KVM: selftests: Fix mapping length truncation in m{,un}map()

max_mem_slots is now declared as uint32_t. The result of (0x200000 * 32767)
is unexpectedly truncated to be 0xffe00000, whilst we actually need to
allocate about, 63GB. Cast max_mem_slots to size_t in both mmap() and
munmap() to fix the length truncation.

We'll otherwise see the failure on arm64 thanks to the access_ok() checking
in __kvm_set_memory_region(), as the unmapped VA happen to go beyond the
task's allowed address space.

# ./set_memory_region_test
Allowed number of memory slots: 32767
Adding slots 0..32766, each memory region with 2048K size
==== Test Assertion Failure ====
set_memory_region_test.c:391: ret == 0
pid=94861 tid=94861 errno=22 - Invalid argument
1 0x00000000004015a7: test_add_max_memory_regions at set_memory_region_test.c:389
2 (inlined by) main at set_memory_region_test.c:426
3 0x0000ffffb8e67bdf: ?? ??:0
4 0x00000000004016db: _start at :?
KVM_SET_USER_MEMORY_REGION IOCTL failed,
rc: -1 errno: 22 slot: 2615

Fixes: 3bf0fcd75434 ("KVM: selftests: Speed up set_memory_region_test")
Signed-off-by: Zenghui Yu <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Paolo Bonzini <[e-mail]>

tools/testing/selftests/kvm/set_memory_region_test.c

···
 	pr_info("Adding slots 0..%i, each memory region with %dK size\n",
 		(max_mem_slots - 1), MEM_REGION_SIZE >> 10);
 
-	mem = mmap(NULL, MEM_REGION_SIZE * max_mem_slots + alignment,
+	mem = mmap(NULL, (size_t)max_mem_slots * MEM_REGION_SIZE + alignment,
 		   PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 	TEST_ASSERT(mem != MAP_FAILED, "Failed to mmap() host");
 	mem_aligned = (void *)(((size_t) mem + alignment - 1) & ~(alignment - 1));
···
 	TEST_ASSERT(ret == -1 && errno == EINVAL,
 		    "Adding one more memory slot should fail with EINVAL");
 
-	munmap(mem, MEM_REGION_SIZE * max_mem_slots + alignment);
+	munmap(mem, (size_t)max_mem_slots * MEM_REGION_SIZE + alignment);
 	munmap(mem_extra, MEM_REGION_SIZE);
 	kvm_vm_free(vm);
 }