167 lines
6.3 KiB
ReStructuredText
167 lines
6.3 KiB
ReStructuredText
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.. SPDX-License-Identifier: GPL-2.0
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====================================
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FLIC (floating interrupt controller)
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====================================
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FLIC handles floating (non per-cpu) interrupts, i.e. I/O, service and some
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machine check interruptions. All interrupts are stored in a per-vm list of
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pending interrupts. FLIC performs operations on this list.
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Only one FLIC instance may be instantiated.
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FLIC provides support to
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- add interrupts (KVM_DEV_FLIC_ENQUEUE)
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- inspect currently pending interrupts (KVM_FLIC_GET_ALL_IRQS)
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- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS)
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- purge one pending floating I/O interrupt (KVM_DEV_FLIC_CLEAR_IO_IRQ)
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- enable/disable for the guest transparent async page faults
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- register and modify adapter interrupt sources (KVM_DEV_FLIC_ADAPTER_*)
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- modify AIS (adapter-interruption-suppression) mode state (KVM_DEV_FLIC_AISM)
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- inject adapter interrupts on a specified adapter (KVM_DEV_FLIC_AIRQ_INJECT)
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- get/set all AIS mode states (KVM_DEV_FLIC_AISM_ALL)
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Groups:
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KVM_DEV_FLIC_ENQUEUE
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Passes a buffer and length into the kernel which are then injected into
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the list of pending interrupts.
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attr->addr contains the pointer to the buffer and attr->attr contains
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the length of the buffer.
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The format of the data structure kvm_s390_irq as it is copied from userspace
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is defined in usr/include/linux/kvm.h.
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KVM_DEV_FLIC_GET_ALL_IRQS
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Copies all floating interrupts into a buffer provided by userspace.
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When the buffer is too small it returns -ENOMEM, which is the indication
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for userspace to try again with a bigger buffer.
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-ENOBUFS is returned when the allocation of a kernelspace buffer has
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failed.
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-EFAULT is returned when copying data to userspace failed.
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All interrupts remain pending, i.e. are not deleted from the list of
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currently pending interrupts.
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attr->addr contains the userspace address of the buffer into which all
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interrupt data will be copied.
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attr->attr contains the size of the buffer in bytes.
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KVM_DEV_FLIC_CLEAR_IRQS
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Simply deletes all elements from the list of currently pending floating
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interrupts. No interrupts are injected into the guest.
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KVM_DEV_FLIC_CLEAR_IO_IRQ
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Deletes one (if any) I/O interrupt for a subchannel identified by the
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subsystem identification word passed via the buffer specified by
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attr->addr (address) and attr->attr (length).
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KVM_DEV_FLIC_APF_ENABLE
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Enables async page faults for the guest. So in case of a major page fault
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the host is allowed to handle this async and continues the guest.
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KVM_DEV_FLIC_APF_DISABLE_WAIT
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Disables async page faults for the guest and waits until already pending
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async page faults are done. This is necessary to trigger a completion interrupt
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for every init interrupt before migrating the interrupt list.
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KVM_DEV_FLIC_ADAPTER_REGISTER
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Register an I/O adapter interrupt source. Takes a kvm_s390_io_adapter
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describing the adapter to register::
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struct kvm_s390_io_adapter {
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__u32 id;
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__u8 isc;
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__u8 maskable;
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__u8 swap;
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__u8 flags;
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};
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id contains the unique id for the adapter, isc the I/O interruption subclass
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to use, maskable whether this adapter may be masked (interrupts turned off),
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swap whether the indicators need to be byte swapped, and flags contains
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further characteristics of the adapter.
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Currently defined values for 'flags' are:
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- KVM_S390_ADAPTER_SUPPRESSIBLE: adapter is subject to AIS
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(adapter-interrupt-suppression) facility. This flag only has an effect if
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the AIS capability is enabled.
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Unknown flag values are ignored.
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KVM_DEV_FLIC_ADAPTER_MODIFY
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Modifies attributes of an existing I/O adapter interrupt source. Takes
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a kvm_s390_io_adapter_req specifying the adapter and the operation::
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struct kvm_s390_io_adapter_req {
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__u32 id;
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__u8 type;
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__u8 mask;
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__u16 pad0;
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__u64 addr;
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};
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id specifies the adapter and type the operation. The supported operations
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are:
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KVM_S390_IO_ADAPTER_MASK
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mask or unmask the adapter, as specified in mask
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KVM_S390_IO_ADAPTER_MAP
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This is now a no-op. The mapping is purely done by the irq route.
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KVM_S390_IO_ADAPTER_UNMAP
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This is now a no-op. The mapping is purely done by the irq route.
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KVM_DEV_FLIC_AISM
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modify the adapter-interruption-suppression mode for a given isc if the
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AIS capability is enabled. Takes a kvm_s390_ais_req describing::
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struct kvm_s390_ais_req {
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__u8 isc;
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__u16 mode;
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};
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isc contains the target I/O interruption subclass, mode the target
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adapter-interruption-suppression mode. The following modes are
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currently supported:
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- KVM_S390_AIS_MODE_ALL: ALL-Interruptions Mode, i.e. airq injection
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is always allowed;
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- KVM_S390_AIS_MODE_SINGLE: SINGLE-Interruption Mode, i.e. airq
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injection is only allowed once and the following adapter interrupts
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will be suppressed until the mode is set again to ALL-Interruptions
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or SINGLE-Interruption mode.
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KVM_DEV_FLIC_AIRQ_INJECT
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Inject adapter interrupts on a specified adapter.
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attr->attr contains the unique id for the adapter, which allows for
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adapter-specific checks and actions.
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For adapters subject to AIS, handle the airq injection suppression for
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an isc according to the adapter-interruption-suppression mode on condition
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that the AIS capability is enabled.
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KVM_DEV_FLIC_AISM_ALL
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Gets or sets the adapter-interruption-suppression mode for all ISCs. Takes
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a kvm_s390_ais_all describing::
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struct kvm_s390_ais_all {
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__u8 simm; /* Single-Interruption-Mode mask */
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__u8 nimm; /* No-Interruption-Mode mask *
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};
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simm contains Single-Interruption-Mode mask for all ISCs, nimm contains
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No-Interruption-Mode mask for all ISCs. Each bit in simm and nimm corresponds
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to an ISC (MSB0 bit 0 to ISC 0 and so on). The combination of simm bit and
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nimm bit presents AIS mode for a ISC.
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KVM_DEV_FLIC_AISM_ALL is indicated by KVM_CAP_S390_AIS_MIGRATION.
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Note: The KVM_SET_DEVICE_ATTR/KVM_GET_DEVICE_ATTR device ioctls executed on
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FLIC with an unknown group or attribute gives the error code EINVAL (instead of
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ENXIO, as specified in the API documentation). It is not possible to conclude
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that a FLIC operation is unavailable based on the error code resulting from a
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usage attempt.
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.. note:: The KVM_DEV_FLIC_CLEAR_IO_IRQ ioctl will return EINVAL in case a
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zero schid is specified.
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