Re: [Qemu-devel] [PATCH 17/35] dimm: add busy address check and address auto-allocation

[Tang Chen <tangchen@cn.fujitsu.com>]

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Hi Igor,

On 04/04/2014 09:36 PM, Igor Mammedov wrote:
......
> +uint64_t dimm_get_free_addr(uint64_t address_space_start,
> +                            uint64_t address_space_size,
> +                            uint64_t *hint, uint64_t size,
> +                            Error **errp)
> +{
> +    GSList *list = NULL, *item;
> +    uint64_t new_start, ret;
> +    uint64_t address_space_end = address_space_start + address_space_size;
> +
> +    object_child_foreach(qdev_get_machine(), dimm_built_list,&list);
> +
> +    if (hint) {
> +        new_start = *hint;
> +    } else {
> +        new_start = address_space_start;
> +    }
> +
> +    /* find address range that will fit new DIMM */
> +    for (item = list; item; item = g_slist_next(item)) {
> +        DimmDevice *dimm = item->data;
> +        uint64_t dimm_size = object_property_get_int(OBJECT(dimm),
> +                             "size",&error_abort);
> +        if (ranges_overlap(dimm->start, dimm_size, new_start, size)) {
> +            if (hint) {
> +                DeviceState *d = DEVICE(dimm);
> +                error_setg(errp, "address range conflicts with '%s'", d->id);
> +                break;

Actually we got an error here.

If we break from here, new_start is set to *hint, and ret will also be 
set to *hint.
So the return value is a little ambiguous.

I can understand that caller will check errp to find out if there is an 
error. And I
also understand we need to free list. But please also see below.

> +            }
> +            new_start = dimm->start + dimm_size;
> +        }
> +    }
> +    ret = new_start;
> +
> +    g_slist_free(list);
> +
> +    if (new_start<  address_space_start) {
> +        error_setg(errp, "can't add memory [0x%" PRIx64 ":0x%" PRIx64
> +                   "] at 0x%" PRIx64, new_start, size, address_space_start);
> +    } else if ((new_start + size)>  address_space_end) {
> +        error_setg(errp, "can't add memory [0x%" PRIx64 ":0x%" PRIx64
> +                   "] beyond 0x%" PRIx64, new_start, size, address_space_end);
> +    }

The error here could also be triggered. If so, errp will be reset, not 
the error
status set above.

> +    return ret;
> +}
>

So, how about the attached patch ?

Thanks. :)

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>From 2af81231d7a5479f70b1444589b01a47d37145c2 Mon Sep 17 00:00:00 2001
From: Igor Mammedov <imammedo@redhat.com>
Date: Fri, 4 Apr 2014 15:36:42 +0200
Subject: [PATCH] dimm: add busy address check and address auto-allocation

- if 'start' property is not specified on -device/device_add command,
treat default value as request for assigning DimmDevice to
the first free memory region.

- if 'start' is provided with -device/device_add command, attempt to
use it or fail command if it's already occupied or falls inside
of an existing DimmDevice memory region.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
---
 hw/i386/pc.c          | 16 +++++++++++-
 hw/mem/dimm.c         | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/mem/dimm.h |  5 ++++
 3 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 4038e2c..29382ec 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1483,15 +1483,29 @@ void qemu_register_pc_machine(QEMUMachine *m)
 static void pc_dimm_plug(HotplugHandler *hotplug_dev,
                          DeviceState *dev, Error **errp)
 {
+    Error *local_err = NULL;
     PCMachineState *pcms = PC_MACHINE(hotplug_dev);
     DimmDevice *dimm = DIMM(dev);
     DimmDeviceClass *ddc = DIMM_GET_CLASS(dimm);
     MemoryRegion *mr = ddc->get_memory_region(dimm);
+    ram_addr_t addr = dimm->start;
+
+    addr = dimm_get_free_addr(pcms->hotplug_memory_base,
+                              memory_region_size(&pcms->hotplug_memory),
+                              !addr ? NULL : &addr,
+                              memory_region_size(mr), &local_err);
+    if (local_err) {
+        goto out;
+    }
+    object_property_set_int(OBJECT(dev), addr, "start", &local_err);
 
     memory_region_add_subregion(&pcms->hotplug_memory,
-                                dimm->start - pcms->hotplug_memory_base,
+                                addr - pcms->hotplug_memory_base,
                                 mr);
     vmstate_register_ram(mr, dev);
+
+out:
+    error_propagate(errp, local_err);
 }
 
 static void pc_machine_device_plug_cb(HotplugHandler *hotplug_dev,
diff --git a/hw/mem/dimm.c b/hw/mem/dimm.c
index 65d4cd0..d8a3c5e 100644
--- a/hw/mem/dimm.c
+++ b/hw/mem/dimm.c
@@ -21,6 +21,76 @@
 #include "hw/mem/dimm.h"
 #include "qemu/config-file.h"
 #include "qapi/visitor.h"
+#include "qemu/range.h"
+
+static gint dimm_addr_sort(gconstpointer a, gconstpointer b)
+{
+    DimmDevice *x = DIMM(a);
+    DimmDevice *y = DIMM(b);
+
+    return x->start - y->start;
+}
+
+static int dimm_built_list(Object *obj, void *opaque)
+{
+    GSList **list = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_DIMM)) {
+        DeviceState *dev = DEVICE(obj);
+        if (dev->realized) { /* only realized DIMMs matter */
+            *list = g_slist_insert_sorted(*list, dev, dimm_addr_sort);
+        }
+    }
+
+    object_child_foreach(obj, dimm_built_list, opaque);
+    return 0;
+}
+
+uint64_t dimm_get_free_addr(uint64_t address_space_start,
+                            uint64_t address_space_size,
+                            uint64_t *hint, uint64_t size,
+                            Error **errp)
+{
+    GSList *list = NULL, *item;
+    uint64_t new_start, ret = 0;
+    uint64_t address_space_end = address_space_start + address_space_size;
+
+    object_child_foreach(qdev_get_machine(), dimm_built_list, &list);
+
+    if (hint) {
+        new_start = *hint;
+    } else {
+        new_start = address_space_start;
+    }
+
+    /* find address range that will fit new DIMM */
+    for (item = list; item; item = g_slist_next(item)) {
+        DimmDevice *dimm = item->data;
+        uint64_t dimm_size = object_property_get_int(OBJECT(dimm),
+                             "size", &error_abort);
+        if (ranges_overlap(dimm->start, dimm_size, new_start, size)) {
+            if (hint) {
+                DeviceState *d = DEVICE(dimm);
+                error_setg(errp, "address range conflicts with '%s'", d->id);
+                goto out;
+            }
+            new_start = dimm->start + dimm_size;
+        }
+    }
+    ret = new_start;
+
+    if (new_start < address_space_start) {
+        error_setg(errp, "can't add memory [0x%" PRIx64 ":0x%" PRIx64
+                   "] at 0x%" PRIx64, new_start, size, address_space_start);
+    } else if ((new_start + size) > address_space_end) {
+        error_setg(errp, "can't add memory [0x%" PRIx64 ":0x%" PRIx64
+                   "] beyond 0x%" PRIx64, new_start, size, address_space_end);
+    }
+
+out:
+    g_slist_free(list);
+    return ret;
+}
 
 static Property dimm_properties[] = {
     DEFINE_PROP_UINT64("start", DimmDevice, start, 0),
diff --git a/include/hw/mem/dimm.h b/include/hw/mem/dimm.h
index 4bbf0ed..d6e4d65 100644
--- a/include/hw/mem/dimm.h
+++ b/include/hw/mem/dimm.h
@@ -62,4 +62,9 @@ typedef struct DimmDeviceClass {
     MemoryRegion *(*get_memory_region)(DimmDevice *dimm);
 } DimmDeviceClass;
 
+
+uint64_t dimm_get_free_addr(uint64_t address_space_start,
+                            uint64_t address_space_size,
+                            uint64_t *hint, uint64_t size,
+                            Error **errp);
 #endif
-- 
1.8.0