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x86: cpuhp: refuse cpu hot-unplug request earlier if not supported 

CPU hot-unplug with SMM requires firmware participation to prevent
guest crash (i.e. CPU can be removed only after OS _and_ firmware
were prepared for the action).
Previous patches introduced ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT
feature bit, which is advertised by firmware when it has support
for CPU hot-unplug. Use it to check if guest is able to handle
unplug and make device_del fail gracefully if hot-unplug feature
hasn't been negotiated.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200923094650.1301166-4-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Igor Mammedov 2020-09-23 05:46:42 -04:00 committed by Michael S. Tsirkin
parent c5be7517d6
commit b48ad7c02b
1 changed files with 12 additions and 0 deletions
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12
hw/acpi/ich9.c
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@ -460,6 +460,18 @@ void ich9_pm_device_unplug_request_cb(HotplugHandler *hotplug_dev,
errp); errp);
} else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU) && } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU) &&
!lpc->pm.cpu_hotplug_legacy) { !lpc->pm.cpu_hotplug_legacy) {
uint64_t negotiated = lpc->smi_negotiated_features;
if (negotiated & BIT_ULL(ICH9_LPC_SMI_F_BROADCAST_BIT) &&
!(negotiated & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT))) {
error_setg(errp, "cpu hot-unplug with SMI wasn't enabled "
"by firmware");
error_append_hint(errp, "update machine type to a version having "
"x-smi-cpu-hotunplug=on and firmware that "
"supports CPU hot-unplug with SMM");
return;
}
acpi_cpu_unplug_request_cb(hotplug_dev, &lpc->pm.cpuhp_state, acpi_cpu_unplug_request_cb(hotplug_dev, &lpc->pm.cpuhp_state,
dev, errp); dev, errp);
} else { } else {