KVM: PPC: Book3S PR: Rework kvmppc_mmu_book3s_64_xlate()

This reworks kvmppc_mmu_book3s_64_xlate() to make it check the large
page bit in the hashed page table entries (HPTEs) it looks at, and
to simplify and streamline the code.  The checking of the first dword
of each HPTE is now done with a single mask and compare operation,
and all the code dealing with the matching HPTE, if we find one,
is consolidated in one place in the main line of the function flow.
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

arch/powerpc/kvm/book3s_64_mmu.c

@@ -182,10 +182,13 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
 	hva_t ptegp;
 	u64 pteg[16];
 	u64 avpn = 0;
+	u64 v, r;
+	u64 v_val, v_mask;
+	u64 eaddr_mask;
 	int i;
-	u8 key = 0;
+	u8 pp, key = 0;
 	bool found = false;
-	int second = 0;
+	bool second = false;
 	ulong mp_ea = vcpu->arch.magic_page_ea;
 
 	/* Magic page override */
@@ -208,8 +211,16 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
 		goto no_seg_found;
 
 	avpn = kvmppc_mmu_book3s_64_get_avpn(slbe, eaddr);
+	v_val = avpn & HPTE_V_AVPN;
+
 	if (slbe->tb)
-		avpn |= SLB_VSID_B_1T;
+		v_val |= SLB_VSID_B_1T;
+	if (slbe->large)
+		v_val |= HPTE_V_LARGE;
+	v_val |= HPTE_V_VALID;
+
+	v_mask = SLB_VSID_B | HPTE_V_AVPN | HPTE_V_LARGE | HPTE_V_VALID |
+		HPTE_V_SECONDARY;
 
 do_second:
 	ptegp = kvmppc_mmu_book3s_64_get_pteg(vcpu_book3s, slbe, eaddr, second);
@@ -227,91 +238,74 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
 		key = 4;
 
 	for (i=0; i<16; i+=2) {
-		u64 v = pteg[i];
-		u64 r = pteg[i+1];
-
-		/* Valid check */
-		if (!(v & HPTE_V_VALID))
-			continue;
-		/* Hash check */
-		if ((v & HPTE_V_SECONDARY) != second)
-			continue;
-
-		/* AVPN compare */
-		if (HPTE_V_COMPARE(avpn, v)) {
-			u8 pp = (r & HPTE_R_PP) | key;
-			int eaddr_mask = 0xFFF;
-
-			gpte->eaddr = eaddr;
-			gpte->vpage = kvmppc_mmu_book3s_64_ea_to_vp(vcpu,
-								    eaddr,
-								    data);
-			if (slbe->large)
-				eaddr_mask = 0xFFFFFF;
-			gpte->raddr = (r & HPTE_R_RPN) | (eaddr & eaddr_mask);
-			gpte->may_execute = ((r & HPTE_R_N) ? false : true);
-			gpte->may_read = false;
-			gpte->may_write = false;
-
-			switch (pp) {
-			case 0:
-			case 1:
-			case 2:
-			case 6:
-				gpte->may_write = true;
-				/* fall through */
-			case 3:
-			case 5:
-			case 7:
-				gpte->may_read = true;
-				break;
-			}
-
-			dprintk("KVM MMU: Translated 0x%lx [0x%llx] -> 0x%llx "
-				"-> 0x%lx\n",
-				eaddr, avpn, gpte->vpage, gpte->raddr);
+		/* Check all relevant fields of 1st dword */
+		if ((pteg[i] & v_mask) == v_val) {
 			found = true;
 			break;
 		}
 	}
 
-	/* Update PTE R and C bits, so the guest's swapper knows we used the
-	 * page */
-	if (found) {
-		u32 oldr = pteg[i+1];
+	if (!found) {
+		if (second)
+			goto no_page_found;
+		v_val |= HPTE_V_SECONDARY;
+		second = true;
+		goto do_second;
+	}
 
-		if (gpte->may_read) {
-			/* Set the accessed flag */
-			pteg[i+1] |= HPTE_R_R;
-		}
-		if (gpte->may_write) {
-			/* Set the dirty flag */
-			pteg[i+1] |= HPTE_R_C;
-		} else {
-			dprintk("KVM: Mapping read-only page!\n");
-		}
+	v = pteg[i];
+	r = pteg[i+1];
+	pp = (r & HPTE_R_PP) | key;
+	eaddr_mask = 0xFFF;
+
+	gpte->eaddr = eaddr;
+	gpte->vpage = kvmppc_mmu_book3s_64_ea_to_vp(vcpu, eaddr, data);
+	if (slbe->large)
+		eaddr_mask = 0xFFFFFF;
+	gpte->raddr = (r & HPTE_R_RPN & ~eaddr_mask) | (eaddr & eaddr_mask);
+	gpte->may_execute = ((r & HPTE_R_N) ? false : true);
+	gpte->may_read = false;
+	gpte->may_write = false;
+
+	switch (pp) {
+	case 0:
+	case 1:
+	case 2:
+	case 6:
+		gpte->may_write = true;
+		/* fall through */
+	case 3:
+	case 5:
+	case 7:
+		gpte->may_read = true;
+		break;
+	}
 
-		/* Write back into the PTEG */
-		if (pteg[i+1] != oldr)
-			copy_to_user((void __user *)ptegp, pteg, sizeof(pteg));
+	dprintk("KVM MMU: Translated 0x%lx [0x%llx] -> 0x%llx "
+		"-> 0x%lx\n",
+		eaddr, avpn, gpte->vpage, gpte->raddr);
 
-		if (!gpte->may_read)
-			return -EPERM;
-		return 0;
-	} else {
-		dprintk("KVM MMU: No PTE found (ea=0x%lx sdr1=0x%llx "
-			"ptegp=0x%lx)\n",
-			eaddr, to_book3s(vcpu)->sdr1, ptegp);
-		for (i = 0; i < 16; i += 2)
-			dprintk("   %02d: 0x%llx - 0x%llx (0x%llx)\n",
-				i, pteg[i], pteg[i+1], avpn);
-
-		if (!second) {
-			second = HPTE_V_SECONDARY;
-			goto do_second;
-		}
+	/* Update PTE R and C bits, so the guest's swapper knows we used the
+	 * page */
+	if (gpte->may_read) {
+		/* Set the accessed flag */
+		r |= HPTE_R_R;
+	}
+	if (data && gpte->may_write) {
+		/* Set the dirty flag -- XXX even if not writing */
+		r |= HPTE_R_C;
+	}
+
+	/* Write back into the PTEG */
+	if (pteg[i+1] != r) {
+		pteg[i+1] = r;
+		copy_to_user((void __user *)ptegp, pteg, sizeof(pteg));
 	}
 
+	if (!gpte->may_read)
+		return -EPERM;
+	return 0;
+
 no_page_found:
 	return -ENOENT;