[POWERPC] Fix Kexec/Kdump for power6

On Power machines supporting VRMA, Kexec/Kdump does not work.
VRMA (virtual real-mode area) means that accesses with IR/DR = 0
(i.e. the MMU "off") actually still go through the hash table,
using entries put there by the hypervisor.

This means that when we clear out the hash table on kexec, we need to
make sure these entries are left untouched.

This also adds plpar_pte_read_raw() on the lines of
plpar_pte_remove_raw().

Signed-off-by : Sachin Sant <sachinp@in.ibm.com>
Signed-off-by : Mohan Kumar M <mohan@in.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Olof Johansson <olof@lixom.net>

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/asm-powerpc/mmu-hash64.h b/include/asm-powerpc/mmu-hash64.h
index ba32019c51dd..695962f02059 100644
--- a/include/asm-powerpc/mmu-hash64.h
+++ b/include/asm-powerpc/mmu-hash64.h
@@ -94,6 +94,9 @@ extern char initial_stab[];
 #define HPTE_R_C                ASM_CONST(0x0000000000000080)
 #define HPTE_R_R                ASM_CONST(0x0000000000000100)
 
+#define HPTE_V_1TB_SEG          ASM_CONST(0x4000000000000000)
+#define HPTE_V_VRMA_MASK        ASM_CONST(0x4001ffffff000000)
+
 /* Values for PP (assumes Ks=0, Kp=1) */
 /* pp0 will always be 0 for linux     */
 #define PP_RWXX 0       /* Supervisor read/write, User none */