linux-kernel - [PATCH AUTOSEL 6.7 01/21] s390/boot: always align vmalloc area on segment boundary

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Date: Mon, 15 Jan 2024 20:03:38 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Alexander Gordeev <agordeev@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Sasha Levin <sashal@...nel.org>,
	gor@...ux.ibm.com,
	imbrenda@...ux.ibm.com,
	linux-s390@...r.kernel.org
Subject: [PATCH AUTOSEL 6.7 01/21] s390/boot: always align vmalloc area on segment boundary

From: Alexander Gordeev <agordeev@...ux.ibm.com>

[ Upstream commit 65f8780e2d70257200547b5a7654974aa7c37ce1 ]

The size of vmalloc area depends from various factors
on boot and could be set to:

1. Default size as determined by VMALLOC_DEFAULT_SIZE macro;
2. One half of the virtual address space not occupied by
   modules and fixed mappings;
3. The size provided by user with vmalloc= kernel command
   line parameter;

In cases [1] and [2] the vmalloc area base address is aligned
on Region3 table type boundary, while in case [3] in might get
aligned on page boundary.

Limit the waste of page tables and always align vmalloc area
size and base address on segment boundary.

Acked-by: Heiko Carstens <hca@...ux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@...ux.ibm.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/s390/boot/ipl_parm.c | 2 +-
 arch/s390/boot/startup.c  | 3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/s390/boot/ipl_parm.c b/arch/s390/boot/ipl_parm.c
index 2ab4872fbee1..b24de9aabf7d 100644
--- a/arch/s390/boot/ipl_parm.c
+++ b/arch/s390/boot/ipl_parm.c
@@ -274,7 +274,7 @@ void parse_boot_command_line(void)
 			memory_limit = round_down(memparse(val, NULL), PAGE_SIZE);
 
 		if (!strcmp(param, "vmalloc") && val) {
-			vmalloc_size = round_up(memparse(val, NULL), PAGE_SIZE);
+			vmalloc_size = round_up(memparse(val, NULL), _SEGMENT_SIZE);
 			vmalloc_size_set = 1;
 		}
 
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 8104e0e3d188..9cc76e631759 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -255,7 +255,8 @@ static unsigned long setup_kernel_memory_layout(void)
 	VMALLOC_END = MODULES_VADDR;
 
 	/* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
-	vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE));
+	vsize = round_down(VMALLOC_END / 2, _SEGMENT_SIZE);
+	vmalloc_size = min(vmalloc_size, vsize);
 	VMALLOC_START = VMALLOC_END - vmalloc_size;
 
 	/* split remaining virtual space between 1:1 mapping & vmemmap array */
-- 
2.43.0