| Message ID | 20170825095212.GB14035@fergus.ozlabs.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Aug 25, 2017 at 07:52:12PM +1000, Paul Mackerras wrote: > 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 <sjitindarsingh@gmail.com> > Fixes: 2f2724630f7a ("KVM: PPC: Book3S HV: Cope with host using large decrementer mode") > Signed-off-by: Paul Mackerras <paulus@ozlabs.org> Patch applied to my kvm-ppc-next branch. Paul.
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index c52184a..9f1521e 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:
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 <sjitindarsingh@gmail.com> Fixes: 2f2724630f7a ("KVM: PPC: Book3S HV: Cope with host using large decrementer mode") Signed-off-by: Paul Mackerras <paulus@ozlabs.org> --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)