Hi Peter,
On 8/6/2020 7:00 PM, pet...@infradead.org wrote:
On Thu, Aug 06, 2020 at 11:18:27AM +0200, pet...@infradead.org wrote:
Suppose we have nested virt:
L0-hv
|
G0/L1-hv
|
G1
And we're running in G0, then:
- 'exclude_hv' would exclude L0 events
- 'exclude_host' would ... exclude L1-hv events?
- 'exclude_guest' would ... exclude G1 events?
So in arch/x86/events/intel/core.c we have:
static inline void intel_set_masks(struct perf_event *event, int idx)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
if (event->attr.exclude_host)
__set_bit(idx, (unsigned long *)&cpuc->intel_ctrl_guest_mask);
if (event->attr.exclude_guest)
__set_bit(idx, (unsigned long *)&cpuc->intel_ctrl_host_mask);
if (event_is_checkpointed(event))
__set_bit(idx, (unsigned long *)&cpuc->intel_cp_status);
}
exclude_host is now set by guest (pmc_reprogram_counter, arch/x86/kvm/pmu.c). When enabling the
event, we can check exclude_host to know if it's a guest.
Otherwise we may need more flags in event->attr to indicate the status.
which is, afaict, just plain wrong. Should that not be something like:
if (!event->attr.exclude_host)
__set_bit(idx, (unsigned long *)&cpuc->intel_ctrl_host_mask);
if (!event->attr.exclude_guest)
__set_bit(idx, (unsigned long *)&cpuc->intel_ctrl_guest_mask);
How can we know it's guest or host even if exclude_host is set in guest?
Thanks
Jin Yao
Also, ARM64 seems to also implement this stuff, Mark, do you have any
insight on how all this is 'supposed' to work?
