On Thu, 14 Feb 2019 20:53:31 +0000
Wei Yang <richard.weiy...@gmail.com> wrote:
> On Thu, Feb 14, 2019 at 12:25:27PM +0100, Igor Mammedov wrote:
> >On Thu, 14 Feb 2019 08:52:25 +0800
> >Wei Yang <richardw.y...@linux.intel.com> 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 would allocate necessary
> >> resources and check the capacity.
> >'capacity' probably is not right word to use here
> >maybe s/the capacity/if 'memory-hotplug-support' property is enabled/
> >
> >>
> >> While we leave acpi_memory_hotplug capacity check in the last step. This
> >wouldn't use 'leave' and 'capacity' here either, pls rephrase.
> >
> >> looks not comply with current architecture and does some unnecessary
> >s/looks not/doesn't/
> >> work.
> >add more explanation about 'unnecessary work'.
> >problem as I see it, is that after successful pc_dimm_plug()
> >we get into piix4_device_plug_cb() and since
> > s->acpi_memory_hotplug.is_enabled == false
> >and all other 'if' conditions also false we would endup
> >at g_assert_not_reached() causing QEMU crash in piix4 case
> >and with error_abort up the call chain in case of ich9.
> >
>
> Thanks Igor, I rephrase above change log like this. Does this look
> better to you now?
>
> Before we do device realization and plug, we would allocate
s/would/should/
> necessary resources and check if memory-hotplug-support property is
> enabled.
>
> In piix4 and ich9, the acpi_memory_hotplug property is checked in
s/in/at the/
> plug stage, this doesn't comply with current architecture. This
drop ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> means we have prepared everything and even do pc_dimm_plug()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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).
or something like this, I'm not native speaker either so CC Eric Blake
on next respin so he could check commit message.
> successfuly, but failed at last because
> acpi_memory_hotplug.is_enabled == false. Which is worse is in piix4,
> this endup at g_assert_not_reached() and cause QEMU crash.
>
>
> >> This patch abstract the check on acpi_memory_hotplug capacity in
> >> pre_plug stage.
> >>
> >> Signed-off-by: Wei Yang <richardw.y...@linux.intel.com>
> >> ---
> >> hw/acpi/piix4.c | 14 ++++++++++++--
> >> hw/i386/pc.c | 8 ++++++++
> >doesn't look complete, why did you skip on similar code in ich9
> >(Q35 machine)?
> >
>
> You are right, I missed this part.
>
> >> 2 files changed, 20 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
> >> index e330f24c71..c97b747496 100644
> >> --- a/hw/acpi/piix4.c
> >> +++ b/hw/acpi/piix4.c
> >> @@ -370,13 +370,22 @@ static void piix4_pm_powerdown_req(Notifier *n, void
> >> *opaque)
> >> acpi_pm1_evt_power_down(&s->ar);
> >> }
> >>
> >> +static void piix4_device_pre_plug_cb(HotplugHandler *hotplug_dev,
> >> + DeviceState *dev, Error **errp)
> >> +{
> >> + PIIX4PMState *s = PIIX4_PM(hotplug_dev);
> >> +
> >> + if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
> >> + !s->acpi_memory_hotplug.is_enabled)
> >> + error_setg(errp,
> >> + "memory hotplug is not enabled: PIIX4 memory hotplug
> >> disabled");
> >> +}
> >> static void piix4_device_plug_cb(HotplugHandler *hotplug_dev,
> >> DeviceState *dev, Error **errp)
> >> {
> >> 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 {
> >> @@ -702,6 +711,7 @@ 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->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 734d3268fa..3c6eed0cd3 100644
> >> --- a/hw/i386/pc.c
> >> +++ b/hw/i386/pc.c
> >> @@ -1662,6 +1662,7 @@ static void pc_memory_pre_plug(HotplugHandler
> >> *hotplug_dev, DeviceState *dev,
> >> const PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
> >> const bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
> >> const uint64_t legacy_align = TARGET_PAGE_SIZE;
> >> + HotplugHandlerClass *hhc;
> >>
> >> /*
> >> * When -no-acpi is used with Q35 machine type, no ACPI is built,
> >> @@ -1674,6 +1675,13 @@ static void pc_memory_pre_plug(HotplugHandler
> >> *hotplug_dev, DeviceState *dev,
> >> return;
> >> }
> >>
> >> + /*
> >> + * Check acpi_dev memory hotplug capacity
> >> + */
> >> + hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
> >> + if (hcc->pre_plug)
> >> + hhc->pre_plug(HOTPLUG_HANDLER(pcms->acpi_dev), dev, errp);
> >use hotplug_handler_pre_plug() instead of open-coding check
> >
>
> Thanks, will fix this.
>
> >> if (is_nvdimm && !pcms->acpi_nvdimm_state.is_enabled) {
> >> error_setg(errp, "nvdimm is not enabled: missing 'nvdimm' in
> >> '-M'");
> >> return;
> >
>
