Commit 3716fd27 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/irq: Check vector allocation early 



__assign_irq_vector() uses the vector_cpumask which is assigned by
apic->vector_allocation_domain() without doing basic sanity checks. That can
result in a situation where the final assignement of a newly found vector
fails in apic->cpu_mask_to_apicid_and(). So we have to do rollbacks for no
reason.

apic->cpu_mask_to_apicid_and() only fails if 

  vector_cpumask & requested_cpumask & cpu_online_mask 

is empty.

Check for this condition right away and if the result is empty try immediately
the next possible cpu in the requested mask. So in case of a failure the old
setting is unchanged and we can remove the rollback code.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarBorislav Petkov <bp@alien8.de>
Tested-by: default avatarJoe Lawrence <joe.lawrence@stratus.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Jeremiah Mahler <jmmahler@gmail.com>
Cc: andy.shevchenko@gmail.com
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: stable@vger.kernel.org #4.3+
Link: http://lkml.kernel.org/r/20151231160106.561877324@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 95ffeb4b

arch/x86/kernel/apic/vector.c

+25 −13
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ struct apic_chip_data { 
struct irq_domain *x86_vector_domain;

EXPORT_SYMBOL_GPL(x86_vector_domain);

static DEFINE_RAW_SPINLOCK(vector_lock);

static cpumask_var_t vector_cpumask, searched_cpumask;

static cpumask_var_t vector_cpumask, vector_searchmask, searched_cpumask;

static struct irq_chip lapic_controller;

#ifdef	CONFIG_X86_IO_APIC

static struct apic_chip_data *legacy_irq_data[NR_IRQS_LEGACY];
@@ -130,8 +130,20 @@ static int __assign_irq_vector(int irq, struct apic_chip_data *d, 
	while (cpu < nr_cpu_ids) {

		int new_cpu, vector, offset;



		/* Get the possible target cpus for @mask/@cpu from the apic */

		apic->vector_allocation_domain(cpu, vector_cpumask, mask);



		/*

		 * Clear the offline cpus from @vector_cpumask for searching

		 * and verify whether the result overlaps with @mask. If true,

		 * then the call to apic->cpu_mask_to_apicid_and() will

		 * succeed as well. If not, no point in trying to find a

		 * vector in this mask.

		 */

		cpumask_and(vector_searchmask, vector_cpumask, cpu_online_mask);

		if (!cpumask_intersects(vector_searchmask, mask))

			goto next_cpu;



		if (cpumask_subset(vector_cpumask, d->domain)) {

			if (cpumask_equal(vector_cpumask, d->domain))

				goto success;
@@ -164,7 +176,7 @@ next: 
		if (test_bit(vector, used_vectors))

			goto next;



		for_each_cpu_and(new_cpu, vector_cpumask, cpu_online_mask) {

		for_each_cpu(new_cpu, vector_searchmask) {

			if (!IS_ERR_OR_NULL(per_cpu(vector_irq, new_cpu)[vector]))

				goto next;

		}
@@ -176,7 +188,7 @@ next: 
			d->move_in_progress =

			   cpumask_intersects(d->old_domain, cpu_online_mask);

		}

		for_each_cpu_and(new_cpu, vector_cpumask, cpu_online_mask)

		for_each_cpu(new_cpu, vector_searchmask)

			per_cpu(vector_irq, new_cpu)[vector] = irq_to_desc(irq);

		d->cfg.vector = vector;

		cpumask_copy(d->domain, vector_cpumask);
@@ -198,8 +210,14 @@ next_cpu: 
	return -ENOSPC;



success:

	/* cache destination APIC IDs into cfg->dest_apicid */

	return apic->cpu_mask_to_apicid_and(mask, d->domain, &d->cfg.dest_apicid);

	/*

	 * Cache destination APIC IDs into cfg->dest_apicid. This cannot fail

	 * as we already established, that mask & d->domain & cpu_online_mask

	 * is not empty.

	 */

	BUG_ON(apic->cpu_mask_to_apicid_and(mask, d->domain,

					    &d->cfg.dest_apicid));

	return 0;

}



static int assign_irq_vector(int irq, struct apic_chip_data *data,
@@ -409,6 +427,7 @@ int __init arch_early_irq_init(void) 
	arch_init_htirq_domain(x86_vector_domain);



	BUG_ON(!alloc_cpumask_var(&vector_cpumask, GFP_KERNEL));

	BUG_ON(!alloc_cpumask_var(&vector_searchmask, GFP_KERNEL));

	BUG_ON(!alloc_cpumask_var(&searched_cpumask, GFP_KERNEL));



	return arch_early_ioapic_init();
@@ -498,14 +517,7 @@ static int apic_set_affinity(struct irq_data *irq_data, 
		return -EINVAL;



	err = assign_irq_vector(irq, data, dest);

	if (err) {

		if (assign_irq_vector(irq, data,

				      irq_data_get_affinity_mask(irq_data)))

			pr_err("Failed to recover vector for irq %d\n", irq);

		return err;

	}



	return IRQ_SET_MASK_OK;

	return err ? err : IRQ_SET_MASK_OK;

}



static struct irq_chip lapic_controller = {

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