Re: [PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

[Aneesh Kumar K.V]

Oliver O'Halloran  writes:

> From: "Aneesh Kumar K.V" 
>
> Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't
> currently support PUD faults so we haven't extended it to the PUD
> level.
>
> Cc: Aneesh Kumar K.V 
> Signed-off-by: Oliver O'Halloran 


Few changes we would need. We will now need to make sure a devmap
pmd entry is not confused with THP. ie,

we should compare against _PAGE_PTE and _PAGE_DEVMAP in
pmd_trans_huge(). hash already has one bit we use to differentiate
between hugetlb and THP. May be we can genarlize this and come up with a
way to differentiate THP, HUGETLB,pmd DEVMAP entries ?


also I don't see you handing get_user_pages_fast() ?


-aneesh

Re: [PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

[Aneesh Kumar K.V]

On Wednesday 12 April 2017 05:49 AM, Stephen Rothwell wrote:

Hi Oliver,

On Wed, 12 Apr 2017 03:42:27 +1000 Oliver O'Halloran  wrote:


From: "Aneesh Kumar K.V" 

Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't
currently support PUD faults so we haven't extended it to the PUD
level.

Cc: Aneesh Kumar K.V 
Signed-off-by: Oliver O'Halloran 


This needs Aneesh's Signed-off-by.



Signed-off-by: Aneesh Kumar K.V 

-aneesh

Re: [PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

[Stephen Rothwell]

Hi Oliver,

On Wed, 12 Apr 2017 03:42:27 +1000 Oliver O'Halloran  wrote:
>
> From: "Aneesh Kumar K.V" 
> 
> Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't
> currently support PUD faults so we haven't extended it to the PUD
> level.
> 
> Cc: Aneesh Kumar K.V 
> Signed-off-by: Oliver O'Halloran 

This needs Aneesh's Signed-off-by.

-- 
Cheers,
Stephen Rothwell

[PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

[Oliver O'Halloran]

From: "Aneesh Kumar K.V" 

Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't
currently support PUD faults so we haven't extended it to the PUD
level.

Cc: Aneesh Kumar K.V 
Signed-off-by: Oliver O'Halloran 
---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 37 +++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h 
b/arch/powerpc/include/asm/book3s/64/pgtable.h
index fb72ff6b98e6..b5fc6337649e 100644
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -78,6 +78,9 @@
 
 #define _PAGE_SOFT_DIRTY   _RPAGE_SW3 /* software: software dirty tracking 
*/
 #define _PAGE_SPECIAL  _RPAGE_SW2 /* software: special page */
+#define _PAGE_DEVMAP   _RPAGE_SW1
+#define __HAVE_ARCH_PTE_DEVMAP
+
 /*
  * Drivers request for cache inhibited pte mapping using _PAGE_NO_CACHE
  * Instead of fixing all of them, add an alternate define which
@@ -602,6 +605,16 @@ static inline pte_t pte_mkhuge(pte_t pte)
return pte;
 }
 
+static inline pte_t pte_mkdevmap(pte_t pte)
+{
+   return __pte(pte_val(pte) | _PAGE_SPECIAL|_PAGE_DEVMAP);
+}
+
+static inline int pte_devmap(pte_t pte)
+{
+   return !!(pte_raw(pte) & cpu_to_be64(_PAGE_DEVMAP));
+}
+
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
/* FIXME!! check whether this need to be a conditional */
@@ -966,6 +979,9 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
 #define pmd_mk_savedwrite(pmd) pte_pmd(pte_mk_savedwrite(pmd_pte(pmd)))
 #define pmd_clear_savedwrite(pmd)  
pte_pmd(pte_clear_savedwrite(pmd_pte(pmd)))
 
+#define pud_pfn(...) (0)
+#define pgd_pfn(...) (0)
+
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 #define pmd_soft_dirty(pmd)pte_soft_dirty(pmd_pte(pmd))
 #define pmd_mksoft_dirty(pmd)  pte_pmd(pte_mksoft_dirty(pmd_pte(pmd)))
@@ -1140,7 +1156,6 @@ static inline int pmd_move_must_withdraw(struct spinlock 
*new_pmd_ptl,
return true;
 }
 
-
 #define arch_needs_pgtable_deposit arch_needs_pgtable_deposit
 static inline bool arch_needs_pgtable_deposit(void)
 {
@@ -1149,6 +1164,26 @@ static inline bool arch_needs_pgtable_deposit(void)
return true;
 }
 
+static inline pmd_t pmd_mkdevmap(pmd_t pmd)
+{
+   return pte_pmd(pte_mkdevmap(pmd_pte(pmd)));
+}
+
+static inline int pmd_devmap(pmd_t pmd)
+{
+   return pte_devmap(pmd_pte(pmd));
+}
+
+static inline int pud_devmap(pud_t pud)
+{
+   return 0;
+}
+
+static inline int pgd_devmap(pgd_t pgd)
+{
+   return 0;
+}
+
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 #endif /* __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */
-- 
2.9.3