From 63443383e9f73df375dd2734986bfc758955ddc7 Mon Sep 17 00:00:00 2001
From: Yoshihisa Morizumi <yoshi.morizumi@fujitsu.com>
Date: Fri, 29 Jan 2021 05:17:47 +0900
Subject: [PATCH] xpmem: truncates the size of xpmem_attach at the page
 boundary (workaround for fjmpi)

Fujitsu MPI tries to attach a segment with the size of the source range size plus one.

Change-Id: Iab3801727f938dfb6242b6b90c88e4986b84d08e
Refs: #1507
---
 CMakeLists.txt | 18 ++++++++++++++++++
 kernel/xpmem.c |  9 +++++++++
 2 files changed, 27 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 04f6aad0..f2c20519 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -83,6 +83,23 @@ if(ENABLE_FUGAKU_HACKS)
 	set(KBUILD_C_FLAGS "${KBUILD_C_FLAGS} -DENABLE_FUGAKU_HACKS")
 endif()
 
+# Fujitsu MPI tries to xpmem-attach segment with size of range size + 1?
+set(FJMPI_VERSION_COMMAND "a=\$(which mpifcc); b=\${a%/*/*}; c=\${b##*/}; d=\${c#*-}; echo \$d")
+execute_process(COMMAND bash -c "${FJMPI_VERSION_COMMAND}"
+  OUTPUT_VARIABLE FJMPI_VERSION OUTPUT_STRIP_TRAILING_WHITESPACE)
+message("FJMPI_VERSION: ${FJMPI_VERSION}")
+
+if(NOT "${FJMPI_VERSION}" STREQUAL "")
+	option(ENABLE_FJMPI_WORKAROUND "Fujitsu MPI workaround" ON)
+else()
+	option(ENABLE_FJMPI_WORKAROUND "Fujitsu MPI workaround" OFF)
+endif()
+
+if(ENABLE_FJMPI_WORKAROUND)
+	add_definitions(-DENABLE_FJMPI_WORKAROUND)
+	set(KBUILD_C_FLAGS "${KBUILD_C_FLAGS} -DENABLE_FJMPI_WORKAROUND")
+endif()
+
 # krm that mandates reserved memory amount >= available at boot time?
 execute_process(COMMAND bash -c "rpm -qi FJSVpxkrm-plugin-mckernel | awk '$1 == \"Version\" && $2 == \":\" { print $3 }'"
   OUTPUT_VARIABLE KRM_VERSION OUTPUT_STRIP_TRAILING_WHITESPACE)
@@ -315,6 +332,7 @@ message("ENABLE_TOFU: ${ENABLE_TOFU}")
 message("ENABLE_FUGAKU_HACKS: ${ENABLE_FUGAKU_HACKS}")
 message("ENABLE_FUGAKU_DEBUG: ${ENABLE_FUGAKU_DEBUG}")
 message("ENABLE_KRM_WORKAROUND: ${ENABLE_KRM_WORKAROUND}")
+message("ENABLE_FJMPI_WORKAROUND: ${ENABLE_FJMPI_WORKAROUND}")
 message("PROFILE_ENABLE: ${PROFILE_ENABLE}")
 message("ENABLE_RUSAGE: ${ENABLE_RUSAGE}")
 message("ENABLE_QLMPI: ${ENABLE_QLMPI}")
diff --git a/kernel/xpmem.c b/kernel/xpmem.c
index 3a3525b0..4bde18d3 100644
--- a/kernel/xpmem.c
+++ b/kernel/xpmem.c
@@ -1027,10 +1027,19 @@ static int xpmem_attach(
 		return -EINVAL;
 	}
 
+#ifdef ENABLE_FJMPI_WORKAROUND
+	/* Truncate size at page boundary because Fujitsu MPI
+	 * erroneously passes (source range size + 1) as "size"
+	 */
+	size = (size & ~(PAGE_SIZE - 1));
+#else
 	/* If the size is not page aligned, fix it */
 	if (offset_in_page(size) != 0) {
 		size += PAGE_SIZE - offset_in_page(size);
 	}
+#endif
+
+	XPMEM_DEBUG("size after fix: 0x%lx", size);
 
 	ap_tg = xpmem_tg_ref_by_apid(apid);
 	if (IS_ERR(ap_tg))