Re: [Xen-devel] [PATCH 11/14] xen/x86: mm: Re-implement set_gpfn_from_mfn() as a static inline function

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 10/05/2019 13:43, Jan Beulich wrote:
> > > > On 07.05.19 at 17:14, <julien.grall@xxxxxxx> wrote:
> > +static inline void set_gpfn_from_mfn(unsigned long mfn, unsigned long pfn)
> > +{
> > +    struct domain *d = page_get_owner(mfn_to_page(_mfn(mfn)));
> > +    unsigned long entry = (d && (d == dom_cow)) ? SHARED_M2P_ENTRY : pfn;
> The && here looks, ehm, funny, but I guess it's needed for early boot?
I have no idea, this is x86 not Arm...

> But that's perhaps a separate thing to clean up. However, looking at
> this - why is Arm setting up dom_cow in the first place?
Common code is using dom_cow, so I don't think we want it to be NULL on Arm to 
avoid weird issues.
> > +    if (!machine_to_phys_mapping_valid)
> Please add the missing blanks.
Ok.

> > +        return;
> > +
> > +    if ( mfn >= (RDWR_COMPAT_MPT_VIRT_END - RDWR_COMPAT_MPT_VIRT_START) / 4 )
> You've inverted the original condition (by re-using it verbatim) - I'm pretty
> sure this is going to crash.
Good point, I will update the patch.

Cheers,

--
Julien Grall

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