From: David Gibson <david@gibson.dropbear.id.au>
To: "Cédric Le Goater" <clg@kaod.org>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 02/10] ppc/xive: introduce a XiveTCTX pointer under PowerPCCPU
Date: Fri, 4 Jan 2019 16:25:38 +1100 [thread overview]
Message-ID: <20190104052538.GF2801@umbus.fritz.box> (raw)
In-Reply-To: <76f4f558-5e0d-52ee-5c99-c208d005f643@kaod.org>
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On Thu, Jan 03, 2019 at 06:44:30PM +0100, Cédric Le Goater wrote:
> On 1/3/19 4:57 AM, David Gibson wrote:
> > On Wed, Jan 02, 2019 at 06:57:35AM +0100, Cédric Le Goater wrote:
> >> which will be used by the machine only when the XIVE interrupt mode is
> >> in use.
> >
> > I don't love the idea of putting a hook this specific into the
> > PowerPCCPU structure, though it might be the easiest path in the short
> > term.
> >
> > A couple of approaches: 1) revisit my changes to allow for a pointer
> > to machine-defined per-cpu data.
>
> ok but we still need two different presenters objects, one for each
> mode.
>
> > or 2) do we actually need a cpu to tctx pointer.
> >
> > Expanding on (2) - here you use the pointer to find the right TIMA
> > state to access,
>
> yes.
>
> > but that could also be handled by having different TIMA IO instances
> > and mapping those individually to cpu_as.
>
> It might work for QEMU but I am not sure how to implement the KVM
> backend with such a design. We only have a single ram ptr mapping
> for the machine in the KVM case.
>
> There are a couple of places where we need to loop on the XiveTCTX
> (presenter, KVM) and we use the QEMU CPU list and the cpu->tctx for
> that. One of the reasons we introduced the cpu->intc pointer some
> time ago was to get rid of the ICP array.
>
> I don't think we want to introduce a XiveTCTX array again.
>
> > On the interrupt delivery side I think a tctx to cpu link will suffice.
>
> yes. that we already have. It is mostly used by KVM in fact.
>
> > For sPAPR there might be complications with translating cpu numbers in
> > hcalls to the right tctx.
>
> The XiveTCTX is not used by the hcalls. We are fine on that side.
>
>
> The double pointer solution is what I prefer today, but if you are
> uncomfortable with it, we can come back to the previous where I was
> allocating a XiveTCTX child under the CPU and switching the presenter
> objects at reset. The only issue remaining was the child unparenting
> in the unrealize() method.
Hm, yes, I see your point. For now I'm applying patches 1-3, and hope
to clean it up later with a revised version of my machine specific
per-cpu patch when I get the chance.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2019-01-04 10:52 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-02 5:57 [Qemu-devel] [PATCH 00/10] spapr: introduce the 'dual' interrupt mode XICS/XIVE Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 01/10] spapr: modify the prototype of the cpu_intc_create() method Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 02/10] ppc/xive: introduce a XiveTCTX pointer under PowerPCCPU Cédric Le Goater
2019-01-03 3:57 ` David Gibson
2019-01-03 17:44 ` Cédric Le Goater
2019-01-04 5:25 ` David Gibson [this message]
2019-01-02 5:57 ` [Qemu-devel] [PATCH 03/10] ppc: replace the 'Object *intc' by a 'ICPState *icp' pointer under the CPU Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 04/10] spapr/xive: simplify the sPAPR IRQ qirq method for XIVE Cédric Le Goater
2019-01-03 3:58 ` David Gibson
2019-01-02 5:57 ` [Qemu-devel] [PATCH 05/10] ppc: export the XICS and XIVE set_irq handlers Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 06/10] pnv/psi: move the ICSState qemu_irq array under the PSI device model Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 07/10] spapr: move the qemu_irq array under the machine Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 08/10] ppc/xics: allow ICSState to have an offset 0 Cédric Le Goater
2019-01-03 4:33 ` David Gibson
2019-01-03 17:45 ` Cédric Le Goater
2019-01-07 4:29 ` David Gibson
2019-01-02 5:57 ` [Qemu-devel] [PATCH 09/10] spapr: introduce a new sPAPR IRQ backend supporting XIVE and XICS Cédric Le Goater
2019-01-03 4:35 ` David Gibson
2019-01-03 17:45 ` Cédric Le Goater
2019-01-02 5:57 ` [Qemu-devel] [PATCH 10/10] spapr: enable XIVE MMIOs at reset Cédric Le Goater
2019-01-07 4:48 ` [Qemu-devel] [PATCH 00/10] spapr: introduce the 'dual' interrupt mode XICS/XIVE David Gibson
2019-01-07 6:54 ` Cédric Le Goater
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