Re: [Xen-devel] [PATCH v5 1/4] xen: introduce a helper to allocate non-contiguous memory

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.05.15 at 16:34, <roger.pau@xxxxxxxxxx> wrote:
> +void vfree(void *va)
> +{
> +    unsigned int i, pages = vm_size(va);
> +
> +    if ( pages == 0 )
> +        return;
> +
> +    for ( i = 0; i < pages; i++ )
> +        free_domheap_pages(vmap_to_page(va + i * PAGE_SIZE), 1);
> +
> +    vunmap(va);
> +}

There actually is another problem here: You must not free the
pages before having torn down the mapping. An option (to
avoid the need for a memory allocation) might be to zap the
present bits (or whatever their equivalent on ARM) in a first
pass (making sure to flush TLBs), free, and then vunmap().

And you would of course better use the single page shortcut
macros of the domheap allocation/free functions.

Jan


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