[Xen-devel] [PATCH 1/5] x86/dpci: allow hvm_irq_dpci to handle a variable number of GSIs

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

By making the girq array variable length. For the hardware domain this array is
going to match the actual number of GSIs present on the system.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/physdev.c       | 2 +-
 xen/drivers/passthrough/io.c | 8 +++++---
 xen/include/xen/hvm/irq.h    | 6 ++++--
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/physdev.c b/xen/arch/x86/physdev.c
index 6c15f9bf49..d12086d0ec 100644
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -52,7 +52,7 @@ static int physdev_hvm_map_pirq(
         {
             const struct hvm_girq_dpci_mapping *girq;
 
-            BUILD_BUG_ON(ARRAY_SIZE(hvm_irq_dpci->girq) < NR_HVM_IRQS);
+            BUG_ON(hvm_domain_irq(d)->nr_gsis < NR_HVM_IRQS);
             list_for_each_entry ( girq,
                                   &hvm_irq_dpci->girq[*index],
                                   list )
diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index 50e2f00214..3345db5759 100644
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -322,15 +322,17 @@ int pt_irq_create_bind(
     hvm_irq_dpci = domain_get_irq_dpci(d);
     if ( hvm_irq_dpci == NULL )
     {
-        unsigned int i;
+        unsigned int i, nr_gsis;
 
-        hvm_irq_dpci = xzalloc(struct hvm_irq_dpci);
+        nr_gsis = is_hardware_domain(d) ? hvm_domain_irq(d)->nr_gsis
+                                        : NR_HVM_IRQS;
+        hvm_irq_dpci = xzalloc_bytes(hvm_irq_dpci_size(nr_gsis));
         if ( hvm_irq_dpci == NULL )
         {
             spin_unlock(&d->event_lock);
             return -ENOMEM;
         }
-        for ( i = 0; i < NR_HVM_IRQS; i++ )
+        for ( i = 0; i < nr_gsis; i++ )
             INIT_LIST_HEAD(&hvm_irq_dpci->girq[i]);
 
         d->arch.hvm_domain.irq->dpci = hvm_irq_dpci;
diff --git a/xen/include/xen/hvm/irq.h b/xen/include/xen/hvm/irq.h
index d3f8623c0c..8304cb5725 100644
--- a/xen/include/xen/hvm/irq.h
+++ b/xen/include/xen/hvm/irq.h
@@ -81,14 +81,16 @@ struct hvm_girq_dpci_mapping {
 
 /* Protected by domain's event_lock */
 struct hvm_irq_dpci {
-    /* Guest IRQ to guest device/intx mapping. */
-    struct list_head girq[NR_HVM_IRQS];
     /* Record of mapped ISA IRQs */
     DECLARE_BITMAP(isairq_map, NR_ISAIRQS);
     /* Record of mapped Links */
     uint8_t link_cnt[NR_LINK];
+    /* Guest IRQ to guest device/intx mapping. */
+    struct list_head girq[];
 };
 
+#define hvm_irq_dpci_size(cnt) offsetof(struct hvm_irq_dpci, girq[cnt])
+
 /* Machine IRQ to guest device/intx mapping. */
 struct hvm_pirq_dpci {
     uint32_t flags;
-- 
2.12.1


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