[S390] Add architecture code for unmapping crashkernel memory

This patch implements the crash_map_pages() function for s390.
KEXEC_CRASH_MEM_ALIGN is set to HPAGE_SIZE, in order to support
kernel mappings that use large pages. We also use HPAGE_SIZE alignment
for CONFIG_HUGETLB_PAGE=n in order to have the same 1 MiB alignment on
all s390 systems.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 40 insertions, 4 deletions

diff --git a/arch/s390/include/asm/kexec.h b/arch/s390/include/asm/kexec.h
index fb1c96fa348c..cf4e47b0948c 100644
--- a/arch/s390/include/asm/kexec.h
+++ b/arch/s390/include/asm/kexec.h
@@ -36,6 +36,9 @@
 /* Allocate one page for the pdp and the second for the code */
 #define KEXEC_CONTROL_PAGE_SIZE 4096
 
+/* Alignment of crashkernel memory */
+#define KEXEC_CRASH_MEM_ALIGN HPAGE_SIZE
+
 /* The native architecture */
 #define KEXEC_ARCH KEXEC_ARCH_S390
 
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 0ceac06a0299..13a0b528c70b 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -133,6 +133,37 @@ static int kdump_csum_valid(struct kimage *image)
 }
 
 /*
+ * Map or unmap crashkernel memory
+ */
+static void crash_map_pages(int enable)
+{
+        unsigned long size = resource_size(&crashk_res);
+
+        BUG_ON(crashk_res.start % KEXEC_CRASH_MEM_ALIGN ||
+               size % KEXEC_CRASH_MEM_ALIGN);
+        if (enable)
+                vmem_add_mapping(crashk_res.start, size);
+        else
+                vmem_remove_mapping(crashk_res.start, size);
+}
+
+/*
+ * Map crashkernel memory
+ */
+void crash_map_reserved_pages(void)
+{
+        crash_map_pages(1);
+}
+
+/*
+ * Unmap crashkernel memory
+ */
+void crash_unmap_reserved_pages(void)
+{
+        crash_map_pages(0);
+}
+
+/*
  * Give back memory to hypervisor before new kdump is loaded
  */
 static int machine_kexec_prepare_kdump(void)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 63c81de665ec..6f8e3777a0c8 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -446,6 +446,7 @@ static void __init setup_resources(void)
                 res->flags = IORESOURCE_BUSY | IORESOURCE_MEM;
                 switch (memory_chunk[i].type) {
                 case CHUNK_READ_WRITE:
+                case CHUNK_CRASHK:
                         res->name = "System RAM";
                         break;
                 case CHUNK_READ_ONLY:
@@ -720,8 +721,8 @@ static void __init reserve_crashkernel(void)
                                &crash_base);
         if (rc || crash_size == 0)
                 return;
-        crash_base = PAGE_ALIGN(crash_base);
-        crash_size = PAGE_ALIGN(crash_size);
+        crash_base = ALIGN(crash_base, KEXEC_CRASH_MEM_ALIGN);
+        crash_size = ALIGN(crash_size, KEXEC_CRASH_MEM_ALIGN);
         if (register_memory_notifier(&kdump_mem_nb))
                 return;
         if (!crash_base)
@@ -741,7 +742,7 @@ static void __init reserve_crashkernel(void)
         crashk_res.start = crash_base;
         crashk_res.end = crash_base + crash_size - 1;
         insert_resource(&iomem_resource, &crashk_res);
-        reserve_kdump_bootmem(crash_base, crash_size, CHUNK_READ_WRITE);
+        reserve_kdump_bootmem(crash_base, crash_size, CHUNK_CRASHK);
         pr_info("Reserving %lluMB of memory at %lluMB "
                 "for crashkernel (System RAM: %luMB)\n",
                 crash_size >> 20, crash_base >> 20, memory_end >> 20);
@@ -816,7 +817,8 @@ setup_memory(void)
         for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
                 unsigned long start_chunk, end_chunk, pfn;
 
-                if (memory_chunk[i].type != CHUNK_READ_WRITE)
+                if (memory_chunk[i].type != CHUNK_READ_WRITE &&
+                    memory_chunk[i].type != CHUNK_CRASHK)
                         continue;
                 start_chunk = PFN_DOWN(memory_chunk[i].addr);
                 end_chunk = start_chunk + PFN_DOWN(memory_chunk[i].size);