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authorKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>2014-12-03 22:40:32 +0100
committerDavid Vrabel <david.vrabel@citrix.com>2014-12-04 13:42:02 +0100
commitb1df4a56bf4a61113e8928f932d346bed6eef553 (patch)
tree5cf357104c15548775dec5b67c7540ca0976881b
parentPCI: Expose pci_load_saved_state for public consumption. (diff)
downloadlinux-b1df4a56bf4a61113e8928f932d346bed6eef553.tar.xz
linux-b1df4a56bf4a61113e8928f932d346bed6eef553.zip
xen/pciback: Restore configuration space when detaching from a guest.
The commit "xen/pciback: Don't deadlock when unbinding." was using the version of pci_reset_function which would lock the device lock. That is no good as we can dead-lock. As such we swapped to using the lock-less version and requiring that the callers of 'pcistub_put_pci_dev' take the device lock. And as such this bug got exposed. Using the lock-less version is OK, except that we tried to use 'pci_restore_state' after the lock-less version of __pci_reset_function_locked - which won't work as 'state_saved' is set to false. Said 'state_saved' is a toggle boolean that is to be used by the sequence of a) pci_save_state/pci_restore_state or b) pci_load_and_free_saved_state/pci_restore_state. We don't want to use a) as the guest might have messed up the PCI configuration space and we want it to revert to the state when the PCI device was binded to us. Therefore we pick b) to restore the configuration space. We restore from our 'golden' version of PCI configuration space, when an: - Device is unbinded from pciback - Device is detached from a guest. Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
-rw-r--r--drivers/xen/xen-pciback/pci_stub.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/drivers/xen/xen-pciback/pci_stub.c b/drivers/xen/xen-pciback/pci_stub.c
index 843a2baffc2b..8580e53355ec 100644
--- a/drivers/xen/xen-pciback/pci_stub.c
+++ b/drivers/xen/xen-pciback/pci_stub.c
@@ -105,7 +105,7 @@ static void pcistub_device_release(struct kref *kref)
*/
__pci_reset_function_locked(dev);
if (pci_load_and_free_saved_state(dev, &dev_data->pci_saved_state))
- dev_dbg(&dev->dev, "Could not reload PCI state\n");
+ dev_info(&dev->dev, "Could not reload PCI state\n");
else
pci_restore_state(dev);
@@ -257,6 +257,8 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
{
struct pcistub_device *psdev, *found_psdev = NULL;
unsigned long flags;
+ struct xen_pcibk_dev_data *dev_data;
+ int ret;
spin_lock_irqsave(&pcistub_devices_lock, flags);
@@ -280,8 +282,18 @@ void pcistub_put_pci_dev(struct pci_dev *dev)
*/
device_lock_assert(&dev->dev);
__pci_reset_function_locked(dev);
- pci_restore_state(dev);
+ dev_data = pci_get_drvdata(dev);
+ ret = pci_load_saved_state(dev, dev_data->pci_saved_state);
+ if (!ret) {
+ /*
+ * The usual sequence is pci_save_state & pci_restore_state
+ * but the guest might have messed the configuration space up.
+ * Use the initial version (when device was bound to us).
+ */
+ pci_restore_state(dev);
+ } else
+ dev_info(&dev->dev, "Could not reload PCI state\n");
/* This disables the device. */
xen_pcibk_reset_device(dev);