From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51371) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT2DO-0005aC-5S for qemu-devel@nongnu.org; Wed, 04 Mar 2015 00:51:27 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YT2DG-0005Xm-3i for qemu-devel@nongnu.org; Wed, 04 Mar 2015 00:51:26 -0500 Received: from e32.co.us.ibm.com ([32.97.110.150]:52153) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YT2DF-0005XS-US for qemu-devel@nongnu.org; Wed, 04 Mar 2015 00:51:18 -0500 Received: from /spool/local by e32.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 3 Mar 2015 22:51:16 -0700 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: Michael Roth In-Reply-To: <20150303053339.GN29409@voom.fritz.box> References: <1425006675-19976-1-git-send-email-mdroth@linux.vnet.ibm.com> <1425006675-19976-8-git-send-email-mdroth@linux.vnet.ibm.com> <20150302070246.GH29409@voom.fritz.box> <20150303044016.27171.3218@loki> <20150303053339.GN29409@voom.fritz.box> Message-ID: <20150304055034.27171.34590@loki> Date: Tue, 03 Mar 2015 23:50:34 -0600 Subject: Re: [Qemu-devel] [PATCH v6 07/15] spapr_rtas: add ibm, configure-connector RTAS interface List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Gibson Cc: aik@ozlabs.ru, qemu-devel@nongnu.org, agraf@suse.de, ncmike@ncultra.org, qemu-ppc@nongnu.org, tyreld@linux.vnet.ibm.com, bharata.rao@gmail.com, nfont@linux.vnet.ibm.com Quoting David Gibson (2015-03-02 23:33:39) > On Mon, Mar 02, 2015 at 10:40:16PM -0600, Michael Roth wrote: > > Quoting David Gibson (2015-03-02 01:02:46) > > > On Thu, Feb 26, 2015 at 09:11:07PM -0600, Michael Roth wrote: > > > > This interface is used to fetch an OF device-tree nodes that descri= bes a > > > > newly-attached device to guest. It is called multiple times to walk= the > > > > device-tree node and fetch individual properties into a 'workarea'/= buffer > > > > provided by the guest. > > > > = > > > > The device-tree is generated by QEMU and passed to an sPAPRDRConnec= tor during > > > > the initial hotplug operation, and the state of these RTAS calls is= tracked by > > > > the sPAPRDRConnector. When the last of these properties is successf= ully > > > > fetched, we report as special return value to the guest and transit= ion > > > > the device to a 'configured' state on the QEMU/DRC side. > > > > = > > > > See docs/specs/ppc-spapr-hotplug.txt for a complete description of > > > > this interface. > > > > = > > > > Signed-off-by: Michael Roth > > > = > > > = > > > So, actually, here's probably the best place to explain what I had in > > > mind for changing the internal interface for this stuff. I was > > > thinking something like this pseudocode: > > > = > > > struct DRCCCState { > > > void *fdt; > > > int offset; > > > int depth; > > > }; > > > = > > > rtas_configure_connector() > > > { > > > ... > > > DRCCCState *ccstate; > > > ... > > > = > > > /* check parameters, retrieve drc */ > > > ccstate =3D drc->ccstate; > > > = > > > if (!ccstate) { > > > /* Haven't started configuring yet */ > > > ccstate =3D malloc(...); > > > /* Retrieve the dt fragment from the backend */ > > > ccstate->fdt =3D drck->get_dt(...); > > > ccstate->offset =3D 0; > > > } > > > = > > > while (get next tag from fdt) { > > > switch (tag) > > > case FDT_PROPERTY: > > > /* Translate property into rtas return values= */ > > > return SPAPR_DR_CC_RESPONSE_NEXT_PROPERTY; > > > = > > > /* other cases ... */ > > > } > > > = > > > /* Fall through only if we've completed streaming out the dt > > > */ > > > = > > > /* Tell the back end we've finished configuring */ > > > drck->cc_completed(...); > > > return SPAPR_DR_CC_RESPONSE_SUCCESS; > > > } > > > = > > > On reset, or anything else which interrupts the configuration process, > > > just blow away drc->ccstate. > > = > > Ok, that seems reasonable. I took a stab at it here: > > = > > https://github.com/mdroth/qemu/commit/79ce372743da1b63a6fa33e3de1f1= daba8ea1fdc > > https://github.com/mdroth/qemu/commits/spapr-hotplug-pci > = > It's looking pretty close now, thanks for the rework. > = > > It exposes the ccstate as you suggested, via drck->get_cc_state(), and = in > > place of drck->cc_completed() I have drck->set_configured() which serves > > roughly the same purpose I think. I opted not to let RTAS handle > > allocation, since it seemed to imply RTAS owns it and not the DRC. > = > So, that was intentional; basically RTAS *does* own the CCstate. But > for convenience of index we need connect it to the DRC. Think of it > like an rtas_priv field in the DRC. > = > In particular I think the CCstate should be opaque to everything > except the RTAS code itself, which means initializing the offset and > depth in RTAS, not in a drck callback. As far as the drck callback > is concerned, it's supplying a dt fragment, but it doesn't care about > the details of how the upper layer communicates that through to the > guest. Ah ok, so it was about moving the CCState out of DRC, and not just the awkward interface that wraps FDT traversal. So I went ahead and did it as you suggested, but also making it actually opaque, and relying on a couple callbacks that configure-connector passes to drc->begin_configure_connector to handle init/reset of the CCState fields (such as the fdt, and the start offset (which isn't necessarilly 0)): https://github.com/mdroth/qemu/commits/spapr-hotplug-pci https://github.com/mdroth/qemu/commit/732aa10fa2e41951c396373e7df7d318613= 22531 I think I have all your other comments addressed, so if that looks ok I'll post v7 soon. Thanks! > = > -- = > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _othe= r_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson