Re: New CPUID/MSR driver; virtualization hooks

["H. Peter Anvin" <hpa@zytor.com>]

Chris Wright wrote:
>>
>> http://git.kernel.org/?p=linux/kernel/git/hpa/linux-2.6-cpuidmsr.git;a=summary
> 
> Bleah, and gitweb is unhappy ATM too.
> 

??? Works for me?

> Without having seen the patch yet, you'll need to make sure
> that the final point which is issuing asm("cpuid") is wrapped
> and split to CONFIG_PARAVIRT and non CONFIG_PARAVIRT modes.

It's not *quite* that easy.  The assembly code around this is pretty 
extensive, because it has to stand on its head in order to present the 
proper register image.

Pretty much as far as I can see it, there are two possible points where 
one can break out CONFIG_PARAVIRT:

a) int do_foo(int cpu, const u64 ireg[16], u64 oreg[16]);

b) int foo_everything(const u64 ireg[16], u64 oreg[16]);

The difference, of course, is that the former is invoked on the 
originating CPU and the latter on the target CPU at interrupt level. 
Those are pretty much the choices.

	-hpa