[Xen-devel] [PATCH v4 5/8] ARM: VGIC: factor out vgic_connect_hw_irq()

[Andre Przywara <andre.przywara@xxxxxxx>]

At the moment we happily access VGIC internal data structures like
the rank and struct pending_irq in gic.c, which should be VGIC agnostic.

Factor out a new function vgic_connect_hw_irq(), which allows a virtual
IRQ to be connected to a hardware IRQ (using the hw bit in the LR).

This removes said accesses to VGIC data structures and improves abstraction.

Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 xen/arch/arm/gic-vgic.c    | 36 ++++++++++++++++++++++++++++++++++++
 xen/arch/arm/gic.c         | 44 ++++++++++----------------------------------
 xen/include/asm-arm/vgic.h |  2 ++
 3 files changed, 48 insertions(+), 34 deletions(-)

diff --git a/xen/arch/arm/gic-vgic.c b/xen/arch/arm/gic-vgic.c
index 1d5744ecc8..fff7c01ee8 100644
--- a/xen/arch/arm/gic-vgic.c
+++ b/xen/arch/arm/gic-vgic.c
@@ -397,6 +397,42 @@ void gic_dump_vgic_info(struct vcpu *v)
         printk("Pending irq=%d\n", p->irq);
 }
 
+int vgic_connect_hw_irq(struct domain *d, struct vcpu *v, unsigned int virq,
+                        struct irq_desc *desc, bool connect)
+{
+    unsigned long flags;
+    /* Use vcpu0 to retrieve the pending_irq struct. Given that we only
+     * route SPIs to guests, it doesn't make any difference. */
+    struct vcpu *v_target = vgic_get_target_vcpu(d->vcpu[0], virq);
+    struct vgic_irq_rank *rank = vgic_rank_irq(v_target, virq);
+    struct pending_irq *p = irq_to_pending(v_target, virq);
+    int ret = 0;
+
+    ASSERT(connect && desc);
+
+    /* We are taking to rank lock to prevent parallel connections. */
+    vgic_lock_rank(v_target, rank, flags);
+
+    if ( connect )
+    {
+        /* The VIRQ should not be already enabled by the guest */
+        if ( !p->desc &&
+             !test_bit(GIC_IRQ_GUEST_ENABLED, &p->status) )
+            p->desc = desc;
+        else
+            ret = -EBUSY;
+    }
+    else
+    {
+        if ( !desc || p->desc == desc )
+            p->desc = NULL;
+    }
+
+    vgic_unlock_rank(v_target, rank, flags);
+
+    return ret;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 4cb74d449e..968e46fabb 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -128,13 +128,7 @@ void gic_route_irq_to_xen(struct irq_desc *desc, unsigned 
int priority)
 int gic_route_irq_to_guest(struct domain *d, unsigned int virq,
                            struct irq_desc *desc, unsigned int priority)
 {
-    unsigned long flags;
-    /* Use vcpu0 to retrieve the pending_irq struct. Given that we only
-     * route SPIs to guests, it doesn't make any difference. */
-    struct vcpu *v_target = vgic_get_target_vcpu(d->vcpu[0], virq);
-    struct vgic_irq_rank *rank = vgic_rank_irq(v_target, virq);
-    struct pending_irq *p = irq_to_pending(v_target, virq);
-    int res = -EBUSY;
+    int ret;
 
     ASSERT(spin_is_locked(&desc->lock));
     /* Caller has already checked that the IRQ is an SPI */
@@ -142,12 +136,9 @@ int gic_route_irq_to_guest(struct domain *d, unsigned int 
virq,
     ASSERT(virq < vgic_num_irqs(d));
     ASSERT(!is_lpi(virq));
 
-    vgic_lock_rank(v_target, rank, flags);
-
-    if ( p->desc ||
-         /* The VIRQ should not be already enabled by the guest */
-         test_bit(GIC_IRQ_GUEST_ENABLED, &p->status) )
-        goto out;
+    ret = vgic_connect_hw_irq(d, NULL, virq, desc, true);
+    if ( ret )
+        return ret;
 
     desc->handler = gic_hw_ops->gic_guest_irq_type;
     set_bit(_IRQ_GUEST, &desc->status);
@@ -156,31 +147,19 @@ int gic_route_irq_to_guest(struct domain *d, unsigned int 
virq,
         gic_set_irq_type(desc, desc->arch.type);
     gic_set_irq_priority(desc, priority);
 
-    p->desc = desc;
-    res = 0;
-
-out:
-    vgic_unlock_rank(v_target, rank, flags);
-
-    return res;
+    return 0;
 }
 
 /* This function only works with SPIs for now */
 int gic_remove_irq_from_guest(struct domain *d, unsigned int virq,
                               struct irq_desc *desc)
 {
-    struct vcpu *v_target = vgic_get_target_vcpu(d->vcpu[0], virq);
-    struct vgic_irq_rank *rank = vgic_rank_irq(v_target, virq);
-    struct pending_irq *p = irq_to_pending(v_target, virq);
-    unsigned long flags;
+    int ret;
 
     ASSERT(spin_is_locked(&desc->lock));
     ASSERT(test_bit(_IRQ_GUEST, &desc->status));
-    ASSERT(p->desc == desc);
     ASSERT(!is_lpi(virq));
 
-    vgic_lock_rank(v_target, rank, flags);
-
     if ( d->is_dying )
     {
         desc->handler->shutdown(desc);
@@ -198,19 +177,16 @@ int gic_remove_irq_from_guest(struct domain *d, unsigned 
int virq,
          */
         if ( test_bit(_IRQ_INPROGRESS, &desc->status) ||
              !test_bit(_IRQ_DISABLED, &desc->status) )
-        {
-            vgic_unlock_rank(v_target, rank, flags);
             return -EBUSY;
-        }
     }
 
+    ret = vgic_connect_hw_irq(d, NULL, virq, desc, false);
+    if ( ret )
+        return ret;
+
     clear_bit(_IRQ_GUEST, &desc->status);
     desc->handler = &no_irq_type;
 
-    p->desc = NULL;
-
-    vgic_unlock_rank(v_target, rank, flags);
-
     return 0;
 }
 
diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
index 22c8502c95..fda082395b 100644
--- a/xen/include/asm-arm/vgic.h
+++ b/xen/include/asm-arm/vgic.h
@@ -219,6 +219,8 @@ int vgic_v2_init(struct domain *d, int *mmio_count);
 int vgic_v3_init(struct domain *d, int *mmio_count);
 
 bool vgic_evtchn_irq_pending(struct vcpu *v);
+int vgic_connect_hw_irq(struct domain *d, struct vcpu *v, unsigned int virq,
+                        struct irq_desc *desc, bool connect);
 
 extern int domain_vgic_register(struct domain *d, int *mmio_count);
 extern int vcpu_vgic_free(struct vcpu *v);
-- 
2.14.1


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