Re: [Xen-devel] [PATCH v2] x86/monitor: add support for descriptor access events

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 06.04.17 at 11:37, <apop@xxxxxxxxxxxxxxx> wrote:
> On Thu, Apr 06, 2017 at 03:20:21AM -0600, Jan Beulich wrote:
>> >>> On 06.04.17 at 10:59, <apop@xxxxxxxxxxxxxxx> wrote:
>> > On Wed, Apr 05, 2017 at 08:26:27AM -0600, Jan Beulich wrote:
>> >> >>> On 04.04.17 at 11:57, <apop@xxxxxxxxxxxxxxx> wrote:
>> >> > --- a/xen/arch/x86/hvm/hvm.c
>> >> > +++ b/xen/arch/x86/hvm/hvm.c
>> >> > @@ -3572,6 +3572,43 @@ gp_fault:
>> >> >      return X86EMUL_EXCEPTION;
>> >> >  }
>> >> >  
>> >> > +int hvm_descriptor_access_intercept(uint64_t exit_info,
>> >> > +                                    uint64_t vmx_exit_qualification,
>> >> > +                                    uint8_t descriptor, bool is_write)
>> >> 
>> >> Why uint8_t?
>> > 
>> > The descriptor type from struct vm_event_desc_access is uint8_t since
>> > there are only 4 possible descriptors:
>> > 
>> >> > +#define VM_EVENT_DESC_IDTR           1
>> >> > +#define VM_EVENT_DESC_GDTR           2
>> >> > +#define VM_EVENT_DESC_LDTR           3
>> >> > +#define VM_EVENT_DESC_TR             4
>> > 
>> > Should it be something else?
>> 
>> Well, you should avoid fixed width types where they're not really
>> needed (their use should signal a true dependency on the specified
>> width). "unsigned int" would be quite fine here afaict.
> 
> So should it be changed in the struct definition as well?

You mean in the public interface? No, there you _need_ to use fixed
width types.

Jan


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