Re: [Xen-devel] [PATCH 13/14] xen/mm: Convert {s, g}et_gpfn_from_mfn() to use typesafe MFN

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 10/05/2019 15:02, Jan Beulich wrote:
>>>> On 10.05.19 at 15:46, <julien.grall@xxxxxxx> wrote:
>> On 10/05/2019 14:41, Jan Beulich wrote:
>>>>>> On 10.05.19 at 15:34, <julien.grall@xxxxxxx> wrote:
>>>> On 10/05/2019 14:21, Jan Beulich wrote:
>>>>>>>> On 07.05.19 at 17:14, <julien.grall@xxxxxxx> wrote:
>>>>>> @@ -1030,19 +1031,19 @@ long p2m_pt_audit_p2m(struct p2m_domain *p2m)
>>>>>> @@ -2795,54 +2795,54 @@ void audit_p2m(struct domain *d,
>>>>>>        spin_lock(&d->page_alloc_lock);
>>>>>>        page_list_for_each ( page, &d->page_list )
>>>>>>        {
>>>>>> -        mfn = mfn_x(page_to_mfn(page));
>>>>>> +        mfn = page_to_mfn(page);
>>>>>>    
>>>>>> -        P2M_PRINTK("auditing guest page, mfn=%#lx\n", mfn);
>>>>>> +        P2M_PRINTK("auditing guest page, mfn=%"PRI_mfn"\n", mfn_x(mfn));
>>>>>>    
>>>>>>            od = page_get_owner(page);
>>>>>>    
>>>>>>            if ( od != d )
>>>>>>            {
>>>>>> -            P2M_PRINTK("wrong owner %#lx -> %p(%u) != %p(%u)\n",
>>>>>> -                       mfn, od, (od?od->domain_id:-1), d, d->domain_id);
>>>>>> +            P2M_PRINTK("wrong owner %"PRI_mfn" -> %p(%u) != %p(%u)\n",
>>>>>> +                       mfn_x(mfn), od, (od?od->domain_id:-1), d, 
>>>>>> d->domain_id);
>>>>> Please be careful not to drop 0x prefixes from the resulting output
>>>>> (which are an effect of the # flag that you delete), at least when
>>>>> log messages contain a mix of hex and dec numbers. (I am, btw,
>>>>> not convinced that switching to PRI_mfn here is helpful.)
>>>> Last time I keeped %# for MFN, I have been asked to remove the #. I prefer
>>>> having 0x for all the hex, and I am happy to be keep as is. But I would 
>>>> like a
>>>> bit of consistency on the way we print MFN...
>>> Well, "%#"PRI_mfn is bogus (because of the combination with the
>>> minimum width specification), so it ought to be "%#lx" or "0x%"PRI_mfn.
>>> Have you really been asked for something else? If so, and if it was me,
>>> then I apologize.
>> I am not sure why this is bogus. The thing is using different format for the 
>> MFN 
>> makes it difficult to read a message without looking format string.
> We look to be in agreement that there should be a 0x prefix here.
> What I'm asking for is to avoid the value logged to de-generate into
> a 3-digit one (0x???) when a five digit one is meant (see PRI_mfn).
> Not to speak of the further inconsistent string that would be logged
> for MFN 0.

The overwhelming majority way of printing mfns is via:

mfn %"PRI_mfn"

which is almost fully consistent across the x86 code.

Various bits of common code, and most of ARM code use variations of
%#"PRI_mfn", and this ought to be fixed.

~Andrew

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