Re: [PATCH v2 6/7] kvm,x86: RCU based table free

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

On Tue, 5 Jun 2012, Nikunj A Dadhania wrote:
> On Tue, 5 Jun 2012 12:58:32 +0100, Stefano Stabellini <stefano.stabellini@eu.citrix.com> wrote:
> > On Tue, 5 Jun 2012, Nikunj A Dadhania wrote:
> > > On Tue, 5 Jun 2012 11:48:02 +0100, Stefano Stabellini <stefano.stabellini@eu.citrix.com> wrote:
> > > > 
> > > > I am also interested in introducing HAVE_RCU_TABLE_FREE on x86 for Xen.
> > > > Maybe we can pull our efforts together :-)
> > > > 
> > > > Giving a look at this patch, it doesn't look like it is introducing
> > > > CONFIG_HAVE_RCU_TABLE_FREE anywhere under arch/x86.
> > > > How is the user supposed to set it?
> > > >
> > > I am doing that in the next patch only for KVM-ParavirtTLB flush, as
> > > there is a bug in this implementation that patch [7/7] fixes.
> > > 
> > > Refer following thread for details:
> > > http://mid.gmane.org/1337254086.4281.26.camel@twins
> > > http://mid.gmane.org/1337273959.4281.62.camel@twins
> > 
> > Thanks, somehow I missed the 7/7 patch.
> > 
> > From the Xen POV, your patch is fine because we'll just select
> > PARAVIRT_TLB_FLUSH on CONFIG_XEN (see appended patch for completeness).
> > 
> Selecting ARCH_HW_WALKS_PAGE_TABLE in place of PARAVIRT_TLB_FLUSH should
> suffice.

We would also need to select HAVE_RCU_TABLE_FREE, but it could be a good
idea, not go through PARAVIRT_TLB_FLUSH.