Re: [PATCH] kvm: Document KVM_IOEVENTFD

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On Sat, 28 May 2011 14:12:30 +0300
Sasha Levin <levinsasha928@xxxxxxxxx> wrote:

> Document KVM_IOEVENTFD that can be used to receive
> notifications of PIO/MMIO events without triggering
> an exit.
> 
> Cc: Avi Kivity <avi@xxxxxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <levinsasha928@xxxxxxxxx>
> ---
>  Documentation/virtual/kvm/api.txt |   30 ++++++++++++++++++++++++++++++
>  1 files changed, 30 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 42542eb..80c5fcd 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -1291,6 +1291,36 @@ Returns the tsc frequency of the guest. The unit of the return value is
>  KHz. If the host has unstable tsc this ioctl returns -EIO instead as an
>  error.
>  
> +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 deattaches an ioeventfd to a legal pio/mmio address

Typo: attach -- detach (probably, I'm not a native)

Thanks,
  Takuya

> +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
> -- 
> 1.7.5.rc3
> 
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-- 
Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
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