On Thu, Jan 28, 2016 at 04:45:36PM +0000, Marc Zyngier wrote: > On 28/01/16 16:31, Andrew Jones wrote: > > On Wed, Jan 27, 2016 at 11:51:35AM +0800, Shannon Zhao wrote: > >> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx> > >> > >> When we use tools like perf on host, perf passes the event type and the > >> id of this event type category to kernel, then kernel will map them to > >> hardware event number and write this number to PMU PMEVTYPER<n>_EL0 > >> register. When getting the event number in KVM, directly use raw event > >> type to create a perf_event for it. > >> > >> Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx> > >> Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx> > >> --- > >> arch/arm64/include/asm/pmu.h | 3 ++ > >> arch/arm64/kvm/Makefile | 1 + > >> include/kvm/arm_pmu.h | 10 ++++ > >> virt/kvm/arm/pmu.c | 122 +++++++++++++++++++++++++++++++++++++++++++ > >> 4 files changed, 136 insertions(+) > >> create mode 100644 virt/kvm/arm/pmu.c > >> > >> diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h > >> index 4406184..2588f9c 100644 > >> --- a/arch/arm64/include/asm/pmu.h > >> +++ b/arch/arm64/include/asm/pmu.h > >> @@ -21,6 +21,7 @@ > >> > >> #define ARMV8_MAX_COUNTERS 32 > >> #define ARMV8_COUNTER_MASK (ARMV8_MAX_COUNTERS - 1) > >> +#define ARMV8_CYCLE_IDX (ARMV8_MAX_COUNTERS - 1) > > > > I'm not sure we want to add this. It's name is wrong, as it's really > > PMCNTENSET_EL0.C, and just a few lines above we have the idx defined > > already (ARMV8_IDX_CYCLE_COUNTER), but as zero, because > > arch/arm64/kernel/perf_event.c maps it that way. > > > > I think we should do the same with the pmc array, i.e. map the cycle > > counter to idx zero. > > I tend to have the opposite view. Not for the sake of it, but because I > find it helpful to directly map the code to the architecture > documentation without having to bend another handful of neurons. > > Will probably had some good reasons to structure it that way, but I > don't know the rational. Will? It was years ago, but I suspect that the cycle counter is index zero because its mandated, whilst the number of event counters is IMPDEF. Will -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
