[PATCH v1 5/6] powerpc/64e: Reorganise virtual memory

From: Christophe Leroy
Date: Tue Jun 28 2022 - 10:49:39 EST


Reduce the size of IO map in order to leave the last
quarter of virtual MAP for KASAN shadow mapping.

This gives the following layout.

+------------------------+ Kernel virtual map end (0xc000200000000000)
| |
| 16TB (unused) |
| |
+------------------------+ Kernel IO map end
| |
| 16TB of IO map |
| |
+------------------------+ Kernel IO map start
| |
| 16TB of vmemmap |
| |
+------------------------+ Kernel vmemmap start
| |
| 16TB of vmap |
| |
+------------------------+ Kernel virt start (0xc000100000000000)
| |
| 64TB of linear mem |
| |
+------------------------+ Kernel linear (0xc.....)

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/include/asm/nohash/64/pgtable.h | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/nohash/64/pgtable.h b/arch/powerpc/include/asm/nohash/64/pgtable.h
index 76a144b58f9b..88906d9194c5 100644
--- a/arch/powerpc/include/asm/nohash/64/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/64/pgtable.h
@@ -38,15 +38,16 @@
#define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE)

/*
- * The second half of the kernel virtual space is used for IO mappings,
+ * The third quarter of the kernel virtual space is used for IO mappings,
* it's itself carved into the PIO region (ISA and PHB IO space) and
* the ioremap space
*
* ISA_IO_BASE = KERN_IO_START, 64K reserved area
* PHB_IO_BASE = ISA_IO_BASE + 64K to ISA_IO_BASE + 2G, PHB IO spaces
- * IOREMAP_BASE = ISA_IO_BASE + 2G to VMALLOC_START + PGTABLE_RANGE
+ * IOREMAP_BASE = ISA_IO_BASE + 2G to KERN_IO_START + KERN_IO_SIZE
*/
#define KERN_IO_START (KERN_VIRT_START + (KERN_VIRT_SIZE >> 1))
+#define KERN_IO_SIZE (KERN_VIRT_SIZE >> 2)
#define FULL_IO_SIZE 0x80000000ul
#define ISA_IO_BASE (KERN_IO_START)
#define ISA_IO_END (KERN_IO_START + 0x10000ul)
@@ -54,7 +55,7 @@
#define PHB_IO_END (KERN_IO_START + FULL_IO_SIZE)
#define IOREMAP_BASE (PHB_IO_END)
#define IOREMAP_START (ioremap_bot)
-#define IOREMAP_END (KERN_VIRT_START + KERN_VIRT_SIZE - FIXADDR_SIZE)
+#define IOREMAP_END (KERN_IO_START + KERN_IO_SIZE - FIXADDR_SIZE)
#define FIXADDR_SIZE SZ_32M

/*
--
2.36.1