Xen devel - Feb 2008 - [PATCH] Prevent frontend network accelerator plugin loading in dom0

Generate error if frontend plugin tries to connect on dom0

diff -r bb5ece87256b drivers/xen/netfront/accel.c
--- a/drivers/xen/netfront/accel.c
+++ b/drivers/xen/netfront/accel.c
@@ -446,6 +446,9 @@ int netfront_accelerator_loaded(int vers
 {
 	struct netfront_accelerator *accelerator;
 
+	if (is_initial_xendomain())
+		return -EINVAL;
+
 	if (version != NETFRONT_ACCEL_VERSION) {
 		if (version > NETFRONT_ACCEL_VERSION) {
 			/* Caller has higher version number, leave it



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On Fri, 2008-02-08 at 14:30 +0000, Kieran Mansley wrote:
> Generate error if frontend plugin tries to connect on dom0
Forgot the:

Signed-off-by: Kieran Mansley <kmansley@solarflare.com>
> diff -r bb5ece87256b drivers/xen/netfront/accel.c
> --- a/drivers/xen/netfront/accel.c
> +++ b/drivers/xen/netfront/accel.c
> @@ -446,6 +446,9 @@ int netfront_accelerator_loaded(int vers
>  {
>  	struct netfront_accelerator *accelerator;
>  
> +	if (is_initial_xendomain())
> +		return -EINVAL;
> +
>  	if (version != NETFRONT_ACCEL_VERSION) {
>  		if (version > NETFRONT_ACCEL_VERSION) {
>  			/* Caller has higher version number, leave it
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

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Kieran Mansley writes ("[Xen-devel] [PATCH] Prevent frontend network
accelerator plugin loading in dom0"):
> Generate error if frontend plugin tries to connect on dom0
If you''re doing something with driver domains you might have frontends
in dom0 and backends in the driver domain.  I don''t think any of our
current toolstack supports this but it would seem wrong to go out of
our way to break it in the netfront driver.

Or have I misunderstood the point of the change ?

Ian.

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On Mon, 2008-02-11 at 14:52 +0000, Ian Jackson wrote:
> Kieran Mansley writes ("[Xen-devel] [PATCH] Prevent frontend network
accelerator plugin loading in dom0"):
> > Generate error if frontend plugin tries to connect on dom0
> 
> If you''re doing something with driver domains you might have
frontends
> in dom0 and backends in the driver domain.  I don''t think any of
our
> current toolstack supports this but it would seem wrong to go out of
> our way to break it in the netfront driver.
> 
> Or have I misunderstood the point of the change ?
It''s there to mirror the existing check in netfront.c:netif.init():

  if (is_initial_xendomain())
    return 0;

i.e. If that test has failed, you''ve got no useful netfront
functionality, so having a plugin for it isn''t much use, but netfront
is
still present and the plugin could try and connect.  I''m just making it
consistent.

In addition, the acceleration plugin stuff in netfront is only
initialised if you get past that test, so making sure it can only be
used if it''s been initialised is a good idea. 

I''d be happy if someone wanted to remove these tests and make netfront
work in dom0 but I didn''t want to make that more invasive change just
now.

Kieran


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