powerpc/pseries: Fix to handle slb resize across migration

The SLB can change sizes across a live migration, which was not
being handled, resulting in possible machine crashes during
migration if migrating to a machine which has a smaller max SLB
size than the source machine. Fix this by first reducing the
SLB size to the minimum possible value, which is 32, prior to
migration. Then during the device tree update which occurs after
migration, we make the call to ensure the SLB gets updated. Also
add the slb_size to the lparcfg output so that the migration
tools can check to make sure the kernel has this capability
before allowing migration in scenarios where the SLB size will change.

BenH: Fixed #include <asm/mmu-hash64.h> -> <asm/mmu.h> to avoid
      breaking ppc32 build

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index b537903b9fca..bebe31c2e907 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -41,6 +41,7 @@ extern char initial_stab[];
 
 #define SLB_NUM_BOLTED          3
 #define SLB_CACHE_ENTRIES       8
+#define SLB_MIN_SIZE            32
 
 /* Bits in the SLB ESID word */
 #define SLB_ESID_V              ASM_CONST(0x0000000008000000) /* valid */
@@ -276,6 +277,7 @@ extern void slb_flush_and_rebolt(void);
 extern void stab_initialize(unsigned long stab);
 
 extern void slb_vmalloc_update(void);
+extern void slb_set_size(u16 size);
 #endif /* __ASSEMBLY__ */
 
 /*