[PATCH v7 19/19] KVM: ARM64: Add a new kvm ARM PMU device

Shannon Zhao
2015-12-15T15:50:54Z

On 2015/12/15 23:33, Marc Zyngier wrote:
> On 15/12/15 08:49, Shannon Zhao wrote:
>> >From: Shannon Zhao<shannon.zhao@linaro.org>
>> >
>> >Add a new kvm device type KVM_DEV_TYPE_ARM_PMU_V3 for ARM PMU. Implement
>> >the kvm_device_ops for it.
>> >
>> >Signed-off-by: Shannon Zhao<shannon.zhao@linaro.org>
>> >---
>> > Documentation/virtual/kvm/devices/arm-pmu.txt | 16 ++++
>> > arch/arm64/include/uapi/asm/kvm.h | 3 +
>> > include/linux/kvm_host.h | 1 +
>> > include/uapi/linux/kvm.h | 2 +
>> > virt/kvm/arm/pmu.c | 115 ++++++++++++++++++++++++++
>> > virt/kvm/kvm_main.c | 4 +
>> > 6 files changed, 141 insertions(+)
>> > create mode 100644 Documentation/virtual/kvm/devices/arm-pmu.txt
>> >
>> >diff --git a/Documentation/virtual/kvm/devices/arm-pmu.txt b/Documentation/virtual/kvm/devices/arm-pmu.txt
>> >new file mode 100644
>> >index 0000000..5121f1f
>> >--- /dev/null
>> >+++ b/Documentation/virtual/kvm/devices/arm-pmu.txt
>> >@@ -0,0 +1,16 @@
>> >+ARM Virtual Performance Monitor Unit (vPMU)
>> >+===========================================
>> >+
>> >+Device types supported:
>> >+ KVM_DEV_TYPE_ARM_PMU_V3 ARM Performance Monitor Unit v3
>> >+
>> >+Instantiate one PMU instance for per VCPU through this API.
>> >+
>> >+Groups:
>> >+ KVM_DEV_ARM_PMU_GRP_IRQ
>> >+ Attributes:
>> >+ A value describing the interrupt number of PMU overflow interrupt. This
>> >+ interrupt should be a PPI.
>> >+
>> >+ Errors:
>> >+ -EINVAL: Value set is out of the expected range (from 16 to 31)
>> >diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
>> >index 2d4ca4b..568afa2 100644
>> >--- a/arch/arm64/include/uapi/asm/kvm.h
>> >+++ b/arch/arm64/include/uapi/asm/kvm.h
>> >@@ -204,6 +204,9 @@ struct kvm_arch_memory_slot {
>> > #define KVM_DEV_ARM_VGIC_GRP_CTRL 4
>> > #define KVM_DEV_ARM_VGIC_CTRL_INIT 0
>> >
>> >+/* Device Control API: ARM PMU */
>> >+#define KVM_DEV_ARM_PMU_GRP_IRQ 0
>> >+
>> > /* KVM_IRQ_LINE irq field index values */
>> > #define KVM_ARM_IRQ_TYPE_SHIFT 24
>> > #define KVM_ARM_IRQ_TYPE_MASK 0xff
>> >diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>> >index c923350..608dea6 100644
>> >--- a/include/linux/kvm_host.h
>> >+++ b/include/linux/kvm_host.h
>> >@@ -1161,6 +1161,7 @@ extern struct kvm_device_ops kvm_mpic_ops;
>> > extern struct kvm_device_ops kvm_xics_ops;
>> > extern struct kvm_device_ops kvm_arm_vgic_v2_ops;
>> > extern struct kvm_device_ops kvm_arm_vgic_v3_ops;
>> >+extern struct kvm_device_ops kvm_arm_pmu_ops;
>> >
>> > #ifdef CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT
>> >
>> >diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> >index 03f3618..4ba6fdd 100644
>> >--- a/include/uapi/linux/kvm.h
>> >+++ b/include/uapi/linux/kvm.h
>> >@@ -1032,6 +1032,8 @@ enum kvm_device_type {
>> > #define KVM_DEV_TYPE_FLIC KVM_DEV_TYPE_FLIC
>> > KVM_DEV_TYPE_ARM_VGIC_V3,
>> > #define KVM_DEV_TYPE_ARM_VGIC_V3 KVM_DEV_TYPE_ARM_VGIC_V3
>> >+ KVM_DEV_TYPE_ARM_PMU_V3,
>> >+#define KVM_DEV_TYPE_ARM_PMU_V3 KVM_DEV_TYPE_ARM_PMU_V3
>> > KVM_DEV_TYPE_MAX,
>> > };
>> >
>> >diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
>> >index d113ee4..1965d0d 100644
>> >--- a/virt/kvm/arm/pmu.c
>> >+++ b/virt/kvm/arm/pmu.c
>> >@@ -19,6 +19,7 @@
>> > #include <linux/kvm.h>
>> > #include <linux/kvm_host.h>
>> > #include <linux/perf_event.h>
>> >+#include <linux/uaccess.h>
>> > #include <asm/kvm_emulate.h>
>> > #include <kvm/arm_pmu.h>
>> > #include <kvm/arm_vgic.h>
>> >@@ -357,3 +358,117 @@ void kvm_pmu_set_counter_event_type(struct kvm_vcpu *vcpu, u64 data,
>> >
>> > pmc->perf_event = event;
>> > }
>> >+
>> >+static inline bool kvm_arm_pmu_initialized(struct kvm_vcpu *vcpu)
>> >+{
>> >+ return vcpu->arch.pmu.irq_num != -1;
>> >+}
>> >+
>> >+static int kvm_arm_pmu_irq_access(struct kvm *kvm, int *irq, bool is_set)
>> >+{
>> >+ int j;
>> >+ struct kvm_vcpu *vcpu;
>> >+
>> >+ kvm_for_each_vcpu(j, vcpu, kvm) {
>> >+ struct kvm_pmu *pmu = &vcpu->arch.pmu;
>> >+
>> >+ if (!is_set) {
>> >+ if (!kvm_arm_pmu_initialized(vcpu))
>> >+ return -EBUSY;
> Returning -EBUSY is a bit odd. Maybe -EINVAL? But this seems weird
> anyway. Actually, why would you return an error in this case?
>
While this is a unexpected operation from user space and it's already
initialized and working, so I think it should return an error to user
and tell user that it's already initialized and working (this should
mean "busy" ?).

--
Shannon