linux-kernel - [PATCH V9 0/2] powerpc/dlpar: Correct display of hot-add/hot-remove CPUs and memory

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Message-Id: <9e5050e1-e0cc-0e0e-7b31-5dcb38b307f4@linux.vnet.ibm.com>
Date:   Mon, 21 Aug 2017 16:44:12 -0500
From:   Michael Bringmann <mwb@...ux.vnet.ibm.com>
To:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Cc:     nfont@...ux.vnet.ibm.com,
        Michael Bringmann <mwb@...ux.vnet.ibm.com>,
        John Allen <jallen@...ux.vnet.ibm.com>
Subject: [PATCH V9 0/2] powerpc/dlpar: Correct display of hot-add/hot-remove
 CPUs and memory

On Power systems with shared configurations of CPUs and memory, there
are some issues with association of additional CPUs and memory to nodes
when hot-adding resources.  These patches address some of those problems.

powerpc/numa: Correct the currently broken capability to set the
topology for shared CPUs in LPARs.  At boot time for shared CPU
lpars, the topology for each shared CPU is set to node zero, however,
this is now updated correctly using the Virtual Processor Home Node
(VPHN) capabilities information provided by the pHyp. The VPHN handling
in Linux is disabled, if PRRN handling is present.

powerpc/nodes: On systems like PowerPC which allow 'hot-add' of CPU
or memory resources, it may occur that the new resources are to be
inserted into nodes that were not used for these resources at bootup.
In the kernel, any node that is used must be defined and initialized
at boot.

This patch extracts the value of the lowest domain level (number of
allocable resources) from the "rtas" device tree property
"ibm,max-associativity-domains" to use as the maximum number of nodes
to setup as possibly available in the system.  This new setting will
override the instruction,

    nodes_and(node_possible_map, node_possible_map, node_online_map);

presently seen in the function arch/powerpc/mm/numa.c:initmem_init().

If the property is not present at boot, no operation will be performed
to define or enable additional nodes.

Signed-off-by: Michael Bringmann <mwb@...ux.vnet.ibm.com>

Michael Bringmann (2):
  powerpc/numa: Update CPU topology when VPHN enabled
  powerpc/nodes: Ensure enough nodes avail for operations
---
Changes in V9:
  -- Calculate number of nodes via property "ibm,max-associativity-domains"