xref: /aosp_15_r20/external/crosvm/kvm/tests/read_only_memory.rs (revision bb4ee6a4ae7042d18b07a98463b9c8b875e44b39)
1 // Copyright 2017 The ChromiumOS Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #![cfg(any(target_os = "android", target_os = "linux"))]
6 #![cfg(target_arch = "x86_64")]
7 
8 use base::MemoryMappingBuilder;
9 use base::SharedMemory;
10 use kvm::*;
11 use kvm_sys::kvm_regs;
12 use vm_memory::GuestAddress;
13 use vm_memory::GuestMemory;
14 
15 #[test]
test_run()16 fn test_run() {
17     /*
18     0000  268A07  mov al,[es:bx]
19     0003  0401    add al,0x1
20     0005  268807  mov [es:bx],al
21     0008  F4      hlt
22     */
23     let code = [0x26, 0x8a, 0x07, 0x04, 0x01, 0x26, 0x88, 0x07, 0xf4];
24     let mem_size = 0x2000;
25     let load_addr = GuestAddress(0x1000);
26     let guest_mem = GuestMemory::new(&[]).unwrap();
27     let mem = SharedMemory::new("test", mem_size).expect("failed to create shared memory");
28     let mmap = MemoryMappingBuilder::new(mem_size as usize)
29         .from_shared_memory(&mem)
30         .build()
31         .expect("failed to create memory mapping");
32 
33     mmap.write_slice(&code[..], load_addr.offset() as usize)
34         .expect("Writing code to memory failed.");
35 
36     let kvm = Kvm::new().expect("new kvm failed");
37     let mut vm = Vm::new(&kvm, guest_mem).expect("new vm failed");
38     let vcpu = Vcpu::new(0, &kvm, &vm).expect("new vcpu failed");
39     let mut vcpu_sregs = vcpu.get_sregs().expect("get sregs failed");
40     vcpu_sregs.cs.base = 0;
41     vcpu_sregs.cs.selector = 0;
42     vcpu_sregs.es.base = 0x3000;
43     vcpu_sregs.es.selector = 0;
44     vcpu.set_sregs(&vcpu_sregs).expect("set sregs failed");
45 
46     // SAFETY: trivially safe
47     let mut vcpu_regs: kvm_regs = unsafe { std::mem::zeroed() };
48     vcpu_regs.rip = load_addr.offset();
49     vcpu_regs.rflags = 2;
50     vcpu_regs.rax = 0x66;
51     vcpu_regs.rbx = 0;
52     vcpu.set_regs(&vcpu_regs).expect("set regs failed");
53     vm.add_memory_region(
54         GuestAddress(0),
55         Box::new(
56             MemoryMappingBuilder::new(mem_size as usize)
57                 .from_shared_memory(&mem)
58                 .build()
59                 .expect("failed to create memory mapping"),
60         ),
61         false,
62         false,
63     )
64     .expect("failed to register memory");
65 
66     // Give some read only memory for the test code to read from and force a vcpu exit when it reads
67     // from it.
68     let mem_ro = SharedMemory::new("test", 0x1000).expect("failed to create shared memory");
69     let mmap_ro = MemoryMappingBuilder::new(0x1000)
70         .from_shared_memory(&mem_ro)
71         .build()
72         .expect("failed to create memory mapping");
73     mmap_ro
74         .write_obj(vcpu_regs.rax as u8, 0)
75         .expect("failed writing data to ro memory");
76     vm.add_memory_region(
77         GuestAddress(vcpu_sregs.es.base),
78         Box::new(
79             MemoryMappingBuilder::new(0x1000)
80                 .from_shared_memory(&mem_ro)
81                 .build()
82                 .expect("failed to create memory mapping"),
83         ),
84         true,
85         false,
86     )
87     .expect("failed to register memory");
88 
89     // Ensure we get exactly 1 exit from attempting to write to read only memory.
90     let mut exits = 0;
91 
92     let runnable_vcpu = vcpu.to_runnable(None).unwrap();
93     loop {
94         match runnable_vcpu.run().expect("run failed") {
95             VcpuExit::Hlt => break,
96             VcpuExit::MmioWrite {
97                 address,
98                 size: 1,
99                 data,
100             } => {
101                 assert_eq!(address, vcpu_sregs.es.base);
102                 assert_eq!(data[0] as u64, vcpu_regs.rax + 1);
103                 exits += 1;
104             }
105             r => panic!("unexpected exit reason: {:?}", r),
106         }
107     }
108 
109     // Check that exactly 1 attempt to write to read only memory was made, and that the memory is
110     // unchanged after that attempt.
111     assert_eq!(exits, 1);
112     assert_eq!(
113         mmap_ro
114             .read_obj::<u8>(0)
115             .expect("failed to read data from ro memory"),
116         vcpu_regs.rax as u8
117     );
118 }
119