KVM: selftests: Plumb "struct kvm_mmu" into x86's MMU APIs

In preparation for generalizing the x86 virt mapping APIs to work with
TDP (stage-2) page tables, plumb "struct kvm_mmu" into all of the helper
functions instead of operating on vm->mmu directly.

Opportunistically swap the order of the check in virt_get_pte() to first
assert that the parent is the PGD, and then check that the PTE is present,
as it makes more sense to check if the parent PTE is the PGD/root (i.e.
not a PTE) before checking that the PTE is PRESENT.

No functional change intended.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
[sean: rebase on common kvm_mmu structure, rewrite changelog]
Link: https://patch.msgid.link/20251230230150.4150236-8-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

tools/testing/selftests/kvm/include/x86/processor.h

@@ -1451,7 +1451,8 @@ enum pg_level {
 #define PG_SIZE_2M PG_LEVEL_SIZE(PG_LEVEL_2M)
 #define PG_SIZE_1G PG_LEVEL_SIZE(PG_LEVEL_1G)
 
-void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level);
+void __virt_pg_map(struct kvm_vm *vm, struct kvm_mmu *mmu, uint64_t vaddr,
+		   uint64_t paddr,  int level);
 void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 		    uint64_t nr_bytes, int level);
 

tools/testing/selftests/kvm/lib/x86/processor.c

@@ -156,40 +156,46 @@ bool kvm_is_tdp_enabled(void)
 		return get_kvm_amd_param_bool("npt");
 }
 
+static void virt_mmu_init(struct kvm_vm *vm, struct kvm_mmu *mmu)
+{
+	/* If needed, create the top-level page table. */
+	if (!mmu->pgd_created) {
+		mmu->pgd = vm_alloc_page_table(vm);
+		mmu->pgd_created = true;
+	}
+}
+
 void virt_arch_pgd_alloc(struct kvm_vm *vm)
 {
 	TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
 		    "Unknown or unsupported guest mode: 0x%x", vm->mode);
 
-	/* If needed, create the top-level page table. */
-	if (!vm->mmu.pgd_created) {
-		vm->mmu.pgd = vm_alloc_page_table(vm);
-		vm->mmu.pgd_created = true;
-	}
+	virt_mmu_init(vm, &vm->mmu);
 }
 
-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, struct kvm_mmu *mmu,
+			  uint64_t *parent_pte, uint64_t vaddr, int level)
 {
 	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 & PTE_PRESENT_MASK) || parent_pte == &vm->mmu.pgd,
+	TEST_ASSERT((*parent_pte == mmu->pgd) || (*parent_pte & PTE_PRESENT_MASK),
 		    "Parent PTE (level %d) not PRESENT for gva: 0x%08lx",
 		    level + 1, vaddr);
 
 	return &page_table[index];
 }
 
 static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
+				       struct kvm_mmu *mmu,
 				       uint64_t *parent_pte,
 				       uint64_t vaddr,
 				       uint64_t paddr,
 				       int current_level,
 				       int target_level)
 {
-	uint64_t *pte = virt_get_pte(vm, parent_pte, vaddr, current_level);
+	uint64_t *pte = virt_get_pte(vm, mmu, parent_pte, vaddr, current_level);
 
 	paddr = vm_untag_gpa(vm, paddr);
 
@@ -215,10 +221,11 @@ static uint64_t *virt_create_upper_pte(struct kvm_vm *vm,
 	return pte;
 }
 
-void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
+void __virt_pg_map(struct kvm_vm *vm, struct kvm_mmu *mmu, uint64_t vaddr,
+		   uint64_t paddr, int level)
 {
 	const uint64_t pg_size = PG_LEVEL_SIZE(level);
-	uint64_t *pte = &vm->mmu.pgd;
+	uint64_t *pte = &mmu->pgd;
 	int current_level;
 
 	TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
@@ -243,17 +250,17 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
 	 * Allocate upper level page tables, if not already present.  Return
 	 * early if a hugepage was created.
 	 */
-	for (current_level = vm->mmu.pgtable_levels;
+	for (current_level = mmu->pgtable_levels;
 	     current_level > PG_LEVEL_4K;
 	     current_level--) {
-		pte = virt_create_upper_pte(vm, pte, vaddr, paddr,
+		pte = virt_create_upper_pte(vm, mmu, pte, vaddr, paddr,
 					    current_level, level);
 		if (*pte & PTE_LARGE_MASK)
 			return;
 	}
 
 	/* Fill in page table entry. */
-	pte = virt_get_pte(vm, pte, vaddr, PG_LEVEL_4K);
+	pte = virt_get_pte(vm, mmu, pte, vaddr, PG_LEVEL_4K);
 	TEST_ASSERT(!(*pte & PTE_PRESENT_MASK),
 		    "PTE already present for 4k page at vaddr: 0x%lx", vaddr);
 	*pte = PTE_PRESENT_MASK | PTE_WRITABLE_MASK | (paddr & PHYSICAL_PAGE_MASK);
@@ -270,7 +277,7 @@ void __virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr, int level)
 
 void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
 {
-	__virt_pg_map(vm, vaddr, paddr, PG_LEVEL_4K);
+	__virt_pg_map(vm, &vm->mmu, vaddr, paddr, PG_LEVEL_4K);
 }
 
 void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
@@ -285,7 +292,7 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 		    nr_bytes, pg_size);
 
 	for (i = 0; i < nr_pages; i++) {
-		__virt_pg_map(vm, vaddr, paddr, level);
+		__virt_pg_map(vm, &vm->mmu, vaddr, paddr, level);
 		sparsebit_set_num(vm->vpages_mapped, vaddr >> vm->page_shift,
 				  nr_bytes / PAGE_SIZE);
 
@@ -294,7 +301,8 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 	}
 }
 
-static bool vm_is_target_pte(uint64_t *pte, int *level, int current_level)
+static bool vm_is_target_pte(struct kvm_mmu *mmu, uint64_t *pte,
+			     int *level, int current_level)
 {
 	if (*pte & PTE_LARGE_MASK) {
 		TEST_ASSERT(*level == PG_LEVEL_NONE ||
@@ -306,17 +314,19 @@ static bool vm_is_target_pte(uint64_t *pte, int *level, int current_level)
 	return *level == current_level;
 }
 
-static uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
+static uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm,
+					   struct kvm_mmu *mmu,
+					   uint64_t vaddr,
 					   int *level)
 {
-	int va_width = 12 + (vm->mmu.pgtable_levels) * 9;
-	uint64_t *pte = &vm->mmu.pgd;
+	int va_width = 12 + (mmu->pgtable_levels) * 9;
+	uint64_t *pte = &mmu->pgd;
 	int current_level;
 
 	TEST_ASSERT(!vm->arch.is_pt_protected,
 		    "Walking page tables of protected guests is impossible");
 
-	TEST_ASSERT(*level >= PG_LEVEL_NONE && *level <= vm->mmu.pgtable_levels,
+	TEST_ASSERT(*level >= PG_LEVEL_NONE && *level <= mmu->pgtable_levels,
 		    "Invalid PG_LEVEL_* '%d'", *level);
 
 	TEST_ASSERT(vm->mode == VM_MODE_PXXVYY_4K,
@@ -332,22 +342,22 @@ static uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr,
 		    (((int64_t)vaddr << (64 - va_width) >> (64 - va_width))),
 		    "Canonical check failed.  The virtual address is invalid.");
 
-	for (current_level = vm->mmu.pgtable_levels;
+	for (current_level = mmu->pgtable_levels;
 	     current_level > PG_LEVEL_4K;
 	     current_level--) {
-		pte = virt_get_pte(vm, pte, vaddr, current_level);
-		if (vm_is_target_pte(pte, level, current_level))
+		pte = virt_get_pte(vm, mmu, pte, vaddr, current_level);
+		if (vm_is_target_pte(mmu, pte, level, current_level))
 			return pte;
 	}
 
-	return virt_get_pte(vm, pte, vaddr, PG_LEVEL_4K);
+	return virt_get_pte(vm, mmu, pte, 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);
+	return __vm_get_page_table_entry(vm, &vm->mmu, vaddr, &level);
 }
 
 void virt_arch_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
@@ -497,7 +507,7 @@ static void kvm_seg_set_kernel_data_64bit(struct kvm_segment *segp)
 vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
 {
 	int level = PG_LEVEL_NONE;
-	uint64_t *pte = __vm_get_page_table_entry(vm, gva, &level);
+	uint64_t *pte = __vm_get_page_table_entry(vm, &vm->mmu, gva, &level);
 
 	TEST_ASSERT(*pte & PTE_PRESENT_MASK,
 		    "Leaf PTE not PRESENT for gva: 0x%08lx", gva);