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

[Igor Mammedov]

On Mon, 25 Feb 2019 09:15:34 +0800
Wei Yang <address@hidden> wrote:

> 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 <address@hidden>
> >CC: Igor Mammedov <address@hidden>
> >CC: Eric Blake <address@hidden>
> >Signed-off-by: Wei Yang <address@hidden>
> >
> >---
> >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:
> >   * (address@hidden)
> >     - 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.
not sure what do you mean, could you be more specific?

> 
> 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  
>