On Mon, Apr 15, 2019 at 02:49:41PM +0100, Suzuki K Poulose wrote: > > > On 09/04/2019 20:22, Andrew Murray wrote: > > Upon entering or exiting a guest we may modify multiple PMU counters to > > enable of disable EL0 filtering. We presently do this via the indirect > > PMXEVTYPER_EL0 system register (where the counter we modify is selected > > by PMSELR). With this approach it is necessary to order the writes via > > isb instructions such that we select the correct counter before modifying > > it. > > > > Let's avoid potentially expensive instruction barriers by using the > > direct PMEVTYPER<n>_EL0 registers instead. > > > > As the change to counter type relates only to EL0 filtering we can rely > > on the implicit instruction barrier which occurs when we transition from > > EL2 to EL1 on entering the guest. On returning to userspace we can, at the > > latest, rely on the implicit barrier between EL2 and EL0. We can also > > depend on the explicit isb in armv8pmu_select_counter to order our write > > against any other kernel changes by the PMU driver to the type register as > > a result of preemption. > > > > Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx> > > --- > > arch/arm64/kvm/pmu.c | 84 ++++++++++++++++++++++++++++++++++++++------ > > 1 file changed, 74 insertions(+), 10 deletions(-) > > > > diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c > > index 3407a529e116..4d55193ccc71 100644 > > --- a/arch/arm64/kvm/pmu.c > > +++ b/arch/arm64/kvm/pmu.c > > @@ -91,6 +91,74 @@ void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt) > > write_sysreg(pmu->events_host, pmcntenset_el0); > > } > > +#define PMEVTYPER_READ_CASE(idx) \ > > + case idx: \ > > + return read_sysreg(pmevtyper##idx##_el0) > > + > > +#define PMEVTYPER_WRITE_CASE(idx) \ > > + case idx: \ > > + write_sysreg(val, pmevtyper##idx##_el0); \ > > + break > > + > > +#define PMEVTYPER_CASES(readwrite) \ > > + PMEVTYPER_##readwrite##_CASE(0); \ > > + PMEVTYPER_##readwrite##_CASE(1); \ > > + PMEVTYPER_##readwrite##_CASE(2); \ > > + PMEVTYPER_##readwrite##_CASE(3); \ > > + PMEVTYPER_##readwrite##_CASE(4); \ > > + PMEVTYPER_##readwrite##_CASE(5); \ > > + PMEVTYPER_##readwrite##_CASE(6); \ > > + PMEVTYPER_##readwrite##_CASE(7); \ > > + PMEVTYPER_##readwrite##_CASE(8); \ > > + PMEVTYPER_##readwrite##_CASE(9); \ > > + PMEVTYPER_##readwrite##_CASE(10); \ > > + PMEVTYPER_##readwrite##_CASE(11); \ > > + PMEVTYPER_##readwrite##_CASE(12); \ > > + PMEVTYPER_##readwrite##_CASE(13); \ > > + PMEVTYPER_##readwrite##_CASE(14); \ > > + PMEVTYPER_##readwrite##_CASE(15); \ > > + PMEVTYPER_##readwrite##_CASE(16); \ > > + PMEVTYPER_##readwrite##_CASE(17); \ > > + PMEVTYPER_##readwrite##_CASE(18); \ > > + PMEVTYPER_##readwrite##_CASE(19); \ > > + PMEVTYPER_##readwrite##_CASE(20); \ > > + PMEVTYPER_##readwrite##_CASE(21); \ > > + PMEVTYPER_##readwrite##_CASE(22); \ > > + PMEVTYPER_##readwrite##_CASE(23); \ > > + PMEVTYPER_##readwrite##_CASE(24); \ > > + PMEVTYPER_##readwrite##_CASE(25); \ > > + PMEVTYPER_##readwrite##_CASE(26); \ > > + PMEVTYPER_##readwrite##_CASE(27); \ > > + PMEVTYPER_##readwrite##_CASE(28); \ > > + PMEVTYPER_##readwrite##_CASE(29); \ > > + PMEVTYPER_##readwrite##_CASE(30) > > + > > Don't we need case 31 and deal with the PMCCFILTR, instead of WARN_ON(1) > below ? > > Otherwise, > > Reviewed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> Yes we do - I'll add this, thanks for spotting. Thanks, Andrew Murray _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
