From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50355) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YR6pk-0003Ho-T9 for qemu-devel@nongnu.org; Thu, 26 Feb 2015 17:23:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YR6ph-0001qx-Ks for qemu-devel@nongnu.org; Thu, 26 Feb 2015 17:23:04 -0500 Received: from e8.ny.us.ibm.com ([32.97.182.138]:55888) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YR6ph-0001qq-Hi for qemu-devel@nongnu.org; Thu, 26 Feb 2015 17:23:01 -0500 Received: from /spool/local by e8.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 26 Feb 2015 17:23:00 -0500 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable From: Michael Roth In-Reply-To: <20150225004823.GA15695@voom.fritz.box> References: <1424096872-29868-1-git-send-email-mdroth@linux.vnet.ibm.com> <1424096872-29868-8-git-send-email-mdroth@linux.vnet.ibm.com> <20150224064032.GQ4536@voom.redhat.com> <20150224204345.31752.42274@loki> <20150225004823.GA15695@voom.fritz.box> Message-ID: <20150226222155.31752.51742@loki> Date: Thu, 26 Feb 2015 16:21:55 -0600 Subject: Re: [Qemu-devel] [PATCH v5 07/16] 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 (2015-02-24 18:48:23) > On Tue, Feb 24, 2015 at 02:43:45PM -0600, Michael Roth wrote: > > Quoting David Gibson (2015-02-24 00:40:32) > > > On Mon, Feb 16, 2015 at 08:27:43AM -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 > > > > --- > > > > hw/ppc/spapr_rtas.c | 81 +++++++++++++++++++++++++++++++++++++++++= ++++++++++++ > > > > 1 file changed, 81 insertions(+) > > > > = > > > > diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c > > > > index f80beb2..b8551b0 100644 > > > > --- a/hw/ppc/spapr_rtas.c > > > > +++ b/hw/ppc/spapr_rtas.c > > > > @@ -418,6 +418,85 @@ static void rtas_get_sensor_state(PowerPCCPU *= cpu, sPAPREnvironment *spapr, > > > > rtas_st(rets, 1, entity_sense); > > > > } > > > > = > > > > +/* configure-connector work area offsets, int32_t units for field > > > > + * indexes, bytes for field offset/len values. > > > > + * > > > > + * as documented by PAPR+ v2.7, 13.5.3.5 > > > > + */ > > > > +#define CC_IDX_NODE_NAME_OFFSET 2 > > > > +#define CC_IDX_PROP_NAME_OFFSET 2 > > > > +#define CC_IDX_PROP_LEN 3 > > > > +#define CC_IDX_PROP_DATA_OFFSET 4 > > > > +#define CC_VAL_DATA_OFFSET ((CC_IDX_PROP_DATA_OFFSET + 1) * 4) > > > > +#define CC_WA_LEN 4096 > > > > + > > > > +static void rtas_ibm_configure_connector(PowerPCCPU *cpu, > > > > + sPAPREnvironment *spapr, > > > > + uint32_t token, uint32_t = nargs, > > > > + target_ulong args, uint32= _t nret, > > > > + target_ulong rets) > > > > +{ > > > > + uint64_t wa_addr =3D ((uint64_t)rtas_ld(args, 1) << 32) | rtas= _ld(args, 0); > > > = > > > You need to check nargs and nret first. > > = > > Could've sworn I'd fixed all those cases. Will make sure to take care o= f it on > > the next one. > > = > > > = > > > > + uint64_t wa_offset; > > > > + uint32_t drc_index; > > > > + sPAPRDRConnector *drc; > > > > + sPAPRDRConnectorClass *drck; > > > > + sPAPRDRCCResponse resp; > > > > + const struct fdt_property *prop =3D NULL; > > > > + char *prop_name =3D NULL; > > > > + int prop_len, rc; > > > > + > > > > + drc_index =3D rtas_ld(wa_addr, 0); > > > > + drc =3D spapr_dr_connector_by_index(drc_index); > > > > + if (!drc) { > > > > + DPRINTF("rtas_ibm_configure_connector: invalid sensor/DRC = index: %xh\n", > > > > + drc_index); > > > > + rc =3D RTAS_OUT_PARAM_ERROR; > > > > + goto out; > > > > + } > > > > + drck =3D SPAPR_DR_CONNECTOR_GET_CLASS(drc); > > > > + resp =3D drck->configure_connector(drc, &prop_name, &prop, &pr= op_len); > > > = > > > You may have answered this last time round, but if so I forgot the > > > reason. > > > = > > > Why does the awkward iteration need to go down to the drck callback? > > > Coudln't the drck callback part just supply the fdt fragment blob, > > > then have generic code which streams it out via iteration? > > > = > > > Obviously we have to support the horrid PAPR interface, but it would > > > be nice to confine the PAPR derived horridness to as small an area as > > > we can. > > = > > That horrid interface percolates all the way up the QEMU stack, > > unfortunately :) > > = > > Upon successfully having it's device tree node received, a DRC transiti= ons > > to a 'configured' state that's defined in the DR state machine (PAPR+ 1= 3.4). > > = > > We need to track that state, since it's used to differentiate between > > a case where a device is set to 'isolated' as part of entity-sense/devi= ce > > configuration, as opposed to 'isolated' as part the unplug path. The > > overlap between the 2 can occur if we do device_add followed by an imme= diate > > device_del, but since the 'configured' transition must occur before the= latter, > > it becomes unambiguous. > > = > > It's also possible that a guest might be reset in the middle of a serie= s of > > calls to configure-connector, in which case that state needs to be rese= t. This > > is currently handled by sPAPRDRConnector's reset hook, so if we moved t= hat > > aspect out I think we'd need to wire up a reset hook for the configure-= connector > > state, which is kinda messy. We'd also need a list of some sort, keyed = by > > the DRC indexes, to handle the subsequent call-per-iteration's (no guar= antee > > only one device configuration is 'in-flight' at a time), so we end up > > duplicating a lot of tracking/functionality. > = > Hmm. You should still be able to handle that with just 2 hooks and 1 > bit of state right? Say "start_configuration" and "end_configuration" > or similar. start_configuration gets the blob from the backend, then > end_configuration is called once RTAS has finished streaming it out to > the guest and updates to the cnofigured state. {start,end}_configuration callbacks would work for handling the normal 'configured' state transitions induced by the call, but we'd also need hooks in the "other direction" for a couple cases: This scenario for instance: qemu: guest: add device0 to drc0 drmgr0: rtas-configure-connector drc0 drc0->start_configuration... drmgr0: rtas-configure-connector drc0 drmgr0: rtas-configure-connector drc0 ... drmgr0: rtas-configure-connector drc0 del device0 drmgr0: rtas-configure-connector drc0 system_reset device0 removed by drc0 reset hook add device1 to drc0 drmgr0: rtas-configure-connector drc0 So I think we'd need at least a reset hook wired up to the RTAS state. It's also possible for the guest to force a transition out of the configured state by ISOLATE'ing the device. This can happen in the middle of the guests configure-connector calls if there's an error. If rtas-configure-connector is the one generating the error, it can anticipate this and automatically reset the state, but in some cases the error is guest internal: the get_node() in src/drmgr/rtas_calls.c can fail for memory allocation errors, or unexpected workarea structure, after which point it simply stops calling rtas-configure-connector and ISOLATEs the device. If we don't track that, a subsequent unplug/plug could also result in stale FDT fragments being sent to the guest. So we'd the RTAS state tracking code to provide an interface of some sort for the DRC code to call into, which results in a lot of duplicated state-tracking. It's a bit unintuitive, but those FDT bits are closely coupled to the DRC state, so in the end I think that ends up being the most straight-forward place to manage them. > = > -- = > 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