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s390/mm: implement MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers

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MEM_PREPARE_ONLINE memory notifier makes memory block physical
accessible via sclp assign command. The notifier ensures self-contained
memory maps are accessible and hence enabling the "memmap on memory" on
s390.

MEM_FINISH_OFFLINE memory notifier shifts the memory block to an
inaccessible state via sclp unassign command.

Implementation considerations:
* When MHP_MEMMAP_ON_MEMORY is disabled, the system retains the old
  behavior. This means the memory map is allocated from default memory.
* If MACHINE_HAS_EDAT1 is unavailable, MHP_MEMMAP_ON_MEMORY is
  automatically disabled. This ensures that vmemmap pagetables do not
  consume additional memory from the default memory allocator.
* The MEM_GOING_ONLINE notifier has been modified to perform no
  operation, as MEM_PREPARE_ONLINE already executes the sclp assign
  command.
* The MEM_CANCEL_ONLINE/MEM_OFFLINE notifier now performs no operation, as
  MEM_FINISH_OFFLINE already executes the sclp unassign command.

Link: https://lkml.kernel.org/r/20240108132747.3238763-5-sumanthk@linux.ibm.com
Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Sumanth Korikkar 2024-01-08 14:27:46 +01:00 committed by Andrew Morton
parent fb6d5eb9f4
commit 890a4212de
1 changed files with 35 additions and 6 deletions
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41
drivers/s390/char/sclp_cmd.c
View File

@ -18,6 +18,7 @@
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/module.h>
#include <asm/ctlreg.h>
#include <asm/chpid.h>
@ -26,6 +27,7 @@
#include <asm/sclp.h>
#include <asm/numa.h>
#include <asm/facility.h>
#include <asm/page-states.h>
#include "sclp.h"
@ -340,13 +342,38 @@ static int sclp_mem_notifier(struct notifier_block *nb,
if (contains_standby_increment(start, start + size))
rc = -EPERM;
break;
case MEM_GOING_ONLINE:
case MEM_PREPARE_ONLINE:
/*
* Access the altmap_start_pfn and altmap_nr_pages fields
* within the struct memory_notify specifically when dealing
* with only MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE notifiers.
*
* When altmap is in use, take the specified memory range
* online, which includes the altmap.
*/
if (arg->altmap_nr_pages) {
start = PFN_PHYS(arg->altmap_start_pfn);
size += PFN_PHYS(arg->altmap_nr_pages);
}
rc = sclp_mem_change_state(start, size, 1);
if (rc || !arg->altmap_nr_pages)
break;
/*
* Set CMMA state to nodat here, since the struct page memory
* at the beginning of the memory block will not go through the
* buddy allocator later.
*/
__arch_set_page_nodat((void *)__va(start), arg->altmap_nr_pages);
break;
case MEM_CANCEL_ONLINE:
sclp_mem_change_state(start, size, 0);
break;
case MEM_OFFLINE:
case MEM_FINISH_OFFLINE:
/*
* When altmap is in use, take the specified memory range
* offline, which includes the altmap.
*/
if (arg->altmap_nr_pages) {
start = PFN_PHYS(arg->altmap_start_pfn);
size += PFN_PHYS(arg->altmap_nr_pages);
}
sclp_mem_change_state(start, size, 0);
break;
default:
@ -397,7 +424,9 @@ static void __init add_memory_merged(u16 rn)
if (!size)
goto skip_add;
for (addr = start; addr < start + size; addr += block_size)
add_memory(0, addr, block_size, MHP_NONE);
add_memory(0, addr, block_size,
MACHINE_HAS_EDAT1 ?
MHP_MEMMAP_ON_MEMORY | MHP_OFFLINE_INACCESSIBLE : MHP_NONE);
skip_add:
first_rn = rn;
num = 1;