Re: [PATCH v3 08/16] powerpc/pseries/svm: Use shared memory for LPPACA structures

[Michael Ellerman]

Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx> writes:
> Michael Ellerman <mpe@xxxxxxxxxxxxxx> writes:
>> Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx> writes:
>>> From: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
>>>
>>> LPPACA structures need to be shared with the host. Hence they need to be in
>>> shared memory. Instead of allocating individual chunks of memory for a
>>> given structure from memblock, a contiguous chunk of memory is allocated
>>> and then converted into shared memory. Subsequent allocation requests will
>>> come from the contiguous chunk which will be always shared memory for all
>>> structures.
>>>
>>> While we are able to use a kmem_cache constructor for the Debug Trace Log,
>>> LPPACAs are allocated very early in the boot process (before SLUB is
>>> available) so we need to use a simpler scheme here.
>>>
>>> Introduce helper is_svm_platform() which uses the S bit of the MSR to tell
>>> whether we're running as a secure guest.
>>>
>>> Signed-off-by: Anshuman Khandual <khandual@xxxxxxxxxxxxxxxxxx>
>>> Signed-off-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
>>> ---
>>>  arch/powerpc/include/asm/svm.h | 26 ++++++++++++++++++++
>>>  arch/powerpc/kernel/paca.c     | 43 +++++++++++++++++++++++++++++++++-
>>>  2 files changed, 68 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/arch/powerpc/include/asm/svm.h b/arch/powerpc/include/asm/svm.h
>>> new file mode 100644
>>> index 000000000000..fef3740f46a6
>>> --- /dev/null
>>> +++ b/arch/powerpc/include/asm/svm.h
>>> @@ -0,0 +1,26 @@
>>> +/* SPDX-License-Identifier: GPL-2.0+ */
>>> +/*
>>> + * SVM helper functions
>>> + *
>>> + * Copyright 2019 Anshuman Khandual, IBM Corporation.
>>
>> Are we sure this copyright date is correct?
>
> I may be confused about which year the copyright refers to. I thought it
> was the year when the patch was committed. If it is the first time the
> patch was published then this one should be 2018.

I'm not a lawyer etc. but AIUI the date above is about the authorship,
ie. when it was originally written, not when it was published or
committed.

In general I don't think it matters too much, but in this case I'm
pretty sure Anshuman can't have possibly written it in 2019 on behalf of
IBM :)

So we can either change the date to 2018, or drop his name and just say
it's copyright 2019 by IBM.

cheers