[Xen-devel] [PATCH v3 3/3] xen/pciback: support driver_override

[Juergen Gross <jgross@xxxxxxxx>]

Support the driver_override scheme introduced with commit 782a985d7af2
("PCI: Introduce new device binding path using pci_dev.driver_override")

As pcistub_probe() is called for all devices (it has to check for a
match based on the slot address rather than device type) it has to
check for driver_override set to "pciback" itself.

Up to now for assigning a pci device to pciback you need something like:

echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind
echo 0000:07:10.0 > /sys/bus/pci/drivers/pciback/new_slot
echo 0000:07:10.0 > /sys/bus/pci/drivers_probe

while with the patch you can use the same mechanism as for similar
drivers like pci-stub and vfio-pci:

echo pciback > /sys/bus/pci/devices/0000\:07\:10.0/driver_override
echo 0000:07:10.0 > /sys/bus/pci/devices/0000\:07\:10.0/driver/unbind
echo 0000:07:10.0 > /sys/bus/pci/drivers_probe

So e.g. libvirt doesn't need special handling for pciback.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V3: Move override check up in order not to miss the PCI_HEADER_TYPE
    check.
    Add an assigned device to the slot list.

V2: Removed now unused label
---
 drivers/xen/xen-pciback/pci_stub.c | 36 +++++++++++++++++++++++++++++-------
 1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/xen/xen-pciback/pci_stub.c 
b/drivers/xen/xen-pciback/pci_stub.c
index 0179333..6331a95 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -25,6 +25,8 @@
 #include "conf_space.h"
 #include "conf_space_quirks.h"
 
+#define PCISTUB_DRIVER_NAME "pciback"
+
 static char *pci_devs_to_hide;
 wait_queue_head_t xen_pcibk_aer_wait_queue;
 /*Add sem for sync AER handling and xen_pcibk remove/reconfigue ops,
@@ -508,15 +510,18 @@ static void pcistub_device_id_add_list(struct 
pcistub_device_id *new,
                kfree(new);
 }
 
-static int pcistub_seize(struct pci_dev *dev)
+static int pcistub_seize(struct pci_dev *dev,
+                        struct pcistub_device_id *pci_dev_id)
 {
        struct pcistub_device *psdev;
        unsigned long flags;
        int err = 0;
 
        psdev = pcistub_device_alloc(dev);
-       if (!psdev)
+       if (!psdev) {
+               kfree(pci_dev_id);
                return -ENOMEM;
+       }
 
        spin_lock_irqsave(&pcistub_devices_lock, flags);
 
@@ -537,8 +542,12 @@ static int pcistub_seize(struct pci_dev *dev)
 
        spin_unlock_irqrestore(&pcistub_devices_lock, flags);
 
-       if (err)
+       if (err) {
+               kfree(pci_dev_id);
                pcistub_device_put(psdev);
+       } else if (pci_dev_id)
+               pcistub_device_id_add_list(pci_dev_id, pci_domain_nr(dev->bus),
+                                          dev->bus->number, dev->devfn);
 
        return err;
 }
@@ -547,11 +556,16 @@ static int pcistub_seize(struct pci_dev *dev)
  * other functions that take the sysfs lock. */
 static int pcistub_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
-       int err = 0;
+       int err = 0, match;
+       struct pcistub_device_id *pci_dev_id = NULL;
 
        dev_dbg(&dev->dev, "probing...\n");
 
-       if (pcistub_match(dev)) {
+       match = pcistub_match(dev);
+
+       if ((dev->driver_override &&
+            !strcmp(dev->driver_override, PCISTUB_DRIVER_NAME)) ||
+           match) {
 
                if (dev->hdr_type != PCI_HEADER_TYPE_NORMAL
                    && dev->hdr_type != PCI_HEADER_TYPE_BRIDGE) {
@@ -562,8 +576,16 @@ static int pcistub_probe(struct pci_dev *dev, const struct 
pci_device_id *id)
                        goto out;
                }
 
+               if (!match) {
+                       pci_dev_id = kmalloc(sizeof(*pci_dev_id), GFP_ATOMIC);
+                       if (!pci_dev_id) {
+                               err = -ENOMEM;
+                               goto out;
+                       }
+               }
+
                dev_info(&dev->dev, "seizing device\n");
-               err = pcistub_seize(dev);
+               err = pcistub_seize(dev, pci_dev_id);
        } else
                /* Didn't find the device */
                err = -ENODEV;
@@ -975,7 +997,7 @@ static const struct pci_error_handlers 
xen_pcibk_error_handler = {
 static struct pci_driver xen_pcibk_pci_driver = {
        /* The name should be xen_pciback, but until the tools are updated
         * we will keep it as pciback. */
-       .name = "pciback",
+       .name = PCISTUB_DRIVER_NAME,
        .id_table = pcistub_ids,
        .probe = pcistub_probe,
        .remove = pcistub_remove,
-- 
2.6.6


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