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Commit 55399a02 authored by Sasha Levin's avatar Sasha Levin Committed by Avi Kivity
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KVM: Document KVM_IOEVENTFD 



Document KVM_IOEVENTFD that can be used to receive
notifications of PIO/MMIO events without triggering
an exit.

Signed-off-by: default avatarSasha Levin <levinsasha928@gmail.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 823e3965

Documentation/virtual/kvm/api.txt

+30 −0
Original line number Diff line number Diff line
@@ -1323,6 +1323,36 @@ struct kvm_lapic_state { 
Copies the input argument into the the Local APIC registers.  The data format

and layout are the same as documented in the architecture manual.



4.56 KVM_IOEVENTFD



Capability: KVM_CAP_IOEVENTFD

Architectures: all

Type: vm ioctl

Parameters: struct kvm_ioeventfd (in)

Returns: 0 on success, !0 on error



This ioctl attaches or detaches an ioeventfd to a legal pio/mmio address

within the guest.  A guest write in the registered address will signal the

provided event instead of triggering an exit.



struct kvm_ioeventfd {

	__u64 datamatch;

	__u64 addr;        /* legal pio/mmio address */

	__u32 len;         /* 1, 2, 4, or 8 bytes    */

	__s32 fd;

	__u32 flags;

	__u8  pad[36];

};



The following flags are defined:



#define KVM_IOEVENTFD_FLAG_DATAMATCH (1 << kvm_ioeventfd_flag_nr_datamatch)

#define KVM_IOEVENTFD_FLAG_PIO       (1 << kvm_ioeventfd_flag_nr_pio)

#define KVM_IOEVENTFD_FLAG_DEASSIGN  (1 << kvm_ioeventfd_flag_nr_deassign)



If datamatch flag is set, the event will be signaled only if the written value

to the registered address is equal to datamatch in struct kvm_ioeventfd.



5. The kvm_run structure



Application code obtains a pointer to the kvm_run structure by