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author | Marc Zyngier <maz@kernel.org> | 2020-02-12 17:40:24 +0300 |
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committer | Marc Zyngier <maz@kernel.org> | 2020-09-29 16:19:40 +0300 |
commit | 8be86a5eec046cb8bd06b4393d373cd433a32cba (patch) | |
tree | 00aadfef39ad439141be3a2209c8a6065eb2adbe /Documentation | |
parent | 88865beca90621ae33217d5f23664d382f99205a (diff) | |
download | linux-8be86a5eec046cb8bd06b4393d373cd433a32cba.tar.xz |
KVM: arm64: Document PMU filtering API
Add a small blurb describing how the event filtering API gets used.
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Diffstat (limited to 'Documentation')
-rw-r--r-- | Documentation/virt/kvm/devices/vcpu.rst | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst index ca374d3fe085..c8b707afca6e 100644 --- a/Documentation/virt/kvm/devices/vcpu.rst +++ b/Documentation/virt/kvm/devices/vcpu.rst @@ -55,6 +55,52 @@ Request the initialization of the PMUv3. If using the PMUv3 with an in-kernel virtual GIC implementation, this must be done after initializing the in-kernel irqchip. +1.3 ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_FILTER +----------------------------------------- + +:Parameters: in kvm_device_attr.addr the address for a PMU event filter is a + pointer to a struct kvm_pmu_event_filter + +:Returns: + + ======= ====================================================== + -ENODEV: PMUv3 not supported or GIC not initialized + -ENXIO: PMUv3 not properly configured or in-kernel irqchip not + configured as required prior to calling this attribute + -EBUSY: PMUv3 already initialized + -EINVAL: Invalid filter range + ======= ====================================================== + +Request the installation of a PMU event filter described as follows: + +struct kvm_pmu_event_filter { + __u16 base_event; + __u16 nevents; + +#define KVM_PMU_EVENT_ALLOW 0 +#define KVM_PMU_EVENT_DENY 1 + + __u8 action; + __u8 pad[3]; +}; + +A filter range is defined as the range [@base_event, @base_event + @nevents), +together with an @action (KVM_PMU_EVENT_ALLOW or KVM_PMU_EVENT_DENY). The +first registered range defines the global policy (global ALLOW if the first +@action is DENY, global DENY if the first @action is ALLOW). Multiple ranges +can be programmed, and must fit within the event space defined by the PMU +architecture (10 bits on ARMv8.0, 16 bits from ARMv8.1 onwards). + +Note: "Cancelling" a filter by registering the opposite action for the same +range doesn't change the default action. For example, installing an ALLOW +filter for event range [0:10) as the first filter and then applying a DENY +action for the same range will leave the whole range as disabled. + +Restrictions: Event 0 (SW_INCR) is never filtered, as it doesn't count a +hardware event. Filtering event 0x1E (CHAIN) has no effect either, as it +isn't strictly speaking an event. Filtering the cycle counter is possible +using event 0x11 (CPU_CYCLES). + 2. GROUP: KVM_ARM_VCPU_TIMER_CTRL ================================= |