Best Regards Junjie Mao > -----Original Message----- > From: Avi Kivity [mailto:avi@xxxxxxxxxx] > Sent: Sunday, May 13, 2012 6:03 PM > To: Mao, Junjie > Cc: 'kvm@xxxxxxxxxxxxxxx' > Subject: Re: [PATCH] KVM: x86: Implement PCID/INVPCID for guests with EPT > > On 05/11/2012 08:58 AM, Mao, Junjie wrote: > > > > > > > > +static bool vmx_pcid_supported(void) { > > > > + /* Enable PCID for non-ept guests may cause performance > > > > +regression */ > > > > > > Why is that? > > > > For guests using shadow page tables, every INVPCID must be intercepted so > that changes in guest page tables can be reflected on the shadow ones, which > brings about performance troubles. Without INVPCID, the PCID feature has > little benefits. As a result, PCID/INVPCID is not exposed to non-ept guests. > Sorry for being unclear in the comment. > > Okay, please update the comment. btw, are there plans to add PCID support > to Linux in the OS role? > As far as I know, there isn't any plans to do it yet. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
