xen/pciback: Support pci_reset_function, aka FLR or D3 support.

We use the __pci_reset_function_locked to perform the action.
Also on attaching ("bind") and detaching ("unbind") we save and
restore the configuration states. When the device is disconnected
from a guest we use the "pci_reset_function" to also reset the
device before being passed to another guest.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

2 files changed, 39 insertions, 3 deletions

diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 7944a17f5cbf..6f63b9d954fb 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -85,19 +85,34 @@ static struct pcistub_device *pcistub_device_alloc(struct pci_dev *dev)
 static void pcistub_device_release(struct kref *kref)
 {
         struct pcistub_device *psdev;
+        struct xen_pcibk_dev_data *dev_data;
 
         psdev = container_of(kref, struct pcistub_device, kref);
+        dev_data = pci_get_drvdata(psdev->dev);
 
         dev_dbg(&psdev->dev->dev, "pcistub_device_release\n");
 
         xen_unregister_device_domain_owner(psdev->dev);
 
-        /* Clean-up the device */
+        /* Call the reset function which does not take lock as this
+         * is called from "unbind" which takes a device_lock mutex.
+         */
+        __pci_reset_function_locked(psdev->dev);
+        if (pci_load_and_free_saved_state(psdev->dev,
+                                          &dev_data->pci_saved_state)) {
+                dev_dbg(&psdev->dev->dev, "Could not reload PCI state\n");
+        } else
+                pci_restore_state(psdev->dev);
+
+        /* Disable the device */
         xen_pcibk_reset_device(psdev->dev);
+
+        kfree(dev_data);
+        pci_set_drvdata(psdev->dev, NULL);
+
+        /* Clean-up the device */
         xen_pcibk_config_free_dyn_fields(psdev->dev);
         xen_pcibk_config_free_dev(psdev->dev);
-        kfree(pci_get_drvdata(psdev->dev));
-        pci_set_drvdata(psdev->dev, NULL);
 
         psdev->dev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
         pci_dev_put(psdev->dev);
@@ -231,7 +246,17 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
         /* Cleanup our device
          * (so it's ready for the next domain)
          */
+
+        /* This is OK - we are running from workqueue context
+         * and want to inhibit the user from fiddling with 'reset'
+         */
+        pci_reset_function(dev);
+        pci_restore_state(psdev->dev);
+
+        /* This disables the device. */
         xen_pcibk_reset_device(found_psdev->dev);
+
+        /* And cleanup up our emulated fields. */
         xen_pcibk_config_free_dyn_fields(found_psdev->dev);
         xen_pcibk_config_reset_dev(found_psdev->dev);
 
@@ -328,6 +353,16 @@ static int __devinit pcistub_init_device(struct pci_dev *dev)
         if (err)
                 goto config_release;
 
+        dev_dbg(&dev->dev, "reseting (FLR, D3, etc) the device\n");
+        __pci_reset_function_locked(dev);
+
+        /* We need the device active to save the state. */
+        dev_dbg(&dev->dev, "save state of device\n");
+        pci_save_state(dev);
+        dev_data->pci_saved_state = pci_store_saved_state(dev);
+        if (!dev_data->pci_saved_state)
+                dev_err(&dev->dev, "Could not store PCI conf saved state!\n");
+
         /* Now disable the device (this also ensures some private device
          * data is setup before we export)
          */
diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h
index e9b4011c5f9a..a7def010eba3 100644
--- a/drivers/xen/xen-pciback/pciback.h
+++ b/drivers/xen/xen-pciback/pciback.h
@@ -41,6 +41,7 @@ struct xen_pcibk_device {
 
 struct xen_pcibk_dev_data {
         struct list_head config_fields;
+        struct pci_saved_state *pci_saved_state;
         unsigned int permissive:1;
         unsigned int warned_on_write:1;
         unsigned int enable_intx:1;