[PATCH v2 13/23] KVM: selftests: Pass the root GPA into virt_get_pte()

[Yosry Ahmed <yosry.ahmed@linux.dev>]

Instead of hardcoding the root check against vm->pgd, pass the root_gpa
into virt_get_pte(). There's a subtle change here, instead of checking
that the parent pointer has the address of vm->pgd, check if the value
pointed at by the parent pointer is the root_gpa. No change in behavior
expected, but this will be required for following changes that
generalize __virt_pg_map() to other MMUs.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
---
 tools/testing/selftests/kvm/lib/x86/processor.c | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index 8a838f208abe4..92a2b5aefd880 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -179,15 +179,15 @@ const struct pte_masks x86_pte_masks = {
 	.nx		=	BIT_ULL(63),
 };
 
-static void *virt_get_pte(struct kvm_vm *vm, uint64_t *parent_pte,
-			  uint64_t vaddr, int level,
+static void *virt_get_pte(struct kvm_vm *vm, vm_paddr_t root_gpa,
+			  uint64_t *parent_pte, uint64_t vaddr, int level,
 			  const struct pte_masks *masks)
 {
 	uint64_t pt_gpa = PTE_GET_PA(*parent_pte);
 	uint64_t *page_table = addr_gpa2hva(vm, pt_gpa);
 	int index = (vaddr >> PG_LEVEL_SHIFT(level)) & 0x1ffu;
 
-	TEST_ASSERT((*parent_pte & masks->present) || parent_pte == &vm->pgd,
+	TEST_ASSERT((*parent_pte == root_gpa) || (*parent_pte & masks->present),
 		    "Parent PTE (level %d) not PRESENT for gva: 0x%08lx",
 		    level + 1, vaddr);
 
@@ -195,6 +195,7 @@ static void *virt_get_pte(struct kvm_vm *vm, uint64_t *parent_pte,
 }
 
 static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
+				       vm_paddr_t root_gpa,
 				       uint64_t *parent_pte,
 				       uint64_t vaddr,
 				       uint64_t paddr,
@@ -202,7 +203,8 @@ static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
 				       int target_level,
 				       const struct pte_masks *masks)
 {
-	uint64_t *pte = virt_get_pte(vm, parent_pte, vaddr, current_level, masks);
+	uint64_t *pte = virt_get_pte(vm, root_gpa, parent_pte,
+				     vaddr, current_level, masks);
 
 	paddr = vm_untag_gpa(vm, paddr);
 
@@ -259,13 +261,14 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 	 * early if a hugepage was created.
 	 */
 	for (current_level = vm->pgtable_levels; current_level > PG_LEVEL_4K; current_level--) {
-		pte = virt_create_upper_pte(vm, pte, vaddr, paddr, current_level, level, masks);
+		pte = virt_create_upper_pte(vm, vm->pgd, pte, vaddr, paddr,
+					    current_level, level, masks);
 		if (*pte & masks->large)
 			return;
 	}
 
 	/* Fill in page table entry. */
-	pte = virt_get_pte(vm, pte, vaddr, PG_LEVEL_4K, masks);
+	pte = virt_get_pte(vm, vm->pgd, pte, vaddr, PG_LEVEL_4K, masks);
 	TEST_ASSERT(!(*pte & masks->present),
 		    "PTE already present for 4k page at vaddr: 0x%lx", vaddr);
 	*pte = masks->present | masks->writeable | (paddr & PHYSICAL_PAGE_MASK);
@@ -348,7 +351,7 @@ static uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm,
 		"Canonical check failed.  The virtual address is invalid.");
 
 	for (current_level = vm->pgtable_levels; current_level >= PG_LEVEL_4K; current_level--) {
-		pte = virt_get_pte(vm, pte, vaddr, current_level, masks);
+		pte = virt_get_pte(vm, vm->pgd, pte, vaddr, current_level, masks);
 		if (vm_is_target_pte(pte, level, current_level, masks))
 			return pte;
 	}
-- 
2.51.0.869.ge66316f041-goog