Re: [PATCH] KVM: PPC: Book3S HV: Sanitize special-purpose register values on guest exit

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/03/2016 12:12, Paul Mackerras wrote:
> Thomas Huth discovered that a guest could cause a hard hang of a
> host CPU by setting the Instruction Authority Mask Register (IAMR)
> to a suitable value.  It turns out that this is because when the
> code was added to context-switch the new special-purpose registers
> (SPRs) that were added in POWER8, we forgot to add code to ensure
> that they were restored to a sane value on guest exit.
> 
> This adds code to set the those registers where a bad value could
> compromise the execution of the host kernel to a suitable neutral
> value on guest exit.
> 
> Cc: stable@vger.kernel.org # v3.14+
> Fixes: b73117c49364
> Reported-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Paul Mackerras <paulus@samba.org>
> ---
> Paolo, since this fixes a bug where a guest can cause a hard hang
> of a host CPU, I'd like it to go in 4.5 if possible.

Sure.

Paolo