Re: [Xen-devel] [PATCH] xen/arm: p2m: Don't create new table when the mapping is removed

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 18 Dec 2013, Julien Grall wrote:
> On 12/18/2013 07:28 PM, Stefano Stabellini wrote:
> > On Wed, 18 Dec 2013, Julien Grall wrote:
> > > When  Xen is removing/relinquishing mapping, it will create second/third
> > > tables
> > > if they don't exist.
> > > 
> > > Non-existent table means the address range was never mapped, so Xen can
> > > safely
> > > skip them.
> > > 
> > > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > > 
> > > ---
> > >      Release: This is an improvement for Xen 4.4. It will save time during
> > >      relinquish phase and avoid dummy allocation.
> > >      The downside is the patch is modifying p2m loop which is used
> > > everywhere.
> > > ---
> > >   xen/arch/arm/p2m.c |   22 ++++++++++++++++++++--
> > >   1 file changed, 20 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > > index d24a6fc..9ef8819 100644
> > > --- a/xen/arch/arm/p2m.c
> > > +++ b/xen/arch/arm/p2m.c
> > > @@ -246,10 +246,12 @@ static int create_p2m_entries(struct domain *d,
> > >                     cur_first_offset = ~0,
> > >                     cur_second_offset = ~0;
> > >       unsigned long count = 0;
> > > +    bool_t populate = (op == INSERT || op == ALLOCATE);
> > 
> > why don't you just check for op == REMOVE?
> 
> Because you also need to check op == RELINQUISH (added by my patch series on
> foreign mapping).

I see. In that case

Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

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