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Diffstat (limited to 'Documentation/virtual/kvm/devices/s390_flic.txt')
| -rw-r--r-- | Documentation/virtual/kvm/devices/s390_flic.txt | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt new file mode 100644 index 000000000000..4ceef53164b0 --- /dev/null +++ b/Documentation/virtual/kvm/devices/s390_flic.txt @@ -0,0 +1,91 @@ +FLIC (floating interrupt controller) +==================================== + +FLIC handles floating (non per-cpu) interrupts, i.e. I/O, service and some +machine check interruptions. All interrupts are stored in a per-vm list of +pending interrupts. FLIC performs operations on this list. + +Only one FLIC instance may be instantiated. + +FLIC provides support to +- add interrupts (KVM_DEV_FLIC_ENQUEUE) +- inspect currently pending interrupts (KVM_FLIC_GET_ALL_IRQS) +- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS) +- enable/disable for the guest transparent async page faults +- register and modify adapter interrupt sources (KVM_DEV_FLIC_ADAPTER_*) + +Groups: + KVM_DEV_FLIC_ENQUEUE + Passes a buffer and length into the kernel which are then injected into + the list of pending interrupts. + attr->addr contains the pointer to the buffer and attr->attr contains + the length of the buffer. + The format of the data structure kvm_s390_irq as it is copied from userspace + is defined in usr/include/linux/kvm.h. + + KVM_DEV_FLIC_GET_ALL_IRQS + Copies all floating interrupts into a buffer provided by userspace. + When the buffer is too small it returns -ENOMEM, which is the indication + for userspace to try again with a bigger buffer. + All interrupts remain pending, i.e. are not deleted from the list of + currently pending interrupts. + attr->addr contains the userspace address of the buffer into which all + interrupt data will be copied. + attr->attr contains the size of the buffer in bytes. + + KVM_DEV_FLIC_CLEAR_IRQS + Simply deletes all elements from the list of currently pending floating + interrupts. No interrupts are injected into the guest. + + KVM_DEV_FLIC_APF_ENABLE + Enables async page faults for the guest. So in case of a major page fault + the host is allowed to handle this async and continues the guest. + + KVM_DEV_FLIC_APF_DISABLE_WAIT + Disables async page faults for the guest and waits until already pending + async page faults are done. This is necessary to trigger a completion interrupt + for every init interrupt before migrating the interrupt list. + + KVM_DEV_FLIC_ADAPTER_REGISTER + Register an I/O adapter interrupt source. Takes a kvm_s390_io_adapter + describing the adapter to register: + +struct kvm_s390_io_adapter { + __u32 id; + __u8 isc; + __u8 maskable; + __u8 swap; + __u8 pad; +}; + + id contains the unique id for the adapter, isc the I/O interruption subclass + to use, maskable whether this adapter may be masked (interrupts turned off) + and swap whether the indicators need to be byte swapped. + + + KVM_DEV_FLIC_ADAPTER_MODIFY + Modifies attributes of an existing I/O adapter interrupt source. Takes + a kvm_s390_io_adapter_req specifiying the adapter and the operation: + +struct kvm_s390_io_adapter_req { + __u32 id; + __u8 type; + __u8 mask; + __u16 pad0; + __u64 addr; +}; + + id specifies the adapter and type the operation. The supported operations + are: + + KVM_S390_IO_ADAPTER_MASK + mask or unmask the adapter, as specified in mask + + KVM_S390_IO_ADAPTER_MAP + perform a gmap translation for the guest address provided in addr, + pin a userspace page for the translated address and add it to the + list of mappings + + KVM_S390_IO_ADAPTER_UNMAP + release a userspace page for the translated address specified in addr + from the list of mappings |