Re: [Xen-devel] [RFC PATCH 3/3] Implement 3-level event channel routines.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.01.13 at 12:31, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Wed, 2013-01-09 at 11:24 +0000, Jan Beulich wrote:
>> >>> On 09.01.13 at 11:56, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
>> > On Wed, 2013-01-09 at 08:38 +0000, Jan Beulich wrote:
>> >> >>> On 08.01.13 at 18:33, Wei Liu <Wei.Liu2@xxxxxxxxxx> wrote:
>> >> > On Thu, 2013-01-03 at 11:35 +0000, Jan Beulich wrote:
>> >> >> >>> On 31.12.12 at 19:22, Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
>> >> >> >
>> >> >> > +static void __unmap_l2_sel(struct vcpu *v)
>> >> >> > +{
>> >> >> > +    unsigned long mfn;
>> >> >> > +
>> >> >> > +    if ( v->evtchn_pending_sel_l2 != 0 )
>> >> >> > +    {
>> >> >> > +        unmap_domain_page_global(v->evtchn_pending_sel_l2);
>> >> >> > +        mfn = virt_to_mfn(v->evtchn_pending_sel_l2);
>> >> >> 
>> >> >> virt_to_mfn() is not valid on the output of
>> >> >> map_domain_page{,_global}() (same further down). Yes, there is
>> >> >> at least one example of this in the existing code, but that's wrong
>> >> >> too, and is getting eliminated by the 16Tb patch series I'm in the
>> >> >> process of putting together.
>> >> >> 
>> >> > 
>> >> > So what's the correct way to do this? Do I need to wait for your patch
>> >> > series?
>> >> 
>> >> Considering that the old 32-bit case of map_domain_page()
>> >> doesn't matter anymore,
>> > 
>> > We still care about it on 32-bit ARM FWIW. (I@m not sure if that
>> > invalidates your advice below though)
>> 
>> Right - which would require ARM to implement
>> domain_page_map_to_mfn() (so far used only in x86 and tmem
>> code).
> 
> I only see it in x86 (specifically hvm_unmap_guest_frame) but I guess
> this is a useful interface for ARM to implement in any case and it
> doesn't look to be terribly hard.

Oh, the tmem one is from my 16Tb series that I'm hoping to post
soon.

Jan


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