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>
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@ -460,6 +460,18 @@ void ich9_pm_device_unplug_request_cb(HotplugHandler *hotplug_dev,
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errp);
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} else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU) &&
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!lpc->pm.cpu_hotplug_legacy) {
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uint64_t negotiated = lpc->smi_negotiated_features;
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if (negotiated & BIT_ULL(ICH9_LPC_SMI_F_BROADCAST_BIT) &&
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!(negotiated & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT))) {
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error_setg(errp, "cpu hot-unplug with SMI wasn't enabled "
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"by firmware");
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error_append_hint(errp, "update machine type to a version having "
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"x-smi-cpu-hotunplug=on and firmware that "
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"supports CPU hot-unplug with SMM");
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return;
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}
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acpi_cpu_unplug_request_cb(hotplug_dev, &lpc->pm.cpuhp_state,
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dev, errp);
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} else {
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