[PATCH v2 1/2] powerpc/mm: Fix build break when PPC_NATIVE=n

The recent commit to rework the hash MMU setup broke the build when
CONFIG_PPC_NATIVE=n. Fix it by adding an IS_ENABLED() check before
calling hpte_init_native().

Removing the else clause opens the possibility that we don't set any
ops, which would probably lead to a strange crash later. So add a check
that we correctly initialised at least one member of the struct.

Fixes: 166dd7d3fbf2 ("powerpc/64: Move MMU backend selection out of platform code")
Reported-by: Stephen Rothwell <redacted>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/mm/hash_utils_64.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 341632471b9d..381b5894cc99 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -931,9 +931,12 @@ void __init hash__early_init_mmu(void)
 		ps3_early_mm_init();
 	else if (firmware_has_feature(FW_FEATURE_LPAR))
 		hpte_init_lpar();
-	else
+	else if IS_ENABLED(CONFIG_PPC_NATIVE)
 		hpte_init_native();
 
+	if (!mmu_hash_ops.hpte_insert)
+		panic("hash__early_init_mmu: No MMU hash ops defined!\n");
+
 	/* Initialize the MMU Hash table and create the linear mapping
 	 * of memory. Has to be done before SLB initialization as this is
 	 * currently where the page size encoding is obtained.

-- 
2.7.4

hpte_init_lpar() is part of the pseries platform, so name it as such.

Move the fallback implementation for when PSERIES=n into the header,
dropping the weak implementation. The panic() is now handled by the
calling code.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
 arch/powerpc/include/asm/book3s/64/mmu-hash.h | 7 ++++++-
 arch/powerpc/mm/hash_utils_64.c               | 7 +------
 arch/powerpc/platforms/pseries/lpar.c         | 2 +-
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
index b0f4dffe12ae..450b017fdc19 100644
--- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h

@@ -391,8 +391,13 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 extern void add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages);
 extern void demote_segment_4k(struct mm_struct *mm, unsigned long addr);
 
+#ifdef CONFIG_PPC_PSERIES
+void hpte_init_pseries(void);
+#else
+static inline void hpte_init_pseries(void) { }
+#endif
+
 extern void hpte_init_native(void);
-extern void hpte_init_lpar(void);
 extern void hpte_init_beat(void);
 extern void hpte_init_beat_v3(void);
 

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 381b5894cc99..1ff11c1bb182 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c

@@ -885,11 +885,6 @@ static void __init htab_initialize(void)
 #undef KB
 #undef MB
 
-void __init __weak hpte_init_lpar(void)
-{
-	panic("FW_FEATURE_LPAR set but no LPAR support compiled\n");
-}
-
 void __init hash__early_init_mmu(void)
 {
 	/*

@@ -930,7 +925,7 @@ void __init hash__early_init_mmu(void)
 	if (firmware_has_feature(FW_FEATURE_PS3_LV1))
 		ps3_early_mm_init();
 	else if (firmware_has_feature(FW_FEATURE_LPAR))
-		hpte_init_lpar();
+		hpte_init_pseries();
 	else if IS_ENABLED(CONFIG_PPC_NATIVE)
 		hpte_init_native();
 

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 0e91388d0af9..86707e67843f 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c

@@ -589,7 +589,7 @@ static int __init disable_bulk_remove(char *str)
 
 __setup("bulk_remove=", disable_bulk_remove);
 
-void __init hpte_init_lpar(void)
+void __init hpte_init_pseries(void)
 {
 	mmu_hash_ops.hpte_invalidate	 = pSeries_lpar_hpte_invalidate;
 	mmu_hash_ops.hpte_updatepp	 = pSeries_lpar_hpte_updatepp;

-- 
2.7.4

Hi Michael,

On Tue, 26 Jul 2016 13:38:38 +1000 Michael Ellerman [off-list ref] wrote:

hpte_init_lpar() is part of the pseries platform, so name it as such.

Move the fallback implementation for when PSERIES=n into the header,
dropping the weak implementation. The panic() is now handled by the
calling code.

Of course, this could have been handled the same way as the native one.

 	else if (firmware_has_feature(FW_FEATURE_LPAR))

        else if (IS_ENABLED(CONFIG_PPC_PSERIES) && firmware_has_feature(FW_FEATURE_LPAR))

-		hpte_init_lpar();
+		hpte_init_pseries();

and no need to modify the header file.
-- 
Cheers,
Stephen Rothwell

Hi Michael,

On Tue, 26 Jul 2016 13:38:37 +1000 Michael Ellerman [off-list ref] wrote:

The recent commit to rework the hash MMU setup broke the build when
CONFIG_PPC_NATIVE=n. Fix it by adding an IS_ENABLED() check before
calling hpte_init_native().

Removing the else clause opens the possibility that we don't set any
ops, which would probably lead to a strange crash later. So add a check
that we correctly initialised at least one member of the struct.

Fixes: 166dd7d3fbf2 ("powerpc/64: Move MMU backend selection out of platform code")
Reported-by: Stephen Rothwell <redacted>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Acked-by: Stephen Rothwell <redacted>
-- 
Cheers,
Stephen Rothwell

On Tue, 2016-26-07 at 03:38:37 UTC, Michael Ellerman wrote:

The recent commit to rework the hash MMU setup broke the build when
CONFIG_PPC_NATIVE=n. Fix it by adding an IS_ENABLED() check before
calling hpte_init_native().

Removing the else clause opens the possibility that we don't set any
ops, which would probably lead to a strange crash later. So add a check
that we correctly initialised at least one member of the struct.

Fixes: 166dd7d3fbf2 ("powerpc/64: Move MMU backend selection out of platform code")
Reported-by: Stephen Rothwell <redacted>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Stephen Rothwell <redacted>

Series applied to powerpc next.

https://git.kernel.org/powerpc/c/7353644fa9df875aee778a802e

cheers