Commit b2b15f07 authored by Alexander Gordeev's avatar Alexander Gordeev
Browse files

s390/boot: Consider DCSS segments on memory layout setup 



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: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
parent 47bf8176

arch/s390/boot/startup.c

+5 −2
Original line number Diff line number Diff line
@@ -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;

}

arch/s390/include/asm/extmem.h

+7 −0
Original line number Diff line number Diff line
@@ -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