On 2015/7/17 17:58, Christoffer Dall wrote:

On Fri, Jul 17, 2015 at 04:13:35PM +0800, Shannon Zhao wrote:

quoted

On 2015/7/17 2:25, Christoffer Dall wrote:

quoted

On Mon, Jul 06, 2015 at 10:17:32AM +0800, shannon.zhao at linaro.org wrote:

quoted

From: Shannon Zhao <redacted>

Here we plan to support virtual PMU for guest by full software
emulation, so define some basic structs and functions preparing for
futher steps. Define struct kvm_pmc for performance monitor counter and
struct kvm_pmu for performance monitor unit for each vcpu. According to
ARMv8 spec, the PMU contains at most 32(ARMV8_MAX_COUNTERS) counters.
Initialize PMU for each vcpu when kvm initialize vcpus, while reset PMU
when kvm reset vcpus.
Since this only supports ARM64 (or PMUv3), add a separate config symbol
for it.

Signed-off-by: Shannon Zhao <redacted>
---
  arch/arm/kvm/arm.c                |  4 +++
  arch/arm64/include/asm/kvm_host.h |  2 ++
  arch/arm64/include/asm/pmu.h      |  2 ++
  arch/arm64/kvm/Kconfig            |  7 +++++
  arch/arm64/kvm/Makefile           |  1 +
  arch/arm64/kvm/reset.c            |  3 +++
  include/kvm/arm_pmu.h             | 54 ++++++++++++++++++++++++++++++++++++++
  virt/kvm/arm/pmu.c                | 55 +++++++++++++++++++++++++++++++++++++++
  8 files changed, 128 insertions(+)
  create mode 100644 include/kvm/arm_pmu.h
  create mode 100644 virt/kvm/arm/pmu.c

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index bc738d2..4e82625 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c

@@ -28,6 +28,7 @@
  #include <linux/sched.h>
  #include <linux/kvm.h>
  #include <trace/events/kvm.h>
+#include <kvm/arm_pmu.h>

  #define CREATE_TRACE_POINTS
  #include "trace.h"

@@ -278,6 +279,9 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
  	/* Set up the timer */
  	kvm_timer_vcpu_init(vcpu);

+	/* Set up the PMU */
+	kvm_pmu_init(vcpu);
+
  	return 0;
  }

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 2709db2..3c88873 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h

@@ -42,6 +42,7 @@

  #include <kvm/arm_vgic.h>
  #include <kvm/arm_arch_timer.h>
+#include <kvm/arm_pmu.h>

  #define KVM_VCPU_MAX_FEATURES 3

@@ -116,6 +117,7 @@ struct kvm_vcpu_arch {
  	/* VGIC state */
  	struct vgic_cpu vgic_cpu;
  	struct arch_timer_cpu timer_cpu;
+	struct kvm_pmu pmu;

  	/*
  	 * Anything that is not used directly from assembly code goes

diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h
index b9f394a..95681e6 100644
--- a/arch/arm64/include/asm/pmu.h
+++ b/arch/arm64/include/asm/pmu.h

@@ -19,6 +19,8 @@
  #ifndef __ASM_PMU_H
  #define __ASM_PMU_H

+#include <linux/perf_event.h>
+
  #define ARMV8_MAX_COUNTERS      32
  #define ARMV8_COUNTER_MASK      (ARMV8_MAX_COUNTERS - 1)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index bfffe8f..eae3a1b 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig

@@ -31,6 +31,7 @@ config KVM
  	select KVM_VFIO
  	select HAVE_KVM_EVENTFD
  	select HAVE_KVM_IRQFD
+	select KVM_ARM_PMU
  	---help---
  	  Support hosting virtualized guest machines.

@@ -52,4 +53,10 @@ config KVM_ARM_MAX_VCPUS
  	  large, so only choose a reasonable number that you expect to
  	  actually use.

+config KVM_ARM_PMU
+	bool
+	depends on KVM_ARM_HOST
+	---help---
+	  Adds support for the Performance Monitoring in virtual machines.

Adds support for a virtual Performance Monitoring Unit (PMU) in virtual
machines.

quoted

+
  endif # VIRTUALIZATION

diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index f90f4aa..78db4ee 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile

@@ -27,3 +27,4 @@ kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic-v3.o
  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/vgic-v3-emul.o
  kvm-$(CONFIG_KVM_ARM_HOST) += vgic-v3-switch.o
  kvm-$(CONFIG_KVM_ARM_HOST) += $(KVM)/arm/arch_timer.o
+kvm-$(CONFIG_KVM_ARM_PMU) += $(KVM)/arm/pmu.o

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index 0b43265..ee2c2e9 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c

@@ -107,5 +107,8 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
  	/* Reset timer */
  	kvm_timer_vcpu_reset(vcpu, cpu_vtimer_irq);

+	/* Reset PMU */
+	kvm_pmu_vcpu_reset(vcpu);
+
  	return 0;
  }

diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
new file mode 100644
index 0000000..27d14ca
--- /dev/null
+++ b/include/kvm/arm_pmu.h

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2015 Linaro Ltd.
+ * Author: Shannon Zhao <shannon.zhao@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ASM_ARM_KVM_PMU_H
+#define __ASM_ARM_KVM_PMU_H
+
+#include <asm/pmu.h>
+#include <linux/irq_work.h>
+
+struct kvm_pmc {
+	u8 idx;

which index is this?  Does it map to something architecturally or is it
just the array index number?

It's the index of the PMU counter.

sorry, I don't feel this answers my question? ;)

This index is only used for kvm_pmu_perf_overflow to locate the index of 
this PMU counter and kvm_pmu_perf_overflow will set the corresponding 
bit of overflow_status to show whether this counter overflows.

See patch 17/18:

+static void kvm_pmu_perf_overflow(struct perf_event *perf_event,
+				  struct perf_sample_data *data,
+				  struct pt_regs *regs)
+{
+	struct kvm_pmc *pmc = perf_event->overflow_handler_context;
+	struct kvm_vcpu *vcpu = pmc->vcpu;
+	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+
+	if (pmc->interrupt == true) {
+		__set_bit(pmc->idx, (unsigned long *)&pmu->overflow_status);

quoted

quoted

quoted

+	u64 counter;
+	u64 eventsel;

does this map to PMEVTYPER<n>_EL0.evtCount?

No, it just stores the event type.

can you specify more clearly what this maps to/how I derive its meaning?

Is this a perf (Linux) event type number, or an architecturally defined
thing?

Yes, it stores a perf event type number. This is used for 
kvm_pmu_set_counter_event_type to check whether event type of this time 
is same with the previous one. If they are same, it will return and 
doesn't create a new perf event for it and just reuses the previous one.

See PATCH 07/18:

+void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned 
long data,
+				    unsigned long select_idx)
+{
+	struct kvm_pmu *pmu = &vcpu->arch.pmu;
+	struct kvm_pmc *pmc = &pmu->pmc[select_idx];
+	struct perf_event *event;
+	struct perf_event_attr attr;
+	unsigned config, type = PERF_TYPE_RAW;
+
+	if ((data & ARMV8_EVTYPE_EVENT) == pmc->eventsel)
+		return;

Thanks,
-Christoffer

-- 
Shannon