KVM: selftests: Compute number of extra pages needed in mmu_stress_test

Create mmu_stress_tests's VM with the correct number of extra pages needed
to map all of memory in the guest.  The bug hasn't been noticed before as
the test currently runs only on x86, which maps guest memory with 1GiB
pages, i.e. doesn't need much memory in the guest for page tables.

Reviewed-by: James Houghton <[email protected]>
Reviewed-by: Andrew Jones <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>

Author: sean-jc

tools/testing/selftests/kvm/mmu_stress_test.c

@@ -209,7 +209,13 @@ int main(int argc, char *argv[])
 	vcpus = malloc(nr_vcpus * sizeof(*vcpus));
 	TEST_ASSERT(vcpus, "Failed to allocate vCPU array");
 
-	vm = vm_create_with_vcpus(nr_vcpus, guest_code, vcpus);
+	vm = __vm_create_with_vcpus(VM_SHAPE_DEFAULT, nr_vcpus,
+#ifdef __x86_64__
+				    max_mem / SZ_1G,
+#else
+				    max_mem / vm_guest_mode_params[VM_MODE_DEFAULT].page_size,
+#endif
+				    guest_code, vcpus);
 
 	max_gpa = vm->max_gfn << vm->page_shift;
 	TEST_ASSERT(max_gpa > (4 * slot_size), "MAXPHYADDR <4gb ");