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

[Steven Rostedt <srostedt@xxxxxxxxxx>]

Keir Fraser wrote:
> On 3/11/06 10:46 pm, "Steven Rostedt" <srostedt@xxxxxxxxxx> wrote:
>
> > It's much worst than that!
> >
> > Without this patch, my patch is still broken.  In the hypervisor this
> > flag is checked, and will go down the wrong path when it is missing:
> The hypervisor remembers the flags for itself, so the kernel can only
> confuse itself. Still, it was a bug.
Well the flag for the application map isn't the problem. But I do see 
missing the flag for contains pte is a problem.
>
int create_grant_host_mapping(
    u64 addr, unsigned long frame, unsigned int flags)
{
    l1_pgentry_t pte = l1e_from_pfn(frame, GRANT_PTE_FLAGS);

    if ( (flags & GNTMAP_application_map) )
        l1e_add_flags(pte,_PAGE_USER);
    if ( !(flags & GNTMAP_readonly) )
        l1e_add_flags(pte,_PAGE_RW);

    if ( flags & GNTMAP_contains_pte )
        return create_grant_pte_mapping(addr, pte, current);
    return create_grant_va_mapping(addr, pte, current);
}

int destroy_grant_host_mapping(
    u64 addr, unsigned long frame, unsigned int flags)
{
    if ( flags & GNTMAP_contains_pte )
        return destroy_grant_pte_mapping(addr, frame, current->domain);
    return destroy_grant_va_mapping(addr, frame, current);
}

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?
-- Steve

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