From 0b9d46dd7debf8e6dc8614106f1c1909fa8de64d Mon Sep 17 00:00:00 2001 From: Igor Mammedov Date: Mon, 5 May 2014 22:49:49 +0200 Subject: ACPI / processor: do not mark present at boot but not onlined CPU as onlined acpi_processor_add() assumes that present at boot CPUs are always onlined, it is not so if a CPU failed to become onlined. As result acpi_processor_add() will mark such CPU device as onlined in sysfs and following attempts to online/offline it using /sys/device/system/cpu/cpuX/online attribute will fail. Do not poke into device internals in acpi_processor_add() and touch "struct device { .offline }" attribute, since for CPUs onlined at boot it's set by: topology_init() -> arch_register_cpu() -> register_cpu() before ACPI device tree is parsed, and for hotplugged CPUs it's set when userspace onlines CPU via sysfs. Signed-off-by: Igor Mammedov Acked-by: Toshi Kani Cc: 3.11+ # 3.11+ Signed-off-by: Rafael J. Wysocki --- drivers/acpi/acpi_processor.c | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/acpi/acpi_processor.c') diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c index b06f5f55ada..52c81c49cc7 100644 --- a/drivers/acpi/acpi_processor.c +++ b/drivers/acpi/acpi_processor.c @@ -405,7 +405,6 @@ static int acpi_processor_add(struct acpi_device *device, goto err; pr->dev = dev; - dev->offline = pr->flags.need_hotplug_init; /* Trigger the processor driver's .probe() if present. */ if (device_attach(dev) >= 0) -- cgit v1.2.3-70-g09d2 From c401eb8ee374a5fc2b56042c0072ce51a0beb0dc Mon Sep 17 00:00:00 2001 From: Baoquan He Date: Mon, 5 May 2014 12:48:26 +0800 Subject: ACPI / processor: Check if LAPIC is present during initialization In acpi_processor_get_info(), ACPI processor info is initialized including ID, namely CPU index. Currently, on a UP system running an SMP kerenl with no LAPIC in the MADT, cpu0_initialized is checked to decide whether or not the CPU has been initialized. However, this check may not be sufficient for kdump kernels. Most of time only 1 CPU is supported because of known problems in kdump kernels. So say the multiple CPUs are present in the boot kernel and a crash happens on one specific CPU, say CPU2. Then it jumps into the kdump kernel with "nr_cpus=1" in the command line. In this situation, the kdump kernel will reuse the ACPI resources from the crashed kernel directly. That means all LAPIC instances are enabled in the MADT while only one CPU is in use. In the kdump kernel, x86_cpu_to_apicid contains the correct APIC ID and it's related to the CPU ID. If cpu0_initialized is checked only, 0 will be used as the CPU index instead of that APIC ID, which is not correct. In addition to checking cpu0_initialized, check acpi_lapic. If acpi_lapic is 0, then no LAPIC is available from the MADT and the system should be treated as a UP one without a LAPIC (that is, assign 0 to the CPU index). Otherwise, use the original (valid) CPU index. Signed-off-by: Baoquan He [rjw: Subject and changelog] Signed-off-by: Rafael J. Wysocki --- drivers/acpi/acpi_processor.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/acpi/acpi_processor.c') diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c index 52c81c49cc7..1c085742644 100644 --- a/drivers/acpi/acpi_processor.c +++ b/drivers/acpi/acpi_processor.c @@ -268,7 +268,7 @@ static int acpi_processor_get_info(struct acpi_device *device) pr->apic_id = apic_id; cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id); - if (!cpu0_initialized) { + if (!cpu0_initialized && !acpi_lapic) { cpu0_initialized = 1; /* Handle UP system running SMP kernel, with no LAPIC in MADT */ if ((cpu_index == -1) && (num_online_cpus() == 1)) -- cgit v1.2.3-70-g09d2