[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC v1 14/15] Suppress posting interrupts when 'SN' is set
> -----Original Message----- > From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx] > Sent: Friday, March 27, 2015 9:49 PM > To: Wu, Feng; xen-devel@xxxxxxxxxxxxx > Cc: Zhang, Yang Z; Tian, Kevin; keir@xxxxxxx; JBeulich@xxxxxxxx > Subject: Re: [Xen-devel] [RFC v1 14/15] Suppress posting interrupts when 'SN' > is > set > > On 27/03/15 13:45, Wu, Feng wrote: > > > >> -----Original Message----- > >> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx] > >> Sent: Friday, March 27, 2015 8:06 PM > >> To: Wu, Feng; xen-devel@xxxxxxxxxxxxx > >> Cc: Zhang, Yang Z; Tian, Kevin; keir@xxxxxxx; JBeulich@xxxxxxxx > >> Subject: Re: [Xen-devel] [RFC v1 14/15] Suppress posting interrupts when > 'SN' is > >> set > >> > >> On 27/03/15 03:00, Wu, Feng wrote: > >>>>> static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector) > >>>>> { > >>>>> + int r, sn; > >>>>> + > >>>>> if ( pi_test_and_set_pir(vector, &v->arch.hvm_vmx.pi_desc) ) > >>>>> return; > >>>>> > >>>>> + /* > >>>>> + * Currently, we don't support urgent interrupt, all interrupts > >>>>> + * are recognized as non-urgent interrupt, so we cannot send > >>>>> + * posted-interrupt when 'SN' is set. > >>>>> + */ > >>>>> + > >>>>> + sn = pi_test_sn(&v->arch.hvm_vmx.pi_desc); > >>>> Is there anywhere which sets sn at all? I cant spot anywhere. > >>>> > >>> SN is set in [13/15] while vCPU is going to runnable state. > >> Then please do not set SN in the first place if we don't support it. > > > > What do you mean here. Setting 'SN' can suppress non-urgent interrupt. (we > only support this) > > Sorry, in which case patch 13 shouldn't clear SN then. > > Either way - we should not be fixing up something in this patch which > was introduced in the previous patch. I think there are some misunderstanding here. - In patch 13, we need to set 'SN', so as to suppress the interrupts when vCPU is in runnable state, since we don't need to send notification event then. - Here in patch 14, it is another story. From hardware p.o.v, if 'SN' is set, it doesn't send notification event. vmx_deliver_posted_intr() is the software way to delivery posted-interrupts, so we need to follow the HW's behavior. Hence we check 'SN' first, and not send notification event if it is set. Thanks, Feng > > ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |