linux-kernel - [105/107] Revert "KVM: Save/restore state of assigned PCI device"

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Date:	Thu, 07 Jul 2011 17:17:17 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org, greg@...ah.com
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	avi@...hat.com, mtosatti@...hat.com,
	Alex Williamson <alex.williamson@...hat.com>,
	"Acked-by: Jan Kiszka" <jan.kiszka@...mens.com>
Subject: [105/107] Revert "KVM: Save/restore state of assigned PCI device"

2.6.39-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Alex Williamson <alex.williamson@...hat.com>

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@...hat.com>
Acked-by: Jan Kiszka <jan.kiszka@...mens.com>
Signed-off-by: Avi Kivity <avi@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 virt/kvm/assigned-dev.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -197,8 +197,7 @@ static void kvm_free_assigned_device(str
 {
 	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(st
 	}
 
 	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:


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