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
         -ENXIO: The overflow interrupt not set when attempting to get it
         -ENODEV: PMUv3 not supported
         -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: -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

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.


2. GROUP: KVM_ARM_VCPU_TIMER_CTRL
Architectures: ARM,ARM64

2.1. ATTRIBUTE: KVM_ARM_VCPU_TIMER_IRQ_VTIMER
2.2. ATTRIBUTE: 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 Documentation/virt/kvm/arm/pvtime.txt for more information
including the layout of the stolen time structure.
