s390/vmcp: make use of contiguous memory allocator
If memory is fragmented it is unlikely that large order memory
allocations succeed. This has been an issue with the vmcp device
driver since a long time, since it requires large physical contiguous
memory ares for large responses.
To hopefully resolve this issue make use of the contiguous memory
allocator (cma). This patch adds a vmcp specific vmcp cma area with a
default size of 4MB. The size can be changed either via the
VMCP_CMA_SIZE config option at compile time or with the "vmcp_cma"
kernel parameter (e.g. "vmcp_cma=16m").
For any vmcp response buffers larger than 16k memory from the cma area
will be allocated. If such an allocation fails, there is a fallback to
the buddy allocator.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
index 61da4bd..490e035b 100644
--- a/arch/s390/include/asm/setup.h
+++ b/arch/s390/include/asm/setup.h
@@ -108,6 +108,12 @@ extern void pfault_fini(void);
#define pfault_fini() do { } while (0)
#endif /* CONFIG_PFAULT */
+#ifdef CONFIG_VMCP
+void vmcp_cma_reserve(void);
+#else
+static inline void vmcp_cma_reserve(void) { }
+#endif
+
void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault);
void cmma_init(void);