From b48ad7c02ba77c151bb8b10db6418615fa4ff458 Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Wed, 23 Sep 2020 05:46:42 -0400 Subject: [PATCH] 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 Tested-by: Laszlo Ersek Reviewed-by: Laszlo Ersek Message-Id: <20200923094650.1301166-4-imammedo@redhat.com> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/acpi/ich9.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c index 0acc9a3107..95cb0f935b 100644 --- a/hw/acpi/ich9.c +++ b/hw/acpi/ich9.c @@ -460,6 +460,18 @@ void ich9_pm_device_unplug_request_cb(HotplugHandler *hotplug_dev, errp); } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU) && !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, dev, errp); } else { -- 2.11.4.GIT