irqchip/GICv3: Convert to EOImode == 1

So far, GICv3 has been used in 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 ICC_EOIR1_EL1 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 ICC_DIR_EL1 marks the interrupt as inactive, meaning
  it can now be taken again.

This patch converts the driver to be able to use this new mode,
depending on whether or not the kernel can behave as a hypervisor.
No feature change.

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/1440604845-28229-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index e406bc5f13e4f10083ff2d91aa9d81785a8cc2fe..5c31cc9353d5f55071636426d1872631ad5f955e 100644 (file)
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -31,6 +31,7 @@
 #include <asm/cputype.h>
 #include <asm/exception.h>
 #include <asm/smp_plat.h>
+#include <asm/virt.h>
 
 #include "irq-gic-common.h"
 
@@ -50,6 +51,7 @@ struct gic_chip_data {
 };
 
 static struct gic_chip_data gic_data __read_mostly;
+static struct static_key supports_deactivate = STATIC_KEY_INIT_TRUE;
 
 #define gic_data_rdist()               (this_cpu_ptr(gic_data.rdists.rdist))
 #define gic_data_rdist_rd_base()       (gic_data_rdist()->rd_base)
@@ -231,6 +233,11 @@ static void gic_mask_irq(struct irq_data *d)
        gic_poke_irq(d, GICD_ICENABLER);
 }
 
+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, GICD_ISENABLER);
@@ -296,6 +303,16 @@ static void gic_eoi_irq(struct irq_data *d)
        gic_write_eoir(gic_irq(d));
 }
 
+static void gic_eoimode1_eoi_irq(struct irq_data *d)
+{
+       /*
+        * No need to deactivate an LPI.
+        */
+       if (gic_irq(d) >= 8192)
+               return;
+       gic_write_dir(gic_irq(d));
+}
+
 static int gic_set_type(struct irq_data *d, unsigned int type)
 {
        unsigned int irq = gic_irq(d);
@@ -343,15 +360,26 @@ static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs
 
                if (likely(irqnr > 15 && irqnr < 1020) || irqnr >= 8192) {
                        int err;
+
+                       if (static_key_true(&supports_deactivate))
+                               gic_write_eoir(irqnr);
+
                        err = handle_domain_irq(gic_data.domain, irqnr, regs);
                        if (err) {
                                WARN_ONCE(true, "Unexpected interrupt received!\n");
-                               gic_write_eoir(irqnr);
+                               if (static_key_true(&supports_deactivate)) {
+                                       if (irqnr < 8192)
+                                               gic_write_dir(irqnr);
+                               } else {
+                                       gic_write_eoir(irqnr);
+                               }
                        }
                        continue;
                }
                if (irqnr < 16) {
                        gic_write_eoir(irqnr);
+                       if (static_key_true(&supports_deactivate))
+                               gic_write_dir(irqnr);
 #ifdef CONFIG_SMP
                        handle_IPI(irqnr, regs);
 #else
@@ -451,8 +479,13 @@ static void gic_cpu_sys_reg_init(void)
        /* Set priority mask register */
        gic_write_pmr(DEFAULT_PMR_VALUE);
 
-       /* EOI deactivates interrupt too (mode 0) */
-       gic_write_ctlr(ICC_CTLR_EL1_EOImode_drop_dir);
+       if (static_key_true(&supports_deactivate)) {
+               /* EOI drops priority only (mode 1) */
+               gic_write_ctlr(ICC_CTLR_EL1_EOImode_drop);
+       } else {
+               /* EOI deactivates interrupt too (mode 0) */
+               gic_write_ctlr(ICC_CTLR_EL1_EOImode_drop_dir);
+       }
 
        /* ... and let's hit the road... */
        gic_write_grpen1(1);
@@ -661,11 +694,28 @@ static struct irq_chip gic_chip = {
        .flags                  = IRQCHIP_SET_TYPE_MASKED,
 };
 
+static struct irq_chip gic_eoimode1_chip = {
+       .name                   = "GICv3",
+       .irq_mask               = gic_eoimode1_mask_irq,
+       .irq_unmask             = gic_unmask_irq,
+       .irq_eoi                = gic_eoimode1_eoi_irq,
+       .irq_set_type           = gic_set_type,
+       .irq_set_affinity       = gic_set_affinity,
+       .irq_get_irqchip_state  = gic_irq_get_irqchip_state,
+       .irq_set_irqchip_state  = gic_irq_set_irqchip_state,
+       .flags                  = IRQCHIP_SET_TYPE_MASKED,
+};
+
 #define GIC_ID_NR              (1U << gic_data.rdists.id_bits)
 
 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))
+               chip = &gic_eoimode1_chip;
+
        /* SGIs are private to the core kernel */
        if (hw < 16)
                return -EPERM;
@@ -679,13 +729,13 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
        /* PPIs */
        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);
        }
        /* SPIs */
        if (hw >= 32 && hw < gic_data.irq_nr) {
-               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);
        }
@@ -693,7 +743,7 @@ static int gic_irq_domain_map(struct irq_domain *d, unsigned int irq,
        if (hw >= 8192 && hw < GIC_ID_NR) {
                if (!gic_dist_supports_lpis())
                        return -EPERM;
-               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);
        }
@@ -820,6 +870,12 @@ static int __init gic_of_init(struct device_node *node, struct device_node *pare
        if (of_property_read_u64(node, "redistributor-stride", &redist_stride))
                redist_stride = 0;
 
+       if (!is_hyp_mode_available())
+               static_key_slow_dec(&supports_deactivate);
+
+       if (static_key_true(&supports_deactivate))
+               pr_info("GIC: Using split EOI/Deactivate mode\n");
+
        gic_data.dist_base = dist_base;
        gic_data.redist_regions = rdist_regs;
        gic_data.nr_redist_regions = nr_redist_regions;

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index bf982e021fbd043f8fddf0903a6926f3558a679b..71e4faf33091a114ba666054bc020adaed4a08d5 100644 (file)
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -104,6 +104,8 @@
 #define GICR_SYNCR                     0x00C0
 #define GICR_MOVLPIR                   0x0100
 #define GICR_MOVALLR                   0x0110
+#define GICR_ISACTIVER                 GICD_ISACTIVER
+#define GICR_ICACTIVER                 GICD_ICACTIVER
 #define GICR_IDREGS                    GICD_IDREGS
 #define GICR_PIDR2                     GICD_PIDR2
 
@@ -288,6 +290,7 @@
 #define ICH_VMCR_PMR_MASK              (0xffUL << ICH_VMCR_PMR_SHIFT)
 
 #define ICC_EOIR1_EL1                  sys_reg(3, 0, 12, 12, 1)
+#define ICC_DIR_EL1                    sys_reg(3, 0, 12, 11, 1)
 #define ICC_IAR1_EL1                   sys_reg(3, 0, 12, 12, 0)
 #define ICC_SGI1R_EL1                  sys_reg(3, 0, 12, 11, 5)
 #define ICC_PMR_EL1                    sys_reg(3, 0, 4, 6, 0)
@@ -385,6 +388,12 @@ static inline void gic_write_eoir(u64 irq)
        isb();
 }
 
+static inline void gic_write_dir(u64 irq)
+{
+       asm volatile("msr_s " __stringify(ICC_DIR_EL1) ", %0" : : "r" (irq));
+       isb();
+}
+
 struct irq_domain;
 int its_cpu_init(void);
 int its_init(struct device_node *node, struct rdists *rdists,