On Sun, May 04, 2014 at 10:56:08PM +0530, Aneesh Kumar K.V wrote:
> With debug option "sleep inside atomic section checking" enabled we get
> the below WARN_ON during a PR KVM boot. This is because upstream now
> have PREEMPT_COUNT enabled even if we have preempt disabled. Fix the
> warning by adding preempt_disable/enable around floating point and altivec
> enable.
This worries me a bit. In this code:
> if (msr & MSR_FP) {
> + preempt_disable();
> enable_kernel_fp();
> load_fp_state(&vcpu->arch.fp);
> t->fp_save_area = &vcpu->arch.fp;
> + preempt_enable();
What would happen if we actually did get preempted at this point?
Wouldn't we lose the FP state we just loaded?
In other words, how come we're not already preempt-disabled at this
point?
Paul.
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