[Qemu-devel] Re: [PATCH 11/21] ioport: insert event_tap_ioport() to ioport_write().

[Michael S. Tsirkin]

On Thu, Dec 16, 2010 at 06:50:04PM +0900, Yoshiaki Tamura wrote:
> 2010/12/16 Michael S. Tsirkin <address@hidden>:
> > On Thu, Dec 16, 2010 at 04:37:41PM +0900, Yoshiaki Tamura wrote:
> >> 2010/11/28 Yoshiaki Tamura <address@hidden>:
> >> > 2010/11/28 Michael S. Tsirkin <address@hidden>:
> >> >> On Thu, Nov 25, 2010 at 03:06:50PM +0900, Yoshiaki Tamura wrote:
> >> >>> Record ioport event to replay it upon failover.
> >> >>>
> >> >>> Signed-off-by: Yoshiaki Tamura <address@hidden>
> >> >>
> >> >> Interesting. This will have to be extended to support ioeventfd.
> >> >> Since each eventfd is really just a binary trigger
> >> >> it should be enough to read out the fd state.
> >> >
> >> > Haven't thought about eventfd yet.  Will try doing it in the next
> >> > spin.
> >>
> >> Hi Michael,
> >>
> >> I looked into eventfd and realized it's only used with vhost now.
> >
> > There are patches on list to use it for block/userspace net.
> 
> Thanks.  Now I understand.
> In that case, inserting an even-tap function to the following code
> should be appropriate?
> 
> int event_notifier_test_and_clear(EventNotifier *e)
> {
>     uint64_t value;
>     int r = read(e->fd, &value, sizeof(value));
>     return r == sizeof(value);
> }

Possibly.

> >
> >>  However, I
> >> believe vhost bypass the net layer in qemu, and there is no way for Kemari 
> >> to
> >> detect the outputs.


Then maybe you should check for this combination and either disable
vhost-net on the backend when kemari is active or fail.

> >>  To me, it doesn't make sense to extend this patch to
> >> support eventfd...
> >> Thanks,
> >>
> >> Yoshi
> >>
> >> >
> >> > Yoshi
> >> >
> >> >>
> >> >>> ---
> >> >>>  ioport.c |    2 ++
> >> >>>  1 files changed, 2 insertions(+), 0 deletions(-)
> >> >>>
> >> >>> diff --git a/ioport.c b/ioport.c
> >> >>> index aa4188a..74aebf5 100644
> >> >>> --- a/ioport.c
> >> >>> +++ b/ioport.c
> >> >>> @@ -27,6 +27,7 @@
> >> >>>
> >> >>>  #include "ioport.h"
> >> >>>  #include "trace.h"
> >> >>> +#include "event-tap.h"
> >> >>>
> >> >>>  /***********************************************************/
> >> >>>  /* IO Port */
> >> >>> @@ -76,6 +77,7 @@ static void ioport_write(int index, uint32_t 
> >> >>> address, uint32_t data)
> >> >>>          default_ioport_writel
> >> >>>      };
> >> >>>      IOPortWriteFunc *func = ioport_write_table[index][address];
> >> >>> +    event_tap_ioport(index, address, data);
> >> >>>      if (!func)
> >> >>>          func = default_func[index];
> >> >>>      func(ioport_opaque[address], address, data);
> >> >>> --
> >> >>> 1.7.1.2
> >> >>>
> >> >>> --
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> >> >>
> >> >
> > --
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> >