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

Thiago Jung Bauermann [off-list ref] writes:

Michael Ellerman [off-list ref] writes:

quoted

Thiago Jung Bauermann [off-list ref] writes:

quoted

From: Anshuman Khandual <redacted>

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 <redacted>
Signed-off-by: Thiago Jung Bauermann <redacted>
---
 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