Hi Andrew,
On Mon, Jan 14, 2019 at 04:11:47PM +0000, Andrew Murray wrote:
> Add support for the :G and :H attributes in perf by handling the
> exclude_host/exclude_guest event attributes.
>
> We notify KVM of counters that we wish to be enabled or disabled on
> guest entry/exit and thus defer from starting or stopping :G events
> as per the events exclude_host attribute.
>
> With both VHE and non-VHE we switch the counters between host/guest
> at EL2. We are able to eliminate counters counting host events on
> the boundaries of guest entry/exit when using :G by filtering out
> EL2 for exclude_host. However when using :H unless exclude_hv is set
> on non-VHE then there is a small blackout window at the guest
> entry/exit where host events are not captured.
>
> Signed-off-by: Andrew Murray <andrew.murray at arm.com>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose at arm.com>
> ---
> arch/arm64/kernel/perf_event.c | 53 ++++++++++++++++++++++++++++++++++++------
> 1 file changed, 46 insertions(+), 7 deletions(-)
[...]
> static inline int armv8pmu_enable_intens(int idx)
> @@ -824,16 +851,25 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
> * Therefore we ignore exclude_hv in this configuration, since
> * there's no hypervisor to sample anyway. This is consistent
> * with other architectures (x86 and Power).
> + *
> + * To eliminate counting host events on the boundaries of
> + * guest entry/exit we ensure EL2 is not included in hyp mode
> + * with !exclude_host.
> */
> if (is_kernel_in_hyp_mode()) {
> - if (!attr->exclude_kernel)
> + if (!attr->exclude_kernel && !attr->exclude_host)
> config_base |= ARMV8_PMU_INCLUDE_EL2;
> } else {
> - if (attr->exclude_kernel)
> - config_base |= ARMV8_PMU_EXCLUDE_EL1;
> if (!attr->exclude_hv)
> config_base |= ARMV8_PMU_INCLUDE_EL2;
> }
> +
> + /*
> + * Filter out !VHE kernels and guest kernels
> + */
> + if (attr->exclude_kernel)
> + config_base |= ARMV8_PMU_EXCLUDE_EL1;
> +
This series needs acks from the KVM folks, but I'd also like Christoffer to
confirm that he's happy with the way these checks ended up because I lost
track of where we got to on that.
Will
