On Tue, 2010-11-16 at 10:54 -0700, Alex Williamson wrote:
> On Tue, 2010-11-09 at 17:09 -0800, Tom Lyon wrote:
> > Cleans up config space virtualization, especialy handling of bytes
> > which have some virtual and some real bits, like PCI_COMMAND.
> >
> > Alex, I hope you can test this with your setups.
>
> Sorry for the delay. FWIW, I'm not having much luck with this, I'll try
> to debug the problem. Thanks,
This seems to be the bug. Thanks,
Alex
vfio: Don't write random bits on read
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
---
diff --git a/drivers/vfio/vfio_pci_config.c b/drivers/vfio/vfio_pci_config.c
index 7132ac4..422d7b1 100644
--- a/drivers/vfio/vfio_pci_config.c
+++ b/drivers/vfio/vfio_pci_config.c
@@ -964,11 +964,6 @@ static int vfio_config_rwbyte(int write,
return 0;
}
- if (write) {
- if (copy_from_user(&newval, buf, 1))
- return -EFAULT;
- }
-
if (~virt) { /* mix of real and virt bits */
/* update vconfig with latest hw bits */
ret = vfio_read_config_byte(vdev, pos, &realbits);
@@ -978,9 +973,14 @@ static int vfio_config_rwbyte(int write,
(vdev->vconfig[pos] & virt) | (realbits & ~virt);
}
- /* update vconfig with writeable bits */
- vdev->vconfig[pos] =
- (vdev->vconfig[pos] & ~wr) | (newval & wr);
+ if (write) {
+ if (copy_from_user(&newval, buf, 1))
+ return -EFAULT;
+
+ /* update vconfig with writeable bits */
+ vdev->vconfig[pos] =
+ (vdev->vconfig[pos] & ~wr) | (newval & wr);
+ }
/*
* Now massage virtual fields
--
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