Merge tag 'irq-core-2020-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull irq updates from Thomas Gleixner:
 "The interrupt departement provides:

   - A mechanism to shield isolated tasks from managed interrupts:

     The affinity of managed interrupts is completely controlled by the
     kernel and user space has no influence on them. The reason is that
     the automatically assigned affinity correlates to the multi-queue
     CPU handling of block devices.

     If the generated affinity mask spaws both housekeeping and isolated
     CPUs the interrupt could be routed to an isolated CPU which would
     then be disturbed by I/O submitted by a housekeeping CPU.

     The new mechamism ensures that as long as one housekeeping CPU is
     online in the assigned affinity mask the interrupt is routed to a
     housekeeping CPU.

     If there is no online housekeeping CPU in the affinity mask, then
     the interrupt is routed to an isolated CPU to keep the device queue
     intact, but unless the isolated CPU submits I/O by itself these
     interrupts are not raised.

   - A small addon to the device tree irqdomain core code to avoid
     duplication in irq chip drivers

   - Conversion of the SiFive PLIC to hierarchical domains

   - The usual pile of new irq chip drivers: SiFive GPIO, Aspeed SCI,
     NXP INTMUX, Meson A1 GPIO

   - The first cut of support for the new ARM GICv4.1

   - The usual pile of fixes and improvements in core and driver code"

* tag 'irq-core-2020-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (33 commits)
  genirq, sched/isolation: Isolate from handling managed interrupts
  irqchip/gic-v4.1: Allow direct invalidation of VLPIs
  irqchip/gic-v4.1: Suppress per-VLPI doorbell
  irqchip/gic-v4.1: Add VPE INVALL callback
  irqchip/gic-v4.1: Add VPE eviction callback
  irqchip/gic-v4.1: Add VPE residency callback
  irqchip/gic-v4.1: Add mask/unmask doorbell callbacks
  irqchip/gic-v4.1: Plumb skeletal VPE irqchip
  irqchip/gic-v4.1: Implement the v4.1 flavour of VMOVP
  irqchip/gic-v4.1: Don't use the VPE proxy if RVPEID is set
  irqchip/gic-v4.1: Implement the v4.1 flavour of VMAPP
  irqchip/gic-v4.1: VPE table (aka GICR_VPROPBASER) allocation
  irqchip/gic-v3: Add GICv4.1 VPEID size discovery
  irqchip/gic-v3: Detect GICv4.1 supporting RVPEID
  irqchip/gic-v3-its: Fix get_vlpi_map() breakage with doorbells
  irqdomain: Fix a memory leak in irq_domain_push_irq()
  irqchip: Add NXP INTMUX interrupt multiplexer support
  dt-bindings: interrupt-controller: Add binding for NXP INTMUX interrupt multiplexer
  irqchip: Define EXYNOS_IRQ_COMBINER
  irqchip/meson-gpio: Add support for meson a1 SoCs
  ...

1 files changed, 19 insertions, 2 deletions

diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
index 6c7ca2e983a5..02236b13b359 100644
--- a/kernel/irq/cpuhotplug.c
+++ b/kernel/irq/cpuhotplug.c
@@ -12,6 +12,7 @@
 #include <linux/interrupt.h>
 #include <linux/ratelimit.h>
 #include <linux/irq.h>
+#include <linux/sched/isolation.h>
 
 #include "internals.h"
 
@@ -171,6 +172,20 @@ void irq_migrate_all_off_this_cpu(void)
 	}
 }
 
+static bool hk_should_isolate(struct irq_data *data, unsigned int cpu)
+{
+	const struct cpumask *hk_mask;
+
+	if (!housekeeping_enabled(HK_FLAG_MANAGED_IRQ))
+		return false;
+
+	hk_mask = housekeeping_cpumask(HK_FLAG_MANAGED_IRQ);
+	if (cpumask_subset(irq_data_get_effective_affinity_mask(data), hk_mask))
+		return false;
+
+	return cpumask_test_cpu(cpu, hk_mask);
+}
+
 static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
 {
 	struct irq_data *data = irq_desc_get_irq_data(desc);
@@ -188,9 +203,11 @@ static void irq_restore_affinity_of_irq(struct irq_desc *desc, unsigned int cpu)
 	/*
 	 * If the interrupt can only be directed to a single target
 	 * CPU then it is already assigned to a CPU in the affinity
-	 * mask. No point in trying to move it around.
+	 * mask. No point in trying to move it around unless the
+	 * isolation mechanism requests to move it to an upcoming
+	 * housekeeping CPU.
 	 */
-	if (!irqd_is_single_target(data))
+	if (!irqd_is_single_target(data) || hk_should_isolate(data, cpu))
 		irq_set_affinity_locked(data, affinity, false);
 }