[PATCH 2/4] KVM: selftests: Use a loop to walk guest page tables

[Jim Mattson]

Walk the guest page tables via a loop when searching for a PTE,
instead of using unique variables for each level of the page tables.

This simplifies the code and makes it easier to support 5-level paging
in the future.

Signed-off-by: Jim Mattson <jmatt...@google.com>
---
 .../testing/selftests/kvm/lib/x86/processor.c | 21 +++++++------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c 
b/tools/testing/selftests/kvm/lib/x86/processor.c
index 0238e674709d..433365c8196d 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -270,7 +270,8 @@ static bool vm_is_target_pte(uint64_t *pte, int *level, int 
current_level)
 uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
                                    int *level)
 {
-       uint64_t *pml4e, *pdpe, *pde;
+       uint64_t *pte = &vm->pgd;
+       int current_level;
 
        TEST_ASSERT(!vm->arch.is_pt_protected,
                    "Walking page tables of protected guests is impossible");
@@ -291,19 +292,13 @@ uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, 
uint64_t vaddr,
        TEST_ASSERT(vaddr == (((int64_t)vaddr << 16) >> 16),
                "Canonical check failed.  The virtual address is invalid.");
 
-       pml4e = virt_get_pte(vm, &vm->pgd, vaddr, PG_LEVEL_512G);
-       if (vm_is_target_pte(pml4e, level, PG_LEVEL_512G))
-               return pml4e;
-
-       pdpe = virt_get_pte(vm, pml4e, vaddr, PG_LEVEL_1G);
-       if (vm_is_target_pte(pdpe, level, PG_LEVEL_1G))
-               return pdpe;
-
-       pde = virt_get_pte(vm, pdpe, vaddr, PG_LEVEL_2M);
-       if (vm_is_target_pte(pde, level, PG_LEVEL_2M))
-               return pde;
+       for (current_level = vm->pgtable_levels; current_level > 0; 
current_level--) {
+               pte = virt_get_pte(vm, pte, vaddr, current_level);
+               if (vm_is_target_pte(pte, level, current_level))
+                       return pte;
+       }
 
-       return virt_get_pte(vm, pde, vaddr, PG_LEVEL_4K);
+       return pte;
 }
 
 uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr)
-- 
2.51.0.470.ga7dc726c21-goog