[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>

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 362dfbc..8cc6eee 100644 (file)
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -373,12 +373,23 @@ static void pSeries_lpar_hptab_clear(void)
 {
        unsigned long size_bytes = 1UL << ppc64_pft_size;
        unsigned long hpte_count = size_bytes >> 4;
-       unsigned long dummy1, dummy2;
+       unsigned long dummy1, dummy2, dword0;
+       long lpar_rc;
        int i;
 
        /* TODO: Use bulk call */
-       for (i = 0; i < hpte_count; i++)
-               plpar_pte_remove_raw(0, i, 0, &dummy1, &dummy2);
+       for (i = 0; i < hpte_count; i++) {
+               /* dont remove HPTEs with VRMA mappings */
+               lpar_rc = plpar_pte_remove_raw(H_ANDCOND, i, HPTE_V_1TB_SEG,
+                                               &dummy1, &dummy2);
+               if (lpar_rc == H_NOT_FOUND) {
+                       lpar_rc = plpar_pte_read_raw(0, i, &dword0, &dummy1);
+                       if (!lpar_rc && ((dword0 & HPTE_V_VRMA_MASK)
+                               != HPTE_V_VRMA_MASK))
+                               /* Can be hpte for 1TB Seg. So remove it */
+                               plpar_pte_remove_raw(0, i, 0, &dummy1, &dummy2);
+               }
+       }
 }
 
 /*

diff --git a/arch/powerpc/platforms/pseries/plpar_wrappers.h b/arch/powerpc/platforms/pseries/plpar_wrappers.h
index 2e4d10c..d003c80 100644 (file)
--- a/arch/powerpc/platforms/pseries/plpar_wrappers.h
+++ b/arch/powerpc/platforms/pseries/plpar_wrappers.h
@@ -108,6 +108,21 @@ static inline long plpar_pte_read(unsigned long flags, unsigned long ptex,
        return rc;
 }
 
+/* plpar_pte_read_raw can be called in real mode. It calls plpar_hcall_raw */
+static inline long plpar_pte_read_raw(unsigned long flags, unsigned long ptex,
+               unsigned long *old_pteh_ret, unsigned long *old_ptel_ret)
+{
+       long rc;
+       unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+
+       rc = plpar_hcall_raw(H_READ, retbuf, flags, ptex);
+
+       *old_pteh_ret = retbuf[0];
+       *old_ptel_ret = retbuf[1];
+
+       return rc;
+}
+
 static inline long plpar_pte_protect(unsigned long flags, unsigned long ptex,
                unsigned long avpn)
 {

diff --git a/include/asm-powerpc/mmu-hash64.h b/include/asm-powerpc/mmu-hash64.h
index ba32019..695962f 100644 (file)
--- 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 */