[PATCH V2] KVM: PPC: BOOK3S: HV: Use base page size when comparing against slb value

[PATCH V2] KVM: PPC: BOOK3S: HV: Use base page size when comparing against slb value

[Aneesh Kumar K.V]

With guests supporting Multiple page size per segment (MPSS),
hpte_page_size returns the actual page size used. Add a new function to
return base page size and use that to compare against the the page size
calculated from SLB. Without this patch a hpte lookup can fail since
we are comparing wrong page size in kvmppc_hv_find_lock_hpte.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
Changes from V1:
* Remove obsolete comment from the code
* Update commit message

 arch/powerpc/include/asm/kvm_book3s_64.h | 19 +++++++++++++++++--
 arch/powerpc/kvm/book3s_64_mmu_hv.c      |  2 +-
 arch/powerpc/kvm/book3s_hv_rm_mmu.c      |  7 ++-----
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index 34422be566ce..3d0f3fb9c6b6 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -202,8 +202,10 @@ static inline unsigned long compute_tlbie_rb(unsigned long v, unsigned long r,
 	return rb;
 }
 
-static inline unsigned long hpte_page_size(unsigned long h, unsigned long l)
+static inline unsigned long __hpte_page_size(unsigned long h, unsigned long l,
+					     bool is_base_size)
 {
+
 	int size, a_psize;
 	/* Look at the 8 bit LP value */
 	unsigned int lp = (l >> LP_SHIFT) & ((1 << LP_BITS) - 1);
@@ -218,14 +220,27 @@ static inline unsigned long hpte_page_size(unsigned long h, unsigned long l)
 				continue;
 
 			a_psize = __hpte_actual_psize(lp, size);
-			if (a_psize != -1)
+			if (a_psize != -1) {
+				if (is_base_size)
+					return 1ul << mmu_psize_defs[size].shift;
 				return 1ul << mmu_psize_defs[a_psize].shift;
+			}
 		}
 
 	}
 	return 0;
 }
 
+static inline unsigned long hpte_page_size(unsigned long h, unsigned long l)
+{
+	return __hpte_page_size(h, l, 0);
+}
+
+static inline unsigned long hpte_base_page_size(unsigned long h, unsigned long l)
+{
+	return __hpte_page_size(h, l, 1);
+}
+
 static inline unsigned long hpte_rpn(unsigned long ptel, unsigned long psize)
 {
 	return ((ptel & HPTE_R_RPN) & ~(psize - 1)) >> PAGE_SHIFT;
diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index f53cf2eae36a..7ff45ed27c65 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -1567,7 +1567,7 @@ static ssize_t kvm_htab_write(struct file *file, const char __user *buf,
 				goto out;
 			}
 			if (!rma_setup && is_vrma_hpte(v)) {
-				unsigned long psize = hpte_page_size(v, r);
+				unsigned long psize = hpte_base_page_size(v, r);
 				unsigned long senc = slb_pgsize_encoding(psize);
 				unsigned long lpcr;
 
diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
index 87624ab5ba82..d86356bfc970 100644
--- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
+++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
@@ -833,13 +833,10 @@ long kvmppc_hv_find_lock_hpte(struct kvm *kvm, gva_t eaddr, unsigned long slb_v,
 			r = be64_to_cpu(hpte[i+1]);
 
 			/*
-			 * Check the HPTE again, including large page size
-			 * Since we don't currently allow any MPSS (mixed
-			 * page-size segment) page sizes, it is sufficient
-			 * to check against the actual page size.
+			 * Check the HPTE again, including base page size
 			 */
 			if ((v & valid) && (v & mask) == val &&
-			    hpte_page_size(v, r) == (1ul << pshift))
+			    hpte_base_page_size(v, r) == (1ul << pshift))
 				/* Return with the HPTE still locked */
 				return (hash << 3) + (i >> 1);
 
-- 
1.9.1

Re: [PATCH V2] KVM: PPC: BOOK3S: HV: Use base page size when comparing against slb value

[Alexander Graf]

On 15.06.14 20:47, Aneesh Kumar K.V wrote:
> With guests supporting Multiple page size per segment (MPSS),
> hpte_page_size returns the actual page size used. Add a new function to
> return base page size and use that to compare against the the page size
> calculated from SLB. Without this patch a hpte lookup can fail since
> we are comparing wrong page size in kvmppc_hv_find_lock_hpte.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Thanks, applied to for-3.16.


Alex