On Thu, Sep 03, 2015 at 03:21:23PM +1000, Paul Mackerras wrote: > From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com> > > The code that handles the case when we receive a H_DOORBELL interrupt > has a comment which says "Hypervisor doorbell - exit only if host IPI > flag set". However, the current code does not actually check if the > host IPI flag is set. This is due to a comparison instruction that > got missed. > > As a result, the current code performs the exit to host only > if some sibling thread or a sibling sub-core is exiting to the > host. This implies that, an IPI sent to a sibling core in > (subcores-per-core != 1) mode will be missed by the host unless the > sibling core is on the exit path to the host. > > This patch adds the missing comparison operation which will ensure > that when HOST_IPI flag is set, we unconditionally exit to the host. > > Fixes: 66feed61cdf6 > Cc: sta...@vger.kernel.org # v4.1+ > Signed-off-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com> > Signed-off-by: Paul Mackerras <pau...@samba.org>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
> arch/powerpc/kvm/book3s_hv_rmhandlers.S | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> index b07f045..2273dca 100644
> --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
> @@ -1213,6 +1213,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
> cmpwi r12, BOOK3S_INTERRUPT_H_DOORBELL
> bne 3f
> lbz r0, HSTATE_HOST_IPI(r13)
> + cmpwi r0, 0
> beq 4f
> b guest_exit_cont
> 3:
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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