Re: [BACKPORT PATCH 3.10..3.16] KVM: MIPS: Drop other CPU ASIDs on guest MMU changes

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Nov 09, 2016 at 10:00:43PM +0000, James Hogan wrote:
> On Wed, Nov 09, 2016 at 10:22:01PM +0100, Jiri Slaby wrote:
> > On 11/09/2016, 03:46 PM, James Hogan wrote:
> > > commit 91e4f1b6073dd680d86cdb7e42d7cccca9db39d8 upstream.
> > > 
> > > When a guest TLB entry is replaced by TLBWI or TLBWR, we only invalidate
> > > TLB entries on the local CPU. This doesn't work correctly on an SMP host
> > > when the guest is migrated to a different physical CPU, as it could pick
> > > up stale TLB mappings from the last time the vCPU ran on that physical
> > > CPU.
> > > 
> > > Therefore invalidate both user and kernel host ASIDs on other CPUs,
> > > which will cause new ASIDs to be generated when it next runs on those
> > > CPUs.
> > > 
> > > We're careful only to do this if the TLB entry was already valid, and
> > > only for the kernel ASID where the virtual address it mapped is outside
> > > of the guest user address range.
> > > 
> > > Signed-off-by: James Hogan <james.hogan@imgtec.com>
> > > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > > Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> > > Cc: Ralf Baechle <ralf@linux-mips.org>
> > > Cc: linux-mips@linux-mips.org
> > > Cc: kvm@vger.kernel.org
> > > Cc: <stable@vger.kernel.org> # 3.10.x-
> > > Cc: Jiri Slaby <jslaby@suse.cz>
> > > [james.hogan@imgtec.com: Backport to 3.10..3.16]
> > > Signed-off-by: James Hogan <james.hogan@imgtec.com>
> > > ---
> > > Unfortunately the original commit went in to v3.12.65 as commit
> > > 168e5ebbd63e, without fixing up the references to tlb_lo[0/1] to
> > > tlb_lo0/1 which broke the MIPS KVM build, and I didn't twig that I
> > > already had a correct backport outstanding (sorry!). That commit should
> > > be reverted before applying this backport to 3.12.
> > 
> > Thanks, reverted and applied. I wonder the builders didn't break given 4
> > mips configurations are tested. I indeed could reproduce locally.
> 
> I'm guessing malta_kvm_defconfig isn't one of those defconfigs (and the
> imgtec buildbots don't yet test stable branches). Which builders do you
> use?

I use 0-day for these types of things, and it is not showing up any
errors for the 4.4-stable kernel.  Can you get these configurations
added to it so that we can ensure it doesn't regress?

thanks,

greg k-h