Re: [kvm-devel] [PATCH]: Fix MSR_K7_EVNTSEL{0,3} for SVM

[Chris L. <cla...@re...>]

Avi Kivity wrote:
> 
> Hmm, looking back at the dump:
> 
>>     1811:	8d 86 00 00 ff 3f    	lea    0x3fff0000(%rsi),%eax
>>     1817:	83 f8 03             	cmp    $0x3,%eax
>>     181a:	0f 87 e2 01 00 00    	ja     1a02 <svm_set_msr+0x27f>
> 
> So while gcc is using %rsi, it loads the result back into %eax, which 
> has the effect of dropping back into 32-bits.  So looks like gcc was 
> right here.  Sorry for spreading confusion and apologies to gcc.
> 

OK.  Well, then I can't explain why we are unconditionally calling
kvm_set_msr_common(), regardless of whether data == 0 or not.  Avi, you said it
works for you; what version of gcc are you using, and can you send me your
objdump -Sr?  I'd like to compare the assembly output with what 4.3.0 is
spitting out.

Chris Lalancette