xen: events: separate MSI PIRQ allocation from PIRQ binding to IRQ

Split the binding aspect of xen_allocate_pirq_msi out into a new
xen_bind_pirq_to_irq function.

In xen_hvm_setup_msi_irq when allocating a pirq write the MSI message
to signal the PIRQ as soon as the pirq is obtained. There is no way to
free the pirq back so if the subsequent binding to an IRQ fails we
want to ensure that we will reuse the PIRQ next time rather than leak
it.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 26 insertions, 42 deletions

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 0d5087eeced8..93e42152d8d0 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c
@@ -86,7 +86,7 @@ static void xen_msi_compose_msg(struct pci_dev *pdev, unsigned int pirq,
 
 static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
 {
-        int irq, pirq, ret = 0;
+        int irq, pirq;
         struct msi_desc *msidesc;
         struct msi_msg msg;
 
@@ -94,39 +94,32 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
                 __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) {
-                        irq = xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
-                                                    "msi-x" : "msi", &pirq, 0);
-                        if (irq < 0)
+                if (msg.data != XEN_PIRQ_MSI_DATA ||
+                    xen_irq_from_pirq(pirq) < 0) {
+                        pirq = xen_allocate_pirq_msi(dev, msidesc);
+                        if (pirq < 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_msi_compose_msg(dev, pirq, &msg);
+                        __write_msi_msg(msidesc, &msg);
+                        dev_dbg(&dev->dev, "xen: msi bound to pirq=%d\n", pirq);
+                } else {
+                        dev_dbg(&dev->dev,
+                                "xen: msi already bound to pirq=%d\n", pirq);
                 }
-                irq = xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
-                                            "msi-x" : "msi", &pirq, 1);
-                if (irq < 0 || pirq < 0)
+                irq = xen_bind_pirq_msi_to_irq(dev, msidesc, pirq,
+                                               (type == PCI_CAP_ID_MSIX) ?
+                                               "msi-x" : "msi");
+                if (irq < 0)
                         goto error;
-                printk(KERN_DEBUG "xen: msi --> irq=%d, pirq=%d\n", irq, pirq);
-                xen_msi_compose_msg(dev, pirq, &msg);
-                ret = set_irq_msi(irq, msidesc);
-                if (ret < 0)
-                        goto error_while;
-                write_msi_msg(irq, &msg);
+                dev_dbg(&dev->dev,
+                        "xen: msi --> pirq=%d --> irq=%d\n", pirq, irq);
         }
         return 0;
 
-error_while:
-        unbind_from_irqhandler(irq, NULL);
 error:
-        if (ret == -ENODEV)
-                dev_err(&dev->dev, "Xen PCI frontend has not registered" \
-                                " MSI/MSI-X support!\n");
-
-        return ret;
+        dev_err(&dev->dev,
+                "Xen PCI frontend has not registered MSI/MSI-X support!\n");
+        return -ENODEV;
 }
 
 /*
@@ -152,28 +145,19 @@ static int xen_setup_msi_irqs(struct pci_dev *dev, int nvec, int type)
                 goto error;
         i = 0;
         list_for_each_entry(msidesc, &dev->msi_list, list) {
-                irq = xen_allocate_pirq_msi(
-                        (type == PCI_CAP_ID_MSIX) ?
-                        "pcifront-msi-x" : "pcifront-msi",
-                        &v[i], 0);
-                if (irq < 0) {
-                        ret = -1;
+                irq = xen_bind_pirq_msi_to_irq(dev, msidesc, v[i],
+                                               (type == PCI_CAP_ID_MSIX) ?
+                                               "pcifront-msi-x" :
+                                               "pcifront-msi");
+                if (irq < 0)
                         goto free;
-                }
-                ret = set_irq_msi(irq, msidesc);
-                if (ret)
-                        goto error_while;
                 i++;
         }
         kfree(v);
         return 0;
 
-error_while:
-        unbind_from_irqhandler(irq, NULL);
 error:
-        if (ret == -ENODEV)
-                dev_err(&dev->dev, "Xen PCI frontend has not registered" \
-                        " MSI/MSI-X support!\n");
+        dev_err(&dev->dev, "Xen PCI frontend has not registered MSI/MSI-X support!\n");
 free:
         kfree(v);
         return ret;