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xen/m2p: do not reuse kmap_op->dev_bus_addr

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If the caller passes a valid kmap_op to m2p_add_override, we use
kmap_op->dev_bus_addr to store the original mfn, but dev_bus_addr is
part of the interface with Xen and if we are batching the hypercalls it
might not have been written by the hypervisor yet. That means that later
on Xen will write to it and we'll think that the original mfn is
actually what Xen has written to it.

Rather than "stealing" struct members from kmap_op, keep using
page->index to store the original mfn and add another parameter to
m2p_remove_override to get the corresponding kmap_op instead.
It is now responsibility of the caller to keep track of which kmap_op
corresponds to a particular page in the m2p_override (gntdev, the only
user of this interface that passes a valid kmap_op, is already doing that).

CC: stable@kernel.org
Reported-and-Tested-By: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Stefano Stabellini 2012-09-12 12:44:30 +01:00 • committed by Konrad Rzeszutek Wilk
parent 80ba77dfbc
commit 2fc136eecd
6 changed files with 23 additions and 23 deletions
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5
drivers/xen/gntdev.c
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@ -314,8 +314,9 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
}
}
err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset,
pages, true);
err = gnttab_unmap_refs(map->unmap_ops + offset,
use_ptemod ? map->kmap_ops + offset : NULL, map->pages + offset,
pages);
if (err)
return err;