Re: [Qemu-devel] [RFC PATCH 3/3] spapr: generate a CAS reset for the XIVE exploitation mode

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Sep 08, 2017 at 04:33:44PM +0200, Cédric Le Goater wrote:
> When the platform and the guest agree on using the XIVE exploitation
> mode for interrupts, the "interrupt-controller" node needs to reflect
> the change and the device tree needs an update.
> 
> Reseting the guest after the CAS negotiation makes this change
> possible, as the device tree is built at reset time. We use the
> 'ov5_cas' field to check which interrupt model was negotiated before
> reset and populate the tree accordingly.
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>

Looks reasonable, though I'm not going to apply it until we actually
have something to go..

> ---
>  hw/ppc/spapr.c       | 6 +++++-
>  hw/ppc/spapr_hcall.c | 6 ++++++
>  2 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 3e3ff1fbc988..be467ab61ad0 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1073,7 +1073,11 @@ static void *spapr_build_fdt(sPAPRMachineState *spapr,
>      _FDT(fdt_setprop_cell(fdt, 0, "#size-cells", 2));
>  
>      /* /interrupt controller */
> -    spapr_dt_xics(xics_max_server_number(), fdt, PHANDLE_XICP);
> +    if (!spapr_ovec_test(spapr->ov5_cas, OV5_XIVE_EXPLOIT)) {
> +        spapr_dt_xics(xics_max_server_number(), fdt, PHANDLE_XICP);
> +    } else {
> +        /* populate device tree for XIVE */ ;

.. here.

> +    }
>  
>      ret = spapr_populate_memory(spapr, fdt);
>      if (ret < 0) {
> diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> index 92f1e21358b8..ba00b8d3fdd6 100644
> --- a/hw/ppc/spapr_hcall.c
> +++ b/hw/ppc/spapr_hcall.c
> @@ -1613,6 +1613,12 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
>              (spapr_h_cas_compose_response(spapr, args[1], args[2],
>                                            ov5_updates) != 0);
>      }
> +
> +    /* We need to rebuild the device tree for XIVE, generate a reset */
> +    if (!spapr->cas_reboot) {
> +        spapr->cas_reboot = spapr_ovec_test(ov5_updates, OV5_XIVE_EXPLOIT);
> +    }

At some point we may well want to make XIVE exploitation the default
for POWER9 guests, but that's a detail easily adjusted later.

>      spapr_ovec_cleanup(ov5_updates);
>  
>      if (spapr->cas_reboot) {

-- 
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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