Re: [PATCH v3 1/2] powerpc/mm: Export flush_all_mm()

[Frederic Barrat]

Le 13/09/2017 à 06:04, Alistair Popple a écrit :
+static inline void hash__local_flush_all_mm(struct mm_struct *mm)
+{
+       /*
+        * There's no Page Walk Cache for hash, so what is needed is
+        * the same as flush_tlb_mm(), which doesn't really make sense
+        * with hash. So the only thing we could do is flush the
+        * entire LPID! Punt for now, as it's not being used.
+        */

Do you think it is worth putting a WARN_ON_ONCE here if we're asserting this
isn't used on hash?

I toyed with the idea. The reason I didn't add it was because 
hash__local_flush_tlb_mm() and hash__flush_tlb_mm() don't have one, yet 
it's also not supported. And I had faith in a developer thinking about 
using it would see the comment.
I was actually pretty close to have hash__local_flush_all_mm() call 
directly hash__local_flush_tlb_mm(), since the "all" stands for "pwc and 
tlb" and pwc doesn't exist for hash. But that doesn't do us any good for 
the time being.

Michael: any preference?

Side note: I'm under the impression that flush_tlb_mm() may be called on 
hash, even though it does nothing. kernel/fork.c, dup_mmap() and 
potentially another (through cscope).

  Fred


Otherwise looks good and is also needed for NPU.

Reviewed-By: Alistair Popple <alist...@popple.id.au>

+}
+
+static inline void hash__flush_all_mm(struct mm_struct *mm)
+{
+       /*
+        * There's no Page Walk Cache for hash, so what is needed is
+        * the same as flush_tlb_mm(), which doesn't really make sense
+        * with hash. So the only thing we could do is flush the
+        * entire LPID! Punt for now, as it's not being used.
+        */
+}
+
  static inline void hash__local_flush_tlb_page(struct vm_area_struct *vma,
                                          unsigned long vmaddr)
  {
diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h 
b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
index 9b433a624bf3..af06c6fe8a9f 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush-radix.h
@@ -21,17 +21,20 @@ extern void radix__flush_tlb_range(struct vm_area_struct 
*vma, unsigned long sta
  extern void radix__flush_tlb_kernel_range(unsigned long start, unsigned long 
end);
  
  extern void radix__local_flush_tlb_mm(struct mm_struct *mm);
+extern void radix__local_flush_all_mm(struct mm_struct *mm);
  extern void radix__local_flush_tlb_page(struct vm_area_struct *vma, unsigned 
long vmaddr);
  extern void radix__local_flush_tlb_page_psize(struct mm_struct *mm, unsigned 
long vmaddr,
                                              int psize);
  extern void radix__tlb_flush(struct mmu_gather *tlb);
  #ifdef CONFIG_SMP
  extern void radix__flush_tlb_mm(struct mm_struct *mm);
+extern void radix__flush_all_mm(struct mm_struct *mm);
  extern void radix__flush_tlb_page(struct vm_area_struct *vma, unsigned long 
vmaddr);
  extern void radix__flush_tlb_page_psize(struct mm_struct *mm, unsigned long 
vmaddr,
                                        int psize);
  #else
  #define radix__flush_tlb_mm(mm)               radix__local_flush_tlb_mm(mm)
+#define radix__flush_all_mm(mm)                radix__local_flush_all_mm(mm)
  #define radix__flush_tlb_page(vma,addr)       
radix__local_flush_tlb_page(vma,addr)
  #define radix__flush_tlb_page_psize(mm,addr,p) 
radix__local_flush_tlb_page_psize(mm,addr,p)
  #endif
diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h 
b/arch/powerpc/include/asm/book3s/64/tlbflush.h
index 72b925f97bab..70760d018bcd 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h
@@ -57,6 +57,13 @@ static inline void local_flush_tlb_page(struct 
vm_area_struct *vma,
        return hash__local_flush_tlb_page(vma, vmaddr);
  }
  
+static inline void local_flush_all_mm(struct mm_struct *mm)
+{
+       if (radix_enabled())
+               return radix__local_flush_all_mm(mm);
+       return hash__local_flush_all_mm(mm);
+}
+
  static inline void tlb_flush(struct mmu_gather *tlb)
  {
        if (radix_enabled())
@@ -79,9 +86,17 @@ static inline void flush_tlb_page(struct vm_area_struct *vma,
                return radix__flush_tlb_page(vma, vmaddr);
        return hash__flush_tlb_page(vma, vmaddr);
  }
+
+static inline void flush_all_mm(struct mm_struct *mm)
+{
+       if (radix_enabled())
+               return radix__flush_all_mm(mm);
+       return hash__flush_all_mm(mm);
+}
  #else
  #define flush_tlb_mm(mm)              local_flush_tlb_mm(mm)
  #define flush_tlb_page(vma, addr)     local_flush_tlb_page(vma, addr)
+#define flush_all_mm(mm)               local_flush_all_mm(mm)
  #endif /* CONFIG_SMP */
  /*
   * flush the page walk cache for the address
diff --git a/arch/powerpc/mm/tlb-radix.c b/arch/powerpc/mm/tlb-radix.c
index b3e849c4886e..5a1f46eff3a2 100644
--- a/arch/powerpc/mm/tlb-radix.c
+++ b/arch/powerpc/mm/tlb-radix.c
@@ -144,7 +144,7 @@ void radix__local_flush_tlb_mm(struct mm_struct *mm)
  EXPORT_SYMBOL(radix__local_flush_tlb_mm);
  
  #ifndef CONFIG_SMP
-static void radix__local_flush_all_mm(struct mm_struct *mm)
+void radix__local_flush_all_mm(struct mm_struct *mm)
  {
        unsigned long pid;
  
@@ -154,6 +154,7 @@ static void radix__local_flush_all_mm(struct mm_struct *mm)
                _tlbiel_pid(pid, RIC_FLUSH_ALL);
        preempt_enable();
  }
+EXPORT_SYMBOL(radix__local_flush_all_mm);
  #endif /* CONFIG_SMP */
  
  void radix__local_flush_tlb_page_psize(struct mm_struct *mm, unsigned long vmaddr,
@@ -200,7 +201,7 @@ void radix__flush_tlb_mm(struct mm_struct *mm)
  }
  EXPORT_SYMBOL(radix__flush_tlb_mm);
  
-static void radix__flush_all_mm(struct mm_struct *mm)
+void radix__flush_all_mm(struct mm_struct *mm)
  {
        unsigned long pid;
  
@@ -216,6 +217,7 @@ static void radix__flush_all_mm(struct mm_struct *mm)
  no_context:
        preempt_enable();
  }
+EXPORT_SYMBOL(radix__flush_all_mm);
  
  void radix__flush_tlb_pwc(struct mmu_gather *tlb, unsigned long addr)
  {