From a4faf2e77a565432278430deaaba2f3295b6a2df Mon Sep 17 00:00:00 2001 From: Paul Mackerras Date: Fri, 25 Aug 2017 19:52:12 +1000 Subject: [PATCH] KVM: PPC: Book3S HV: Fix case where HDEC is treated as 32-bit on POWER9 Commit 2f2724630f7a ("KVM: PPC: Book3S HV: Cope with host using large decrementer mode", 2017-05-22) added code to treat the hypervisor decrementer (HDEC) as a 64-bit value on POWER9 rather than 32-bit. Unfortunately, that commit missed one place where HDEC is treated as a 32-bit value. This fixes it. This bug should not have any user-visible consequences that I can think of, beyond an occasional unnecessary exit to the host kernel. If the hypervisor decrementer has gone negative, then the bottom 32 bits will be negative for about 4 seconds after that, so as long as we get out of the guest within those 4 seconds we won't conclude that the HDEC interrupt is spurious. Reported-by: Suraj Jitindar Singh Fixes: 2f2724630f7a ("KVM: PPC: Book3S HV: Cope with host using large decrementer mode") Signed-off-by: Paul Mackerras --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 0bc400f882f4..29ec462d11c5 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -1280,7 +1280,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR) cmpwi r12,BOOK3S_INTERRUPT_HV_DECREMENTER bne 2f mfspr r3,SPRN_HDEC - cmpwi r3,0 + EXTEND_HDEC(r3) + cmpdi r3,0 mr r4,r9 bge fast_guest_return 2: -- 2.20.1