diff mbox series

[v1,3/4] arm64: decouple check whether pfn is in linear map from pfn_valid()

Message ID 20210420090925.7457-4-rppt@kernel.org (mailing list archive)
State New
Headers show
Series arm64: drop pfn_valid_within() and simplify pfn_valid() | expand

Commit Message

Mike Rapoport April 20, 2021, 9:09 a.m. UTC
From: Mike Rapoport <rppt@linux.ibm.com>

The intended semantics of pfn_valid() is to verify whether there is a
struct page for the pfn in question and nothing else.

Yet, on arm64 it is used to distinguish memory areas that are mapped in the
linear map vs those that require ioremap() to access them.

Introduce a dedicated pfn_is_map_memory() wrapper for
memblock_is_map_memory() to perform such check and use it where
appropriate.

Using a wrapper allows to avoid cyclic include dependencies.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
---
 arch/arm64/include/asm/memory.h | 2 +-
 arch/arm64/include/asm/page.h   | 1 +
 arch/arm64/kvm/mmu.c            | 2 +-
 arch/arm64/mm/init.c            | 6 ++++++
 arch/arm64/mm/ioremap.c         | 4 ++--
 arch/arm64/mm/mmu.c             | 2 +-
 6 files changed, 12 insertions(+), 5 deletions(-)

Comments

David Hildenbrand April 20, 2021, 3:57 p.m. UTC | #1
On 20.04.21 11:09, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> The intended semantics of pfn_valid() is to verify whether there is a
> struct page for the pfn in question and nothing else.
> 
> Yet, on arm64 it is used to distinguish memory areas that are mapped in the
> linear map vs those that require ioremap() to access them.
> 
> Introduce a dedicated pfn_is_map_memory() wrapper for
> memblock_is_map_memory() to perform such check and use it where
> appropriate.
> 
> Using a wrapper allows to avoid cyclic include dependencies.
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> ---
>   arch/arm64/include/asm/memory.h | 2 +-
>   arch/arm64/include/asm/page.h   | 1 +
>   arch/arm64/kvm/mmu.c            | 2 +-
>   arch/arm64/mm/init.c            | 6 ++++++
>   arch/arm64/mm/ioremap.c         | 4 ++--
>   arch/arm64/mm/mmu.c             | 2 +-
>   6 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index 0aabc3be9a75..194f9f993d30 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -351,7 +351,7 @@ static inline void *phys_to_virt(phys_addr_t x)
>   
>   #define virt_addr_valid(addr)	({					\
>   	__typeof__(addr) __addr = __tag_reset(addr);			\
> -	__is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr));	\
> +	__is_lm_address(__addr) && pfn_is_map_memory(virt_to_pfn(__addr));	\
>   })
>   
>   void dump_mem_limit(void);
> diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
> index 012cffc574e8..99a6da91f870 100644
> --- a/arch/arm64/include/asm/page.h
> +++ b/arch/arm64/include/asm/page.h
> @@ -38,6 +38,7 @@ void copy_highpage(struct page *to, struct page *from);
>   typedef struct page *pgtable_t;
>   
>   extern int pfn_valid(unsigned long);
> +extern int pfn_is_map_memory(unsigned long);
>   
>   #include <asm/memory.h>
>   
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 8711894db8c2..23dd99e29b23 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -85,7 +85,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
>   
>   static bool kvm_is_device_pfn(unsigned long pfn)
>   {
> -	return !pfn_valid(pfn);
> +	return !pfn_is_map_memory(pfn);
>   }
>   
>   /*
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 3685e12aba9b..c54e329aca15 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -258,6 +258,12 @@ int pfn_valid(unsigned long pfn)
>   }
>   EXPORT_SYMBOL(pfn_valid);
>   
> +int pfn_is_map_memory(unsigned long pfn)
> +{

I think you might have to add (see pfn_valid())

if (PHYS_PFN(PFN_PHYS(pfn)) != pfn)
	return 0;

to catch false positives.

> +	return memblock_is_map_memory(PFN_PHYS(pfn));
> +}
> +EXPORT_SYMBOL(pfn_is_map_memory);
> +
>   static phys_addr_t memory_limit = PHYS_ADDR_MAX;
>   
>   /*
> diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
> index b5e83c46b23e..b7c81dacabf0 100644
> --- a/arch/arm64/mm/ioremap.c
> +++ b/arch/arm64/mm/ioremap.c
> @@ -43,7 +43,7 @@ static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size,
>   	/*
>   	 * Don't allow RAM to be mapped.
>   	 */
> -	if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr))))
> +	if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr))))
>   		return NULL;
>   
>   	area = get_vm_area_caller(size, VM_IOREMAP, caller);
> @@ -84,7 +84,7 @@ EXPORT_SYMBOL(iounmap);
>   void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
>   {
>   	/* For normal memory we already have a cacheable mapping. */
> -	if (pfn_valid(__phys_to_pfn(phys_addr)))
> +	if (pfn_is_map_memory(__phys_to_pfn(phys_addr)))
>   		return (void __iomem *)__phys_to_virt(phys_addr);
>   
>   	return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL),
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 5d9550fdb9cf..26045e9adbd7 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -81,7 +81,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
>   pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
>   			      unsigned long size, pgprot_t vma_prot)
>   {
> -	if (!pfn_valid(pfn))
> +	if (!pfn_is_map_memory(pfn))
>   		return pgprot_noncached(vma_prot);
>   	else if (file->f_flags & O_SYNC)
>   		return pgprot_writecombine(vma_prot);
> 

As discussed, in the future it would be nice if we could just rely on 
the memmap state. There are cases where pfn_is_map_memory() will now be 
slower than pfn_valid() -- e.g., we don't check for valid_section() in 
case of CONFIG_SPARSEMEM. This would apply where pfn_valid() would have 
returned "0".

As we're not creating the direct map, kern_addr_valid() shouldn't need 
love. It'd be some kind of ugly if some generic code used by arm64 would 
be relying in case of arm64 on pfn_valid() to return the expected 
result; I doubt it.

Acked-by: David Hildenbrand <david@redhat.com>
Mike Rapoport April 21, 2021, 5:32 a.m. UTC | #2
On Tue, Apr 20, 2021 at 05:57:57PM +0200, David Hildenbrand wrote:
> On 20.04.21 11:09, Mike Rapoport wrote:
> > From: Mike Rapoport <rppt@linux.ibm.com>
> > 
> > The intended semantics of pfn_valid() is to verify whether there is a
> > struct page for the pfn in question and nothing else.
> > 
> > Yet, on arm64 it is used to distinguish memory areas that are mapped in the
> > linear map vs those that require ioremap() to access them.
> > 
> > Introduce a dedicated pfn_is_map_memory() wrapper for
> > memblock_is_map_memory() to perform such check and use it where
> > appropriate.
> > 
> > Using a wrapper allows to avoid cyclic include dependencies.
> > 
> > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
> > ---
> >   arch/arm64/include/asm/memory.h | 2 +-
> >   arch/arm64/include/asm/page.h   | 1 +
> >   arch/arm64/kvm/mmu.c            | 2 +-
> >   arch/arm64/mm/init.c            | 6 ++++++
> >   arch/arm64/mm/ioremap.c         | 4 ++--
> >   arch/arm64/mm/mmu.c             | 2 +-
> >   6 files changed, 12 insertions(+), 5 deletions(-)
> > 
> > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> > index 0aabc3be9a75..194f9f993d30 100644
> > --- a/arch/arm64/include/asm/memory.h
> > +++ b/arch/arm64/include/asm/memory.h
> > @@ -351,7 +351,7 @@ static inline void *phys_to_virt(phys_addr_t x)
> >   #define virt_addr_valid(addr)	({					\
> >   	__typeof__(addr) __addr = __tag_reset(addr);			\
> > -	__is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr));	\
> > +	__is_lm_address(__addr) && pfn_is_map_memory(virt_to_pfn(__addr));	\
> >   })
> >   void dump_mem_limit(void);
> > diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
> > index 012cffc574e8..99a6da91f870 100644
> > --- a/arch/arm64/include/asm/page.h
> > +++ b/arch/arm64/include/asm/page.h
> > @@ -38,6 +38,7 @@ void copy_highpage(struct page *to, struct page *from);
> >   typedef struct page *pgtable_t;
> >   extern int pfn_valid(unsigned long);
> > +extern int pfn_is_map_memory(unsigned long);
> >   #include <asm/memory.h>
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 8711894db8c2..23dd99e29b23 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -85,7 +85,7 @@ void kvm_flush_remote_tlbs(struct kvm *kvm)
> >   static bool kvm_is_device_pfn(unsigned long pfn)
> >   {
> > -	return !pfn_valid(pfn);
> > +	return !pfn_is_map_memory(pfn);
> >   }
> >   /*
> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> > index 3685e12aba9b..c54e329aca15 100644
> > --- a/arch/arm64/mm/init.c
> > +++ b/arch/arm64/mm/init.c
> > @@ -258,6 +258,12 @@ int pfn_valid(unsigned long pfn)
> >   }
> >   EXPORT_SYMBOL(pfn_valid);
> > +int pfn_is_map_memory(unsigned long pfn)
> > +{
> 
> I think you might have to add (see pfn_valid())
> 
> if (PHYS_PFN(PFN_PHYS(pfn)) != pfn)
> 	return 0;
> 
> to catch false positives.
 
Yeah, makes sense. 

> > +	return memblock_is_map_memory(PFN_PHYS(pfn));
> > +}
> > +EXPORT_SYMBOL(pfn_is_map_memory);
> > +
> >   static phys_addr_t memory_limit = PHYS_ADDR_MAX;
> >   /*
> > diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
> > index b5e83c46b23e..b7c81dacabf0 100644
> > --- a/arch/arm64/mm/ioremap.c
> > +++ b/arch/arm64/mm/ioremap.c
> > @@ -43,7 +43,7 @@ static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size,
> >   	/*
> >   	 * Don't allow RAM to be mapped.
> >   	 */
> > -	if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr))))
> > +	if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr))))
> >   		return NULL;
> >   	area = get_vm_area_caller(size, VM_IOREMAP, caller);
> > @@ -84,7 +84,7 @@ EXPORT_SYMBOL(iounmap);
> >   void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
> >   {
> >   	/* For normal memory we already have a cacheable mapping. */
> > -	if (pfn_valid(__phys_to_pfn(phys_addr)))
> > +	if (pfn_is_map_memory(__phys_to_pfn(phys_addr)))
> >   		return (void __iomem *)__phys_to_virt(phys_addr);
> >   	return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL),
> > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> > index 5d9550fdb9cf..26045e9adbd7 100644
> > --- a/arch/arm64/mm/mmu.c
> > +++ b/arch/arm64/mm/mmu.c
> > @@ -81,7 +81,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
> >   pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
> >   			      unsigned long size, pgprot_t vma_prot)
> >   {
> > -	if (!pfn_valid(pfn))
> > +	if (!pfn_is_map_memory(pfn))
> >   		return pgprot_noncached(vma_prot);
> >   	else if (file->f_flags & O_SYNC)
> >   		return pgprot_writecombine(vma_prot);
> > 
> 
> As discussed, in the future it would be nice if we could just rely on the
> memmap state. There are cases where pfn_is_map_memory() will now be slower
> than pfn_valid() -- e.g., we don't check for valid_section() in case of
> CONFIG_SPARSEMEM. This would apply where pfn_valid() would have returned
> "0".
>
> As we're not creating the direct map, kern_addr_valid() shouldn't need love.
> It'd be some kind of ugly if some generic code used by arm64 would be
> relying in case of arm64 on pfn_valid() to return the expected result; I
> doubt it.

No doubt there is a room for further improvement in this area.
 
> Acked-by: David Hildenbrand <david@redhat.com>

Thanks!
diff mbox series

Patch

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index 0aabc3be9a75..194f9f993d30 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -351,7 +351,7 @@  static inline void *phys_to_virt(phys_addr_t x)
 
 #define virt_addr_valid(addr)	({					\
 	__typeof__(addr) __addr = __tag_reset(addr);			\
-	__is_lm_address(__addr) && pfn_valid(virt_to_pfn(__addr));	\
+	__is_lm_address(__addr) && pfn_is_map_memory(virt_to_pfn(__addr));	\
 })
 
 void dump_mem_limit(void);
diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h
index 012cffc574e8..99a6da91f870 100644
--- a/arch/arm64/include/asm/page.h
+++ b/arch/arm64/include/asm/page.h
@@ -38,6 +38,7 @@  void copy_highpage(struct page *to, struct page *from);
 typedef struct page *pgtable_t;
 
 extern int pfn_valid(unsigned long);
+extern int pfn_is_map_memory(unsigned long);
 
 #include <asm/memory.h>
 
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 8711894db8c2..23dd99e29b23 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -85,7 +85,7 @@  void kvm_flush_remote_tlbs(struct kvm *kvm)
 
 static bool kvm_is_device_pfn(unsigned long pfn)
 {
-	return !pfn_valid(pfn);
+	return !pfn_is_map_memory(pfn);
 }
 
 /*
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 3685e12aba9b..c54e329aca15 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -258,6 +258,12 @@  int pfn_valid(unsigned long pfn)
 }
 EXPORT_SYMBOL(pfn_valid);
 
+int pfn_is_map_memory(unsigned long pfn)
+{
+	return memblock_is_map_memory(PFN_PHYS(pfn));
+}
+EXPORT_SYMBOL(pfn_is_map_memory);
+
 static phys_addr_t memory_limit = PHYS_ADDR_MAX;
 
 /*
diff --git a/arch/arm64/mm/ioremap.c b/arch/arm64/mm/ioremap.c
index b5e83c46b23e..b7c81dacabf0 100644
--- a/arch/arm64/mm/ioremap.c
+++ b/arch/arm64/mm/ioremap.c
@@ -43,7 +43,7 @@  static void __iomem *__ioremap_caller(phys_addr_t phys_addr, size_t size,
 	/*
 	 * Don't allow RAM to be mapped.
 	 */
-	if (WARN_ON(pfn_valid(__phys_to_pfn(phys_addr))))
+	if (WARN_ON(pfn_is_map_memory(__phys_to_pfn(phys_addr))))
 		return NULL;
 
 	area = get_vm_area_caller(size, VM_IOREMAP, caller);
@@ -84,7 +84,7 @@  EXPORT_SYMBOL(iounmap);
 void __iomem *ioremap_cache(phys_addr_t phys_addr, size_t size)
 {
 	/* For normal memory we already have a cacheable mapping. */
-	if (pfn_valid(__phys_to_pfn(phys_addr)))
+	if (pfn_is_map_memory(__phys_to_pfn(phys_addr)))
 		return (void __iomem *)__phys_to_virt(phys_addr);
 
 	return __ioremap_caller(phys_addr, size, __pgprot(PROT_NORMAL),
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 5d9550fdb9cf..26045e9adbd7 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -81,7 +81,7 @@  void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
 			      unsigned long size, pgprot_t vma_prot)
 {
-	if (!pfn_valid(pfn))
+	if (!pfn_is_map_memory(pfn))
 		return pgprot_noncached(vma_prot);
 	else if (file->f_flags & O_SYNC)
 		return pgprot_writecombine(vma_prot);