From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
When we use tools like perf on host, perf passes the event type and the
id of this event type category to kernel, then kernel will map them to
hardware event number and write this number to PMU PMEVTYPER<n>_EL0
register. While we're trapping and emulating guest accesses to PMU
registers, we get the hardware event number and map it to the event type
and the id reversely. Then call perf_event kernel API to create an event
for it.
Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
---
arch/arm64/include/asm/pmu.h | 2 +
arch/arm64/kvm/Makefile | 1 +
include/kvm/arm_pmu.h | 15 +++
virt/kvm/arm/pmu.c | 240 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 258 insertions(+)
create mode 100644 virt/kvm/arm/pmu.c
diff --git a/arch/arm64/include/asm/pmu.h b/arch/arm64/include/asm/pmu.h
index 95681e6..42e7093 100644
--- a/arch/arm64/include/asm/pmu.h
+++ b/arch/arm64/include/asm/pmu.h
@@ -33,6 +33,8 @@
#define ARMV8_PMCR_D (1 << 3) /* CCNT counts every 64th cpu cycle */
#define ARMV8_PMCR_X (1 << 4) /* Export to ETM */
#define ARMV8_PMCR_DP (1 << 5) /* Disable CCNT if non-invasive debug*/
+/* Determines which PMCCNTR_EL0 bit generates an overflow */
+#define ARMV8_PMCR_LC (1 << 6)
#define ARMV8_PMCR_N_SHIFT 11 /* Number of counters supported */
#define ARMV8_PMCR_N_MASK 0x1f
#define ARMV8_PMCR_MASK 0x3f /* Mask for writable bits */
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/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
index 64af88a..387ec6f 100644
--- a/include/kvm/arm_pmu.h
+++ b/include/kvm/arm_pmu.h
@@ -36,4 +36,19 @@ struct kvm_pmu {
#endif
};
+#ifdef CONFIG_KVM_ARM_PMU
+unsigned long kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
+ unsigned long select_idx);
+void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
+ unsigned long select_idx);
+#else
+unsigned long kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
+ unsigned long select_idx)
+{
+ return 0;
+}
+void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, unsigned long data,
+ unsigned long select_idx) {}
+#endif
+
#endif
diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
new file mode 100644
index 0000000..0c7fe5c
--- /dev/null
+++ b/virt/kvm/arm/pmu.c
@@ -0,0 +1,240 @@
+/*
+ * Copyright (C) 2015 Linaro Ltd.
+ * Author: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
+ *
+ * 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/>.
+ */
+
+#include <linux/cpu.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/perf_event.h>
+#include <asm/kvm_emulate.h>
+#include <kvm/arm_pmu.h>
+
+/* PMU HW events mapping. */
+static struct kvm_pmu_hw_event_map {
+ unsigned eventsel;
+ unsigned event_type;
+} kvm_pmu_hw_events[] = {
+ [0] = { 0x11, PERF_COUNT_HW_CPU_CYCLES },
+ [1] = { 0x08, PERF_COUNT_HW_INSTRUCTIONS },
+ [2] = { 0x04, PERF_COUNT_HW_CACHE_REFERENCES },
+ [3] = { 0x03, PERF_COUNT_HW_CACHE_MISSES },
+ [4] = { 0x10, PERF_COUNT_HW_BRANCH_MISSES },
+};
+
+/* PMU HW cache events mapping. */
+static struct kvm_pmu_hw_cache_event_map {
+ unsigned eventsel;
+ unsigned cache_type;
+ unsigned cache_op;
+ unsigned cache_result;
+} kvm_pmu_hw_cache_events[] = {
+ [0] = { 0x12, PERF_COUNT_HW_CACHE_BPU, PERF_COUNT_HW_CACHE_OP_READ,
+ PERF_COUNT_HW_CACHE_RESULT_ACCESS },
+ [1] = { 0x12, PERF_COUNT_HW_CACHE_BPU, PERF_COUNT_HW_CACHE_OP_WRITE,
+ PERF_COUNT_HW_CACHE_RESULT_ACCESS },
+};
+
+static void kvm_pmu_set_evttyper(struct kvm_vcpu *vcpu, unsigned long idx,
+ unsigned long val)
+{
+ if (!vcpu_mode_is_32bit(vcpu))
+ vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + idx) = val;
+ else
+ vcpu_cp15(vcpu, c14_PMEVTYPER0 + idx) = val;
+}
+
+static unsigned long kvm_pmu_get_evttyper(struct kvm_vcpu *vcpu,
+ unsigned long idx)
+{
+ if (!vcpu_mode_is_32bit(vcpu))
+ return vcpu_sys_reg(vcpu, PMEVTYPER0_EL0 + idx)
+ & ARMV8_EVTYPE_EVENT;
+ else
+ return vcpu_cp15(vcpu, c14_PMEVTYPER0 + idx)
+ & ARMV8_EVTYPE_EVENT;
+}
+
+/**
+ * kvm_pmu_stop_counter - stop PMU counter for the selected counter
+ * @vcpu: The vcpu pointer
+ * @select_idx: The counter index
+ *
+ * If this counter has been configured to monitor some event, disable and
+ * release it.
+ */
+static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu,
+ unsigned long select_idx)
+{
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
+ struct kvm_pmc *pmc = &pmu->pmc[select_idx];
+
+ if (pmc->perf_event) {
+ perf_event_disable(pmc->perf_event);
+ perf_event_release_kernel(pmc->perf_event);
+ pmc->perf_event = NULL;
+ }
+ kvm_pmu_set_evttyper(vcpu, select_idx, ARMV8_EVTYPE_EVENT);
+}
+
+/**
+ * kvm_pmu_get_counter_value - get PMU counter value
+ * @vcpu: The vcpu pointer
+ * @select_idx: The counter index
+ */
+unsigned long kvm_pmu_get_counter_value(struct kvm_vcpu *vcpu,
+ unsigned long select_idx)
+{
+ u64 enabled, running;
+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
+ struct kvm_pmc *pmc = &pmu->pmc[select_idx];
+ unsigned long counter;
+
+ if (!vcpu_mode_is_32bit(vcpu))
+ counter = vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + select_idx);
+ else
+ counter = vcpu_cp15(vcpu, c14_PMEVCNTR0 + select_idx);
+
+ if (pmc->perf_event) {
+ counter += perf_event_read_value(pmc->perf_event,
+ &enabled, &running);
+ }
+ return counter;
+}
+
+/**
+ * kvm_pmu_find_hw_event - find hardware event
+ * @pmu: The pmu pointer
+ * @event_select: The number of selected event type
+ *
+ * Based on the number of selected event type, find out whether it belongs to
+ * PERF_TYPE_HARDWARE. If so, return the corresponding event id.
+ */
+static unsigned kvm_pmu_find_hw_event(struct kvm_pmu *pmu,
+ unsigned long event_select)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(kvm_pmu_hw_events); i++)
+ if (kvm_pmu_hw_events[i].eventsel == event_select)
+ return kvm_pmu_hw_events[i].event_type;
+
+ return PERF_COUNT_HW_MAX;
+}
+
+/**
+ * kvm_pmu_find_hw_cache_event - find hardware cache event
+ * @pmu: The pmu pointer
+ * @event_select: The number of selected event type
+ *
+ * Based on the number of selected event type, find out whether it belongs to
+ * PERF_TYPE_HW_CACHE. If so, return the corresponding event id.
+ */
+static unsigned kvm_pmu_find_hw_cache_event(struct kvm_pmu *pmu,
+ unsigned long event_select)
+{
+ int i;
+ unsigned config;
+
+ for (i = 0; i < ARRAY_SIZE(kvm_pmu_hw_cache_events); i++)
+ if (kvm_pmu_hw_cache_events[i].eventsel == event_select) {
+ config = (kvm_pmu_hw_cache_events[i].cache_type & 0xff)
+ | ((kvm_pmu_hw_cache_events[i].cache_op & 0xff) << 8)
+ | ((kvm_pmu_hw_cache_events[i].cache_result & 0xff) << 16);
+ }
+
+ return PERF_COUNT_HW_CACHE_MAX;
+}
+
+/**
+ * kvm_pmu_set_counter_event_type - set selected counter to monitor some event
+ * @vcpu: The vcpu pointer
+ * @data: The data guest writes to PMXEVTYPER_EL0
+ * @select_idx: The number of selected counter
+ *
+ * When OS accesses PMXEVTYPER_EL0, that means it wants to set a PMC to count an
+ * event with given hardware event number. Here we call perf_event API to
+ * emulate this action and create a kernel perf event for it.
+ */
+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;
+ unsigned int new_eventsel, old_eventsel;
+ u64 counter;
+ int overflow_bit, pmcr_lc;
+
+ old_eventsel = kvm_pmu_get_evttyper(vcpu, select_idx);
+ new_eventsel = data & ARMV8_EVTYPE_EVENT;
+ if (new_eventsel == old_eventsel) {
+ if (pmc->perf_event)
+ local64_set(&pmc->perf_event->count, 0);
+ return;
+ }
+
+ kvm_pmu_stop_counter(vcpu, select_idx);
+ kvm_pmu_set_evttyper(vcpu, select_idx, data);
+
+ config = kvm_pmu_find_hw_event(pmu, new_eventsel);
+ if (config != PERF_COUNT_HW_MAX) {
+ type = PERF_TYPE_HARDWARE;
+ } else {
+ config = kvm_pmu_find_hw_cache_event(pmu, new_eventsel);
+ if (config != PERF_COUNT_HW_CACHE_MAX)
+ type = PERF_TYPE_HW_CACHE;
+ }
+
+ if (type == PERF_TYPE_RAW)
+ config = new_eventsel;
+
+ memset(&attr, 0, sizeof(struct perf_event_attr));
+ attr.type = type;
+ attr.size = sizeof(attr);
+ attr.pinned = 1;
+ attr.disabled = 1;
+ attr.exclude_user = data & ARMV8_EXCLUDE_EL0 ? 1 : 0;
+ attr.exclude_kernel = data & ARMV8_EXCLUDE_EL1 ? 1 : 0;
+ attr.exclude_host = 1; /* Don't count host events */
+ attr.config = config;
+
+ overflow_bit = 31; /* Generic counters are 32-bit registers*/
+ if (new_eventsel == 0x11) {
+ /* Cycle counter overflow on increment that changes PMCCNTR[63]
+ * or PMCCNTR[31] from 1 to 0 according to the value of
+ * ARMV8_PMCR_LC
+ */
+ if (!vcpu_mode_is_32bit(vcpu))
+ pmcr_lc = vcpu_sys_reg(vcpu, PMCR_EL0) & ARMV8_PMCR_LC;
+ else
+ pmcr_lc = vcpu_cp15(vcpu, c9_PMCR) & ARMV8_PMCR_LC;
+
+ overflow_bit = pmcr_lc ? 63 : 31;
+ }
+ counter = kvm_pmu_get_counter_value(vcpu, select_idx);
+ /* The initial sample period (overflow count) of an event. */
+ attr.sample_period = (-counter) & (((u64)1 << overflow_bit) - 1);
+
+ event = perf_event_create_kernel_counter(&attr, -1, current, NULL, pmc);
+ if (IS_ERR(event)) {
+ printk_once("kvm: pmu event creation failed %ld\n",
+ PTR_ERR(event));
+ return;
+ }
+ pmc->perf_event = event;
+}
--
2.0.4
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