Re: [Xen-devel] Re: [PATCH] Fix >4G i386 PAE grant table interface

[Steven Rostedt <srostedt@xxxxxxxxxx>]

Keir Fraser wrote:
> On 4/11/06 2:25 pm, "Steven Rostedt" <srostedt@xxxxxxxxxx> wrote:
>
> > So is there a difference between create_grant_pte_mapping and
> > create_grant_va_mapping. As well as destroy_grant_pte_mapping and
> > destroy_grant_va_mapping. So calling pte create, and then va destroy on
> > the same mapping is not a bug?
> That would be a bug, if it were possible, which it's not. 'flags' is not a
> parameter to the gnttab_unmap operation. Xen remembers the flags from the
> original map operation.
OK, took me some time to find what you mean:

__gnttab_unmap_grant_ref(
    struct gnttab_unmap_grant_ref *op)
{
 [...]

    map = &ld->grant_table->maptrack[op->handle];

 [...]

    dom   = map->domid;
    ref   = map->ref;
    flags = map->flags;

 [...]

    if ( (op->host_addr != 0) && (flags & GNTMAP_host_map) )
    {
        if ( (rc = destroy_grant_host_mapping(op->host_addr,
                                              frame, flags)) < 0 )
            goto unmap_out;



OK, but it can be a problem on the kernel side because of the Xen auto 
translate physmap feature.  But not as bad as I thought.
But it's still good to be consistent.

-- Steve

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