3 files changed, 43 insertions, 15 deletions

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index d7b5109f7a9c..25cd4a07d09f 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -70,6 +70,9 @@ static int acpi_register_gsi_xen_hvm(struct device *dev, u32 gsi,
 struct xen_pci_frontend_ops *xen_pci_frontend;
 EXPORT_SYMBOL_GPL(xen_pci_frontend);
 
+#define XEN_PIRQ_MSI_DATA  (MSI_DATA_TRIGGER_EDGE | \
+                MSI_DATA_LEVEL_ASSERT | (3 << 8) | MSI_DATA_VECTOR(0))
+
 static void xen_msi_compose_msg(struct pci_dev *pdev, unsigned int pirq,
                 struct msi_msg *msg)
 {
@@ -83,12 +86,7 @@ static void xen_msi_compose_msg(struct pci_dev *pdev, unsigned int pirq,
                 MSI_ADDR_REDIRECTION_CPU |
                 MSI_ADDR_DEST_ID(pirq);
 
-        msg->data =
-                MSI_DATA_TRIGGER_EDGE |
-                MSI_DATA_LEVEL_ASSERT |
-                /* delivery mode reserved */
-                (3 << 8) |
-                MSI_DATA_VECTOR(0);
+        msg->data = XEN_PIRQ_MSI_DATA;
 }
 
 static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
@@ -98,8 +96,23 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
         struct msi_msg msg;
 
         list_for_each_entry(msidesc, &dev->msi_list, list) {
+                __read_msi_msg(msidesc, &msg);
+                pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
+                        ((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
+                if (xen_irq_from_pirq(pirq) >= 0 && msg.data == XEN_PIRQ_MSI_DATA) {
+                        xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
+                                        "msi-x" : "msi", &irq, &pirq, XEN_ALLOC_IRQ);
+                        if (irq < 0)
+                                goto error;
+                        ret = set_irq_msi(irq, msidesc);
+                        if (ret < 0)
+                                goto error_while;
+                        printk(KERN_DEBUG "xen: msi already setup: msi --> irq=%d"
+                                        " pirq=%d\n", irq, pirq);
+                        return 0;
+                }
                 xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
-                                "msi-x" : "msi", &irq, &pirq);
+                                "msi-x" : "msi", &irq, &pirq, (XEN_ALLOC_IRQ | XEN_ALLOC_PIRQ));
                 if (irq < 0 || pirq < 0)
                         goto error;
                 printk(KERN_DEBUG "xen: msi --> irq=%d, pirq=%d\n", irq, pirq);
diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 7ab43c33f746..f78945ce8aeb 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -668,17 +668,21 @@ out:
 #include <linux/msi.h>
 #include "../pci/msi.h"
 
-void xen_allocate_pirq_msi(char *name, int *irq, int *pirq)
+void xen_allocate_pirq_msi(char *name, int *irq, int *pirq, int alloc)
 {
         spin_lock(&irq_mapping_update_lock);
 
-        *irq = find_unbound_irq();
-        if (*irq == -1)
-                goto out;
+        if (alloc & XEN_ALLOC_IRQ) {
+                *irq = find_unbound_irq();
+                if (*irq == -1)
+                        goto out;
+        }
 
-        *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
-        if (*pirq == -1)
-                goto out;
+        if (alloc & XEN_ALLOC_PIRQ) {
+                *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
+                if (*pirq == -1)
+                        goto out;
+        }
 
         set_irq_chip_and_handler_name(*irq, &xen_pirq_chip,
                                       handle_level_irq, name);
@@ -766,6 +770,7 @@ int xen_destroy_irq(int irq)
                         printk(KERN_WARNING "unmap irq failed %d\n", rc);
                         goto out;
                 }
+                pirq_to_irq[info->u.pirq.pirq] = -1;
         }
         irq_info[irq] = mk_unbound_info();
 
@@ -786,6 +791,11 @@ int xen_gsi_from_irq(unsigned irq)
         return gsi_from_irq(irq);
 }
 
+int xen_irq_from_pirq(unsigned pirq)
+{
+        return pirq_to_irq[pirq];
+}
+
 int bind_evtchn_to_irq(unsigned int evtchn)
 {
         int irq;
diff --git a/include/xen/events.h b/include/xen/events.h
index 646dd17d3aa4..00f53ddcc062 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -76,7 +76,9 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name);
 
 #ifdef CONFIG_PCI_MSI
 /* Allocate an irq and a pirq to be used with MSIs. */
-void xen_allocate_pirq_msi(char *name, int *irq, int *pirq);
+#define XEN_ALLOC_PIRQ (1 << 0)
+#define XEN_ALLOC_IRQ  (1 << 1)
+void xen_allocate_pirq_msi(char *name, int *irq, int *pirq, int alloc_mask);
 int xen_create_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc, int type);
 #endif
 
@@ -89,4 +91,7 @@ int xen_vector_from_irq(unsigned pirq);
 /* Return gsi allocated to pirq */
 int xen_gsi_from_irq(unsigned pirq);
 
+/* Return irq from pirq */
+int xen_irq_from_pirq(unsigned pirq);
+
 #endif  /* _XEN_EVENTS_H */