Re: [PATCH v6] x86/altp2m: Aggregate get entry and populate into common funcs

[Razvan Cojocaru <rcojocaru@bitdefender.com>]

On 5/14/19 6:42 PM, Jan Beulich wrote:
>>>> On 23.04.19 at 16:30, <aisaila@bitdefender.com> wrote:
>> --- a/xen/arch/x86/mm/p2m.c
>> +++ b/xen/arch/x86/mm/p2m.c
>> @@ -478,6 +478,43 @@ void p2m_unlock_and_tlb_flush(struct p2m_domain *p2m)
>>           mm_write_unlock(&p2m->lock);
>>   }
>>   
>> +int altp2m_get_effective_entry(struct p2m_domain *ap2m, gfn_t gfn, mfn_t *mfn,
>> +                               p2m_type_t *t, p2m_access_t *a,
>> +                               bool prepopulate)
>> +{
>> +    *mfn = ap2m->get_entry(ap2m, gfn, t, a, 0, NULL, NULL);
>> +
>> +    /* Check host p2m if no valid entry in alternate */
>> +    if ( !mfn_valid(*mfn) && !p2m_is_hostp2m(ap2m) )
>> +    {
>> +        struct p2m_domain *hp2m = p2m_get_hostp2m(ap2m->domain);
>> +        unsigned int page_order;
>> +        int rc;
>> +
>> +        *mfn = __get_gfn_type_access(hp2m, gfn_x(gfn), t, a,
>> +                                     P2M_ALLOC | P2M_UNSHARE, &page_order, 0);
>> +
>> +        rc = -ESRCH;
>> +        if ( !mfn_valid(*mfn) || *t != p2m_ram_rw )
>> +            return rc;
>> +
>> +        /* If this is a superpage, copy that first */
>> +        if ( prepopulate && page_order != PAGE_ORDER_4K )
>> +        {
>> +            unsigned long mask = ~((1UL << page_order) - 1);
>> +            gfn_t gfn_aligned = _gfn(gfn_x(gfn) & mask);
>> +            mfn_t mfn_aligned = _mfn(mfn_x(*mfn) & mask);
>> +
>> +            rc = ap2m->set_entry(ap2m, gfn_aligned, mfn_aligned, page_order, *t, *a, 1);
>> +            if ( rc )
>> +                return rc;
>> +        }
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>> +
>>   mfn_t __get_gfn_type_access(struct p2m_domain *p2m, unsigned long gfn_l,
>>                       p2m_type_t *t, p2m_access_t *a, p2m_query_t q,
>>                       unsigned int *page_order, bool_t locked)
> 
> May I ask how the placement of this function was chosen? It looks
> as if all its callers live inside #ifdef CONFIG_HVM sections, just this
> function doesn't (reportedly causing build issues together with
> later changes).

I believe it's just an oversight. I've sent out a patch that hopefully 
fixes this in a satisfactory manner.


Thanks,
Razvan

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