On Thu, Sep 03, 2015 at 03:21:23PM +1000, Paul Mackerras wrote: > From: "Gautham R. Shenoy" <ego@xxxxxxxxxxxxxxxxxx> > > 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: stable@xxxxxxxxxxxxxxx # v4.1+ > Signed-off-by: Gautham R. Shenoy <ego@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > --- > 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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