On Mon, 2017-03-13 at 03:13 +1000, Nicholas Piggin wrote: > Hi, > > Just after the previous two fixes, I would like to propose changing > the way we do doorbell vs interrupt controller IPIs, and add support > for global doorbells supported by POWER9 in HV mode. > > After this, the platform code knows about doorbells and interrupt > controller IPIs, rather than they know about each other.
A few things come to mind: - We don't want to use doorbells under KVM. They are going to turn into traps and be emulated, slower than using H_IPI, at least on P9. Even for core only doorbells. I'm not sure how to convey that to the guest. - On PP9 DD1 we need a CI load instead of msgsync (a DARN instruction would do too if it works) - Can we get rid of the atomic ops for manipulating the IPI mux ? What about a cache line per message and just set/clear ? If we clear in the doorbell handler before we call the respective targets, we shouldn't "lose" messages no ? As long as the actual handlers "loop" as necessary of course. Cheers, Ben. > Thanks, > Nick > > Nicholas Piggin (2): > powerpc/64s: change the doorbell IPI calling convention > powerpc/64s: use global doorbell on POWER9 in HV mode > > arch/powerpc/include/asm/dbell.h | 38 ++++++++++++++++++++++ > ----- > arch/powerpc/include/asm/smp.h | 4 +-- > arch/powerpc/include/asm/xics.h | 2 +- > arch/powerpc/kernel/dbell.c | 47 ++++++++++++++++++++++ > ------------ > arch/powerpc/kernel/smp.c | 27 ++++++++++--------- > arch/powerpc/platforms/85xx/smp.c | 9 +------ > arch/powerpc/platforms/powermac/smp.c | 2 +- > arch/powerpc/platforms/powernv/smp.c | 32 +++++++++++++++++------ > arch/powerpc/platforms/pseries/smp.c | 28 ++++++++------------ > arch/powerpc/sysdev/xics/icp-hv.c | 2 +- > arch/powerpc/sysdev/xics/icp-native.c | 12 +-------- > arch/powerpc/sysdev/xics/icp-opal.c | 2 +- > arch/powerpc/sysdev/xics/xics-common.c | 3 --- > 13 files changed, 118 insertions(+), 90 deletions(-) >
