Re: [Xen-devel] [V0 PATCH] SVM: set/unset TF flag for single_step

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.07.14 at 05:36, <boris.ostrovsky@xxxxxxxxxx> wrote:
>> --- a/xen/arch/x86/hvm/svm/svm.c
>> +++ b/xen/arch/x86/hvm/svm/svm.c
>> @@ -2350,6 +2350,8 @@ void svm_vmexit_handler(struct cpu_user_regs
>> *regs)
>>      case VMEXIT_EXCEPTION_DB:
>>          if ( !v->domain->debugger_attached )
>>              goto exit_and_crash;
>> +        else
>> +            regs->eflags &= ~X86_EFLAGS_TF;
>>          domain_pause_for_debugger();
>>          break;
> 
> 
> I poked around debugger code and it looks to me that 
> tools/debugger/gdbsx/xg:_change_TF() manages this flag.

Indeed it shouldn't be the hypervisor to deal with that (unless it had
a built-in one), but the debugger attached.

That said, Mukesh, just as a side note: There's no point for an "else"
after an "if" leading to a "goto".

Jan


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