KVM: selftests: Make sure vm->vpages_mapped is always up-to-date

Call paths leading to __virt_pg_map() are currently:
(a) virt_pg_map() -> virt_arch_pg_map() -> __virt_pg_map()
(b) virt_map_level() -> __virt_pg_map()

For (a), calls to virt_pg_map() from kvm_util.c make sure they update
vm->vpages_mapped, but other callers do not. Move the sparsebit_set()
call into virt_pg_map() to make sure all callers are captured.

For (b), call sparsebit_set_num() from virt_map_level().

It's tempting to have a single the call inside __virt_pg_map(), however:
- The call path in (a) is not x86-specific, while (b) is. Moving the
  call into __virt_pg_map() would require doing something similar for
  other archs implementing virt_pg_map().

- Future changes will reusue __virt_pg_map() for nested PTEs, which should
  not update vm->vpages_mapped, i.e. a triple underscore version that does
  not update vm->vpages_mapped would need to be provided.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://patch.msgid.link/20251021074736.1324328-12-yosry.ahmed@linux.dev
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: yosrym93

tools/testing/selftests/kvm/include/kvm_util.h

@@ -1230,6 +1230,7 @@ void virt_arch_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr);
 static inline void virt_pg_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr)
 {
 	virt_arch_pg_map(vm, vaddr, paddr);
+	sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
 }
 
 

tools/testing/selftests/kvm/lib/kvm_util.c

@@ -1458,8 +1458,6 @@ static vm_vaddr_t ____vm_vaddr_alloc(struct kvm_vm *vm, size_t sz,
 		pages--, vaddr += vm->page_size, paddr += vm->page_size) {
 
 		virt_pg_map(vm, vaddr, paddr);
-
-		sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
 	}
 
 	return vaddr_start;
@@ -1573,7 +1571,6 @@ void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 	while (npages--) {
 		virt_pg_map(vm, vaddr, paddr);
-		sparsebit_set(vm->vpages_mapped, vaddr >> vm->page_shift);
 
 		vaddr += page_size;
 		paddr += page_size;

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

@@ -286,6 +286,8 @@ void virt_map_level(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
 
 	for (i = 0; i < nr_pages; i++) {
 		__virt_pg_map(vm, vaddr, paddr, level);
+		sparsebit_set_num(vm->vpages_mapped, vaddr >> vm->page_shift,
+				  nr_bytes / PAGE_SIZE);
 
 		vaddr += pg_size;
 		paddr += pg_size;