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Subject[PATCH v1 4/8] KVM: x86: Aviod clear the PEBS counter when PEBS enabled in guest
Date
This patch introduce a parameter that avoid clear the PEBS event
counter while running in the guest. The performance counter which
use for PEBS event can be enabled through VM-entry when PEBS is
enabled in guest by PEBS output to Intel PT.

Signed-off-by: Luwei Kang <luwei.kang@intel.com>
---
arch/x86/events/intel/core.c | 19 +++++++++++--------
arch/x86/events/perf_event.h | 2 +-
arch/x86/include/asm/perf_event.h | 5 +++--
arch/x86/kvm/vmx/vmx.c | 3 ++-
4 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index fcef678..1fcc9fc 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3323,16 +3323,16 @@ static int intel_pmu_hw_config(struct perf_event *event)
return 0;
}

-struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
+struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, bool pebs)
{
if (x86_pmu.guest_get_msrs)
- return x86_pmu.guest_get_msrs(nr);
+ return x86_pmu.guest_get_msrs(nr, pebs);
*nr = 0;
return NULL;
}
EXPORT_SYMBOL_GPL(perf_guest_get_msrs);

-static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
+static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr, bool pebs)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct perf_guest_switch_msr *arr = cpuc->guest_switch_msrs;
@@ -3340,10 +3340,13 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL;
arr[0].host = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask;
arr[0].guest = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_host_mask;
- if (x86_pmu.flags & PMU_FL_PEBS_ALL)
- arr[0].guest &= ~cpuc->pebs_enabled;
- else
- arr[0].guest &= ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
+ if (!pebs) {
+ if (x86_pmu.flags & PMU_FL_PEBS_ALL)
+ arr[0].guest &= ~cpuc->pebs_enabled;
+ else
+ arr[0].guest &=
+ ~(cpuc->pebs_enabled & PEBS_COUNTER_MASK);
+ }
*nr = 1;

if (x86_pmu.pebs && x86_pmu.pebs_no_isolation) {
@@ -3364,7 +3367,7 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr)
return arr;
}

-static struct perf_guest_switch_msr *core_guest_get_msrs(int *nr)
+static struct perf_guest_switch_msr *core_guest_get_msrs(int *nr, bool pebs)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct perf_guest_switch_msr *arr = cpuc->guest_switch_msrs;
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index ecacfbf..57058fe 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -696,7 +696,7 @@ struct x86_pmu {
/*
* Intel host/guest support (KVM)
*/
- struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr);
+ struct perf_guest_switch_msr *(*guest_get_msrs)(int *nr, bool pebs);

/*
* Check period value for PERF_EVENT_IOC_PERIOD ioctl.
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index ee26e92..e29075a 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -322,12 +322,13 @@ struct perf_guest_switch_msr {
u64 host, guest;
};

-extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, bool pebs);
extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
extern void perf_check_microcode(void);
extern int x86_perf_rdpmc_index(struct perf_event *event);
#else
-static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
+static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr,
+ bool pebs)
{
*nr = 0;
return NULL;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index e7970a2..170afde 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6428,7 +6428,8 @@ static void atomic_switch_perf_msrs(struct vcpu_vmx *vmx)
int i, nr_msrs;
struct perf_guest_switch_msr *msrs;

- msrs = perf_guest_get_msrs(&nr_msrs);
+ msrs = perf_guest_get_msrs(&nr_msrs,
+ vcpu_to_pmu(&vmx->vcpu)->pebs_enable);

if (!msrs)
return;
--
1.8.3.1
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