Split init_new_context and destroy_context

For KVM we need to allocate a new context id, but don't really care about
all the mm context around it.

So let's split the alloc and destroy functions for the context id, so we can
grab one without allocating an mm context.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index b34e94d9443583d1bd17729a1230e38adde53479..26383e0778aaaa143ad3aa793753204d5f8d7ca9 100644 (file)
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -23,6 +23,8 @@ extern void switch_slb(struct task_struct *tsk, struct mm_struct *mm);
 extern void set_context(unsigned long id, pgd_t *pgd);
 
 #ifdef CONFIG_PPC_BOOK3S_64
+extern int __init_new_context(void);
+extern void __destroy_context(int context_id);
 static inline void mmu_context_init(void) { }
 #else
 extern void mmu_context_init(void);

diff --git a/arch/powerpc/mm/mmu_context_hash64.c b/arch/powerpc/mm/mmu_context_hash64.c
index dbeb86ac90cd79f01396eecbd72b98bc172253dc..b9e4cc2c2057e43bed991c06c4c9cc184bc6f3d2 100644 (file)
--- a/arch/powerpc/mm/mmu_context_hash64.c
+++ b/arch/powerpc/mm/mmu_context_hash64.c
@@ -18,6 +18,7 @@
 #include <linux/mm.h>
 #include <linux/spinlock.h>
 #include <linux/idr.h>
+#include <linux/module.h>
 
 #include <asm/mmu_context.h>
 
@@ -32,7 +33,7 @@ static DEFINE_IDR(mmu_context_idr);
 #define NO_CONTEXT     0
 #define MAX_CONTEXT    ((1UL << 19) - 1)
 
-int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+int __init_new_context(void)
 {
        int index;
        int err;
@@ -57,6 +58,18 @@ again:
                return -ENOMEM;
        }
 
+       return index;
+}
+EXPORT_SYMBOL_GPL(__init_new_context);
+
+int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+       int index;
+
+       index = __init_new_context();
+       if (index < 0)
+               return index;
+
        /* The old code would re-promote on fork, we don't do that
         * when using slices as it could cause problem promoting slices
         * that have been forced down to 4K
@@ -68,11 +81,16 @@ again:
        return 0;
 }
 
-void destroy_context(struct mm_struct *mm)
+void __destroy_context(int context_id)
 {
        spin_lock(&mmu_context_lock);
-       idr_remove(&mmu_context_idr, mm->context.id);
+       idr_remove(&mmu_context_idr, context_id);
        spin_unlock(&mmu_context_lock);
+}
+EXPORT_SYMBOL_GPL(__destroy_context);
 
+void destroy_context(struct mm_struct *mm)
+{
+       __destroy_context(mm->context.id);
        mm->context.id = NO_CONTEXT;
 }