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 aa3e7b8a69c4349bcd775c7c796062bda3b392f2..c835f4c60d21c2224dbe3b9375496d3d0b40e427 100644 (file)
--- 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 @@ static DEFINE_RAW_SPINLOCK(irq_controller_lock);
 #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 @@ static void gic_mask_irq(struct irq_data *d)
        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 @@ static void gic_eoi_irq(struct irq_data *d)
        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 @@ static void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)
                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 @@ static struct irq_chip gic_chip = {
                                  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 @@ static void gic_cpu_if_up(struct gic_chip_data *gic)
 {
        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 @@ static void gic_cpu_if_up(struct gic_chip_data *gic)
        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 @@ void __init gic_init_physaddr(struct device_node *node)
 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 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
                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 @@ gic_of_init(struct device_node *node, struct device_node *parent)
 {
        void __iomem *cpu_base;
        void __iomem *dist_base;
+       struct resource cpu_res;
        u32 percpu_offset;
        int irq;
 
@@ -1022,6 +1069,16 @@ gic_of_init(struct device_node *node, struct device_node *parent)
        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;
 
@@ -1140,6 +1197,14 @@ gic_v2_acpi_init(struct acpi_table_header *table)
                return -ENOMEM;
        }
 
+       /*
+        * 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

diff --git a/include/linux/irqchip/arm-gic.h b/include/linux/irqchip/arm-gic.h
index 65da435d01c10218741ccddc1f99d7107acaad4d..af3d29f7078117f0b3f260804e419e6e7610d3e5 100644 (file)
--- a/include/linux/irqchip/arm-gic.h
+++ b/include/linux/irqchip/arm-gic.h
@@ -20,9 +20,13 @@
 #define GIC_CPU_ALIAS_BINPOINT         0x1c
 #define GIC_CPU_ACTIVEPRIO             0xd0
 #define GIC_CPU_IDENT                  0xfc
+#define GIC_CPU_DEACTIVATE             0x1000
 
 #define GICC_ENABLE                    0x1
 #define GICC_INT_PRI_THRESHOLD         0xf0
+
+#define GIC_CPU_CTRL_EOImodeNS         (1 << 9)
+
 #define GICC_IAR_INT_ID_MASK           0x3ff
 #define GICC_INT_SPURIOUS              1023
 #define GICC_DIS_BYPASS_MASK           0x1e0