powerpc/mm: Add MMU features for TLB reservation & Paired MAS registers

Support for TLB reservation (or TLB Write Conditional) and Paired MAS
registers are optional for a processor implementation so we handle
them via MMU feature sections.

We currently only used paired MAS registers to access the full RPN + perm
bits that are kept in MAS7||MAS3.  We assume that if an implementation has
hardware page table at this time it also implements in TLB reservations.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

2 files changed, 46 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/mmu.h b/arch/powerpc/include/asm/mmu.h
index 2fcfefc60894..7ffbb65ff7a9 100644
--- a/arch/powerpc/include/asm/mmu.h
+++ b/arch/powerpc/include/asm/mmu.h
@@ -58,6 +58,15 @@
  */
 #define MMU_FTR_TLBIE_206               ASM_CONST(0x00400000)
 
+/* Enable use of TLB reservation.  Processor should support tlbsrx.
+ * instruction and MAS0[WQ].
+ */
+#define MMU_FTR_USE_TLBRSRV             ASM_CONST(0x00800000)
+
+/* Use paired MAS registers (MAS7||MAS3, etc.)
+ */
+#define MMU_FTR_USE_PAIRED_MAS          ASM_CONST(0x01000000)
+
 #ifndef __ASSEMBLY__
 #include <asm/cputable.h>
 
diff --git a/arch/powerpc/mm/tlb_low_64e.S b/arch/powerpc/mm/tlb_low_64e.S
index cd92f62f9cf5..ef1cccf71173 100644
--- a/arch/powerpc/mm/tlb_low_64e.S
+++ b/arch/powerpc/mm/tlb_low_64e.S
@@ -189,12 +189,16 @@ normal_tlb_miss:
         clrrdi  r14,r14,3
         or      r10,r15,r14
 
+BEGIN_MMU_FTR_SECTION
         /* Set the TLB reservation and seach for existing entry. Then load
          * the entry.
          */
         PPC_TLBSRX_DOT(0,r16)
         ld      r14,0(r10)
         beq     normal_tlb_miss_done
+MMU_FTR_SECTION_ELSE
+        ld      r14,0(r10)
+ALT_MMU_FTR_SECTION_END_IFSET(MMU_FTR_USE_TLBRSRV)
 
 finish_normal_tlb_miss:
         /* Check if required permissions are met */
@@ -241,7 +245,14 @@ finish_normal_tlb_miss:
         bne     1f
         li      r11,MAS3_SW|MAS3_UW
         andc    r15,r15,r11
-1:      mtspr   SPRN_MAS7_MAS3,r15
+1:
+BEGIN_MMU_FTR_SECTION
+        srdi    r16,r15,32
+        mtspr   SPRN_MAS3,r15
+        mtspr   SPRN_MAS7,r16
+MMU_FTR_SECTION_ELSE
+        mtspr   SPRN_MAS7_MAS3,r15
+ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)
 
         tlbwe
 
@@ -311,11 +322,13 @@ virt_page_table_tlb_miss:
         rlwinm  r10,r10,0,16,1                  /* Clear TID */
         mtspr   SPRN_MAS1,r10
 1:
+BEGIN_MMU_FTR_SECTION
         /* Search if we already have a TLB entry for that virtual address, and
          * if we do, bail out.
          */
         PPC_TLBSRX_DOT(0,r16)
         beq     virt_page_table_tlb_miss_done
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_TLBRSRV)
 
         /* Now, we need to walk the page tables. First check if we are in
          * range.
@@ -367,10 +380,18 @@ virt_page_table_tlb_miss:
          */
         clrldi  r11,r15,4               /* remove region ID from RPN */
         ori     r10,r11,1               /* Or-in SR */
+
+BEGIN_MMU_FTR_SECTION
+        srdi    r16,r10,32
+        mtspr   SPRN_MAS3,r10
+        mtspr   SPRN_MAS7,r16
+MMU_FTR_SECTION_ELSE
         mtspr   SPRN_MAS7_MAS3,r10
+ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)
 
         tlbwe
 
+BEGIN_MMU_FTR_SECTION
 virt_page_table_tlb_miss_done:
 
         /* We have overriden MAS2:EPN but currently our primary TLB miss
@@ -394,6 +415,7 @@ virt_page_table_tlb_miss_done:
         addi    r10,r11,-4
         std     r10,PACA_EXTLB+EX_TLB_SIZE+EX_TLB_SRR0(r13)
 1:
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_USE_TLBRSRV)
         /* Return to caller, normal case */
         TLB_MISS_STATS_X(MMSTAT_TLB_MISS_PT_OK);
         TLB_MISS_EPILOG_SUCCESS
@@ -618,7 +640,14 @@ htw_tlb_miss:
 #else
         ori     r10,r15,(BOOK3E_PAGESZ_4K << MAS3_SPSIZE_SHIFT)
 #endif
+
+BEGIN_MMU_FTR_SECTION
+        srdi    r16,r10,32
+        mtspr   SPRN_MAS3,r10
+        mtspr   SPRN_MAS7,r16
+MMU_FTR_SECTION_ELSE
         mtspr   SPRN_MAS7_MAS3,r10
+ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)
 
         tlbwe
 
@@ -700,7 +729,14 @@ tlb_load_linear:
         clrrdi  r10,r16,30              /* 1G page index */
         clrldi  r10,r10,4               /* clear region bits */
         ori     r10,r10,MAS3_SR|MAS3_SW|MAS3_SX
+
+BEGIN_MMU_FTR_SECTION
+        srdi    r16,r10,32
+        mtspr   SPRN_MAS3,r10
+        mtspr   SPRN_MAS7,r16
+MMU_FTR_SECTION_ELSE
         mtspr   SPRN_MAS7_MAS3,r10
+ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_USE_PAIRED_MAS)
 
         tlbwe