Re: [PATCH v4 0/2] Basic nested VMX test suite

[Jan Kiszka <jan.kiszka@web.de>]

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On 2013-07-17 12:31, Gleb Natapov wrote:
>>>> I think the current version is mostly fine, but I'd prefer to move the
>>>> inline functions to vmx.h, and the tests to a separate file.  Perhaps
>>>> lib/x86/vmx.h, lib/x86/vmx.c, and x86/vmx.c.
>>>>
>>>> All knowledge of setjmp and longjmp should then be hidden in
>>>> lib/x86/vmx.c, perhaps by putting
>>>>
>>>> 	if (setjmp(env) == 0) {
>>>> 		vmx_run();
>>>> 		return 1;
>>>> 	} else
>>>> 		return 0;
>>>>
>>>> or something like that in a new lib/x86/vmx.c function.
>>>>
>>> Use of setjmp to redirect control flow here is absolutely unnecessary. HW
>>> provides you with capability to return control flow back where you want
>>> it but you ignore it and save/restore context by yourself. Why?! Just tell
>>> HW to return to the point you want to return to!
>>
>> This is not super-optimized kernel code, this has to be readable first
>> and foremost.  In C, the way to do global jumps and save/restore context
>> is setjmp/longjmp.
> If you do it right there will be _not point in doing_ global jumps. The
> control flow will be linear, the code will be much more readable.

Indeed. Arthur is already working on a setjmp/longjmp free version,
let's wait for the outcome.

Jan


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