• Stefano Stabellini's avatar
    xen/m2p: do not reuse kmap_op->dev_bus_addr · 2fc136ee
    Stefano Stabellini authored
    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: default avatarSander Eikelenboom <linux@eikelenboom.it>
    Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
    Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
    2fc136ee
blkback.c 23.3 KB