[RFC 05/19] xen/arm: Release IRQ routed to a domain when it's destroying

[Julien Grall <julien.grall@linaro.org>]

Xen has to release IRQ routed to a domain in order to reuse later. Currently
only SPIs can be routed to the guest so we only need to browse SPIs for a
specific domain.

Futhermore, a guest can crash and let the IRQ in an incorrect state (i.e has
not being EOIed). Add a function to reset a given IRQ to allow Xen route again
the IRQ in the future.

Also, reset the desc->handler to no_irq_type. This will let you know if we
did something wrong with the IRQ management.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
---
 xen/arch/arm/gic.c        |   12 ++++++++++++
 xen/arch/arm/irq.c        |    8 ++++++++
 xen/arch/arm/vgic.c       |   10 ++++++++++
 xen/include/asm-arm/gic.h |    3 +++
 4 files changed, 33 insertions(+)

diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 11e53af..42fc3bc 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -928,6 +928,18 @@ int gicv_setup(struct domain *d)
 
 }
 
+/* The guest may not have EOIed the IRQ.
+ * Be sure to reset correctly the IRQ.
+ */
+void gic_reset_guest_irq(struct irq_desc *desc)
+{
+    ASSERT(spin_is_locked(&desc->lock));
+    ASSERT(desc->status & IRQ_GUEST);
+
+    if ( desc->status & IRQ_INPROGRESS )
+        GICC[GICC_DIR] = desc->irq;
+}
+
 static void maintenance_interrupt(int irq, void *dev_id, struct cpu_user_regs *regs)
 {
     /* 
diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 4e51fee..e44a90f 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -274,7 +274,15 @@ void release_irq(unsigned int irq, const void *dev_id)
     if ( !desc->action )
     {
         desc->handler->shutdown(desc);
+
+        if ( desc->status & IRQ_GUEST )
+        {
+            gic_reset_guest_irq(desc);
+            desc->status &= ~IRQ_INPROGRESS;
+        }
+
         desc->status &= ~IRQ_GUEST;
+        desc->handler = &no_irq_type;
     }
 
     spin_unlock_irqrestore(&desc->lock,flags);
diff --git a/xen/arch/arm/vgic.c b/xen/arch/arm/vgic.c
index cb8df3a..e451324 100644
--- a/xen/arch/arm/vgic.c
+++ b/xen/arch/arm/vgic.c
@@ -112,6 +112,16 @@ int domain_vgic_init(struct domain *d)
 
 void domain_vgic_free(struct domain *d)
 {
+    int i;
+
+    for ( i = NR_LOCAL_IRQS; i < d->arch.vgic.nr_lines; i++ )
+    {
+        struct irq_desc *desc = d->arch.vgic.pending_irqs[i].desc;
+
+        if ( desc )
+            release_irq(desc->irq, d);
+    }
+
     xfree(d->arch.vgic.shared_irqs);
     xfree(d->arch.vgic.pending_irqs);
 }
diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index 6e7375c..841d845 100644
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -228,6 +228,9 @@ int gic_irq_xlate(const u32 *intspec, unsigned int intsize,
                   unsigned int *out_hwirq, unsigned int *out_type);
 void gic_clear_lrs(struct vcpu *v);
 
+/* Reset an IRQ passthrough to a guest */
+void gic_reset_guest_irq(struct irq_desc *desc);
+
 #endif /* __ASSEMBLY__ */
 #endif
 
-- 
1.7.10.4