On Tue, Sep 18, 2012 at 8:23 AM, Will Deacon [off-list ref] wrote:

On Sat, Sep 15, 2012 at 04:34:36PM +0100, Christoffer Dall wrote:

quoted

From: Marc Zyngier <redacted>

The KVM hypervisor mmu code requires access to the mem_type prot_pte
field when setting up page tables pointing to a device. Unfortunately,
the mem_type structure is opaque.

Add an accessor (get_mem_type_prot_pte()) to retrieve the prot_pte
value.

Signed-off-by: Marc Zyngier <redacted>
Signed-off-by: Christoffer Dall <redacted>
---
 arch/arm/include/asm/mach/map.h |    1 +
 arch/arm/mm/mmu.c               |    6 ++++++
 2 files changed, 7 insertions(+)

diff --git a/arch/arm/include/asm/mach/map.h b/arch/arm/include/asm/mach/map.h
index a6efcdd..3787c9f 100644
--- a/arch/arm/include/asm/mach/map.h
+++ b/arch/arm/include/asm/mach/map.h

@@ -37,6 +37,7 @@ extern void iotable_init(struct map_desc *, int);

 struct mem_type;
 extern const struct mem_type *get_mem_type(unsigned int type);
+extern pteval_t get_mem_type_prot_pte(unsigned int type);
 /*
  * external interface to remap single page with appropriate type
  */

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 4c2d045..76bf4f5 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c

@@ -301,6 +301,12 @@ const struct mem_type *get_mem_type(unsigned int type)
 }
 EXPORT_SYMBOL(get_mem_type);

+pteval_t get_mem_type_prot_pte(unsigned int type)
+{
+     return get_mem_type(type)->prot_pte;
+}
+EXPORT_SYMBOL(get_mem_type_prot_pte);
+

get_mem_type can return NULL, so you should probably pass the error through
rather than dereferencing it.

right, I guess callers can check against 0, since L_PTE_PRESENT should
always be there.

diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index a153fd4..f2b6287 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c

@@ -305,7 +305,9 @@ EXPORT_SYMBOL(get_mem_type);

 pteval_t get_mem_type_prot_pte(unsigned int type)
 {
-       return get_mem_type(type)->prot_pte;
+       if (get_mem_type(type))
+               return get_mem_type(type)->prot_pte;
+       return 0;
 }
 EXPORT_SYMBOL(get_mem_type_prot_pte);