irqchip/GIC: Convert to EOImode == 1
So far, GICv2 has been used with EOImode == 0. The effect of this
mode is to perform the priority drop and the deactivation of the
interrupt at the same time.
While this works perfectly for Linux (we only have a single priority),
it causes issues when an interrupt is forwarded to a guest, and when
we want the guest to perform the EOI itself.
For this case, the GIC architecture provides EOImode == 1, where:
- A write to the EOI register drops the priority of the interrupt
and leaves it active. Other interrupts at the same priority level
can now be taken, but the active interrupt cannot be taken again
- A write to the DIR marks the interrupt as inactive, meaning it can
now be taken again.
We only enable this feature when booted in HYP mode and that
the device-tree reported a suitable CPU interface. Observable behaviour
should remain unchanged.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-and-tested-by: Eric Auger <eric.auger@linaro.org>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: <linux-arm-kernel@lists.infradead.org>
Cc: kvmarm@lists.cs.columbia.edu
Cc: Jason Cooper <jason@lakedaemon.net>
Link: http://lkml.kernel.org/r/1440604845-28229-4-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
index aa3e7b8..c835f4c 100644
--- a/drivers/irqchip/irq-gic.c
+++ b/drivers/irqchip/irq-gic.c
@@ -47,6 +47,7 @@
#include <asm/irq.h>
#include <asm/exception.h>
#include <asm/smp_plat.h>
+#include <asm/virt.h>
#include "irq-gic-common.h"
@@ -82,6 +83,8 @@
#define NR_GIC_CPU_IF 8
static u8 gic_cpu_map[NR_GIC_CPU_IF] __read_mostly;
+static struct static_key supports_deactivate = STATIC_KEY_INIT_TRUE;
+
#ifndef MAX_GIC_NR
#define MAX_GIC_NR 1
#endif
@@ -157,6 +160,11 @@
gic_poke_irq(d, GIC_DIST_ENABLE_CLEAR);
}
+static void gic_eoimode1_mask_irq(struct irq_data *d)
+{
+ gic_mask_irq(d);
+}
+
static void gic_unmask_irq(struct irq_data *d)
{
gic_poke_irq(d, GIC_DIST_ENABLE_SET);
@@ -167,6 +175,11 @@
writel_relaxed(gic_irq(d), gic_cpu_base(d) + GIC_CPU_EOI);
}
+static void gic_eoimode1_eoi_irq(struct irq_data *d)
+{
+ writel_relaxed(gic_irq(d), gic_cpu_base(d) + GIC_CPU_DEACTIVATE);
+}
+
static int gic_irq_set_irqchip_state(struct irq_data *d,
enum irqchip_irq_state which, bool val)
{
@@ -272,11 +285,15 @@
irqnr = irqstat & GICC_IAR_INT_ID_MASK;
if (likely(irqnr > 15 && irqnr < 1021)) {
+ if (static_key_true(&supports_deactivate))
+ writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI);
handle_domain_irq(gic->domain, irqnr, regs);
continue;
}
if (irqnr < 16) {
writel_relaxed(irqstat, cpu_base + GIC_CPU_EOI);
+ if (static_key_true(&supports_deactivate))
+ writel_relaxed(irqstat, cpu_base + GIC_CPU_DEACTIVATE);
#ifdef CONFIG_SMP
handle_IPI(irqnr, regs);
#endif
@@ -329,6 +346,22 @@
IRQCHIP_MASK_ON_SUSPEND,
};
+static struct irq_chip gic_eoimode1_chip = {
+ .name = "GICv2",
+ .irq_mask = gic_eoimode1_mask_irq,
+ .irq_unmask = gic_unmask_irq,
+ .irq_eoi = gic_eoimode1_eoi_irq,
+ .irq_set_type = gic_set_type,
+#ifdef CONFIG_SMP
+ .irq_set_affinity = gic_set_affinity,
+#endif
+ .irq_get_irqchip_state = gic_irq_get_irqchip_state,
+ .irq_set_irqchip_state = gic_irq_set_irqchip_state,
+ .flags = IRQCHIP_SET_TYPE_MASKED |
+ IRQCHIP_SKIP_SET_WAKE |
+ IRQCHIP_MASK_ON_SUSPEND,
+};
+
void __init gic_cascade_irq(unsigned int gic_nr, unsigned int irq)
{
if (gic_nr >= MAX_GIC_NR)
@@ -360,6 +393,10 @@
{
void __iomem *cpu_base = gic_data_cpu_base(gic);
u32 bypass = 0;
+ u32 mode = 0;
+
+ if (static_key_true(&supports_deactivate))
+ mode = GIC_CPU_CTRL_EOImodeNS;
/*
* Preserve bypass disable bits to be written back later
@@ -367,7 +404,7 @@
bypass = readl(cpu_base + GIC_CPU_CTRL);
bypass &= GICC_DIS_BYPASS_MASK;
- writel_relaxed(bypass | GICC_ENABLE, cpu_base + GIC_CPU_CTRL);
+ writel_relaxed(bypass | mode | GICC_ENABLE, cpu_base + GIC_CPU_CTRL);
}
@@ -803,13 +840,20 @@
static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hw)
{
+ struct irq_chip *chip = &gic_chip;
+
+ if (static_key_true(&supports_deactivate)) {
+ if (d->host_data == (void *)&gic_data[0])
+ chip = &gic_eoimode1_chip;
+ }
+
if (hw < 32) {
irq_set_percpu_devid(irq);
- irq_domain_set_info(d, irq, hw, &gic_chip, d->host_data,
+ irq_domain_set_info(d, irq, hw, chip, d->host_data,
handle_percpu_devid_irq, NULL, NULL);
set_irq_flags(irq, IRQF_VALID | IRQF_NOAUTOEN);
} else {
- irq_domain_set_info(d, irq, hw, &gic_chip, d->host_data,
+ irq_domain_set_info(d, irq, hw, chip, d->host_data,
handle_fasteoi_irq, NULL, NULL);
set_irq_flags(irq, IRQF_VALID | IRQF_PROBE);
}
@@ -995,6 +1039,8 @@
register_cpu_notifier(&gic_cpu_notifier);
#endif
set_handle_irq(gic_handle_irq);
+ if (static_key_true(&supports_deactivate))
+ pr_info("GIC: Using split EOI/Deactivate mode\n");
}
gic_dist_init(gic);
@@ -1010,6 +1056,7 @@
{
void __iomem *cpu_base;
void __iomem *dist_base;
+ struct resource cpu_res;
u32 percpu_offset;
int irq;
@@ -1022,6 +1069,16 @@
cpu_base = of_iomap(node, 1);
WARN(!cpu_base, "unable to map gic cpu registers\n");
+ of_address_to_resource(node, 1, &cpu_res);
+
+ /*
+ * Disable split EOI/Deactivate if either HYP is not available
+ * or the CPU interface is too small.
+ */
+ if (gic_cnt == 0 && (!is_hyp_mode_available() ||
+ resource_size(&cpu_res) < SZ_8K))
+ static_key_slow_dec(&supports_deactivate);
+
if (of_property_read_u32(node, "cpu-offset", &percpu_offset))
percpu_offset = 0;
@@ -1141,6 +1198,14 @@
}
/*
+ * Disable split EOI/Deactivate if HYP is not available. ACPI
+ * guarantees that we'll always have a GICv2, so the CPU
+ * interface will always be the right size.
+ */
+ if (!is_hyp_mode_available())
+ static_key_slow_dec(&supports_deactivate);
+
+ /*
* Initialize zero GIC instance (no multi-GIC support). Also, set GIC
* as default IRQ domain to allow for GSI registration and GSI to IRQ
* number translation (see acpi_register_gsi() and acpi_gsi_to_irq()).