powerpc/mm: Drop WIMG in favour of new constants

PowerISA 3.0 introduces two pte bits with the below meaning for radix:
  00 -> Normal Memory
  01 -> Strong Access Order (SAO)
  10 -> Non idempotent I/O (Cache inhibited and guarded)
  11 -> Tolerant I/O (Cache inhibited)

We drop the existing WIMG bits in the Linux page table in favour of the
above constants. We loose _PAGE_WRITETHRU with this conversion. We only
use writethru via pgprot_cached_wthru() which is used by
fbdev/controlfb.c which is Apple control display and also PPC32.

With respect to _PAGE_COHERENCE, we have been marking hpte always
coherent for some time now. htab_convert_pte_flags() always added
HPTE_R_M.

NOTE: KVM changes need closer review.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 31 insertions, 39 deletions

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index eb224792095f..eee951fd6a33 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -21,11 +21,9 @@
 #define _PAGE_RW		(_PAGE_READ | _PAGE_WRITE)
 #define _PAGE_RWX		(_PAGE_READ | _PAGE_WRITE | _PAGE_EXEC)
 #define _PAGE_PRIVILEGED	0x00008 /* kernel access only */
-#define _PAGE_GUARDED		0x00010 /* G: guarded (side-effect) page */
-/* M (memory coherence) is always set in the HPTE, so we don't need it here */
-#define _PAGE_COHERENT		0x0
-#define _PAGE_NO_CACHE		0x00020 /* I: cache inhibit */
-#define _PAGE_WRITETHRU		0x00040 /* W: cache write-through */
+#define _PAGE_SAO		0x00010 /* Strong access order */
+#define _PAGE_NON_IDEMPOTENT	0x00020 /* non idempotent memory */
+#define _PAGE_TOLERANT		0x00030 /* tolerant memory, cache inhibited */
 #define _PAGE_DIRTY		0x00080 /* C: page changed */
 #define _PAGE_ACCESSED		0x00100 /* R: page referenced */
 #define _PAGE_SPECIAL		0x00400 /* software: special page */
@@ -43,7 +41,12 @@
 #define _PAGE_HASHPTE		(1ul << 61)	/* PTE has associated HPTE */
 #define _PAGE_PTE		(1ul << 62)	/* distinguishes PTEs from pointers */
 #define _PAGE_PRESENT		(1ul << 63)	/* pte contains a translation */
-
+/*
+ * Drivers request for cache inhibited pte mapping using _PAGE_NO_CACHE
+ * Instead of fixing all of them, add an alternate define which
+ * maps CI pte mapping.
+ */
+#define _PAGE_NO_CACHE		_PAGE_TOLERANT
 /*
  * We need to differentiate between explicit huge page and THP huge
  * page, since THP huge page also need to track real subpage details
@@ -126,9 +129,6 @@
 #define _PAGE_KERNEL_RWX	(_PAGE_PRIVILEGED | _PAGE_DIRTY | \
 				 _PAGE_RW | _PAGE_EXEC)
 
-/* Strong Access Ordering */
-#define _PAGE_SAO		(_PAGE_WRITETHRU | _PAGE_NO_CACHE | _PAGE_COHERENT)
-
 /* No page size encoding in the linux PTE */
 #define _PAGE_PSIZE		0
 
@@ -147,10 +147,9 @@
 /*
  * Mask of bits returned by pte_pgprot()
  */
-#define PAGE_PROT_BITS	(_PAGE_GUARDED | _PAGE_COHERENT | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU | _PAGE_4K_PFN | \
-			 _PAGE_PRIVILEGED | _PAGE_ACCESSED |  _PAGE_READ |\
-			 _PAGE_WRITE |  _PAGE_DIRTY | _PAGE_EXEC | \
+#define PAGE_PROT_BITS  (_PAGE_SAO | _PAGE_NON_IDEMPOTENT | _PAGE_TOLERANT | \
+			 _PAGE_4K_PFN | _PAGE_PRIVILEGED | _PAGE_ACCESSED | \
+			 _PAGE_READ | _PAGE_WRITE |  _PAGE_DIRTY | _PAGE_EXEC | \
 			 _PAGE_SOFT_DIRTY)
 /*
  * We define 2 sets of base prot bits, one for basic pages (ie,
@@ -159,7 +158,7 @@
  * the processor might need it for DMA coherency.
  */
 #define _PAGE_BASE_NC	(_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_PSIZE)
-#define _PAGE_BASE	(_PAGE_BASE_NC | _PAGE_COHERENT)
+#define _PAGE_BASE	(_PAGE_BASE_NC)
 
 /* Permission masks used to generate the __P and __S table,
  *
@@ -200,9 +199,9 @@
 /* Permission masks used for kernel mappings */
 #define PAGE_KERNEL	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RW)
 #define PAGE_KERNEL_NC	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
-				 _PAGE_NO_CACHE)
+				 _PAGE_TOLERANT)
 #define PAGE_KERNEL_NCG	__pgprot(_PAGE_BASE_NC | _PAGE_KERNEL_RW | \
-				 _PAGE_NO_CACHE | _PAGE_GUARDED)
+				 _PAGE_NON_IDEMPOTENT)
 #define PAGE_KERNEL_X	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RWX)
 #define PAGE_KERNEL_RO	__pgprot(_PAGE_BASE | _PAGE_KERNEL_RO)
 #define PAGE_KERNEL_ROX	__pgprot(_PAGE_BASE | _PAGE_KERNEL_ROX)
@@ -509,45 +508,26 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr,
 	*ptep = pte;
 }
 
-/*
- * Macro to mark a page protection value as "uncacheable".
- */
-
-#define _PAGE_CACHE_CTL	(_PAGE_COHERENT | _PAGE_GUARDED | _PAGE_NO_CACHE | \
-			 _PAGE_WRITETHRU)
+#define _PAGE_CACHE_CTL	(_PAGE_NON_IDEMPOTENT | _PAGE_TOLERANT)
 
 #define pgprot_noncached pgprot_noncached
 static inline pgprot_t pgprot_noncached(pgprot_t prot)
 {
 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
-			_PAGE_NO_CACHE | _PAGE_GUARDED);
+			_PAGE_NON_IDEMPOTENT);
 }
 
 #define pgprot_noncached_wc pgprot_noncached_wc
 static inline pgprot_t pgprot_noncached_wc(pgprot_t prot)
 {
 	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
-			_PAGE_NO_CACHE);
+			_PAGE_TOLERANT);
 }
 
 #define pgprot_cached pgprot_cached
 static inline pgprot_t pgprot_cached(pgprot_t prot)
 {
-	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
-			_PAGE_COHERENT);
-}
-
-#define pgprot_cached_wthru pgprot_cached_wthru
-static inline pgprot_t pgprot_cached_wthru(pgprot_t prot)
-{
-	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL) |
-			_PAGE_COHERENT | _PAGE_WRITETHRU);
-}
-
-#define pgprot_cached_noncoherent pgprot_cached_noncoherent
-static inline pgprot_t pgprot_cached_noncoherent(pgprot_t prot)
-{
-	return __pgprot(pgprot_val(prot) & ~_PAGE_CACHE_CTL);
+	return __pgprot((pgprot_val(prot) & ~_PAGE_CACHE_CTL));
 }
 
 #define pgprot_writecombine pgprot_writecombine
@@ -555,6 +535,18 @@ static inline pgprot_t pgprot_writecombine(pgprot_t prot)
 {
 	return pgprot_noncached_wc(prot);
 }
+/*
+ * check a pte mapping have cache inhibited property
+ */
+static inline bool pte_ci(pte_t pte)
+{
+	unsigned long pte_v = pte_val(pte);
+
+	if (((pte_v & _PAGE_CACHE_CTL) == _PAGE_TOLERANT) ||
+	    ((pte_v & _PAGE_CACHE_CTL) == _PAGE_NON_IDEMPOTENT))
+		return true;
+	return false;
+}
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 extern void hpte_do_hugepage_flush(struct mm_struct *mm, unsigned long addr,