s390: unify identity mapping limits handling

Currently we have to consider too many different values which
in the end only affect identity mapping size. These are:
1. max_physmem_end - end of physical memory online or standby.
   Always <= end of the last online memory block (get_mem_detect_end()).
2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
   kernel is able to support.
3. "mem=" kernel command line option which limits physical memory usage.
4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
   crash kernel.
5. "hsa" size which is a memory limit when the kernel is executed during
   zfcp/nvme dump.

Through out kernel startup and run we juggle all those values at once
but that does not bring any amusement, only confusion and complexity.

Unify all those values to a single one we should really care, that is
our identity mapping size.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 17 insertions, 20 deletions

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 02bccee5ee85..756936785598 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -94,10 +94,8 @@ char elf_platform[ELF_PLATFORM_SIZE];
 unsigned long int_hwcap = 0;
 
 int __bootdata(noexec_disabled);
-int __bootdata(memory_end_set);
-unsigned long __bootdata(memory_end);
+unsigned long __bootdata(ident_map_size);
 unsigned long __bootdata(vmalloc_size);
-unsigned long __bootdata(max_physmem_end);
 struct mem_detect_info __bootdata(mem_detect);
 
 struct exception_table_entry *__bootdata_preserved(__start_dma_ex_table);
@@ -557,12 +555,12 @@ static void __init setup_resources(void)
 #endif
 }
 
-static void __init setup_memory_end(void)
+static void __init setup_ident_map_size(void)
 {
 	unsigned long vmax, tmp;
 
 	/* Choose kernel address space layout: 3 or 4 levels. */
-	tmp = (memory_end ?: max_physmem_end) / PAGE_SIZE;
+	tmp = ident_map_size / PAGE_SIZE;
 	tmp = tmp * (sizeof(struct page) + PAGE_SIZE);
 	if (tmp + vmalloc_size + MODULES_LEN <= _REGION2_SIZE)
 		vmax = _REGION2_SIZE; /* 3-level kernel page table */
@@ -589,22 +587,22 @@ static void __init setup_memory_end(void)
 	tmp = min(tmp, 1UL << MAX_PHYSMEM_BITS);
 	vmemmap = (struct page *) tmp;
 
-	/* Take care that memory_end is set and <= vmemmap */
-	memory_end = min(memory_end ?: max_physmem_end, (unsigned long)vmemmap);
+	/* Take care that ident_map_size <= vmemmap */
+	ident_map_size = min(ident_map_size, (unsigned long)vmemmap);
 #ifdef CONFIG_KASAN
-	memory_end = min(memory_end, KASAN_SHADOW_START);
+	ident_map_size = min(ident_map_size, KASAN_SHADOW_START);
 #endif
-	vmemmap_size = SECTION_ALIGN_UP(memory_end / PAGE_SIZE) * sizeof(struct page);
+	vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page);
 #ifdef CONFIG_KASAN
 	/* move vmemmap above kasan shadow only if stands in a way */
 	if (KASAN_SHADOW_END > (unsigned long)vmemmap &&
 	    (unsigned long)vmemmap + vmemmap_size > KASAN_SHADOW_START)
 		vmemmap = max(vmemmap, (struct page *)KASAN_SHADOW_END);
 #endif
-	max_pfn = max_low_pfn = PFN_DOWN(memory_end);
-	memblock_remove(memory_end, ULONG_MAX);
+	max_pfn = max_low_pfn = PFN_DOWN(ident_map_size);
+	memblock_remove(ident_map_size, ULONG_MAX);
 
-	pr_notice("The maximum memory size is %luMB\n", memory_end >> 20);
+	pr_notice("The maximum memory size is %luMB\n", ident_map_size >> 20);
 }
 
 #ifdef CONFIG_CRASH_DUMP
@@ -634,12 +632,11 @@ static struct notifier_block kdump_mem_nb = {
 #endif
 
 /*
- * Make sure that the area behind memory_end is protected
+ * Make sure that the area above identity mapping is protected
  */
-static void __init reserve_memory_end(void)
+static void __init reserve_above_ident_map(void)
 {
-	if (memory_end_set)
-		memblock_reserve(memory_end, ULONG_MAX);
+	memblock_reserve(ident_map_size, ULONG_MAX);
 }
 
 /*
@@ -676,7 +673,7 @@ static void __init reserve_crashkernel(void)
 	phys_addr_t low, high;
 	int rc;
 
-	rc = parse_crashkernel(boot_command_line, memory_end, &crash_size,
+	rc = parse_crashkernel(boot_command_line, ident_map_size, &crash_size,
 			       &crash_base);
 
 	crash_base = ALIGN(crash_base, KEXEC_CRASH_MEM_ALIGN);
@@ -1130,7 +1127,7 @@ void __init setup_arch(char **cmdline_p)
 	setup_control_program_code();
 
 	/* Do some memory reservations *before* memory is added to memblock */
-	reserve_memory_end();
+	reserve_above_ident_map();
 	reserve_oldmem();
 	reserve_kernel();
 	reserve_initrd();
@@ -1145,9 +1142,9 @@ void __init setup_arch(char **cmdline_p)
 	remove_oldmem();
 
 	setup_uv();
-	setup_memory_end();
+	setup_ident_map_size();
 	setup_memory();
-	dma_contiguous_reserve(memory_end);
+	dma_contiguous_reserve(ident_map_size);
 	vmcp_cma_reserve();
 
 	check_initrd();