Subject: Re: [RFC v1 2/2] powerpc/64s: Add support for huge pfnmaps

From: Ritesh Harjani (IBM) <[email-masked]>
Date: Fri, 27 Feb 2026 16:02:25 +0530

"Christophe Leroy (CS GROUP)" <[email-masked]> writes:

> Le 27/02/2026 à 07:16, Ritesh Harjani (IBM) a écrit :
>> This uses _RPAGE_SW2 bit for the PMD and PUDs similar to PTEs.
>> This also adds support for {pte,pmd,pud}_pgprot helpers needed for
>> follow_pfnmap APIs.
>> 
>> This allows us to extend the PFN mappings, e.g. PCI MMIO bars where
>> it can grow as large as 8GB or even bigger, to map at PMD / PUD level.
>> VFIO PCI core driver already supports fault handling at PMD / PUD level
>> for more efficient BAR mappings.
>> 
>> Signed-off-by: Ritesh Harjani (IBM) <[email-masked]>
>
> Reviewed-by: Christophe Leroy (CS GROUP) <[email-masked]>
>
>

Thanks for the review!

>>   #define __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
>>   extern int pmdp_set_access_flags(struct vm_area_struct *vma,
>> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
>> index dcd3a88caaf6..2d27cb1c2334 100644
>> --- a/arch/powerpc/include/asm/pgtable.h
>> +++ b/arch/powerpc/include/asm/pgtable.h
>> @@ -63,6 +63,18 @@ static inline pgprot_t pte_pgprot(pte_t pte)
>>   	return __pgprot(pte_flags);
>>   }
>> 
>> +#define pmd_pgprot pmd_pgprot
>> +static inline pgprot_t pmd_pgprot(pmd_t pmd)
>> +{
>> +	return pte_pgprot(pmd_pte(pmd));
>> +}
>> +
>> +#define pud_pgprot pud_pgprot
>> +static inline pgprot_t pud_pgprot(pud_t pud)
>> +{
>> +	return pte_pgprot(pud_pte(pud));
>> +}
>> +

In v2 - I will add above under #ifdef CONFIG_PPC_BOOK3S_64 
to avoid build issues with 32-bit PPC.

-ritesh