[Skiboot] [RFC PATCH v5 13/16] skiboot/imc: Disable IMC node when UV enabled
maddy at linux.ibm.com
Tue Mar 24 15:46:38 AEDT 2020
On 3/12/20 6:49 AM, Alexey Kardashevskiy wrote:
> 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.
SCOM yes, but the latency will be high and
also there are security concerns, hence to disable it.
>> 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()
Will fix it.
>> + * 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))?
We do couple of call to this file before jumping to imc_init(). And
yes I agree, we could move the check to the beginning. Will fix it
Thanks for review
>> * If the dt_attach_root() fails, "imc-counters" node will not be
>> * seen in the device-tree and hence OS should not make any
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