Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "Misc fixes:

   - fix hotplug bugs
   - fix irq live lock
   - fix various topology handling bugs
   - fix APIC ACK ordering
   - fix PV iopl handling
   - fix speling
   - fix/tweak memcpy_mcsafe() return value
   - fix fbcon bug
   - remove stray prototypes"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/msr: Remove unused native_read_tscp()
  x86/apic: Remove declaration of unused hw_nmi_is_cpu_stuck
  x86/oprofile/nmi: Add missing hotplug FROZEN handling
  x86/hpet: Use proper mask to modify hotplug action
  x86/apic/uv: Fix the hotplug notifier
  x86/apb/timer: Use proper mask to modify hotplug action
  x86/topology: Use total_cpus not nr_cpu_ids for logical packages
  x86/topology: Fix Intel HT disable
  x86/topology: Fix logical package mapping
  x86/irq: Cure live lock in fixup_irqs()
  x86/tsc: Prevent NULL pointer deref in calibrate_delay_is_known()
  x86/apic: Fix suspicious RCU usage in smp_trace_call_function_interrupt()
  x86/iopl: Fix iopl capability check on Xen PV
  x86/iopl/64: Properly context-switch IOPL on Xen PV
  selftests/x86: Add an iopl test
  x86/mm, x86/mce: Fix return type/value for memcpy_mcsafe()
  x86/video: Don't assume all FB devices are PCI devices
  arch/x86/irq: Purge useless handler declarations from hw_irq.h
  x86: Fix misspellings in comments

19 files changed, 136 insertions, 48 deletions

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index e75907601a41..8c2f1ef6ca23 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -956,7 +956,7 @@ static int __init early_acpi_parse_madt_lapic_addr_ovr(void)
 
 	/*
 	 * Note that the LAPIC address is obtained from the MADT (32-bit value)
-	 * and (optionally) overriden by a LAPIC_ADDR_OVR entry (64-bit value).
+	 * and (optionally) overridden by a LAPIC_ADDR_OVR entry (64-bit value).
 	 */
 
 	count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC_OVERRIDE,
@@ -984,7 +984,7 @@ static int __init acpi_parse_madt_lapic_entries(void)
 
 	/*
 	 * Note that the LAPIC address is obtained from the MADT (32-bit value)
-	 * and (optionally) overriden by a LAPIC_ADDR_OVR entry (64-bit value).
+	 * and (optionally) overridden by a LAPIC_ADDR_OVR entry (64-bit value).
 	 */
 
 	count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC_OVERRIDE,
diff --git a/arch/x86/kernel/apb_timer.c b/arch/x86/kernel/apb_timer.c
index 222a57076039..cefacbad1531 100644
--- a/arch/x86/kernel/apb_timer.c
+++ b/arch/x86/kernel/apb_timer.c
@@ -221,7 +221,7 @@ static int apbt_cpuhp_notify(struct notifier_block *n,
 	unsigned long cpu = (unsigned long)hcpu;
 	struct apbt_dev *adev = &per_cpu(cpu_apbt_dev, cpu);
 
-	switch (action & 0xf) {
+	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_DEAD:
 		dw_apb_clockevent_pause(adev->timer);
 		if (system_state == SYSTEM_RUNNING) {
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 531b9611c51d..d356987a04e9 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1611,7 +1611,7 @@ void __init enable_IR_x2apic(void)
 	legacy_pic->mask_all();
 	mask_ioapic_entries();
 
-	/* If irq_remapping_prepare() succeded, try to enable it */
+	/* If irq_remapping_prepare() succeeded, try to enable it */
 	if (ir_stat >= 0)
 		ir_stat = try_to_enable_IR();
 	/* ir_stat contains the remap mode or an error code */
diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
index 3b670df4ba7b..ad59d70bcb1a 100644
--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -213,6 +213,7 @@ update:
 	 */
 	cpumask_and(d->old_domain, d->old_domain, cpu_online_mask);
 	d->move_in_progress = !cpumask_empty(d->old_domain);
+	d->cfg.old_vector = d->move_in_progress ? d->cfg.vector : 0;
 	d->cfg.vector = vector;
 	cpumask_copy(d->domain, vector_cpumask);
 success:
@@ -655,46 +656,97 @@ void irq_complete_move(struct irq_cfg *cfg)
 }
 
 /*
- * Called with @desc->lock held and interrupts disabled.
+ * Called from fixup_irqs() with @desc->lock held and interrupts disabled.
  */
 void irq_force_complete_move(struct irq_desc *desc)
 {
 	struct irq_data *irqdata = irq_desc_get_irq_data(desc);
 	struct apic_chip_data *data = apic_chip_data(irqdata);
 	struct irq_cfg *cfg = data ? &data->cfg : NULL;
+	unsigned int cpu;
 
 	if (!cfg)
 		return;
 
-	__irq_complete_move(cfg, cfg->vector);
-
 	/*
 	 * This is tricky. If the cleanup of @data->old_domain has not been
 	 * done yet, then the following setaffinity call will fail with
 	 * -EBUSY. This can leave the interrupt in a stale state.
 	 *
-	 * The cleanup cannot make progress because we hold @desc->lock. So in
-	 * case @data->old_domain is not yet cleaned up, we need to drop the
-	 * lock and acquire it again. @desc cannot go away, because the
-	 * hotplug code holds the sparse irq lock.
+	 * All CPUs are stuck in stop machine with interrupts disabled so
+	 * calling __irq_complete_move() would be completely pointless.
 	 */
 	raw_spin_lock(&vector_lock);
-	/* Clean out all offline cpus (including ourself) first. */
+	/*
+	 * Clean out all offline cpus (including the outgoing one) from the
+	 * old_domain mask.
+	 */
 	cpumask_and(data->old_domain, data->old_domain, cpu_online_mask);
-	while (!cpumask_empty(data->old_domain)) {
+
+	/*
+	 * If move_in_progress is cleared and the old_domain mask is empty,
+	 * then there is nothing to cleanup. fixup_irqs() will take care of
+	 * the stale vectors on the outgoing cpu.
+	 */
+	if (!data->move_in_progress && cpumask_empty(data->old_domain)) {
 		raw_spin_unlock(&vector_lock);
-		raw_spin_unlock(&desc->lock);
-		cpu_relax();
-		raw_spin_lock(&desc->lock);
+		return;
+	}
+
+	/*
+	 * 1) The interrupt is in move_in_progress state. That means that we
+	 *    have not seen an interrupt since the io_apic was reprogrammed to
+	 *    the new vector.
+	 *
+	 * 2) The interrupt has fired on the new vector, but the cleanup IPIs
+	 *    have not been processed yet.
+	 */
+	if (data->move_in_progress) {
 		/*
-		 * Reevaluate apic_chip_data. It might have been cleared after
-		 * we dropped @desc->lock.
+		 * In theory there is a race:
+		 *
+		 * set_ioapic(new_vector) <-- Interrupt is raised before update
+		 *			      is effective, i.e. it's raised on
+		 *			      the old vector.
+		 *
+		 * So if the target cpu cannot handle that interrupt before
+		 * the old vector is cleaned up, we get a spurious interrupt
+		 * and in the worst case the ioapic irq line becomes stale.
+		 *
+		 * But in case of cpu hotplug this should be a non issue
+		 * because if the affinity update happens right before all
+		 * cpus rendevouz in stop machine, there is no way that the
+		 * interrupt can be blocked on the target cpu because all cpus
+		 * loops first with interrupts enabled in stop machine, so the
+		 * old vector is not yet cleaned up when the interrupt fires.
+		 *
+		 * So the only way to run into this issue is if the delivery
+		 * of the interrupt on the apic/system bus would be delayed
+		 * beyond the point where the target cpu disables interrupts
+		 * in stop machine. I doubt that it can happen, but at least
+		 * there is a theroretical chance. Virtualization might be
+		 * able to expose this, but AFAICT the IOAPIC emulation is not
+		 * as stupid as the real hardware.
+		 *
+		 * Anyway, there is nothing we can do about that at this point
+		 * w/o refactoring the whole fixup_irq() business completely.
+		 * We print at least the irq number and the old vector number,
+		 * so we have the necessary information when a problem in that
+		 * area arises.
 		 */
-		data = apic_chip_data(irqdata);
-		if (!data)
-			return;
-		raw_spin_lock(&vector_lock);
+		pr_warn("IRQ fixup: irq %d move in progress, old vector %d\n",
+			irqdata->irq, cfg->old_vector);
 	}
+	/*
+	 * If old_domain is not empty, then other cpus still have the irq
+	 * descriptor set in their vector array. Clean it up.
+	 */
+	for_each_cpu(cpu, data->old_domain)
+		per_cpu(vector_irq, cpu)[cfg->old_vector] = VECTOR_UNUSED;
+
+	/* Cleanup the left overs of the (half finished) move */
+	cpumask_clear(data->old_domain);
+	data->move_in_progress = 0;
 	raw_spin_unlock(&vector_lock);
 }
 #endif
diff --git a/arch/x86/kernel/apic/x2apic_uv_x.c b/arch/x86/kernel/apic/x2apic_uv_x.c
index 624db00583f4..8f4942e2bcbb 100644
--- a/arch/x86/kernel/apic/x2apic_uv_x.c
+++ b/arch/x86/kernel/apic/x2apic_uv_x.c
@@ -792,7 +792,8 @@ static int uv_scir_cpu_notify(struct notifier_block *self, unsigned long action,
 {
 	long cpu = (long)hcpu;
 
-	switch (action) {
+	switch (action & ~CPU_TASKS_FROZEN) {
+	case CPU_DOWN_FAILED:
 	case CPU_ONLINE:
 		uv_heartbeat_enable(cpu);
 		break;
@@ -860,7 +861,7 @@ int uv_set_vga_state(struct pci_dev *pdev, bool decode,
  */
 void uv_cpu_init(void)
 {
-	/* CPU 0 initilization will be done via uv_system_init. */
+	/* CPU 0 initialization will be done via uv_system_init. */
 	if (!uv_blade_info)
 		return;
 
diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
index 052c9c3026cc..9307f182fe30 100644
--- a/arch/x86/kernel/apm_32.c
+++ b/arch/x86/kernel/apm_32.c
@@ -1088,7 +1088,7 @@ static int apm_get_battery_status(u_short which, u_short *status,
  *	@device: identity of device
  *	@enable: on/off
  *
- *	Activate or deactive power management on either a specific device
+ *	Activate or deactivate power management on either a specific device
  *	or the entire system (%APM_DEVICE_ALL).
  */
 
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 5026a13356c4..e51021c9207a 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -85,7 +85,7 @@ static void init_amd_k5(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_32
 /*
  * General Systems BIOSen alias the cpu frequency registers
- * of the Elan at 0x000df000. Unfortuantly, one of the Linux
+ * of the Elan at 0x000df000. Unfortunately, one of the Linux
  * drivers subsequently pokes it, and changes the CPU speed.
  * Workaround : Remove the unneeded alias.
  */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 06ad72383b4e..9988caf42161 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -968,7 +968,7 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	if (this_cpu->c_identify)
 		this_cpu->c_identify(c);
 
-	/* Clear/Set all flags overriden by options, after probe */
+	/* Clear/Set all flags overridden by options, after probe */
 	for (i = 0; i < NCAPINTS; i++) {
 		c->x86_capability[i] &= ~cpu_caps_cleared[i];
 		c->x86_capability[i] |= cpu_caps_set[i];
@@ -1028,7 +1028,7 @@ static void identify_cpu(struct cpuinfo_x86 *c)
 	setup_pku(c);
 
 	/*
-	 * Clear/Set all flags overriden by options, need do it
+	 * Clear/Set all flags overridden by options, need do it
 	 * before following smp all cpus cap AND.
 	 */
 	for (i = 0; i < NCAPINTS; i++) {
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index fcbcb2f678ca..19f57360dfd2 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -42,7 +42,7 @@ EXPORT_SYMBOL_GPL(mtrr_state);
  * "BIOS and Kernel Developer's Guide for the AMD Athlon 64 and AMD
  * Opteron Processors" (26094 Rev. 3.30 February 2006), section
  * "13.2.1.2 SYSCFG Register": "The MtrrFixDramModEn bit should be set
- * to 1 during BIOS initalization of the fixed MTRRs, then cleared to
+ * to 1 during BIOS initialization of the fixed MTRRs, then cleared to
  * 0 for operation."
  */
 static inline void k8_check_syscfg_dram_mod_en(void)
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 21bf92490a7b..8a121991e5ba 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -287,7 +287,7 @@ static __init void early_pci_serial_init(char *s)
 	}
 
 	/*
-	 * Lastly, initalize the hardware
+	 * Lastly, initialize the hardware
 	 */
 	if (*s) {
 		if (strcmp(s, "nocfg") == 0)
diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 0bc3490420c5..8bd1c003942a 100644
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -8,7 +8,7 @@
 /*
  * The xstateregs_active() routine is the same as the regset_fpregs_active() routine,
  * as the "regset->n" for the xstate regset will be updated based on the feature
- * capabilites supported by the xsave.
+ * capabilities supported by the xsave.
  */
 int regset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
 {
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index be0ebbb6d1d1..a1f0e4a5c47e 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -717,7 +717,7 @@ static int hpet_cpuhp_notify(struct notifier_block *n,
 	struct hpet_work_struct work;
 	struct hpet_dev *hdev = per_cpu(cpu_hpet_dev, cpu);
 
-	switch (action & 0xf) {
+	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_ONLINE:
 		INIT_DELAYED_WORK_ONSTACK(&work.work, hpet_work);
 		init_completion(&work.complete);
diff --git a/arch/x86/kernel/ioport.c b/arch/x86/kernel/ioport.c
index 37dae792dbbe..589b3193f102 100644
--- a/arch/x86/kernel/ioport.c
+++ b/arch/x86/kernel/ioport.c
@@ -96,9 +96,14 @@ asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int turn_on)
 SYSCALL_DEFINE1(iopl, unsigned int, level)
 {
 	struct pt_regs *regs = current_pt_regs();
-	unsigned int old = (regs->flags >> 12) & 3;
 	struct thread_struct *t = &current->thread;
 
+	/*
+	 * Careful: the IOPL bits in regs->flags are undefined under Xen PV
+	 * and changing them has no effect.
+	 */
+	unsigned int old = t->iopl >> X86_EFLAGS_IOPL_BIT;
+
 	if (level > 3)
 		return -EINVAL;
 	/* Trying to gain more privileges? */
@@ -106,8 +111,9 @@ SYSCALL_DEFINE1(iopl, unsigned int, level)
 		if (!capable(CAP_SYS_RAWIO))
 			return -EPERM;
 	}
-	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) | (level << 12);
-	t->iopl = level << 12;
+	regs->flags = (regs->flags & ~X86_EFLAGS_IOPL) |
+		(level << X86_EFLAGS_IOPL_BIT);
+	t->iopl = level << X86_EFLAGS_IOPL_BIT;
 	set_iopl_mask(t->iopl);
 
 	return 0;
diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 0f8a6bbaaa44..2af478e3fd4e 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -271,7 +271,7 @@ static int bzImage64_probe(const char *buf, unsigned long len)
 	int ret = -ENOEXEC;
 	struct setup_header *header;
 
-	/* kernel should be atleast two sectors long */
+	/* kernel should be at least two sectors long */
 	if (len < 2 * 512) {
 		pr_err("File is too short to be a bzImage\n");
 		return ret;
diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index ed15cd486d06..2da6ee9ae69b 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -609,9 +609,9 @@ static struct notifier_block kgdb_notifier = {
 };
 
 /**
- *	kgdb_arch_init - Perform any architecture specific initalization.
+ *	kgdb_arch_init - Perform any architecture specific initialization.
  *
- *	This function will handle the initalization of any architecture
+ *	This function will handle the initialization of any architecture
  *	specific callbacks.
  */
 int kgdb_arch_init(void)
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index 72cef58693c7..1d39bfbd26bb 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -226,7 +226,7 @@ static void kvm_setup_secondary_clock(void)
  * registered memory location. If the guest happens to shutdown, this memory
  * won't be valid. In cases like kexec, in which you install a new kernel, this
  * means a random memory location will be kept being written. So before any
- * kind of shutdown from our side, we unregister the clock by writting anything
+ * kind of shutdown from our side, we unregister the clock by writing anything
  * that does not have the 'enable' bit set in the msr
  */
 #ifdef CONFIG_KEXEC_CORE
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index dfa2781610e8..6cbab31ac23a 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -48,6 +48,7 @@
 #include <asm/syscalls.h>
 #include <asm/debugreg.h>
 #include <asm/switch_to.h>
+#include <asm/xen/hypervisor.h>
 
 asmlinkage extern void ret_from_fork(void);
 
@@ -413,6 +414,17 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 		     task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
 		__switch_to_xtra(prev_p, next_p, tss);
 
+#ifdef CONFIG_XEN
+	/*
+	 * On Xen PV, IOPL bits in pt_regs->flags have no effect, and
+	 * current_pt_regs()->flags may not match the current task's
+	 * intended IOPL.  We need to switch it manually.
+	 */
+	if (unlikely(static_cpu_has(X86_FEATURE_XENPV) &&
+		     prev->iopl != next->iopl))
+		xen_set_iopl_mask(next->iopl);
+#endif
+
 	if (static_cpu_has_bug(X86_BUG_SYSRET_SS_ATTRS)) {
 		/*
 		 * AMD CPUs have a misfeature: SYSRET sets the SS selector but
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 643dbdccf4bc..b2c99f811c3f 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -274,11 +274,6 @@ int topology_update_package_map(unsigned int apicid, unsigned int cpu)
 	if (test_and_set_bit(pkg, physical_package_map))
 		goto found;
 
-	if (pkg < __max_logical_packages) {
-		set_bit(pkg, logical_package_map);
-		physical_to_logical_pkg[pkg] = pkg;
-		goto found;
-	}
 	new = find_first_zero_bit(logical_package_map, __max_logical_packages);
 	if (new >= __max_logical_packages) {
 		physical_to_logical_pkg[pkg] = -1;
@@ -317,9 +312,27 @@ static void __init smp_init_package_map(void)
 	/*
 	 * Today neither Intel nor AMD support heterogenous systems. That
 	 * might change in the future....
+	 *
+	 * While ideally we'd want '* smp_num_siblings' in the below @ncpus
+	 * computation, this won't actually work since some Intel BIOSes
+	 * report inconsistent HT data when they disable HT.
+	 *
+	 * In particular, they reduce the APIC-IDs to only include the cores,
+	 * but leave the CPUID topology to say there are (2) siblings.
+	 * This means we don't know how many threads there will be until
+	 * after the APIC enumeration.
+	 *
+	 * By not including this we'll sometimes over-estimate the number of
+	 * logical packages by the amount of !present siblings, but this is
+	 * still better than MAX_LOCAL_APIC.
+	 *
+	 * We use total_cpus not nr_cpu_ids because nr_cpu_ids can be limited
+	 * on the command line leading to a similar issue as the HT disable
+	 * problem because the hyperthreads are usually enumerated after the
+	 * primary cores.
 	 */
-	ncpus = boot_cpu_data.x86_max_cores * smp_num_siblings;
-	__max_logical_packages = DIV_ROUND_UP(nr_cpu_ids, ncpus);
+	ncpus = boot_cpu_data.x86_max_cores;
+	__max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus);
 
 	/*
 	 * Possibly larger than what we need as the number of apic ids per
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 56380440d862..c9c4c7ce3eb2 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -881,7 +881,7 @@ void tsc_restore_sched_clock_state(void)
 	local_irq_save(flags);
 
 	/*
-	 * We're comming out of suspend, there's no concurrency yet; don't
+	 * We're coming out of suspend, there's no concurrency yet; don't
 	 * bother being nice about the RCU stuff, just write to both
 	 * data fields.
 	 */
@@ -1306,11 +1306,15 @@ void __init tsc_init(void)
 unsigned long calibrate_delay_is_known(void)
 {
 	int sibling, cpu = smp_processor_id();
+	struct cpumask *mask = topology_core_cpumask(cpu);
 
 	if (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC))
 		return 0;
 
-	sibling = cpumask_any_but(topology_core_cpumask(cpu), cpu);
+	if (!mask)
+		return 0;
+
+	sibling = cpumask_any_but(mask, cpu);
 	if (sibling < nr_cpu_ids)
 		return cpu_data(sibling).loops_per_jiffy;
 	return 0;