From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH v5 12/22] xen/arm: ITS: Add GICR register emulation Date: Tue, 4 Aug 2015 09:44:18 +0100 Message-ID: <55C07B62.4000001@citrix.com> References: <1437995524-19772-1-git-send-email-vijay.kilari@gmail.com> <1437995524-19772-13-git-send-email-vijay.kilari@gmail.com> <55BA591C.6020004@citrix.com> <55BB5678.2040108@citrix.com> <55BCEB05.5010002@citrix.com> <55BF6612.9030303@citrix.com> <55BF7392.2090803@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Vijay Kilari Cc: Ian Campbell , Stefano Stabellini , Prasun Kapoor , manish.jaggi@caviumnetworks.com, Tim Deegan , "xen-devel@lists.xen.org" , Stefano Stabellini , Vijaya Kumar K List-Id: xen-devel@lists.xenproject.org On 04/08/2015 07:55, Vijay Kilari wrote: >>>>>> >>>>>> What would happen if the LPI is injected before the GICR_PROPBASER is >>>>>> enabled? See for more details on the problem here [1] >>>>> >>>>> Check is required before accessing LPI property table if property >>>>> table is available >>>>> or not?. >>>> >>>> You didn't answer to my question... What would you do if the property is >>>> not available? Ignoring the LPI? Would the LPI can fire back after the >>>> property table is set and the LPI enabled? >>> >>> Same as above solution. Ignore LPI as we don't have LPI property >>> information to inject. >> >> That still not answering to my question. What happen if we ignore the >> LPI? Would the device resend the MSI and therefore the LPI later? If >> not, how do you plan to handle this? >> > LPIs are edge triggered, so device won't raise again. > > We can put in inflight and wait for guest to enabled it, But we are not sure > when LPI property table will be set for this vLPI. On GICR_PROPBASER update > with new property table, we parse the LPI property table and call > vits_{enable/disable}_lpi If we don't put it inflight, we will surely loose some interrupt at some point if the device is not quiet before the guest has booted and/or setup the device before enabling the LPI. >> With the LPI implementation, it's valid to receive an LPI before the >> guest effectively setup the ITS (i.e property table and the mapping to a >> vLPI). This is because we enable to LPI as soon as we route it to the guest. >> >> Regards, >> >> -- >> Julien Grall [1] http://lists.xenproject.org/archives/html/xen-devel/2015-06/msg02591.html -- Julien Grall