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Date: Thu, 25 Feb 2010 13:19:30 -0600
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: [Qemu-devel] Re: [PATCHv2 02/12] kvm: add API to set ioeventfd
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: quintela@redhat.com, mtosatti@redhat.com, qemu-devel@nongnu.org, avi@redhat.com, amit.shah@redhat.com, kraxel@redhat.com

On 02/25/2010 12:28 PM, Michael S. Tsirkin wrote:
> Comment on kvm usage: rather than require users to do if (kvm_enabled())
> and/or ifdefs, this patch adds an API that, internally, is defined to
> stub function on non-kvm build, and checks kvm_enabled for non-kvm
> run.
>
> While rest of qemu code still uses if (kvm_enabled()), I think this
> approach is cleaner, and we should convert rest of code to it
> long term.
>    

I'm not opposed to that.

> Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> ---
>
> Avi, Marcelo, pls review/ack.
>
>   kvm-all.c |   22 ++++++++++++++++++++++
>   kvm.h     |   16 ++++++++++++++++
>   2 files changed, 38 insertions(+), 0 deletions(-)
>
> diff --git a/kvm-all.c b/kvm-all.c
> index 1a02076..9742791 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1138,3 +1138,25 @@ int kvm_set_signal_mask(CPUState *env, const sigset_t *sigset)
>
>       return r;
>   }
> +
> +#ifdef KVM_IOEVENTFD
> +int kvm_set_ioeventfd(uint16_t addr, uint16_t data, int fd, bool assigned)
>    

I think this API could use some love.  You're using a very limited set 
of things that ioeventfd can do and you're multiplexing creation and 
destruction in a single call.

I think:

kvm_set_ioeventfd_pio_word(int fd, uint16_t addr, uint16_t data);
kvm_unset_ioeventfd_pio_word(int fd, uint16_t addr, uint16_t data);

Would be better.  Alternatively, an API that matched ioeventfd exactly:

kvm_set_ioeventfd(int fd, uint64_t addr, int size, uint64_t data, int 
flags);
kvm_unset_ioeventfd(...);

Could work too.

Regards,

Anthony Liguori