[PATCH] KVM: PPC: e6500: support powers of 2K TLB1 sizes

[Laurentiu Tudor <b10716@xxxxxxxxxxxxx>]

Book-E MMUv2 present in e6500 cores supports
powers of 2K page sizes while older MMUv1 cores
support only powers of 4K page sizes, or in other
words the LSB of TSIZE on MMUv1 is always 0.
Thus, on MMUv2 we must not strip the LSB.

Signed-off-by: Mihai Caraman <mihai.caraman@xxxxxxxxxxxxx>
    [Laurentiu.Tudor@xxxxxxxxxxxxx: addressed review
         feedback, split in distinct patch]
Signed-off-by: Laurentiu Tudor <Laurentiu.Tudor@xxxxxxxxxxxxx>
---
 arch/powerpc/kvm/e500_mmu_host.c | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c
index 4d33e19..12d5c67 100644
--- a/arch/powerpc/kvm/e500_mmu_host.c
+++ b/arch/powerpc/kvm/e500_mmu_host.c
@@ -371,6 +371,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 
 			unsigned long start, end;
 			unsigned long slot_start, slot_end;
+			int tsize_inc;
 
 			pfnmap = 1;
 
@@ -392,10 +393,20 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 				MAS1_TSIZE_SHIFT;
 
 			/*
-			 * e500 doesn't implement the lowest tsize bit,
-			 * or 1K pages.
+			 * MMUv1 doesn't implement the lowest tsize bit,
+			 * or translations smaller than 4K.
 			 */
-			tsize = max(BOOK3E_PAGESZ_4K, tsize & ~1);
+			if (!has_feature(&vcpu_e500->vcpu, VCPU_FTR_MMU_V2))
+				tsize &= ~1;
+			tsize = max(BOOK3E_PAGESZ_4K, tsize);
+
+			/*
+			 * Calculate TSIZE increment. MMUv2 supports
+			 * power of 2K translations while MMUv1 is limited
+			 * to power of 4K sizes.
+			 */
+			tsize_inc = has_feature(&vcpu_e500->vcpu,
+						VCPU_FTR_MMU_V2) ? 1 : 2;
 
 			/*
 			 * Now find the largest tsize (up to what the guest
@@ -404,7 +415,8 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 			 * aligned.
 			 */
 
-			for (; tsize > BOOK3E_PAGESZ_4K; tsize -= 2) {
+			for (; tsize > BOOK3E_PAGESZ_4K;
+			     tsize -= tsize_inc) {
 				unsigned long gfn_start, gfn_end;
 				tsize_pages = 1 << (tsize - 2);
 
@@ -437,10 +449,12 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
 			tsize = min(__ilog2(psize) - 10, tsize);
 
 			/*
-			 * e500 doesn't implement the lowest tsize bit,
-			 * or 1K pages.
+			 * MMUv1 doesn't implement the lowest tsize bit,
+			 * or translations smaller than 4K.
 			 */
-			tsize = max(BOOK3E_PAGESZ_4K, tsize & ~1);
+			if (!has_feature(&vcpu_e500->vcpu, VCPU_FTR_MMU_V2))
+				tsize &= ~1;
+			tsize = max(BOOK3E_PAGESZ_4K, tsize);
 		}
 
 		up_read(&current->mm->mmap_sem);
-- 
1.8.3.1
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