[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [PATCH 05/12] evtchn/sched: reject poll requests for unusable ports
> -----Original Message----- > From: Xen-devel <xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of Jan > Beulich > Sent: 28 September 2020 11:59 > To: xen-devel@xxxxxxxxxxxxxxxxxxxx > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>; George Dunlap > <George.Dunlap@xxxxxxxxxxxxx>; Ian > Jackson <iwj@xxxxxxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Wei Liu > <wl@xxxxxxx>; Stefano Stabellini > <sstabellini@xxxxxxxxxx>; Dario Faggioli <dfaggioli@xxxxxxxx> > Subject: [PATCH 05/12] evtchn/sched: reject poll requests for unusable ports > > Before and after XSA-342 there has been an asymmetry in how not really > usable ports get treated in do_poll(): Ones beyond a certain boundary > (max_evtchns originally, valid_evtchns subsequently) did get refused > with -EINVAL, while lower ones were accepted despite there potentially > being no way to wake the vCPU again from its polling state. Arrange to > also honor evtchn_usable() output in the decision. > > Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Paul Durrant <paul@xxxxxxx> > > --- a/xen/common/sched/core.c > +++ b/xen/common/sched/core.c > @@ -1427,13 +1427,13 @@ static long do_poll(struct sched_poll *s > if ( __copy_from_guest_offset(&port, sched_poll->ports, i, 1) ) > goto out; > > - rc = -EINVAL; > - if ( !port_is_valid(d, port) ) > - goto out; > - > - rc = 0; > - if ( evtchn_port_is_pending(d, port) ) > + rc = evtchn_port_poll(d, port); > + if ( rc ) > + { > + if ( rc > 0 ) > + rc = 0; > goto out; > + } > } > > if ( sched_poll->nr_ports == 1 ) > --- a/xen/include/xen/event.h > +++ b/xen/include/xen/event.h > @@ -240,19 +240,6 @@ static inline bool evtchn_is_pending(con > return evtchn_usable(evtchn) && d->evtchn_port_ops->is_pending(d, > evtchn); > } > > -static inline bool evtchn_port_is_pending(struct domain *d, evtchn_port_t > port) > -{ > - struct evtchn *evtchn = evtchn_from_port(d, port); > - bool rc; > - unsigned long flags; > - > - spin_lock_irqsave(&evtchn->lock, flags); > - rc = evtchn_is_pending(d, evtchn); > - spin_unlock_irqrestore(&evtchn->lock, flags); > - > - return rc; > -} > - > static inline bool evtchn_is_masked(const struct domain *d, > const struct evtchn *evtchn) > { > @@ -279,6 +266,24 @@ static inline bool evtchn_is_busy(const > d->evtchn_port_ops->is_busy(d, evtchn); > } > > +static inline int evtchn_port_poll(struct domain *d, evtchn_port_t port) > +{ > + int rc = -EINVAL; > + > + if ( port_is_valid(d, port) ) > + { > + struct evtchn *evtchn = evtchn_from_port(d, port); > + unsigned long flags; > + > + spin_lock_irqsave(&evtchn->lock, flags); > + if ( evtchn_usable(evtchn) ) > + rc = evtchn_is_pending(d, evtchn); > + spin_unlock_irqrestore(&evtchn->lock, flags); > + } > + > + return rc; > +} > + > static inline int evtchn_port_set_priority(struct domain *d, > struct evtchn *evtchn, > unsigned int priority) >
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