KVM: selftests: arm64: Fix pte encode/decode for PA bits > 48

The high bits [51:48] of a physical address should appear at [15:12] in
a 64K pte, not at [51:48] as was previously being programmed. Fix this
with new helper functions that do the conversion correctly. This also
sets us up nicely for adding LPA2 encodings in future.

Fixes: 7a6629e ("kvm: selftests: add virt mem support for aarch64")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230308110948.1820163-3-ryan.roberts@arm.com

Author: ryanhrob

tools/testing/selftests/kvm/lib/aarch64/processor.c

@@ -58,10 +58,27 @@ static uint64_t pte_index(struct kvm_vm *vm, vm_vaddr_t gva)
 	return (gva >> vm->page_shift) & mask;
 }
 
-static uint64_t pte_addr(struct kvm_vm *vm, uint64_t entry)
+static uint64_t addr_pte(struct kvm_vm *vm, uint64_t pa, uint64_t attrs)
 {
-	uint64_t mask = ((1UL << (vm->va_bits - vm->page_shift)) - 1) << vm->page_shift;
-	return entry & mask;
+	uint64_t pte;
+
+	pte = pa & GENMASK(47, vm->page_shift);
+	if (vm->page_shift == 16)
+		pte |= FIELD_GET(GENMASK(51, 48), pa) << 12;
+	pte |= attrs;
+
+	return pte;
+}
+
+static uint64_t pte_addr(struct kvm_vm *vm, uint64_t pte)
+{
+	uint64_t pa;
+
+	pa = pte & GENMASK(47, vm->page_shift);
+	if (vm->page_shift == 16)
+		pa |= FIELD_GET(GENMASK(15, 12), pte) << 48;
+
+	return pa;
 }
 
 static uint64_t ptrs_per_pgd(struct kvm_vm *vm)
@@ -110,18 +127,18 @@ static void _virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 	ptep = addr_gpa2hva(vm, vm->pgd) + pgd_index(vm, vaddr) * 8;
 	if (!*ptep)
-		*ptep = vm_alloc_page_table(vm) | 3;
+		*ptep = addr_pte(vm, vm_alloc_page_table(vm), 3);
 
 	switch (vm->pgtable_levels) {
 	case 4:
 		ptep = addr_gpa2hva(vm, pte_addr(vm, *ptep)) + pud_index(vm, vaddr) * 8;
 		if (!*ptep)
-			*ptep = vm_alloc_page_table(vm) | 3;
+			*ptep = addr_pte(vm, vm_alloc_page_table(vm), 3);
 		/* fall through */
 	case 3:
 		ptep = addr_gpa2hva(vm, pte_addr(vm, *ptep)) + pmd_index(vm, vaddr) * 8;
 		if (!*ptep)
-			*ptep = vm_alloc_page_table(vm) | 3;
+			*ptep = addr_pte(vm, vm_alloc_page_table(vm), 3);
 		/* fall through */
 	case 2:
 		ptep = addr_gpa2hva(vm, pte_addr(vm, *ptep)) + pte_index(vm, vaddr) * 8;
@@ -130,8 +147,7 @@ static void _virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 		TEST_FAIL("Page table levels must be 2, 3, or 4");
 	}
 
-	*ptep = paddr | 3;
-	*ptep |= (attr_idx << 2) | (1 << 10) /* Access Flag */;
+	*ptep = addr_pte(vm, paddr, (attr_idx << 2) | (1 << 10) | 3);  /* AF */
 }
 
 void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)