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s390/boot: Consider DCSS segments on memory layout setup

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The maximum mappable physical address (as returned by
arch_get_mappable_range() callback) is limited by the
value of (1UL << MAX_PHYSMEM_BITS).

The maximum physical address available to a DCSS segment
is 512GB.

In case the available online or offline memory size is less
than the DCSS limit arch_get_mappable_range() would include
never used [512GB..(1UL << MAX_PHYSMEM_BITS)] range.

Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
This commit is contained in:
Alexander Gordeev 2024-03-01 07:03:49 +01:00
parent 47bf817672
commit b2b15f079c
2 changed files with 12 additions and 2 deletions
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7
arch/s390/boot/startup.c
View File

@ -3,6 +3,7 @@
#include <linux/elf.h>
#include <asm/page-states.h>
#include <asm/boot_data.h>
#include <asm/extmem.h>
#include <asm/sections.h>
#include <asm/maccess.h>
#include <asm/cpu_mf.h>
@ -313,14 +314,16 @@ static unsigned long setup_kernel_memory_layout(void)
pages = SECTION_ALIGN_UP(pages);
/* keep vmemmap_start aligned to a top level region table entry */
vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size);
/* maximum address for which linear mapping could be created (DCSS, memory) */
max_mappable = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS);
/* make sure identity map doesn't overlay with vmemmap */
ident_map_size = min(ident_map_size, vmemmap_start);
vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);
/* make sure vmemmap doesn't overlay with vmalloc area */
VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START);
vmemmap = (struct page *)vmemmap_start;
/* maximum address for which linear mapping could be created (DCSS, memory) */
BUILD_BUG_ON(MAX_DCSS_ADDR > (1UL << MAX_PHYSMEM_BITS));
max_mappable = max(ident_map_size, MAX_DCSS_ADDR);
max_mappable = min(max_mappable, vmemmap_start);
return asce_limit;
}

7
arch/s390/include/asm/extmem.h
View File

@ -8,6 +8,13 @@
#define _ASM_S390X_DCSS_H
#ifndef __ASSEMBLY__
/*
* DCSS segment is defined as a contiguous range of pages using DEFSEG command.
* The range start and end is a page number with a value less than or equal to
* 0x7ffffff (see CP Commands and Utilities Reference).
*/
#define MAX_DCSS_ADDR (512UL * SZ_1G)
/* possible values for segment type as returned by segment_info */
#define SEG_TYPE_SW 0
#define SEG_TYPE_EW 1