linux-kernel - [PATCH v13 09/17] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter

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Date:   Fri, 13 May 2022 17:26:11 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     pbonzini@...hat.com
Cc:     jmattson@...gle.com, joro@...tes.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com
Subject: [PATCH v13 09/17] KVM: x86/pmu: Adjust precise_ip to emulate Ice Lake guest PDIR counter

From: Like Xu <likexu@...cent.com>

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 <likexu@...cent.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
v12 -> v13 Changelog:
- Move vmx_icl_pebs_cpu[] from pmu.h to pmu.c;
- Drop unrelated change about arch/x86/events/intel/core.c;

 arch/x86/kvm/pmu.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 36487088f72c..0b8fc86839ba 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -16,6 +16,7 @@
 #include <linux/bsearch.h>
 #include <linux/sort.h>
 #include <asm/perf_event.h>
+#include <asm/cpu_device_id.h>
 #include "x86.h"
 #include "cpuid.h"
 #include "lapic.h"
@@ -24,6 +25,12 @@
 /* This is enough to filter the vast majority of currently defined events. */
 #define KVM_PMU_EVENT_FILTER_MAX_EVENTS 300
 
+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),
+	{}
+};
+
 /* NOTE:
  * - Each perf counter is defined as "struct kvm_pmc";
  * - There are two types of perf counters: general purpose (gp) and fixed.
@@ -175,6 +182,8 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
 		 * could possibly care here is unsupported and needs changes.
 		 */
 		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,
-- 
2.36.1