Generic vcpu interface¶

The virtual cpu “device” also accepts the ioctls KVM_SET_DEVICE_ATTR, KVM_GET_DEVICE_ATTR, and KVM_HAS_DEVICE_ATTR. The interface uses the same struct kvm_device_attr as other devices, but targets VCPU-wide settings and controls.

The groups and attributes per virtual cpu, if any, are architecture specific.

1. GROUP: KVM_ARM_VCPU_PMU_V3_CTRL¶

Architectures:	ARM64

1.1. ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_IRQ¶

Parameters:	in kvm_device_attr.addr the address for PMU overflow interrupt is a pointer to an int

Returns:

-EBUSY The PMU overflow interrupt is already set

-EFAULT Error reading interrupt number

-ENXIO PMUv3 not supported or the overflow interrupt not set when attempting to get it

-ENODEV KVM_ARM_VCPU_PMU_V3 feature missing from VCPU

-EINVAL Invalid PMU overflow interrupt number supplied or trying to set the IRQ number without using an in-kernel irqchip.

A value describing the PMUv3 (Performance Monitor Unit v3) overflow interrupt number for this vcpu. This interrupt could be a PPI or SPI, but the interrupt type must be same for each vcpu. As a PPI, the interrupt number is the same for all vcpus, while as an SPI it must be a separate number per vcpu.

1.2 ATTRIBUTE: KVM_ARM_VCPU_PMU_V3_INIT¶

Parameters:	no additional parameter in kvm_device_attr.addr

Returns:

-EEXIST Interrupt number already used

-ENODEV PMUv3 not supported or GIC not initialized

-ENXIO PMUv3 not supported, missing VCPU feature or interrupt number not set

-EBUSY PMUv3 already initialized

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¶

Architectures:	ARM, ARM64

2.1. ATTRIBUTES: KVM_ARM_VCPU_TIMER_IRQ_VTIMER, KVM_ARM_VCPU_TIMER_IRQ_PTIMER¶

Parameters:	in kvm_device_attr.addr the address for the timer interrupt is a pointer to an int

Returns:

-EINVAL Invalid timer interrupt number

-EBUSY One or more VCPUs has already run

A value describing the architected timer interrupt number when connected to an in-kernel virtual GIC. These must be a PPI (16 <= intid < 32). Setting the attribute overrides the default values (see below).

KVM_ARM_VCPU_TIMER_IRQ_VTIMER	The EL1 virtual timer intid (default: 27)
KVM_ARM_VCPU_TIMER_IRQ_PTIMER	The EL1 physical timer intid (default: 30)

Setting the same PPI for different timers will prevent the VCPUs from running. Setting the interrupt number on a VCPU configures all VCPUs created at that time to use the number provided for a given timer, overwriting any previously configured values on other VCPUs. Userspace should configure the interrupt numbers on at least one VCPU after creating all VCPUs and before running any VCPUs.

3. GROUP: KVM_ARM_VCPU_PVTIME_CTRL¶

Architectures:	ARM64

3.1 ATTRIBUTE: KVM_ARM_VCPU_PVTIME_IPA¶

Parameters:	64-bit base address

Returns:

-ENXIO Stolen time not implemented

-EEXIST Base address already set for this VCPU

-EINVAL Base address not 64 byte aligned

Specifies the base address of the stolen time structure for this VCPU. The base address must be 64 byte aligned and exist within a valid guest memory region. See Paravirtualized time support for arm64 for more information including the layout of the stolen time structure.