[PATCH v6 11/16] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter

From: Like Xu
Date: Mon May 10 2021 - 22:44:00 EST


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@xxxxxxxxxxxxxxx>
---
arch/x86/kvm/pmu.c | 2 ++
arch/x86/kvm/pmu.h | 7 +++++++
2 files changed, 9 insertions(+)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 0f86c1142f17..d3f746877d1b 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -149,6 +149,8 @@ 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,
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 67e753edfa22..1af86ae1d3f2 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -4,6 +4,8 @@

#include <linux/nospec.h>

+#include <asm/cpu_device_id.h>
+
#define vcpu_to_pmu(vcpu) (&(vcpu)->arch.pmu)
#define pmu_to_vcpu(pmu) (container_of((pmu), struct kvm_vcpu, arch.pmu))
#define pmc_to_pmu(pmc) (&(pmc)->vcpu->arch.pmu)
@@ -16,6 +18,11 @@
#define VMWARE_BACKDOOR_PMC_APPARENT_TIME 0x10002

#define MAX_FIXED_COUNTERS 3
+static const struct x86_cpu_id vmx_icl_pebs_cpu[] = {
+ X86_MATCH_INTEL_FAM6_MODEL(ICELAKE_D, NULL),
+ X86_MATCH_INTEL_FAM6_MODEL(ICELAKE_X, NULL),
+ {}
+};

struct kvm_event_hw_type_mapping {
u8 eventsel;
--
2.31.1