Re: [BACKPORT PATCH 3.17..4.4] KVM: MIPS: Drop other CPU ASIDs on guest MMU changes

[Greg KH <greg@kroah.com>]

On Wed, Nov 09, 2016 at 02:45:44PM +0000, 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> # 3.17.x-
> [james.hogan@imgtec.com: Backport to 3.17..4.4]
> Signed-off-by: James Hogan <james.hogan@imgtec.com>
> ---
> Unfortunately the original commit went in to v4.4.25 as commit
> d450527ad04a, 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 4.4.

Thanks for this, now fixed up.

greg k-h