kvm: WARNING in nested_vmx_vmexit

[Dmitry Vyukov]

Hello,

The following program triggers WARNING in nested_vmx_vmexit:
https://gist.githubusercontent.com/dvyukov/16b946d7dc703bb07b9b933f12fb8a6e/raw/dac60506feb8dd9dd22828c486e46ee8a5e30f13/gistfile1.txt


------------[ cut here ]------------
WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029
nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:15 [inline]
 dump_stack+0x2ee/0x3ef lib/dump_stack.c:51
 panic+0x1fb/0x412 kernel/panic.c:179
 __warn+0x1c4/0x1e0 kernel/panic.c:540
 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583
 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029
 vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline]
 vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324
 kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099
 do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128
 __msr_io arch/x86/kvm/x86.c:2577 [inline]
 msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614
 kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497
 kvm_vcpu_ioctl+0x232/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721
 vfs_ioctl fs/ioctl.c:43 [inline]
 do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683
 SYSC_ioctl fs/ioctl.c:698 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689
 entry_SYSCALL_64_fastpath+0x1f/0xc2
RIP: 0033:0x451229
RSP: 002b:00007fc1e7ebec98 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000451229
RDX: 0000000020aecfe8 RSI: 000000004008ae89 RDI: 0000000000000008
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fc1e7ebf9c0 R15: 00007fc1e7ebf700


On commit e5d56efc97f8240d0b5d66c03949382b6d7e5570