[Skiboot] [RFC PATCH v5 13/16] skiboot/imc: Disable IMC node when UV enabled

[Alexey Kardashevskiy]

On 28/02/2020 07:40, Ryan Grimm wrote:
> From: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> 
> Remove the IMC nodes when the ultravisor is enabled,
> since both HOMER and IMC scoms are not accessable in
> hypervisor state.


They are available via UV_READ_SCOM.


> 
> Signed-off-by: Madhavan Srinivasan <maddy at linux.vnet.ibm.com>
> ---
>  hw/imc.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/hw/imc.c b/hw/imc.c
> index 3a5382c0..576eac87 100644
> --- a/hw/imc.c
> +++ b/hw/imc.c
> @@ -603,6 +603,17 @@ imc_mambo:
>  	if (pause_microcode_at_boot())
>  		goto err;
>  
> +	/*
> +	 * If MSR(S) bit is set, disable IMC nodes.
> +	 * IMC nodes need access to specific scom and HOMER region
> +	 * which are not accessible from hypervisor.
> +	 *
> +	 * At this point uv_present cant be used since uv_init()

s/cant/can't/
s/uv_init/init_uv/


> +	 * is called much later. Hencing checking for the MSR bit here.
> +	 */
> +	if (is_msr_bit_set(MSR_S))
> +		goto err;
> +

Do this at the very beginning of imc_init()? Or do not call it at all in
main_cpu_entry() if (is_msr_bit_set(MSR_S))?


>  	/*
>  	 * If the dt_attach_root() fails, "imc-counters" node will not be
>  	 * seen in the device-tree and hence OS should not make any
> 

-- 
Alexey