On Wed, Apr 21, 2021 at 04:29:48PM +0530, Anshuman Khandual wrote:

On 4/21/21 12:21 PM, Mike Rapoport wrote:

quoted

From: Mike Rapoport <redacted>

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 <redacted>
---
 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            | 11 +++++++++++
 arch/arm64/mm/ioremap.c         |  4 ++--
 arch/arm64/mm/mmu.c             |  2 +-
 6 files changed, 17 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);

Check patch is complaining about this.

WARNING: function definition argument 'unsigned long' should also have an identifier name
#50: FILE: arch/arm64/include/asm/page.h:41:
+extern int pfn_is_map_memory(unsigned long);

quoted

 
 #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..dc03bdc12c0f 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c

@@ -258,6 +258,17 @@ int pfn_valid(unsigned long pfn)
 }
 EXPORT_SYMBOL(pfn_valid);
 
+int pfn_is_map_memory(unsigned long pfn)
+{
+	phys_addr_t addr = PFN_PHYS(pfn);
+

Should also bring with it, the comment regarding upper bits in
the pfn from arm64 pfn_valid().

I think a reference to the comment in pfn_valid() will suffice.

BTW, I wonder how is that other architectures do not need this check?
 

quoted

+	if (PHYS_PFN(addr) != pfn)
+		return 0;
+	

 ^^^^^ trailing spaces here.

ERROR: trailing whitespace
#81: FILE: arch/arm64/mm/init.c:263:
+^I$

Oops :)
 

quoted

+	return memblock_is_map_memory(addr);
+}
+EXPORT_SYMBOL(pfn_is_map_memory);
+

Is the EXPORT_SYMBOL() required to build drivers which will use
pfn_is_map_memory() but currently use pfn_valid() ?

Yes, this is required for virt_addr_valid() that is used by modules.

-- 
Sincerely yours,
Mike.

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