Re: [Xen-devel] [PATCH v5 07/10] xen/arm: Handle remove foreign mapping

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Mon, 2013-12-16 at 17:37 +0000, Julien Grall wrote:
> Modify get_page_from_gfn to take reference on foreign mapping. This will avoid
> specific handling in the common code.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> ---
>     Changes in v4.2:
>         - get_page_from_gfn: move foreign checking before get_page
>         - add assert fdom != dom
>     Changes in v4.1:
>         - Remove specific p2m handling in common code
>         - Handle foreign mapping in get_page_from_gfn
>     Changes in v4:
>         - Split patch #6 from dom0 pvh series v6.2 to retrieve only common
>         code.
>         - Rework commit title
>         - Rename xen_rem_foreign_from_p2m in p2m_remove_foreign
>         - Get the mfn from the pte. We are not sure that maddr given in
>         parameters is valid
>     Changes in v3:
>         - Move put_page in create_p2m_entries
>         - Move xenmem_rem_foreign_from_p2m in arch/arm/p2m.c
>     Changes in v2:
>         - Introduce the patch
> ---
>  xen/arch/arm/p2m.c        |   15 +++++++++++++--
>  xen/include/asm-arm/p2m.h |   12 ++++++++++++
>  2 files changed, 25 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 9bdcacd..d05fdff 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -317,10 +317,21 @@ static int create_p2m_entries(struct domain *d,
>                  break;
>              case REMOVE:
>                  {
> -                    lpae_t pte;
> +                    lpae_t pte = third[third_table_offset(addr)];
> +                    unsigned long mfn;
> +
> +                    maddr = (pte.bits & PADDR_MASK & PAGE_MASK);
> +                    mfn = paddr_to_pfn(maddr);

FWIW mfn = pte.p2m.base, I think. I'm not sure we use this everywhere we
could.

> +
> +                    /* TODO: Handle other p2m type */
> +                    if ( pte.p2m.valid && p2m_is_foreign(pte.p2m.type) )

How useful is p2m_is_foreign now that this stuff doesn't need to be in
common code?

Both of the above are really just observations rather than requests for
change, so:
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>



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