[patch 48/52] x86/vector: Handle managed interrupts proper

Thomas Gleixner
2017-09-13T21:36:25Z

[-- Attachment #1: x86-vector--Support-managed-interrupts-proper.patch --]
[-- Type: text/plain, Size: 9970 bytes --]

Managed interrupts need to reserve interrupt vectors permanently, but as
long as the interrupt is deactivated, the vector should not be active.

Reserve a new system vector, which can be used to initially initialize
MSI/DMAR/IOAPIC entries. In that situation the interrupts are disabled in
the corresponding MSI/DMAR/IOAPIC devices. So the vector should never be
sent to any CPU.

When the managed interrupt is started up, a real vector is assigned from
the managed vector space and configured in MSI/DMAR/IOAPIC.

This allows a clear separation of inactive and active modes and simplifies
the final decisions whether the global vector space is sufficient for CPU
offline operations.

The vector space can be reserved even on offline CPUs and will survive CPU
offline/online operations.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/irq_vectors.h | 8 -
arch/x86/kernel/apic/vector.c | 190 +++++++++++++++++++++++++++++++++----
2 files changed, 174 insertions(+), 24 deletions(-)

--- a/arch/x86/include/asm/irq_vectors.h
+++ b/arch/x86/include/asm/irq_vectors.h
@@ -101,12 +101,8 @@
#define POSTED_INTR_NESTED_VECTOR 0xf0
#endif

-/*
- * Local APIC timer IRQ vector is on a different priority level,
- * to work around the 'lost local interrupt if more than 2 IRQ
- * sources per level' errata.
- */
-#define LOCAL_TIMER_VECTOR 0xef
+#define MANAGED_IRQ_SHUTDOWN_VECTOR 0xef
+#define LOCAL_TIMER_VECTOR 0xee

#define NR_VECTORS 256

--- a/arch/x86/kernel/apic/vector.c
+++ b/arch/x86/kernel/apic/vector.c
@@ -32,7 +32,8 @@ struct apic_chip_data {
unsigned int prev_cpu;
unsigned int irq;
struct hlist_node clist;
- u8 move_in_progress : 1;
+ unsigned int move_in_progress : 1,
+ is_managed : 1;
};

struct irq_domain *x86_vector_domain;
@@ -152,6 +153,28 @@ static void apic_update_vector(struct ir
per_cpu(vector_irq, newcpu)[newvec] = desc;
}

+static void vector_assign_managed_shutdown(struct irq_data *irqd)
+{
+ unsigned int cpu = cpumask_first(cpu_online_mask);
+
+ apic_update_irq_cfg(irqd, MANAGED_IRQ_SHUTDOWN_VECTOR, cpu);
+}
+
+static int reserve_managed_vector(struct irq_data *irqd)
+{
+ const struct cpumask *affmsk = irq_data_get_affinity_mask(irqd);
+ struct apic_chip_data *apicd = apic_chip_data(irqd);
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&vector_lock, flags);
+ apicd->is_managed = true;
+ ret = irq_matrix_reserve_managed(vector_matrix, affmsk);
+ raw_spin_unlock_irqrestore(&vector_lock, flags);
+ trace_vector_reserve_managed(irqd->irq, ret);
+ return ret;
+}
+
static int allocate_vector(struct irq_data *irqd, const struct cpumask *dest)
{
struct apic_chip_data *apicd = apic_chip_data(irqd);
@@ -200,20 +223,65 @@ static int assign_irq_vector(struct irq_
return ret;
}

-static int assign_irq_vector_policy(struct irq_data *irqd,
- struct irq_alloc_info *info, int node)
+static int assign_irq_vector_any_locked(struct irq_data *irqd)
+{
+ int node = irq_data_get_node(irqd);
+
+ if (node != NUMA_NO_NODE) {
+ if (!assign_vector_locked(irqd, cpumask_of_node(node)))
+ return 0;
+ }
+ return assign_vector_locked(irqd, cpu_online_mask);
+}
+
+static int assign_irq_vector_any(struct irq_data *irqd)
+{
+ unsigned long flags;
+ int ret;
+
+ raw_spin_lock_irqsave(&vector_lock, flags);
+ ret = assign_irq_vector_any_locked(irqd);
+ raw_spin_unlock_irqrestore(&vector_lock, flags);
+ return ret;
+}
+
+static int
+assign_irq_vector_policy(struct irq_data *irqd, struct irq_alloc_info *info)
{
+ if (irqd_affinity_is_managed(irqd))
+ return reserve_managed_vector(irqd);
if (info->mask)
return assign_irq_vector(irqd, info->mask);
- if (node != NUMA_NO_NODE &&
- !assign_irq_vector(irqd, cpumask_of_node(node)))
+ return assign_irq_vector_any(irqd);
+}
+
+static int
+assign_managed_vector(struct irq_data *irqd, const struct cpumask *dest)
+{
+ const struct cpumask *affmsk = irq_data_get_affinity_mask(irqd);
+ struct apic_chip_data *apicd = apic_chip_data(irqd);
+ int vector, cpu;
+
+ cpumask_and(vector_searchmask, vector_searchmask, affmsk);
+ cpu = cpumask_first(vector_searchmask);
+ if (cpu >= nr_cpu_ids)
+ return -EINVAL;
+ /* set_affinity might call here for nothing */
+ if (apicd->vector && cpumask_test_cpu(apicd->cpu, vector_searchmask))
return 0;
- return assign_irq_vector(irqd, cpu_online_mask);
+ vector = irq_matrix_alloc_managed(vector_matrix, cpu);
+ trace_vector_alloc_managed(irqd->irq, vector, vector);
+ if (vector < 0)
+ return vector;
+ apic_update_vector(irqd, vector, cpu);
+ apic_update_irq_cfg(irqd, vector, cpu);
+ return 0;
}

static void clear_irq_vector(struct irq_data *irqd)
{
struct apic_chip_data *apicd = apic_chip_data(irqd);
+ bool managed = irqd_affinity_is_managed(irqd);
unsigned int vector = apicd->vector;

lockdep_assert_held(&vector_lock);
@@ -225,7 +293,7 @@ static void clear_irq_vector(struct irq_
apicd->prev_cpu);

per_cpu(vector_irq, apicd->cpu)[vector] = VECTOR_UNUSED;
- irq_matrix_free(vector_matrix, apicd->cpu, vector, false);
+ irq_matrix_free(vector_matrix, apicd->cpu, vector, managed);
apicd->vector = 0;

/* Clean up move in progress */
@@ -234,12 +302,86 @@ static void clear_irq_vector(struct irq_
return;

per_cpu(vector_irq, apicd->prev_cpu)[vector] = VECTOR_UNUSED;
- irq_matrix_free(vector_matrix, apicd->prev_cpu, vector, false);
+ irq_matrix_free(vector_matrix, apicd->prev_cpu, vector, managed);
apicd->prev_vector = 0;
apicd->move_in_progress = 0;
hlist_del_init(&apicd->clist);
}

+static void x86_vector_deactivate(struct irq_domain *dom, struct irq_data *irqd)
+{
+ struct apic_chip_data *apicd = apic_chip_data(irqd);
+ unsigned long flags;
+
+ trace_vector_deactivate(irqd->irq, apicd->is_managed,
+ false, false);
+
+ if (apicd->is_managed)
+ return;
+
+ raw_spin_lock_irqsave(&vector_lock, flags);
+ clear_irq_vector(irqd);
+ vector_assign_managed_shutdown(irqd);
+ raw_spin_unlock_irqrestore(&vector_lock, flags);
+}
+
+static int activate_managed(struct irq_data *irqd)
+{
+ const struct cpumask *dest = irq_data_get_affinity_mask(irqd);
+ int ret;
+
+ cpumask_and(vector_searchmask, dest, cpu_online_mask);
+ if (WARN_ON_ONCE(cpumask_empty(vector_searchmask))) {
+ /* Something in the core code broke! Survive gracefully */
+ pr_err("Managed startup for irq %u, but no CPU\n", irqd->irq);
+ return EINVAL;
+ }
+
+ ret = assign_managed_vector(irqd, vector_searchmask);
+ /*
+ * This should not happen. The vector reservation got buggered. Handle
+ * it gracefully.
+ */
+ if (WARN_ON_ONCE(ret < 0)) {
+ pr_err("Managed startup irq %u, no vector available\n",
+ irqd->irq);
+ }
+ return ret;
+}
+
+static int x86_vector_activate(struct irq_domain *dom, struct irq_data *irqd,
+ bool early)
+{
+ struct apic_chip_data *apicd = apic_chip_data(irqd);
+ unsigned long flags;
+ int ret = 0;
+
+ trace_vector_activate(irqd->irq, apicd->is_managed,
+ false, early);
+
+ if (!apicd->is_managed)
+ return 0;
+
+ raw_spin_lock_irqsave(&vector_lock, flags);
+ if (early || irqd_is_managed_and_shutdown(irqd))
+ vector_assign_managed_shutdown(irqd);
+ else
+ ret = activate_managed(irqd);
+ raw_spin_unlock_irqrestore(&vector_lock, flags);
+ return ret;
+}
+
+static void vector_free_reserved_and_managed(struct irq_data *irqd)
+{
+ const struct cpumask *dest = irq_data_get_affinity_mask(irqd);
+ struct apic_chip_data *apicd = apic_chip_data(irqd);
+
+ trace_vector_teardown(irqd->irq, apicd->is_managed, false);
+
+ if (apicd->is_managed)
+ irq_matrix_remove_managed(vector_matrix, dest);
+}
+
static void x86_vector_free_irqs(struct irq_domain *domain,
unsigned int virq, unsigned int nr_irqs)
{
@@ -253,6 +395,7 @@ static void x86_vector_free_irqs(struct
if (irqd && irqd->chip_data) {
raw_spin_lock_irqsave(&vector_lock, flags);
clear_irq_vector(irqd);
+ vector_free_reserved_and_managed(irqd);
apicd = irqd->chip_data;
irq_domain_reset_irq_data(irqd);
raw_spin_unlock_irqrestore(&vector_lock, flags);
@@ -310,7 +453,7 @@ static int x86_vector_alloc_irqs(struct
continue;
}

- err = assign_irq_vector_policy(irqd, info, node);
+ err = assign_irq_vector_policy(irqd, info);
trace_vector_setup(virq + i, false, err);
if (err)
goto error;
@@ -368,6 +511,8 @@ void x86_vector_debug_show(struct seq_fi
static const struct irq_domain_ops x86_vector_domain_ops = {
.alloc = x86_vector_alloc_irqs,
.free = x86_vector_free_irqs,
+ .activate = x86_vector_activate,
+ .deactivate = x86_vector_deactivate,
#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
.debug_show = x86_vector_debug_show,
#endif
@@ -531,13 +676,13 @@ static int apic_set_affinity(struct irq_
{
int err;

- if (!IS_ENABLED(CONFIG_SMP))
- return -EPERM;
-
- if (!cpumask_intersects(dest, cpu_online_mask))
- return -EINVAL;
-
- err = assign_irq_vector(irqd, dest);
+ raw_spin_lock(&vector_lock);
+ cpumask_and(vector_searchmask, dest, cpu_online_mask);
+ if (irqd_affinity_is_managed(irqd))
+ err = assign_managed_vector(irqd, vector_searchmask);
+ else
+ err = assign_vector_locked(irqd, vector_searchmask);
+ raw_spin_unlock(&vector_lock);
return err ? err : IRQ_SET_MASK_OK;
}

@@ -577,9 +722,18 @@ static void free_moved_vector(struct api
{
unsigned int vector = apicd->prev_vector;
unsigned int cpu = apicd->prev_cpu;
+ bool managed = apicd->is_managed;
+
+ /*
+ * This should never happen. Managed interrupts are not
+ * migrated except on CPU down, which does not involve the
+ * cleanup vector. But try to keep the accounting correct
+ * nevertheless.
+ */
+ WARN_ON_ONCE(managed);

- trace_vector_free_moved(apicd->irq, vector, false);
- irq_matrix_free(vector_matrix, cpu, vector, false);
+ trace_vector_free_moved(apicd->irq, vector, managed);
+ irq_matrix_free(vector_matrix, cpu, vector, managed);
__this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
hlist_del_init(&apicd->clist);
apicd->prev_vector = 0;