Re: [Xen-devel] HVMOP_guest_request_vm_event only works from guest in ring0

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.08.16 at 11:24, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 04/08/16 08:13, Jan Beulich wrote:
>>>>> On 03.08.16 at 22:44, <andrew.cooper3@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/hvm/hvm.c
>>> +++ b/xen/arch/x86/hvm/hvm.c
>>> @@ -5194,8 +5194,14 @@ int hvm_do_hypercall(struct cpu_user_regs *regs)
>>>      switch ( mode )
>>>      {
>>>      case 8:       
>>> +        if ( eax == __HYPERVISOR_hvm_op &&
>>> +             regs->rdi == HVMOP_guest_request_vm_event )
>>> +            break;
>>>      case 4:
>>>      case 2:
>>> +        if ( eax == __HYPERVISOR_hvm_op &&
>>> +             regs->ebx == HVMOP_guest_request_vm_event )
>> I think you really mean _ebx here.
> 
> True, but it is very hard in 32 or 16bit code to have upper bits set in
> the 64bit register.

But it's not impossible.

Jan


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