From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jan Beulich" <JBeulich@suse.com>
Subject: Re: [PATCH RFC 1/4] xen: evtchn: make evtchn_reset()
 ready for soft reset
Date: Mon, 08 Jun 2015 15:10:06 +0100
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To: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Olaf Hering <olaf@aepfle.de>, Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Andrew Cooper <andrew.cooper3@citrix.com>, Julien Grall <julien.grall@linaro.org>, Ian Jackson <ian.jackson@eu.citrix.com>, Andrew Jones <drjones@redhat.com>, Tim Deegan <tim@xen.org>, David Vrabel <david.vrabel@citrix.com>, xen-devel@lists.xenproject.org, Daniel De Graaf <dgdegra@tycho.nsa.gov>, Keir Fraser <keir@xen.org>
List-Id: xen-devel@lists.xenproject.org

>>> On 03.06.15 at 15:35, <vkuznets@redhat.com> wrote:
> --- a/xen/common/event_channel.c
> +++ b/xen/common/event_channel.c
> @@ -274,11 +274,13 @@ static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)
>  
>      lchn->u.interdomain.remote_dom  = rd;
>      lchn->u.interdomain.remote_port = rport;
> +    lchn->u.interdomain.opened_by   = current->domain;
>      lchn->state                     = ECS_INTERDOMAIN;
>      evtchn_port_init(ld, lchn);
>      
>      rchn->u.interdomain.remote_dom  = ld;
>      rchn->u.interdomain.remote_port = lport;
> +    rchn->u.interdomain.opened_by   = current->domain;
>      rchn->state                     = ECS_INTERDOMAIN;

For one ld == current->domain. And I don't think you need to store
domain pointers here; storing the domain ID would seem sufficient
(with the nice benefit of not growing struct evtchn). Plus
"opened_by" doesn't really reflect what is being done here - the
event channels are being bound, not opened.

> @@ -933,26 +935,30 @@ int evtchn_unmask(unsigned int port)
>  }
>  
>  
> -static long evtchn_reset(evtchn_reset_t *r)
> +void evtchn_reset(struct domain *d, bool_t soft_reset)
>  {
> -    domid_t dom = r->dom;
> -    struct domain *d;
> -    int i, rc;
> -
> -    d = rcu_lock_domain_by_any_id(dom);
> -    if ( d == NULL )
> -        return -ESRCH;
> -
> -    rc = xsm_evtchn_reset(XSM_TARGET, current->domain, d);
> -    if ( rc )
> -        goto out;
> +    int i;

unsigned int

> +    struct evtchn *chn;

const (and perhaps moved inside the loop below)

> +    /*
> +     * ECS_INTERDOMAIN channels with port number suitable for the 2-level ABI
> +     * opened by other domains should remain opened as the domain doing soft
> +     * reset won't be able to reopen them.

One question of course is - does this really apply to _all_ interdomain
event channels (rather than just to the xenstore and xenconsole ones)?

Jan