Re: [PATCH] x86: svm: don't intercept CR0 TS or MP bit write

[Joel Schopp <joel.schopp@amd.com>]

>> -		clr_cr_intercept(svm, INTERCEPT_CR0_WRITE);
>>  	} else {
>>  		set_cr_intercept(svm, INTERCEPT_CR0_READ);
> (There is no point in checking fpu_active if cr0s are equal.)
>
>> -		set_cr_intercept(svm, INTERCEPT_CR0_WRITE);
> KVM uses lazy FPU and the state is undefined before the first access.
> We set cr0.ts when !svm->vcpu.fpu_active to detect the first access, but
> if we allow the guest to clear cr0.ts without exiting, it can access FPU
> with undefined state.
Thanks for the valuable feedback.  It's apparent I hadn't thought
through the interaction with lazy FPU and will need to go back and
rethink my approach here.