We introduce the io_remap*() equivalents of remap_pfn_range_prepare() and
remap_pfn_range_complete() to allow for I/O remapping via mmap_prepare.

We have to make some architecture-specific changes for those architectures
which define customised handlers.

It doesn't really make sense to make this internal-only as arches specify
their version of these functions so we declare these in mm.h.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 arch/csky/include/asm/pgtable.h     |  5 +++++
 arch/mips/alchemy/common/setup.c    | 28 ++++++++++++++++++++++---
 arch/mips/include/asm/pgtable.h     | 10 +++++++++
 arch/sparc/include/asm/pgtable_32.h | 32 +++++++++++++++++++++++++----
 arch/sparc/include/asm/pgtable_64.h | 32 +++++++++++++++++++++++++----
 include/linux/mm.h                  | 18 ++++++++++++++++
 6 files changed, 114 insertions(+), 11 deletions(-)

diff --git a/arch/csky/include/asm/pgtable.h b/arch/csky/include/asm/pgtable.h
index 5a394be09c35..c83505839a06 100644
--- a/arch/csky/include/asm/pgtable.h
+++ b/arch/csky/include/asm/pgtable.h
@@ -266,4 +266,9 @@ void update_mmu_cache_range(struct vm_fault *vmf, struct vm_area_struct *vma,
 #define io_remap_pfn_range(vma, vaddr, pfn, size, prot) \
 	remap_pfn_range(vma, vaddr, pfn, size, prot)
 
+/* default io_remap_pfn_range_prepare can be used. */
+
+#define io_remap_pfn_range_complete(vma, addr, pfn, size, prot) \
+	remap_pfn_range_complete(vma, addr, pfn, size, prot)
+
 #endif /* __ASM_CSKY_PGTABLE_H */
diff --git a/arch/mips/alchemy/common/setup.c b/arch/mips/alchemy/common/setup.c
index a7a6d31a7a41..a4ab02776994 100644
--- a/arch/mips/alchemy/common/setup.c
+++ b/arch/mips/alchemy/common/setup.c
@@ -94,12 +94,34 @@ phys_addr_t fixup_bigphys_addr(phys_addr_t phys_addr, phys_addr_t size)
 	return phys_addr;
 }
 
-int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long vaddr,
-		unsigned long pfn, unsigned long size, pgprot_t prot)
+static unsigned long calc_pfn(unsigned long pfn, unsigned long size)
 {
 	phys_addr_t phys_addr = fixup_bigphys_addr(pfn << PAGE_SHIFT, size);
 
-	return remap_pfn_range(vma, vaddr, phys_addr >> PAGE_SHIFT, size, prot);
+	return phys_addr >> PAGE_SHIFT;
+}
+
+int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long vaddr,
+		unsigned long pfn, unsigned long size, pgprot_t prot)
+{
+	return remap_pfn_range(vma, vaddr, calc_pfn(pfn, size), size, prot);
 }
 EXPORT_SYMBOL(io_remap_pfn_range);
+
+void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
+			       unsigned long size)
+{
+	remap_pfn_range_prepare(desc, calc_pfn(pfn, size));
+}
+EXPORT_SYMBOL(io_remap_pfn_range_prepare);
+
+int io_remap_pfn_range_complete(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long pfn, unsigned long size,
+		pgprot_t prot)
+{
+	return remap_pfn_range_complete(vma, addr, calc_pfn(pfn, size),
+			size, prot);
+}
+EXPORT_SYMBOL(io_remap_pfn_range_complete);
+
 #endif /* CONFIG_MIPS_FIXUP_BIGPHYS_ADDR */
diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index ae73ecf4c41a..6a8964f55a31 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -607,6 +607,16 @@ phys_addr_t fixup_bigphys_addr(phys_addr_t addr, phys_addr_t size);
 int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long vaddr,
 		unsigned long pfn, unsigned long size, pgprot_t prot);
 #define io_remap_pfn_range io_remap_pfn_range
+
+void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
+		unsigned long size);
+#define io_remap_pfn_range_prepare io_remap_pfn_range_prepare
+
+int io_remap_pfn_range_complete(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long pfn, unsigned long size,
+		pgprot_t prot);
+#define io_remap_pfn_range_complete io_remap_pfn_range_complete
+
 #else
 #define fixup_bigphys_addr(addr, size)	(addr)
 #endif /* CONFIG_MIPS_FIXUP_BIGPHYS_ADDR */
diff --git a/arch/sparc/include/asm/pgtable_32.h b/arch/sparc/include/asm/pgtable_32.h
index 7c199c003ffe..30749c5ffe95 100644
--- a/arch/sparc/include/asm/pgtable_32.h
+++ b/arch/sparc/include/asm/pgtable_32.h
@@ -397,10 +397,11 @@ __get_iospace (unsigned long addr)
 
 int remap_pfn_range(struct vm_area_struct *, unsigned long, unsigned long,
 		    unsigned long, pgprot_t);
+void remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn);
+int remap_pfn_range_complete(struct vm_area_struct *vma, unsigned long addr,
+		unsigned long pfn, unsigned long size, pgprot_t pgprot);
 
-static inline int io_remap_pfn_range(struct vm_area_struct *vma,
-				     unsigned long from, unsigned long pfn,
-				     unsigned long size, pgprot_t prot)
+static inline unsigned long calc_io_remap_pfn(unsigned long pfn)
 {
 	unsigned long long offset, space, phys_base;
 
@@ -408,10 +409,33 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 	space = GET_IOSPACE(pfn);
 	phys_base = offset | (space << 32ULL);
 
-	return remap_pfn_range(vma, from, phys_base >> PAGE_SHIFT, size, prot);
+	return phys_base >> PAGE_SHIFT;
+}
+
+static inline int io_remap_pfn_range(struct vm_area_struct *vma,
+				     unsigned long from, unsigned long pfn,
+				     unsigned long size, pgprot_t prot)
+{
+	return remap_pfn_range(vma, from, calc_io_remap_pfn(pfn), size, prot);
 }
 #define io_remap_pfn_range io_remap_pfn_range
 
+static inline void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
+		unsigned long size)
+{
+	remap_pfn_range_prepare(desc, calc_io_remap_pfn(pfn));
+}
+#define io_remap_pfn_range_prepare io_remap_pfn_range_prepare
+
+static inline int io_remap_pfn_range_complete(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long pfn, unsigned long size,
+		pgprot_t prot)
+{
+	return remap_pfn_range_complete(vma, addr, calc_io_remap_pfn(pfn),
+			size, prot);
+}
+#define io_remap_pfn_range_complete io_remap_pfn_range_complete
+
 #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
 #define ptep_set_access_flags(__vma, __address, __ptep, __entry, __dirty) \
 ({									  \
diff --git a/arch/sparc/include/asm/pgtable_64.h b/arch/sparc/include/asm/pgtable_64.h
index 669cd02469a1..b06f55915653 100644
--- a/arch/sparc/include/asm/pgtable_64.h
+++ b/arch/sparc/include/asm/pgtable_64.h
@@ -1050,6 +1050,9 @@ int page_in_phys_avail(unsigned long paddr);
 
 int remap_pfn_range(struct vm_area_struct *, unsigned long, unsigned long,
 		    unsigned long, pgprot_t);
+void remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn);
+int remap_pfn_range_complete(struct vm_area_struct *vma, unsigned long addr,
+		unsigned long pfn, unsigned long size, pgprot_t pgprot);
 
 void adi_restore_tags(struct mm_struct *mm, struct vm_area_struct *vma,
 		      unsigned long addr, pte_t pte);
@@ -1084,9 +1087,7 @@ static inline int arch_unmap_one(struct mm_struct *mm,
 	return 0;
 }
 
-static inline int io_remap_pfn_range(struct vm_area_struct *vma,
-				     unsigned long from, unsigned long pfn,
-				     unsigned long size, pgprot_t prot)
+static inline unsigned long calc_io_remap_pfn(unsigned long pfn)
 {
 	unsigned long offset = GET_PFN(pfn) << PAGE_SHIFT;
 	int space = GET_IOSPACE(pfn);
@@ -1094,10 +1095,33 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 
 	phys_base = offset | (((unsigned long) space) << 32UL);
 
-	return remap_pfn_range(vma, from, phys_base >> PAGE_SHIFT, size, prot);
+	return phys_base >> PAGE_SHIFT;
+}
+
+static inline int io_remap_pfn_range(struct vm_area_struct *vma,
+				     unsigned long from, unsigned long pfn,
+				     unsigned long size, pgprot_t prot)
+{
+	return remap_pfn_range(vma, from, calc_io_remap_pfn(pfn), size, prot);
 }
 #define io_remap_pfn_range io_remap_pfn_range
 
+static inline void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
+	unsigned long size)
+{
+	return remap_pfn_range_prepare(desc, calc_io_remap_pfn(pfn));
+}
+#define io_remap_pfn_range_prepare io_remap_pfn_range_prepare
+
+static inline int io_remap_pfn_range_complete(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long pfn, unsigned long size,
+		pgprot_t prot)
+{
+	return remap_pfn_range_complete(vma, addr, calc_io_remap_pfn(pfn),
+					size, prot);
+}
+#define io_remap_pfn_range_complete io_remap_pfn_range_complete
+
 static inline unsigned long __untagged_addr(unsigned long start)
 {
 	if (adi_capable()) {
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 3277e035006d..6d4cc7cdf1e1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3684,6 +3684,24 @@ static inline int io_remap_pfn_range(struct vm_area_struct *vma,
 }
 #endif
 
+#ifndef io_remap_pfn_range_prepare
+static inline void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
+	unsigned long size)
+{
+	return remap_pfn_range_prepare(desc, pfn);
+}
+#endif
+
+#ifndef io_remap_pfn_range_complete
+static inline int io_remap_pfn_range_complete(struct vm_area_struct *vma,
+		unsigned long addr, unsigned long pfn, unsigned long size,
+		pgprot_t prot)
+{
+	return remap_pfn_range_complete(vma, addr, pfn, size,
+			pgprot_decrypted(prot));
+}
+#endif
+
 static inline vm_fault_t vmf_error(int err)
 {
 	if (err == -ENOMEM)
-- 
2.51.0

On Tue, Sep 16, 2025 at 03:11:53PM +0100, Lorenzo Stoakes wrote:
> We introduce the io_remap*() equivalents of remap_pfn_range_prepare() and
> remap_pfn_range_complete() to allow for I/O remapping via mmap_prepare.
> 
> We have to make some architecture-specific changes for those architectures
> which define customised handlers.
> 
> It doesn't really make sense to make this internal-only as arches specify
> their version of these functions so we declare these in mm.h.

Similar question to the remap_pfn_range patch.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

Looks ok, but again, i'm no expert on this.

Acked-by: Pedro Falcato <pfalcato@suse.de>

-- 
Pedro

On Wed, Sep 17, 2025 at 12:12:17PM +0100, Pedro Falcato wrote:
> On Tue, Sep 16, 2025 at 03:11:53PM +0100, Lorenzo Stoakes wrote:
> > We introduce the io_remap*() equivalents of remap_pfn_range_prepare() and
> > remap_pfn_range_complete() to allow for I/O remapping via mmap_prepare.
> >
> > We have to make some architecture-specific changes for those architectures
> > which define customised handlers.
> >
> > It doesn't really make sense to make this internal-only as arches specify
> > their version of these functions so we declare these in mm.h.
>
> Similar question to the remap_pfn_range patch.

There's arch-specific implementations, which in turn invoke the new
prepare/complete helpers.

(This answers your query here and on the remap_pfn_prepare/complete patch).

With the abstraction of the get pfn function suggested by Jason it may be
possible to move these over and just utilise that in internal.h/util.c.

I will look into that.

> >
> > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
>
> Looks ok, but again, i'm no expert on this.
>
> Acked-by: Pedro Falcato <pfalcato@suse.de>

Thanks!

>
> --
> Pedro

Cheers, Lorenzo

On Tue, Sep 16, 2025 at 03:11:53PM +0100, Lorenzo Stoakes wrote:
>  
> -int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long vaddr,
> -		unsigned long pfn, unsigned long size, pgprot_t prot)
> +static unsigned long calc_pfn(unsigned long pfn, unsigned long size)
>  {
>  	phys_addr_t phys_addr = fixup_bigphys_addr(pfn << PAGE_SHIFT, size);
>  
> -	return remap_pfn_range(vma, vaddr, phys_addr >> PAGE_SHIFT, size, prot);
> +	return phys_addr >> PAGE_SHIFT;
> +}

Given you changed all of these to add a calc_pfn why not make that
the arch abstraction?

static unsigned long arch_io_remap_remap_pfn(unsigned long pfn, unsigned long size)
{
..
}
#define arch_io_remap_remap_pfn arch_io_remap_remap_pfn

[..]

#ifndef arch_io_remap_remap_pfn
static inline unsigned long arch_io_remap_remap_pfn(unsigned long pfn, unsigned long size)
{
	return pfn;
}
#endif

static inline void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
	unsigned long size)
{
	return remap_pfn_range_prepare(desc, arch_io_remap_remap_pfn(pfn));
}

etc

Removes alot of the maze here.

Jason

On Tue, Sep 16, 2025 at 02:19:30PM -0300, Jason Gunthorpe wrote:
> On Tue, Sep 16, 2025 at 03:11:53PM +0100, Lorenzo Stoakes wrote:
> >
> > -int io_remap_pfn_range(struct vm_area_struct *vma, unsigned long vaddr,
> > -		unsigned long pfn, unsigned long size, pgprot_t prot)
> > +static unsigned long calc_pfn(unsigned long pfn, unsigned long size)
> >  {
> >  	phys_addr_t phys_addr = fixup_bigphys_addr(pfn << PAGE_SHIFT, size);
> >
> > -	return remap_pfn_range(vma, vaddr, phys_addr >> PAGE_SHIFT, size, prot);
> > +	return phys_addr >> PAGE_SHIFT;
> > +}
>
> Given you changed all of these to add a calc_pfn why not make that
> the arch abstraction?

OK that's reasonable, will do.

>
> static unsigned long arch_io_remap_remap_pfn(unsigned long pfn, unsigned long size)
> {
> ..
> }
> #define arch_io_remap_remap_pfn arch_io_remap_remap_pfn
>
> [..]
>
> #ifndef arch_io_remap_remap_pfn
> static inline unsigned long arch_io_remap_remap_pfn(unsigned long pfn, unsigned long size)
> {
> 	return pfn;
> }
> #endif
>
> static inline void io_remap_pfn_range_prepare(struct vm_area_desc *desc, unsigned long pfn,
> 	unsigned long size)
> {
> 	return remap_pfn_range_prepare(desc, arch_io_remap_remap_pfn(pfn));
> }
>
> etc
>
> Removes alot of the maze here.

Actually nice to restrict what arches can do here also... :)

>
> Jason