selftests: kvm: fix potential issue with ELF loading

vm_vaddr_alloc() sets up GVA to GPA mapping page by page; therefore, GPAs
may not be continuous if same memslot is used for data and page table allocation.

kvm_vm_elf_load() however expects a continuous range of HVAs (and thus GPAs)
because it does not try to read file data page by page.  Fix this mismatch
by allocating memory in one step.
Reported-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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

@@ -1099,6 +1099,9 @@ vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
 	uint64_t pages = (sz >> vm->page_shift) + ((sz % vm->page_size) != 0);
 
 	virt_pgd_alloc(vm, pgd_memslot);
+	vm_paddr_t paddr = vm_phy_pages_alloc(vm, pages,
+					      KVM_UTIL_MIN_PFN * vm->page_size,
+					      data_memslot);
 
 	/*
 	 * Find an unused range of virtual page addresses of at least
@@ -1108,11 +1111,7 @@ vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
 
 	/* Map the virtual pages. */
 	for (vm_vaddr_t vaddr = vaddr_start; pages > 0;
-		pages--, vaddr += vm->page_size) {
-		vm_paddr_t paddr;
-
-		paddr = vm_phy_page_alloc(vm,
-				KVM_UTIL_MIN_PFN * vm->page_size, data_memslot);
+		pages--, vaddr += vm->page_size, paddr += vm->page_size) {
 
 		virt_pg_map(vm, vaddr, paddr, pgd_memslot);