Revert "KVM: Save/restore state of assigned PCI device"

This reverts ed78661f2614d3c9f69c23e280db3bafdabdf5bb as it assumes
the saved PCI state will remain valid for the entire length of time
that it is attached to a guest.  This fails when userspace makes use
of the pci-sysfs reset interface, which invalidates the saved device
state, leaving nothing to be restored after the device is reset on
de-assignment.  This leaves the device in an unusable state.

3.0.0 will add an interface for KVM to save the PCI state in a
buffer unaffected by other callers of pci_reset_function(), but the
most appropriate stable fix seems to be reverting this change since
the original assumption about the device saved state persisting is
incorrect.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Acked-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index ae72ae604c897f44f5c5211cb1d13648a55a18ea..e3f1235a9aec7e7141cc0b7b7f72651d15e44acf 100644 (file)
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -197,8 +197,7 @@ static void kvm_free_assigned_device(struct kvm *kvm,
 {
        kvm_free_assigned_irq(kvm, assigned_dev);
 
-       __pci_reset_function(assigned_dev->dev);
-       pci_restore_state(assigned_dev->dev);
+       pci_reset_function(assigned_dev->dev);
 
        pci_release_regions(assigned_dev->dev);
        pci_disable_device(assigned_dev->dev);
@@ -515,7 +514,6 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
        }
 
        pci_reset_function(dev);
-       pci_save_state(dev);
 
        match->assigned_dev_id = assigned_dev->assigned_dev_id;
        match->host_segnr = assigned_dev->segnr;
@@ -546,7 +544,6 @@ out:
        mutex_unlock(&kvm->lock);
        return r;
 out_list_del:
-       pci_restore_state(dev);
        list_del(&match->list);
        pci_release_regions(dev);
 out_disable: