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Re: [Xen-devel] Restart domU failure (memory allocation issue)

On 03/14/2014 12:45 PM, Andrii Anisov wrote:
>     It seems that unmap will be done at the end of xc_dom_boot_image (see
>     xc_dom_unmap_all).
>     The latter function will go through the list of all mappings and close
>     it one by one.
>     You can add a print in xc_dom_unmap_one (tools/libxc/xc_dom_core.c) and
>     check if you have the same number of print with
>     xc_dom_pfn_to_ptr_retcount.
> As I see xc_dom_unmap_all ends with munmap(), what actually unmaps pages
> from process virtual memory space. But I have doubts if it is aware
> about cross domain mapping and cares about it.

This is done in kernel space. When you map the pages, privcmd will set
specific callbacks that will be use when munmap will be called (see
privcmd_close in drivers/xen/privcmd.c).

The privcmd_close function will call the hypercall to remove the foreign
page from the p2m.

Julien Grall

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