enabled) {
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index 2b7588e32a..2ccc90feb4 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -45,7 +45,7 @@
>   #include "sysemu/block-backend.h"
>   #include "hw/block/flash.h"
>   #include "qemu/error-report.h"
> -
> +#include "hw/mem/memory-device.h"
>   
>   static void virt_flash_create(LoongArchMachineState *lams)
>   {
> @@ -804,8 +804,8 @@ static void loongarch_init(MachineState *machine)
>   
>       /* initialize device memory address space */
>       if (machine->ram_size < machine->maxram_size) {
> -        machine->device_memory = g_malloc0(sizeof(*machine->device_memory));
>           ram_addr_t device_mem_size = machine->maxram_size - machine->ram_size;
> +        hwaddr device_mem_base;
>   
>           if (machine->ram_slots > ACPI_MAX_RAM_SLOTS) {
>               error_report("unsupported amount of memory slots: %"PRIu64,
> @@ -820,14 +820,8 @@ static void loongarch_init(MachineState *machine)
>               exit(EXIT_FAILURE);
>           }
>           /* device memory base is the top of high memory address. */
> -        machine->device_memory->base = 0x90000000 + highram_size;
> -        machine->device_memory->base =
> -            ROUND_UP(machine->device_memory->base, 1 * GiB);
> -
> -        memory_region_init(&machine->device_memory->mr, OBJECT(lams),
> -                           "device-memory", device_mem_size);
> -        memory_region_add_subregion(address_space_mem, machine->device_memory->base,
> -                                    &machine->device_memory->mr);
> +        device_mem_base = ROUND_UP(0x90000000 + highram_size, 1 * GiB);
> +        memory_devices_init(machine, device_mem_base, device_mem_size);
>       }
>   
>       /* Add isa io region */
> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
> index 6c025b02c1..d99ceb621a 100644
> --- a/hw/mem/memory-device.c
> +++ b/hw/mem/memory-device.c
> @@ -17,6 +17,7 @@
>   #include "qemu/range.h"
>   #include "hw/virtio/vhost.h"
>   #include "sysemu/kvm.h"
> +#include "exec/address-spaces.h"
>   #include "trace.h"
>   
>   static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
> @@ -333,6 +334,25 @@ uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
>       return memory_region_size(mr);
>   }
>   
> +void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size)
> +{
> +    g_assert(!ms->device_memory);
> +    ms->device_memory = g_new0(DeviceMemoryState, 1);
> +    ms->device_memory->base = base;
> +
> +    /*
> +     * See memory_device_get_free_addr(): An empty device memory region
> +     * means "this machine supports memory devices, but they are not enabled".
> +     */
> +    if (size > 0) {
> +        memory_region_init(&ms->device_memory->mr, OBJECT(ms), "device-memory",
> +                           size);
> +        memory_region_add_subregion(get_system_memory(),
> +                                    ms->device_memory->base,
> +                                    &ms->device_memory->mr);
> +    }
> +}
> +
>   static const TypeInfo memory_device_info = {
>       .name          = TYPE_MEMORY_DEVICE,
>       .parent        = TYPE_INTERFACE,
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 1baea16c96..d66dc00ea5 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2866,12 +2866,11 @@ static void spapr_machine_init(MachineState *machine)
>       /* map RAM */
>       memory_region_add_subregion(sysmem, 0, machine->ram);
>   
> -    /* always allocate the device memory information */
> -    machine->device_memory = g_malloc0(sizeof(*machine->device_memory));
> -
>       /* initialize hotplug memory address space */
>       if (machine->ram_size < machine->maxram_size) {
>           ram_addr_t device_mem_size = machine->maxram_size - machine->ram_size;
> +        hwaddr device_mem_base;
> +
>           /*
>            * Limit the number of hotpluggable memory slots to half the number
>            * slots that KVM supports, leaving the other half for PCI and other
> @@ -2890,12 +2889,10 @@ static void spapr_machine_init(MachineState *machine)
>               exit(1);
>           }
>   
> -        machine->device_memory->base = ROUND_UP(machine->ram_size,
> -                                                SPAPR_DEVICE_MEM_ALIGN);
> -        memory_region_init(&machine->device_memory->mr, OBJECT(spapr),
> -                           "device-memory", device_mem_size);
> -        memory_region_add_subregion(sysmem, machine->device_memory->base,
> -                                    &machine->device_memory->mr);
> +        device_mem_base = ROUND_UP(machine->ram_size, SPAPR_DEVICE_MEM_ALIGN);
> +        memory_devices_init(machine, device_mem_base, device_mem_size);
> +    } else {
> +        memory_devices_init(machine, 0, 0);
>       }
>   
>       if (smc->dr_lmb_enabled) {
> diff --git a/include/hw/mem/memory-device.h b/include/hw/mem/memory-device.h
> index 48d2611fc5..6e8a10e2f5 100644
> --- a/include/hw/mem/memory-device.h
> +++ b/include/hw/mem/memory-device.h
> @@ -16,6 +16,7 @@
>   #include "hw/qdev-core.h"
>   #include "qapi/qapi-types-machine.h"
>   #include "qom/object.h"
> +#include "exec/hwaddr.h"
>   
>   #define TYPE_MEMORY_DEVICE "memory-device"
>   
> @@ -113,5 +114,6 @@ void memory_device_plug(MemoryDeviceState *md, MachineState *ms);
>   void memory_device_unplug(MemoryDeviceState *md, MachineState *ms);
>   uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
>                                          Error **errp);
> +void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size);
>   
>   #endif

Re: [PATCH v1 2/3] memory-device: Factor out device memory initialization into memory_devices_init()

[Philippe Mathieu-Daudé]

Hi David,

On 23/5/23 20:51, David Hildenbrand wrote:
> Let's factor the common setup out, to prepare for further changes.
> 
> On arm64, we'll add the subregion to system RAM now earlier -- which
> shouldn't matter, because the system RAM memory region should already be
> alive at that point.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>   hw/arm/virt.c                  |  9 +--------
>   hw/i386/pc.c                   | 17 ++++++-----------
>   hw/loongarch/virt.c            | 14 ++++----------
>   hw/mem/memory-device.c         | 20 ++++++++++++++++++++
>   hw/ppc/spapr.c                 | 15 ++++++---------
>   include/hw/mem/memory-device.h |  2 ++
>   6 files changed, 39 insertions(+), 38 deletions(-)

Split in boring 'first add method then use it for each arch'
would be easier to review.

> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
> index 6c025b02c1..d99ceb621a 100644
> --- a/hw/mem/memory-device.c
> +++ b/hw/mem/memory-device.c
> @@ -17,6 +17,7 @@
>   #include "qemu/range.h"
>   #include "hw/virtio/vhost.h"
>   #include "sysemu/kvm.h"
> +#include "exec/address-spaces.h"
>   #include "trace.h"
>   
>   static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
> @@ -333,6 +334,25 @@ uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
>       return memory_region_size(mr);
>   }
>   
> +void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size)
> +{
> +    g_assert(!ms->device_memory);
> +    ms->device_memory = g_new0(DeviceMemoryState, 1);
> +    ms->device_memory->base = base;
> +
> +    /*
> +     * See memory_device_get_free_addr(): An empty device memory region
> +     * means "this machine supports memory devices, but they are not enabled".
> +     */
> +    if (size > 0) {
> +        memory_region_init(&ms->device_memory->mr, OBJECT(ms), "device-memory",
> +                           size);
> +        memory_region_add_subregion(get_system_memory(),
> +                                    ms->device_memory->base,
> +                                    &ms->device_memory->mr);

What about always init/register and set if enabled?

   memory_region_set_enabled(&ms->device_memory->mr, size > 0);

Otherwise why allocate ms->device_memory?

> +    }
> +}

Re: [PATCH v1 2/3] memory-device: Factor out device memory initialization into memory_devices_init()

[David Hildenbrand]

On 25.05.23 15:30, Philippe Mathieu-Daudé wrote:
> Hi David,
> 
> On 23/5/23 20:51, David Hildenbrand wrote:
>> Let's factor the common setup out, to prepare for further changes.
>>
>> On arm64, we'll add the subregion to system RAM now earlier -- which
>> shouldn't matter, because the system RAM memory region should already be
>> alive at that point.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>    hw/arm/virt.c                  |  9 +--------
>>    hw/i386/pc.c                   | 17 ++++++-----------
>>    hw/loongarch/virt.c            | 14 ++++----------
>>    hw/mem/memory-device.c         | 20 ++++++++++++++++++++
>>    hw/ppc/spapr.c                 | 15 ++++++---------
>>    include/hw/mem/memory-device.h |  2 ++
>>    6 files changed, 39 insertions(+), 38 deletions(-)
> 
> Split in boring 'first add method then use it for each arch'
> would be easier to review.

Right, I agree if I'd be touching more code (I consider this fairly 
minimal and straight-forward refactoring).

> 
>> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
>> index 6c025b02c1..d99ceb621a 100644
>> --- a/hw/mem/memory-device.c
>> +++ b/hw/mem/memory-device.c
>> @@ -17,6 +17,7 @@
>>    #include "qemu/range.h"
>>    #include "hw/virtio/vhost.h"
>>    #include "sysemu/kvm.h"
>> +#include "exec/address-spaces.h"
>>    #include "trace.h"
>>    
>>    static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
>> @@ -333,6 +334,25 @@ uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
>>        return memory_region_size(mr);
>>    }
>>    
>> +void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size)
>> +{
>> +    g_assert(!ms->device_memory);
>> +    ms->device_memory = g_new0(DeviceMemoryState, 1);
>> +    ms->device_memory->base = base;
>> +
>> +    /*
>> +     * See memory_device_get_free_addr(): An empty device memory region
>> +     * means "this machine supports memory devices, but they are not enabled".
>> +     */
>> +    if (size > 0) {
>> +        memory_region_init(&ms->device_memory->mr, OBJECT(ms), "device-memory",
>> +                           size);
>> +        memory_region_add_subregion(get_system_memory(),
>> +                                    ms->device_memory->base,
>> +                                    &ms->device_memory->mr);
> 
> What about always init/register and set if enabled?
> 
>     memory_region_set_enabled(&ms->device_memory->mr, size > 0);
> 
> Otherwise why allocate ms->device_memory?

We have right now:

ms->device_memory not allocated: no support
ms->device_memory->mr with size 0: not enabled
ms->device_memory->mr with size > 0: enabled

Let me see if initializing a memory region with size 0 (and adding a 
subregion with size 0) works.

Thanks!

-- 
Thanks,

David / dhildenb

Re: [PATCH v1 2/3] memory-device: Factor out device memory initialization into memory_devices_init()

[David Hildenbrand]

On 25.05.23 15:30, Philippe Mathieu-Daudé wrote:
> Hi David,
> 
> On 23/5/23 20:51, David Hildenbrand wrote:
>> Let's factor the common setup out, to prepare for further changes.
>>
>> On arm64, we'll add the subregion to system RAM now earlier -- which
>> shouldn't matter, because the system RAM memory region should already be
>> alive at that point.
>>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>    hw/arm/virt.c                  |  9 +--------
>>    hw/i386/pc.c                   | 17 ++++++-----------
>>    hw/loongarch/virt.c            | 14 ++++----------
>>    hw/mem/memory-device.c         | 20 ++++++++++++++++++++
>>    hw/ppc/spapr.c                 | 15 ++++++---------
>>    include/hw/mem/memory-device.h |  2 ++
>>    6 files changed, 39 insertions(+), 38 deletions(-)
> 
> Split in boring 'first add method then use it for each arch'
> would be easier to review.
> 
>> diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
>> index 6c025b02c1..d99ceb621a 100644
>> --- a/hw/mem/memory-device.c
>> +++ b/hw/mem/memory-device.c
>> @@ -17,6 +17,7 @@
>>    #include "qemu/range.h"
>>    #include "hw/virtio/vhost.h"
>>    #include "sysemu/kvm.h"
>> +#include "exec/address-spaces.h"
>>    #include "trace.h"
>>    
>>    static gint memory_device_addr_sort(gconstpointer a, gconstpointer b)
>> @@ -333,6 +334,25 @@ uint64_t memory_device_get_region_size(const MemoryDeviceState *md,
>>        return memory_region_size(mr);
>>    }
>>    
>> +void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size)
>> +{
>> +    g_assert(!ms->device_memory);
>> +    ms->device_memory = g_new0(DeviceMemoryState, 1);
>> +    ms->device_memory->base = base;
>> +
>> +    /*
>> +     * See memory_device_get_free_addr(): An empty device memory region
>> +     * means "this machine supports memory devices, but they are not enabled".
>> +     */
>> +    if (size > 0) {
>> +        memory_region_init(&ms->device_memory->mr, OBJECT(ms), "device-memory",
>> +                           size);
>> +        memory_region_add_subregion(get_system_memory(),
>> +                                    ms->device_memory->base,
>> +                                    &ms->device_memory->mr);
> 
> What about always init/register and set if enabled?
> 
>     memory_region_set_enabled(&ms->device_memory->mr, size > 0);
> 
> Otherwise why allocate ms->device_memory?

With

void memory_devices_init(MachineState *ms, hwaddr base, uint64_t size)
{
     g_assert(!ms->device_memory);
     ms->device_memory = g_new0(DeviceMemoryState, 1);
     ms->device_memory->base = base;

     /*
      * An empty region (size == 0) indicates that memory devices are supported
      * by the machine, but they are not enabled (see memory_device_pre_plug()).
      */
     memory_region_init(&ms->device_memory->mr, OBJECT(ms), "device-memory",
                        size);
     memory_region_set_enabled(&ms->device_memory->mr, !!size);
     memory_region_add_subregion(get_system_memory(), ms->device_memory->base,
                                 &ms->device_memory->mr);
}

"info mtree -D" on x86-64 with only "-m 2G" (no maxmem) will show that the
region is placed at address 0 and disabled:

memory-region: system
   0000000000000000-ffffffffffffffff (prio 0, i/o): system
     0000000000000000-0000000000000000 (prio 0, i/o): device-memory [disabled]
     0000000000000000-000000007fffffff (prio 0, ram): alias ram-below-4g @pc.ram 0000000000000000-000000007fffffff
     0000000000000000-ffffffffffffffff (prio -1, i/o): pci


Good enough for me.

However, I think we could just stop allocating ms->device_memory with size == 0 and
not care about the "not supported" case in memory_device_pre_plug(): this function should
only get called by a machine, and if the machine does not support memory devices, it is
to blame for calling that function after all. (and it will only affect the error message
after all)

-- 
Thanks,

David / dhildenb