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1.. SPDX-License-Identifier: GPL-2.02 3====================================4FLIC (floating interrupt controller)5====================================6 7FLIC handles floating (non per-cpu) interrupts, i.e. I/O, service and some8machine check interruptions. All interrupts are stored in a per-vm list of9pending interrupts. FLIC performs operations on this list.10 11Only one FLIC instance may be instantiated.12 13FLIC provides support to14- add interrupts (KVM_DEV_FLIC_ENQUEUE)15- inspect currently pending interrupts (KVM_FLIC_GET_ALL_IRQS)16- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS)17- purge one pending floating I/O interrupt (KVM_DEV_FLIC_CLEAR_IO_IRQ)18- enable/disable for the guest transparent async page faults19- register and modify adapter interrupt sources (KVM_DEV_FLIC_ADAPTER_*)20- modify AIS (adapter-interruption-suppression) mode state (KVM_DEV_FLIC_AISM)21- inject adapter interrupts on a specified adapter (KVM_DEV_FLIC_AIRQ_INJECT)22- get/set all AIS mode states (KVM_DEV_FLIC_AISM_ALL)23 24Groups:25 KVM_DEV_FLIC_ENQUEUE26 Passes a buffer and length into the kernel which are then injected into27 the list of pending interrupts.28 attr->addr contains the pointer to the buffer and attr->attr contains29 the length of the buffer.30 The format of the data structure kvm_s390_irq as it is copied from userspace31 is defined in usr/include/linux/kvm.h.32 33 KVM_DEV_FLIC_GET_ALL_IRQS34 Copies all floating interrupts into a buffer provided by userspace.35 When the buffer is too small it returns -ENOMEM, which is the indication36 for userspace to try again with a bigger buffer.37 38 -ENOBUFS is returned when the allocation of a kernelspace buffer has39 failed.40 41 -EFAULT is returned when copying data to userspace failed.42 All interrupts remain pending, i.e. are not deleted from the list of43 currently pending interrupts.44 attr->addr contains the userspace address of the buffer into which all45 interrupt data will be copied.46 attr->attr contains the size of the buffer in bytes.47 48 KVM_DEV_FLIC_CLEAR_IRQS49 Simply deletes all elements from the list of currently pending floating50 interrupts. No interrupts are injected into the guest.51 52 KVM_DEV_FLIC_CLEAR_IO_IRQ53 Deletes one (if any) I/O interrupt for a subchannel identified by the54 subsystem identification word passed via the buffer specified by55 attr->addr (address) and attr->attr (length).56 57 KVM_DEV_FLIC_APF_ENABLE58 Enables async page faults for the guest. So in case of a major page fault59 the host is allowed to handle this async and continues the guest.60 61 KVM_DEV_FLIC_APF_DISABLE_WAIT62 Disables async page faults for the guest and waits until already pending63 async page faults are done. This is necessary to trigger a completion interrupt64 for every init interrupt before migrating the interrupt list.65 66 KVM_DEV_FLIC_ADAPTER_REGISTER67 Register an I/O adapter interrupt source. Takes a kvm_s390_io_adapter68 describing the adapter to register::69 70 struct kvm_s390_io_adapter {71 __u32 id;72 __u8 isc;73 __u8 maskable;74 __u8 swap;75 __u8 flags;76 };77 78 id contains the unique id for the adapter, isc the I/O interruption subclass79 to use, maskable whether this adapter may be masked (interrupts turned off),80 swap whether the indicators need to be byte swapped, and flags contains81 further characteristics of the adapter.82 83 Currently defined values for 'flags' are:84 85 - KVM_S390_ADAPTER_SUPPRESSIBLE: adapter is subject to AIS86 (adapter-interrupt-suppression) facility. This flag only has an effect if87 the AIS capability is enabled.88 89 Unknown flag values are ignored.90 91 92 KVM_DEV_FLIC_ADAPTER_MODIFY93 Modifies attributes of an existing I/O adapter interrupt source. Takes94 a kvm_s390_io_adapter_req specifying the adapter and the operation::95 96 struct kvm_s390_io_adapter_req {97 __u32 id;98 __u8 type;99 __u8 mask;100 __u16 pad0;101 __u64 addr;102 };103 104 id specifies the adapter and type the operation. The supported operations105 are:106 107 KVM_S390_IO_ADAPTER_MASK108 mask or unmask the adapter, as specified in mask109 110 KVM_S390_IO_ADAPTER_MAP111 This is now a no-op. The mapping is purely done by the irq route.112 KVM_S390_IO_ADAPTER_UNMAP113 This is now a no-op. The mapping is purely done by the irq route.114 115 KVM_DEV_FLIC_AISM116 modify the adapter-interruption-suppression mode for a given isc if the117 AIS capability is enabled. Takes a kvm_s390_ais_req describing::118 119 struct kvm_s390_ais_req {120 __u8 isc;121 __u16 mode;122 };123 124 isc contains the target I/O interruption subclass, mode the target125 adapter-interruption-suppression mode. The following modes are126 currently supported:127 128 - KVM_S390_AIS_MODE_ALL: ALL-Interruptions Mode, i.e. airq injection129 is always allowed;130 - KVM_S390_AIS_MODE_SINGLE: SINGLE-Interruption Mode, i.e. airq131 injection is only allowed once and the following adapter interrupts132 will be suppressed until the mode is set again to ALL-Interruptions133 or SINGLE-Interruption mode.134 135 KVM_DEV_FLIC_AIRQ_INJECT136 Inject adapter interrupts on a specified adapter.137 attr->attr contains the unique id for the adapter, which allows for138 adapter-specific checks and actions.139 For adapters subject to AIS, handle the airq injection suppression for140 an isc according to the adapter-interruption-suppression mode on condition141 that the AIS capability is enabled.142 143 KVM_DEV_FLIC_AISM_ALL144 Gets or sets the adapter-interruption-suppression mode for all ISCs. Takes145 a kvm_s390_ais_all describing::146 147 struct kvm_s390_ais_all {148 __u8 simm; /* Single-Interruption-Mode mask */149 __u8 nimm; /* No-Interruption-Mode mask *150 };151 152 simm contains Single-Interruption-Mode mask for all ISCs, nimm contains153 No-Interruption-Mode mask for all ISCs. Each bit in simm and nimm corresponds154 to an ISC (MSB0 bit 0 to ISC 0 and so on). The combination of simm bit and155 nimm bit presents AIS mode for a ISC.156 157 KVM_DEV_FLIC_AISM_ALL is indicated by KVM_CAP_S390_AIS_MIGRATION.158 159Note: The KVM_SET_DEVICE_ATTR/KVM_GET_DEVICE_ATTR device ioctls executed on160FLIC with an unknown group or attribute gives the error code EINVAL (instead of161ENXIO, as specified in the API documentation). It is not possible to conclude162that a FLIC operation is unavailable based on the error code resulting from a163usage attempt.164 165.. note:: The KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl will return EINVAL in case a166 zero schid is specified.167