[PATCH v3 11/17] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter

Like Xu
2021-01-04T13:28:05Z

The PEBS-PDIR facility on Ice Lake server is supported on IA31_FIXED0 only.
If the guest configures counter 32 and PEBS is enabled, the PEBS-PDIR
facility is supposed to be used, in which case KVM adjusts attr.precise_ip
to 3 and request host perf to assign the exactly requested counter or fail.

The cpu model check is also required since some platforms may place the
PEBS-PDIR facility in another counter index.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
---
arch/x86/kvm/pmu.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 2e81c50323e2..67c20ab81991 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -144,6 +144,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
* in the PEBS record is calibrated on the guest side.
*/
attr.precise_ip = 1;
+ if (x86_match_cpu(vmx_icl_pebs_cpu) && pmc->idx == 32)
+ attr.precise_ip = 3;
}

event = perf_event_create_kernel_counter(&attr, -1, current,
--
2.29.2