ARM: GIC: Allow tweaking the active and pending state of an IRQ

When playing around with hardware mapped, level triggered virtual IRQs,
there is the need to explicitly set the active or pending state of an
interrupt at some point.
To prepare the GIC for that, we introduce a set_active_state() and a
set_pending_state() function to let the VGIC manipulate the state of
an associated hardware IRQ.
This takes care of properly setting the _IRQ_INPROGRESS bit.

Signed-off-by: Andre Przywara <andre.przywara@linaro.org>
Reviewed-by: Julien Grall <julien.grall@arm.com>

diff --git a/xen/arch/arm/gic-v2.c b/xen/arch/arm/gic-v2.c
index aa0fc6c1a1ee768899fb2a2c4b991ac5c29d15d7..73746862352973b844978c976290097970d3667c 100644 (file)
--- a/xen/arch/arm/gic-v2.c
+++ b/xen/arch/arm/gic-v2.c
@@ -243,6 +243,45 @@ static void gicv2_poke_irq(struct irq_desc *irqd, uint32_t offset)
     writel_gicd(1U << (irqd->irq % 32), offset + (irqd->irq / 32) * 4);
 }
 
+/*
+ * This is forcing the active state of an interrupt, somewhat circumventing
+ * the normal interrupt flow and the GIC state machine. So use with care
+ * and only if you know what you are doing. For this reason we also have to
+ * tinker with the _IRQ_INPROGRESS bit here, since the normal IRQ handler
+ * will not be involved.
+ */
+static void gicv2_set_active_state(struct irq_desc *irqd, bool active)
+{
+    ASSERT(spin_is_locked(&irqd->lock));
+
+    if ( active )
+    {
+        set_bit(_IRQ_INPROGRESS, &irqd->status);
+        gicv2_poke_irq(irqd, GICD_ISACTIVER);
+    }
+    else
+    {
+        clear_bit(_IRQ_INPROGRESS, &irqd->status);
+        gicv2_poke_irq(irqd, GICD_ICACTIVER);
+    }
+}
+
+static void gicv2_set_pending_state(struct irq_desc *irqd, bool pending)
+{
+    ASSERT(spin_is_locked(&irqd->lock));
+
+    if ( pending )
+    {
+        /* The _IRQ_INPROGRESS bit will be set when the interrupt fires. */
+        gicv2_poke_irq(irqd, GICD_ISPENDR);
+    }
+    else
+    {
+        /* The _IRQ_INPROGRESS remains unchanged. */
+        gicv2_poke_irq(irqd, GICD_ICPENDR);
+    }
+}
+
 static void gicv2_set_irq_type(struct irq_desc *desc, unsigned int type)
 {
     uint32_t cfg, actual, edgebit;
@@ -1278,6 +1317,8 @@ const static struct gic_hw_operations gicv2_ops = {
     .eoi_irq             = gicv2_eoi_irq,
     .deactivate_irq      = gicv2_dir_irq,
     .read_irq            = gicv2_read_irq,
+    .set_active_state    = gicv2_set_active_state,
+    .set_pending_state   = gicv2_set_pending_state,
     .set_irq_type        = gicv2_set_irq_type,
     .set_irq_priority    = gicv2_set_irq_priority,
     .send_SGI            = gicv2_send_SGI,

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index cb41844af23176456feffbe2a05554ad8e72dc05..a5105ac9e7eb803b8168478de7a3bfb8028284c2 100644 (file)
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -477,6 +477,41 @@ static unsigned int gicv3_read_irq(void)
     return irq;
 }
 
+/*
+ * This is forcing the active state of an interrupt, somewhat circumventing
+ * the normal interrupt flow and the GIC state machine. So use with care
+ * and only if you know what you are doing. For this reason we also have to
+ * tinker with the _IRQ_INPROGRESS bit here, since the normal IRQ handler
+ * will not be involved.
+ */
+static void gicv3_set_active_state(struct irq_desc *irqd, bool active)
+{
+    ASSERT(spin_is_locked(&irqd->lock));
+
+    if ( active )
+    {
+        set_bit(_IRQ_INPROGRESS, &irqd->status);
+        gicv3_poke_irq(irqd, GICD_ISACTIVER, false);
+    }
+    else
+    {
+        clear_bit(_IRQ_INPROGRESS, &irqd->status);
+        gicv3_poke_irq(irqd, GICD_ICACTIVER, false);
+    }
+}
+
+static void gicv3_set_pending_state(struct irq_desc *irqd, bool pending)
+{
+    ASSERT(spin_is_locked(&irqd->lock));
+
+    if ( pending )
+        /* The _IRQ_INPROGRESS bit will be set when the interrupt fires. */
+        gicv3_poke_irq(irqd, GICD_ISPENDR, false);
+    else
+        /* The _IRQ_INPROGRESS bit will remain unchanged. */
+        gicv3_poke_irq(irqd, GICD_ICPENDR, false);
+}
+
 static inline uint64_t gicv3_mpidr_to_affinity(int cpu)
 {
      uint64_t mpidr = cpu_logical_map(cpu);
@@ -1769,6 +1804,8 @@ static const struct gic_hw_operations gicv3_ops = {
     .eoi_irq             = gicv3_eoi_irq,
     .deactivate_irq      = gicv3_dir_irq,
     .read_irq            = gicv3_read_irq,
+    .set_active_state    = gicv3_set_active_state,
+    .set_pending_state   = gicv3_set_pending_state,
     .set_irq_type        = gicv3_set_irq_type,
     .set_irq_priority    = gicv3_set_irq_priority,
     .send_SGI            = gicv3_send_sgi,

diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index 3079387e06563075c5976a53c46aaea0d27c57b0..2aca243ac32dd4d7bf382311a9d7962d5223d615 100644 (file)
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -345,6 +345,10 @@ struct gic_hw_operations {
     void (*deactivate_irq)(struct irq_desc *irqd);
     /* Read IRQ id and Ack */
     unsigned int (*read_irq)(void);
+    /* Force the active state of an IRQ by accessing the distributor */
+    void (*set_active_state)(struct irq_desc *irqd, bool state);
+    /* Force the pending state of an IRQ by accessing the distributor */
+    void (*set_pending_state)(struct irq_desc *irqd, bool state);
     /* Set IRQ type */
     void (*set_irq_type)(struct irq_desc *desc, unsigned int type);
     /* Set IRQ priority */
@@ -393,6 +397,26 @@ static inline unsigned int gic_get_nr_lrs(void)
     return gic_hw_ops->info->nr_lrs;
 }
 
+/*
+ * Set the active state of an IRQ. This should be used with care, as this
+ * directly forces the active bit, without considering the GIC state machine.
+ * For private IRQs this only works for those of the current CPU.
+ */
+static inline void gic_set_active_state(struct irq_desc *irqd, bool state)
+{
+    gic_hw_ops->set_active_state(irqd, state);
+}
+
+/*
+ * Set the pending state of an IRQ. This should be used with care, as this
+ * directly forces the pending bit, without considering the GIC state machine.
+ * For private IRQs this only works for those of the current CPU.
+ */
+static inline void gic_set_pending_state(struct irq_desc *irqd, bool state)
+{
+    gic_hw_ops->set_pending_state(irqd, state);
+}
+
 void register_gic_ops(const struct gic_hw_operations *ops);
 int gic_make_hwdom_dt_node(const struct domain *d,
                            const struct dt_device_node *gic,