tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1FLIC (floating interrupt controller)
2====================================
3
4FLIC handles floating (non per-cpu) interrupts, i.e. I/O, service and some
5machine check interruptions. All interrupts are stored in a per-vm list of
6pending interrupts. FLIC performs operations on this list.
7
8Only one FLIC instance may be instantiated.
9
10FLIC provides support to
11- add interrupts (KVM_DEV_FLIC_ENQUEUE)
12- inspect currently pending interrupts (KVM_FLIC_GET_ALL_IRQS)
13- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS)
14- enable/disable for the guest transparent async page faults
15- register and modify adapter interrupt sources (KVM_DEV_FLIC_ADAPTER_*)
16
17Groups:
18 KVM_DEV_FLIC_ENQUEUE
19 Passes a buffer and length into the kernel which are then injected into
20 the list of pending interrupts.
21 attr->addr contains the pointer to the buffer and attr->attr contains
22 the length of the buffer.
23 The format of the data structure kvm_s390_irq as it is copied from userspace
24 is defined in usr/include/linux/kvm.h.
25
26 KVM_DEV_FLIC_GET_ALL_IRQS
27 Copies all floating interrupts into a buffer provided by userspace.
28 When the buffer is too small it returns -ENOMEM, which is the indication
29 for userspace to try again with a bigger buffer.
30 -ENOBUFS is returned when the allocation of a kernelspace buffer has
31 failed.
32 -EFAULT is returned when copying data to userspace failed.
33 All interrupts remain pending, i.e. are not deleted from the list of
34 currently pending interrupts.
35 attr->addr contains the userspace address of the buffer into which all
36 interrupt data will be copied.
37 attr->attr contains the size of the buffer in bytes.
38
39 KVM_DEV_FLIC_CLEAR_IRQS
40 Simply deletes all elements from the list of currently pending floating
41 interrupts. No interrupts are injected into the guest.
42
43 KVM_DEV_FLIC_APF_ENABLE
44 Enables async page faults for the guest. So in case of a major page fault
45 the host is allowed to handle this async and continues the guest.
46
47 KVM_DEV_FLIC_APF_DISABLE_WAIT
48 Disables async page faults for the guest and waits until already pending
49 async page faults are done. This is necessary to trigger a completion interrupt
50 for every init interrupt before migrating the interrupt list.
51
52 KVM_DEV_FLIC_ADAPTER_REGISTER
53 Register an I/O adapter interrupt source. Takes a kvm_s390_io_adapter
54 describing the adapter to register:
55
56struct kvm_s390_io_adapter {
57 __u32 id;
58 __u8 isc;
59 __u8 maskable;
60 __u8 swap;
61 __u8 pad;
62};
63
64 id contains the unique id for the adapter, isc the I/O interruption subclass
65 to use, maskable whether this adapter may be masked (interrupts turned off)
66 and swap whether the indicators need to be byte swapped.
67
68
69 KVM_DEV_FLIC_ADAPTER_MODIFY
70 Modifies attributes of an existing I/O adapter interrupt source. Takes
71 a kvm_s390_io_adapter_req specifiying the adapter and the operation:
72
73struct kvm_s390_io_adapter_req {
74 __u32 id;
75 __u8 type;
76 __u8 mask;
77 __u16 pad0;
78 __u64 addr;
79};
80
81 id specifies the adapter and type the operation. The supported operations
82 are:
83
84 KVM_S390_IO_ADAPTER_MASK
85 mask or unmask the adapter, as specified in mask
86
87 KVM_S390_IO_ADAPTER_MAP
88 perform a gmap translation for the guest address provided in addr,
89 pin a userspace page for the translated address and add it to the
90 list of mappings
91
92 KVM_S390_IO_ADAPTER_UNMAP
93 release a userspace page for the translated address specified in addr
94 from the list of mappings