Re: [Xen-devel] [PATCH 4/8] xen/arm: Store p2m type in each page of the guest

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 12/05/2013 03:55 PM, Ian Campbell wrote:
> On Thu, 2013-12-05 at 15:42 +0000, Julien Grall wrote:
> > Use the field 'avail' to store the type of the page. This information will be
> > retrieved in a future patch to change the behaviour when the page is removed.
> >
> > Also introduce guest_physmap_add_entry to map and set a specific p2m type for
> > a page.
> >
> > Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/p2m.c        |   49 +++++++++++++++++++++++++++++++--------------
> >   xen/include/asm-arm/p2m.h |   18 +++++++++++++----
> >   2 files changed, 48 insertions(+), 19 deletions(-)
> >
> > diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> > index 8f8b47e..5449a35 100644
> > --- a/xen/arch/arm/p2m.c
> > +++ b/xen/arch/arm/p2m.c
> > @@ -124,7 +124,8 @@ int p2m_pod_decrease_reservation(struct domain *d,
> >       return -ENOSYS;
> >   }
> >
> > -static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr)
> > +static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr,
> > +                               p2m_type_t t)
> >   {
> >       paddr_t pa = ((paddr_t) mfn) << PAGE_SHIFT;
> >       lpae_t e = (lpae_t) {
> > @@ -132,12 +133,25 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, 
> > unsigned int mattr)
> >           .p2m.af = 1,
> >           .p2m.sh = LPAE_SH_OUTER,
> >           .p2m.read = 1,
> > -        .p2m.write = 1,
> >           .p2m.mattr = mattr,
> >           .p2m.table = 1,
> >           .p2m.valid = 1,
> > +        .p2m.avail = t, /* Use avail to store p2m type */
> Can we change the name in the struct instead and have a comment "using
> avail bits for type" there instead please. We only have 5 types so could
> only steal 3 but we may as well take all 4.
>
> A BUILD_BUG_ON to check that the last p2m entry is < 2^4 would be good
> too.
I will do both modification for the next version.

--
Julien Grall

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