Re: [Qemu-devel] [PATCH v5] i386, acpi: check acpi_memory_hotplug capacity in pre_plug

[Wei Yang <richardw.yang@linux.intel.com>]

On Mon, Feb 25, 2019 at 09:07:08AM +0800, Wei Yang wrote:
>Currently we do device realization like below:
>
>   hotplug_handler_pre_plug()
>   dc->realize()
>   hotplug_handler_plug()
>
>Before we do device realization and plug, we should allocate necessary
>resources and check if memory-hotplug-support property is enabled.
>
>At the piix4 and ich9, the memory-hotplug-support property is checked at
>plug stage. This means that device has been realized and mapped into guest
>address space 'pc_dimm_plug()' by the time acpi plug handler is called,
>where it might fail and crash QEMU due to reaching g_assert_not_reached()
>(piix4) or error_abort (ich9).
>
>Fix it by checking if memory hotplug is enabled at pre_plug stage
>where we can gracefully abort hotplug request.
>
>Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>CC: Igor Mammedov <imammedo@redhat.com>
>CC: Eric Blake <eblake@redhat.com>
>Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
>
>---
>v5:
>   * rebase on latest upstream
>   * remove a comment before hotplug_handler_pre_plug
>   * fix alignment for ich9_pm_device_pre_plug_cb
>v4:
>   * fix code alignment of piix4_device_pre_plug_cb
>v3:
>   * replace acpi_memory_hotplug with memory-hotplug-support in changelog
>   * fix code alignment of ich9_pm_device_pre_plug_cb
>   * print which device type memory-hotplug-support is disabled in
>     ich9_pm_device_pre_plug_cb and piix4_device_pre_plug_cb
>v2:
>   * (imammedo@redhat.com)
>     - Almost the whole third paragraph
>   * apply this change to ich9
>   * use hotplug_handler_pre_plug() instead of open-coding check
>---
> hw/acpi/ich9.c         | 15 +++++++++++++--
> hw/acpi/piix4.c        | 13 ++++++++++---
> hw/i386/pc.c           |  2 ++
> hw/isa/lpc_ich9.c      |  1 +
> include/hw/acpi/ich9.h |  2 ++
> 5 files changed, 28 insertions(+), 5 deletions(-)
>
>diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
>index c5d8646abc..e53dfe1ee3 100644
>--- a/hw/acpi/ich9.c
>+++ b/hw/acpi/ich9.c
>@@ -483,13 +483,24 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm, Error **errp)
>                              NULL);
> }
> 
>+void ich9_pm_device_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>+                                Error **errp)
>+{
>+    ICH9LPCState *lpc = ICH9_LPC_DEVICE(hotplug_dev);
>+
>+    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
>+        !lpc->pm.acpi_memory_hotplug.is_enabled)
>+        error_setg(errp,
>+                   "memory hotplug is not enabled: %s.memory-hotplug-support "
>+                   "is not set", object_get_typename(OBJECT(lpc)));
>+}
>+
> void ich9_pm_device_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>                             Error **errp)
> {
>     ICH9LPCState *lpc = ICH9_LPC_DEVICE(hotplug_dev);
> 
>-    if (lpc->pm.acpi_memory_hotplug.is_enabled &&
>-        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>+    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>         if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
>             nvdimm_acpi_plug_cb(hotplug_dev, dev);
>         } else {
>diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
>index df8c0db909..8b9654e437 100644
>--- a/hw/acpi/piix4.c
>+++ b/hw/acpi/piix4.c
>@@ -374,9 +374,16 @@ static void piix4_pm_powerdown_req(Notifier *n, void *opaque)
> static void piix4_device_pre_plug_cb(HotplugHandler *hotplug_dev,
>                                     DeviceState *dev, Error **errp)

Hmm, I found one interesting thing.

This function is introduced in

    commit ec266f408882fd38475f72c4e864ed576228643b
    pci/pcihp: perform check for bus capability in pre_plug handler

This is just implemented in piix4, but don't has the counterpart in ich9.

So I suggest to have a follow up patch to create the counterpart for ich9 and
then apply this patch on top of that.

Is my understanding correct?

> {
>+    PIIX4PMState *s = PIIX4_PM(hotplug_dev);
>+
>     if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
>         acpi_pcihp_device_pre_plug_cb(hotplug_dev, dev, errp);
>-    } else if (!object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
>+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
>+               !s->acpi_memory_hotplug.is_enabled) {
>+        error_setg(errp,
>+                   "memory hotplug is not enabled: %s.memory-hotplug-support "
>+                   "is not set", object_get_typename(OBJECT(s)));
>+    } else if (
>                !object_dynamic_cast(OBJECT(dev), TYPE_CPU)) {
>         error_setg(errp, "acpi: device pre plug request for not supported"
>                    " device type: %s", object_get_typename(OBJECT(dev)));
>@@ -388,8 +395,7 @@ static void piix4_device_plug_cb(HotplugHandler *hotplug_dev,
> {
>     PIIX4PMState *s = PIIX4_PM(hotplug_dev);
> 
>-    if (s->acpi_memory_hotplug.is_enabled &&
>-        object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>+    if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM)) {
>         if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
>             nvdimm_acpi_plug_cb(hotplug_dev, dev);
>         } else {
>@@ -704,6 +710,7 @@ static void piix4_pm_class_init(ObjectClass *klass, void *data)
>     dc->user_creatable = false;
>     dc->hotpluggable = false;
>     hc->pre_plug = piix4_device_pre_plug_cb;
>+    hc->pre_plug = piix4_device_pre_plug_cb;
>     hc->plug = piix4_device_plug_cb;
>     hc->unplug_request = piix4_device_unplug_request_cb;
>     hc->unplug = piix4_device_unplug_cb;
>diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>index 578f772e7c..64d9e756fa 100644
>--- a/hw/i386/pc.c
>+++ b/hw/i386/pc.c
>@@ -2083,6 +2083,8 @@ static void pc_memory_pre_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
>         return;
>     }
> 
>+    hotplug_handler_pre_plug(pcms->acpi_dev, dev, errp);
>+
>     if (is_nvdimm && !pcms->acpi_nvdimm_state.is_enabled) {
>         error_setg(errp, "nvdimm is not enabled: missing 'nvdimm' in '-M'");
>         return;
>diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
>index e692b9fdc1..ac44aa53be 100644
>--- a/hw/isa/lpc_ich9.c
>+++ b/hw/isa/lpc_ich9.c
>@@ -805,6 +805,7 @@ static void ich9_lpc_class_init(ObjectClass *klass, void *data)
>      * pc_q35_init()
>      */
>     dc->user_creatable = false;
>+    hc->pre_plug = ich9_pm_device_pre_plug_cb;
>     hc->plug = ich9_pm_device_plug_cb;
>     hc->unplug_request = ich9_pm_device_unplug_request_cb;
>     hc->unplug = ich9_pm_device_unplug_cb;
>diff --git a/include/hw/acpi/ich9.h b/include/hw/acpi/ich9.h
>index 59aeb06393..41568d1837 100644
>--- a/include/hw/acpi/ich9.h
>+++ b/include/hw/acpi/ich9.h
>@@ -74,6 +74,8 @@ extern const VMStateDescription vmstate_ich9_pm;
> 
> void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm, Error **errp);
> 
>+void ich9_pm_device_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>+                                Error **errp);
> void ich9_pm_device_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
>                             Error **errp);
> void ich9_pm_device_unplug_request_cb(HotplugHandler *hotplug_dev,
>-- 
>2.19.1

-- 
Wei Yang
Help you, Help me