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Diffstat (limited to 'Documentation/virtual/kvm/api.txt')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 3c248f772ae6..3b4e76e5201e 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -4147,3 +4147,45 @@ This capability, if KVM_CHECK_EXTENSION indicates that it is available, means that that the kernel can support guests using the hashed page table MMU defined in Power ISA V3.00 (as implemented in the POWER9 processor), including in-memory segment tables. + + +8.5 KVM_CAP_ARM_USER_IRQ + +Architectures: arm, arm64 +This capability, if KVM_CHECK_EXTENSION indicates that it is available, means +that if userspace creates a VM without an in-kernel interrupt controller, it +will be notified of changes to the output level of in-kernel emulated devices, +which can generate virtual interrupts, presented to the VM. +For such VMs, on every return to userspace, the kernel +updates the vcpu's run->s.regs.device_irq_level field to represent the actual +output level of the device. + +Whenever kvm detects a change in the device output level, kvm guarantees at +least one return to userspace before running the VM. This exit could either +be a KVM_EXIT_INTR or any other exit event, like KVM_EXIT_MMIO. This way, +userspace can always sample the device output level and re-compute the state of +the userspace interrupt controller. Userspace should always check the state +of run->s.regs.device_irq_level on every kvm exit. +The value in run->s.regs.device_irq_level can represent both level and edge +triggered interrupt signals, depending on the device. Edge triggered interrupt +signals will exit to userspace with the bit in run->s.regs.device_irq_level +set exactly once per edge signal. + +The field run->s.regs.device_irq_level is available independent of +run->kvm_valid_regs or run->kvm_dirty_regs bits. + +If KVM_CAP_ARM_USER_IRQ is supported, the KVM_CHECK_EXTENSION ioctl returns a +number larger than 0 indicating the version of this capability is implemented +and thereby which bits in in run->s.regs.device_irq_level can signal values. + +Currently the following bits are defined for the device_irq_level bitmap: + + KVM_CAP_ARM_USER_IRQ >= 1: + + KVM_ARM_DEV_EL1_VTIMER - EL1 virtual timer + KVM_ARM_DEV_EL1_PTIMER - EL1 physical timer + KVM_ARM_DEV_PMU - ARM PMU overflow interrupt signal + +Future versions of kvm may implement additional events. These will get +indicated by returning a higher number from KVM_CHECK_EXTENSION and will be +listed above. |