Re: [PATCH v3 10/11] x86/mm: Enable CR4.PCIDE on supported systems

[Thomas Gleixner]

On Wed, 21 Jun 2017, Thomas Gleixner wrote:

> On Tue, 20 Jun 2017, Andy Lutomirski wrote:
> > +	/* Set up PCID */
> > +	if (cpu_has(c, X86_FEATURE_PCID)) {
> > +		if (cpu_has(c, X86_FEATURE_PGE)) {
> > +			cr4_set_bits(X86_CR4_PCIDE);
> 
> So I assume that you made sure that the PCID bits in CR3 are zero under all
> circumstances as setting PCIDE would cause a #GP if not.

And what happens on kexec etc? We need to reset the asid and PCIDE I assume.

Thanks,

	tglx