[PATCH 4/4] kvm: powerpc: set cache coherency only for RAM pages

[Bharat Bhushan <r65777@freescale.com>]

If the page is RAM then map this as cacheable and coherent (set "M" bit)
otherwise this page is treated as I/O and map this as cache inhibited
and guarded (set  "I + G")

This helps setting proper MMU mapping for direct assigned device.

NOTE: There can be devices that require cacheable mapping, which is not yet supported.

Signed-off-by: Bharat Bhushan <bharat.bhushan@freescale.com>
---
 arch/powerpc/kvm/e500_mmu_host.c |   24 +++++++++++++++++++-----
 1 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 1c6a9d7..5cbdc8f 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -64,13 +64,27 @@ static inline u32 e500_shadow_mas3_attrib(u32 mas3, int usermode)
 	return mas3;
 }
 
-static inline u32 e500_shadow_mas2_attrib(u32 mas2, int usermode)
+static inline u32 e500_shadow_mas2_attrib(u32 mas2, pfn_t pfn)
 {
+	u32 mas2_attr;
+
+	mas2_attr = mas2 & MAS2_ATTRIB_MASK;
+
+	if (kvm_is_mmio_pfn(pfn)) {
+		/*
+		 * If page is not RAM then it is treated as I/O page.
+		 * Map it with cache inhibited and guarded (set "I" + "G").
+		 */
+		mas2_attr |= MAS2_I | MAS2_G;
+		return mas2_attr;
+	}
+
+	/* Map RAM pages as cacheable (Not setting "I" in MAS2) */
 #ifdef CONFIG_SMP
-	return (mas2 & MAS2_ATTRIB_MASK) | MAS2_M;
-#else
-	return mas2 & MAS2_ATTRIB_MASK;
+	/* Also map as coherent (set "M") in SMP */
+	mas2_attr |= MAS2_M;
 #endif
+	return mas2_attr;
 }
 
 /*
@@ -313,7 +327,7 @@ static void kvmppc_e500_setup_stlbe(
 	/* Force IPROT=0 for all guest mappings. */
 	stlbe->mas1 = MAS1_TSIZE(tsize) | get_tlb_sts(gtlbe) | MAS1_VALID;
 	stlbe->mas2 = (gvaddr & MAS2_EPN) |
-		      e500_shadow_mas2_attrib(gtlbe->mas2, pr);
+		      e500_shadow_mas2_attrib(gtlbe->mas2, pfn);
 	stlbe->mas7_3 = ((u64)pfn << PAGE_SHIFT) |
 			e500_shadow_mas3_attrib(gtlbe->mas7_3, pr);
 
-- 
1.7.0.4