On Tue, 5 Jun 2012 12:58:32 +0100, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> wrote: > On Tue, 5 Jun 2012, Nikunj A Dadhania wrote: > > On Tue, 5 Jun 2012 11:48:02 +0100, Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> 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. > The main difference between the two approaches is that a kernel with > PARAVIRT_TLB_FLUSH and/or CONFIG_XEN enabled is going to have > HAVE_RCU_TABLE_FREE even when running on native. > > Are you proposing this series for 3.5? > If not (because it depends on ticketlocks and KVM Paravirt Spinlock > patches), > 3.6 I suppose as the merge window is already closed and we are having some discussions on PLE results. > could you extract patch 6/7 and 7/7 and send them out > separately? > > I am saying this because Xen needs the HAVE_RCU_TABLE_FREE fix even if > pv ticketlock are not accepted. This is an outstanding bug for us > unfortunately. > PeterZ has a patch in his tlb-unify: mm, x86: Add HAVE_RCU_TABLE_FREE support Implements optional HAVE_RCU_TABLE_FREE support for x86. This is useful for things like Xen and KVM where paravirt tlb flush means the software page table walkers like GUP-fast cannot rely on IRQs disabling like regular x86 can. Cc: Nikunj A Dadhania <nikunj@xxxxxxxxxxxxxxxxxx> Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx> Cc: Avi Kivity <avi@xxxxxxxxxx> Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> http://git.kernel.org/?p=linux/kernel/git/peterz/mmu.git;a=commit;h=8a7e6fa5be9d2645c3394892c870113e6e5d9309 PeterZ, is 7/7 alright to be picked? Regards Nikunj -- 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
