github.com/google/syzkaller@v0.0.0-20251211124644-a066d2bc4b02/sys/linux/test/amd64-syz_kvm_nested_intel_vmwrite_mask (about)

     1  #
     2  # requires: arch=amd64 -threaded
     3  #
     4  r0 = openat$kvm(0, &AUTO='/dev/kvm\x00', 0x0, 0x0)
     5  r1 = ioctl$KVM_CREATE_VM(r0, AUTO, 0x0)
     6  r2 = syz_kvm_setup_syzos_vm$x86(r1, &(0x7f0000c00000/0x400000)=nil)
     7  
     8  # Create a nested VM that performs HLT and INVD.
     9  # 1. L2 executes HLT -> exit to L1.
    10  # 2. L1 disables HLT exiting via vmwrite to CPU_BASED_VM_EXEC_CONTROL.
    11  # 3. L1 resumes L2 (RIP still at HLT).
    12  # 4. L2 executes HLT (no exit), which is delivered to L0.
    13  # 5. L0 resumes L1, which is still running L2.
    14  # 6. L2 executes INVD -> exit to L1.
    15  #
    16  r3 = syz_kvm_add_vcpu$x86(r2, &AUTO={0x0, &AUTO=[@enable_nested={AUTO, AUTO, 0x0}, @nested_create_vm={AUTO, AUTO, 0x0}, @nested_load_code={AUTO, AUTO, {0x0, "f40f08"}}, @nested_vmlaunch={AUTO, AUTO, 0x0}, @nested_intel_vmwrite_mask={AUTO, AUTO, {0x0, @control32=0x4002, 0x0, 0x80, 0x0}}, @nested_vmresume={AUTO, AUTO, 0x0}], AUTO})
    17  r4 = ioctl$KVM_GET_VCPU_MMAP_SIZE(r0, AUTO)
    18  r5 = mmap$KVM_VCPU(&(0x7f0000009000/0x1000)=nil, r4, 0x3, 0x1, r3, 0x0)
    19  
    20  # L2 VM executes HLT. Exit reason is mapped to 0xe2e20001.
    21  #
    22  ioctl$KVM_RUN(r3, AUTO, 0x0)
    23  syz_kvm_assert_syzos_uexit$x86(r5, 0xe2e20001)
    24  
    25  # L1 disables HLT exiting and resumes L2. L2 resumes at HLT, and breaks out of KVM_RUN.
    26  # 0x05 is KVM_EXIT_HLT.
    27  # This confirms that the vmwrite command to disable HLT exiting was successful.
    28  #
    29  ioctl$KVM_RUN(r3, AUTO, 0x0)
    30  syz_kvm_assert_syzos_kvm_exit$x86(r5, 0x5)
    31  
    32  # After resuming, L2 executes INVD. Exit reason is mapped to 0xe2e20002.
    33  #
    34  ioctl$KVM_RUN(r3, AUTO, 0x0)
    35  syz_kvm_assert_syzos_uexit$x86(r5, 0xe2e20002)
    36  
    37  # guest_main should finish with guest_uexit(-1).
    38  #
    39  ioctl$KVM_RUN(r3, AUTO, 0x0)
    40  syz_kvm_assert_syzos_uexit$x86(r5, 0xffffffff)