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>

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 0d5087eeced8a584f3bc7b393f5886b3e0aa74d1..93e42152d8d09e9a4331b3acb2fb680165c461f0 100644 (file)
--- 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;

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index c21066fc30bea679962d15389e588062a607538c..1033f6284f318bd54680c161cdd310ead528d4c5 100644 (file)
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -647,12 +647,12 @@ out:
 #include <linux/msi.h>
 #include "../pci/msi.h"
 
-static int find_unbound_pirq(int type)
+int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc)
 {
        int rc;
        struct physdev_get_free_pirq op_get_free_pirq;
 
-       op_get_free_pirq.type = type;
+       op_get_free_pirq.type = MAP_PIRQ_TYPE_MSI;
        rc = HYPERVISOR_physdev_op(PHYSDEVOP_get_free_pirq, &op_get_free_pirq);
 
        WARN_ONCE(rc == -ENOSYS,
@@ -661,9 +661,10 @@ static int find_unbound_pirq(int type)
        return rc ? -1 : op_get_free_pirq.pirq;
 }
 
-int xen_allocate_pirq_msi(char *name, int *pirq, int alloc_pirq)
+int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
+                            int pirq, const char *name)
 {
-       int irq;
+       int irq, ret;
 
        spin_lock(&irq_mapping_update_lock);
 
@@ -671,24 +672,21 @@ int xen_allocate_pirq_msi(char *name, int *pirq, int alloc_pirq)
        if (irq == -1)
                goto out;
 
-       if (alloc_pirq) {
-               *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
-               if (*pirq == -1) {
-                       xen_free_irq(irq);
-                       irq = -1;
-                       goto out;
-               }
-       }
-
        set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
                                      handle_level_irq, name);
 
-       irq_info[irq] = mk_pirq_info(0, *pirq, 0, 0);
-       pirq_to_irq[*pirq] = irq;
-
+       irq_info[irq] = mk_pirq_info(0, pirq, 0, 0);
+       pirq_to_irq[pirq] = irq;
+       ret = set_irq_msi(irq, msidesc);
+       if (ret < 0)
+               goto error_irq;
 out:
        spin_unlock(&irq_mapping_update_lock);
        return irq;
+error_irq:
+       spin_unlock(&irq_mapping_update_lock);
+       xen_free_irq(irq);
+       return -1;
 }
 
 int xen_create_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc, int type)

diff --git a/include/xen/events.h b/include/xen/events.h
index f70536af921c7dbd95b8fac57ae8abfba2542e5f..18bf825bac6607ef09154a74c23dba6c70e4f8c7 100644 (file)
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -75,7 +75,9 @@ int xen_allocate_pirq(unsigned gsi, int shareable, char *name);
 int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int shareable, char *name);
 
 #ifdef CONFIG_PCI_MSI
-int xen_allocate_pirq_msi(char *name, int *pirq, int alloc_pirq);
+int xen_allocate_pirq_msi(struct pci_dev *dev, struct msi_desc *msidesc);
+int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
+                            int pirq, const char *name);
 int xen_create_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc, int type);
 #endif