KVM: selftests: Play nice with huge pages when getting PTEs/GPAs

Play nice with huge pages when getting PTEs and translating GVAs to GPAs,
there's no reason to disallow using huge pages in selftests.  Use
PG_LEVEL_NONE to indicate that the caller doesn't care about the mapping
level and just wants to get the pte+level.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20221006004512.666529-8-seanjc@google.com

tools/testing/selftests/kvm/include/x86_64/processor.h

@@ -172,11 +172,16 @@ struct kvm_x86_cpu_feature {
 #define PTE_GLOBAL_MASK         BIT_ULL(8)
 #define PTE_NX_MASK             BIT_ULL(63)
 
+#define PHYSICAL_PAGE_MASK      GENMASK_ULL(51, 12)
+
 #define PAGE_SHIFT		12
 #define PAGE_SIZE		(1ULL << PAGE_SHIFT)
-#define PAGE_MASK		(~(PAGE_SIZE-1))
+#define PAGE_MASK		(~(PAGE_SIZE-1) & PHYSICAL_PAGE_MASK)
+
+#define HUGEPAGE_SHIFT(x)	(PAGE_SHIFT + (((x) - 1) * 9))
+#define HUGEPAGE_SIZE(x)	(1UL << HUGEPAGE_SHIFT(x))
+#define HUGEPAGE_MASK(x)	(~(HUGEPAGE_SIZE(x) - 1) & PHYSICAL_PAGE_MASK)
 
-#define PHYSICAL_PAGE_MASK      GENMASK_ULL(51, 12)
 #define PTE_GET_PA(pte)		((pte) & PHYSICAL_PAGE_MASK)
 #define PTE_GET_PFN(pte)        (PTE_GET_PA(pte) >> PAGE_SHIFT)
 
@@ -828,6 +833,8 @@ static inline uint8_t wrmsr_safe(uint32_t msr, uint64_t val)
 
 bool kvm_is_tdp_enabled(void);
 
+uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
+				    int *level);
 uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr);
 
 uint64_t kvm_hypercall(uint64_t nr, uint64_t a0, uint64_t a1, uint64_t a2,

tools/testing/selftests/kvm/lib/x86_64/processor.c

@@ -245,10 +245,26 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 	}
 }
 
-uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr)
+static bool vm_is_target_pte(uint64_t *pte, int *level, int current_level)
+{
+	if (*pte & PTE_LARGE_MASK) {
+		TEST_ASSERT(*level == PG_LEVEL_NONE ||
+			    *level == current_level,
+			    "Unexpected hugepage at level %d\n", current_level);
+		*level = current_level;
+	}
+
+	return *level == current_level;
+}
+
+uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
+				    int *level)
 {
 	uint64_t *pml4e, *pdpe, *pde;
 
+	TEST_ASSERT(*level >= PG_LEVEL_NONE && *level < PG_LEVEL_NUM,
+		    "Invalid PG_LEVEL_* '%d'", *level);
+
 	TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
 		"unknown or unsupported guest mode, mode: 0x%x", vm->mode);
 	TEST_ASSERT(sparsebit_is_set(vm->vpages_valid,
@@ -263,18 +279,27 @@ uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr)
 		"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);
-	TEST_ASSERT(!(*pdpe & PTE_LARGE_MASK),
-		"Expected pdpe to map a pde not a 1-GByte page.");
+	if (vm_is_target_pte(pdpe, level, PG_LEVEL_1G))
+		return pdpe;
 
 	pde = virt_get_pte(vm, pdpe, vaddr, PG_LEVEL_2M);
-	TEST_ASSERT(!(*pde & PTE_LARGE_MASK),
-		"Expected pde to map a pte not a 2-MByte page.");
+	if (vm_is_target_pte(pde, level, PG_LEVEL_2M))
+		return pde;
 
 	return virt_get_pte(vm, pde, vaddr, PG_LEVEL_4K);
 }
 
+uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr)
+{
+	int level = PG_LEVEL_4K;
+
+	return __vm_get_page_table_entry(vm, vaddr, &level);
+}
+
 void virt_arch_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
 {
 	uint64_t *pml4e, *pml4e_start;
@@ -458,11 +483,17 @@ static void kvm_seg_set_kernel_data_64bit(struct kvm_vm *vm, uint16_t selector,
 
 vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
 {
-	uint64_t *pte = vm_get_page_table_entry(vm, gva);
+	int level = PG_LEVEL_NONE;
+	uint64_t *pte = __vm_get_page_table_entry(vm, gva, &level);
 
 	TEST_ASSERT(*pte & PTE_PRESENT_MASK,
 		    "Leaf PTE not PRESENT for gva: 0x%08lx", gva);
-	return PTE_GET_PA(*pte) | (gva & ~PAGE_MASK);
+
+	/*
+	 * No need for a hugepage mask on the PTE, x86-64 requires the "unused"
+	 * address bits to be zero.
+	 */
+	return PTE_GET_PA(*pte) | (gva & ~HUGEPAGE_MASK(level));
 }
 
 static void kvm_setup_gdt(struct kvm_vm *vm, struct kvm_dtable *dt)