diff mbox series

[v2] dma-mapping: use vmalloc_to_page for vmalloc addresses

Message ID 20210716083934.154992-1-rm.skakun@gmail.com (mailing list archive)
State New
Headers show
Series [v2] dma-mapping: use vmalloc_to_page for vmalloc addresses | expand

Commit Message

Roman Skakun July 16, 2021, 8:39 a.m. UTC
From: Roman Skakun <Roman_Skakun@epam.com>

This commit is dedicated to fix incorrect conversion from
cpu_addr to page address in cases when we get virtual
address which allocated in the vmalloc range.
As the result, virt_to_page() cannot convert this address
properly and return incorrect page address.

Need to detect such cases and obtains the page address using
vmalloc_to_page() instead.

Signed-off-by: Roman Skakun <roman_skakun@epam.com>
Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>
---
Hi, Christoph!
It's updated patch in accordance with your and Stefano 
suggestions. 

 drivers/xen/swiotlb-xen.c   |  7 +------
 include/linux/dma-map-ops.h |  2 ++
 kernel/dma/ops_helpers.c    | 16 ++++++++++++++--
 3 files changed, 17 insertions(+), 8 deletions(-)

Comments

Christoph Hellwig July 16, 2021, 9:35 a.m. UTC | #1
Technically this looks good.  But given that exposing a helper
that does either vmalloc_to_page or virt_to_page is one of the
never ending MM discussions I don't want to get into that discussion
and just keep it local in the DMA code.

Are you fine with me applying this version?

---
From 40ac971eab89330d6153e7721e88acd2d98833f9 Mon Sep 17 00:00:00 2001
From: Roman Skakun <Roman_Skakun@epam.com>
Date: Fri, 16 Jul 2021 11:39:34 +0300
Subject: dma-mapping: handle vmalloc addresses in
 dma_common_{mmap,get_sgtable}

xen-swiotlb can use vmalloc backed addresses for dma coherent allocations
and uses the common helpers.  Properly handle them to unbreak Xen on
ARM platforms.

Fixes: 1b65c4e5a9af ("swiotlb-xen: use xen_alloc/free_coherent_pages")
Signed-off-by: Roman Skakun <roman_skakun@epam.com>
Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>
[hch: split the patch, renamed the helpers]
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 kernel/dma/ops_helpers.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
index 910ae69cae77..af4a6ef48ce0 100644
--- a/kernel/dma/ops_helpers.c
+++ b/kernel/dma/ops_helpers.c
@@ -5,6 +5,13 @@
  */
 #include <linux/dma-map-ops.h>
 
+static struct page *dma_common_vaddr_to_page(void *cpu_addr)
+{
+	if (is_vmalloc_addr(cpu_addr))
+		return vmalloc_to_page(cpu_addr);
+	return virt_to_page(cpu_addr);
+}
+
 /*
  * Create scatter-list for the already allocated DMA buffer.
  */
@@ -12,7 +19,7 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
 		 void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		 unsigned long attrs)
 {
-	struct page *page = virt_to_page(cpu_addr);
+	struct page *page = dma_common_vaddr_to_page(cpu_addr);
 	int ret;
 
 	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
@@ -32,6 +39,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 	unsigned long user_count = vma_pages(vma);
 	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long off = vma->vm_pgoff;
+	struct page *page = dma_common_vaddr_to_page(cpu_addr);
 	int ret = -ENXIO;
 
 	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
@@ -43,7 +51,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 		return -ENXIO;
 
 	return remap_pfn_range(vma, vma->vm_start,
-			page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
+			page_to_pfn(page) + vma->vm_pgoff,
 			user_count << PAGE_SHIFT, vma->vm_page_prot);
 #else
 	return -ENXIO;
Roman Skakun July 16, 2021, 12:53 p.m. UTC | #2
> Technically this looks good.  But given that exposing a helper
> that does either vmalloc_to_page or virt_to_page is one of the
> never ending MM discussions I don't want to get into that discussion
> and just keep it local in the DMA code.
>
> Are you fine with me applying this version?

Looks good to me, thanks!
But, Stefano asked me about using created helper in the
xen_swiotlb_free_coherent()
and I created a patch according to this mention.

We can merge this patch and create a new one for
xen_swiotlb_free_coherent() later.

пт, 16 июл. 2021 г. в 12:35, Christoph Hellwig <hch@lst.de>:
>
> Technically this looks good.  But given that exposing a helper
> that does either vmalloc_to_page or virt_to_page is one of the
> never ending MM discussions I don't want to get into that discussion
> and just keep it local in the DMA code.
>
> Are you fine with me applying this version?
>
> ---
> From 40ac971eab89330d6153e7721e88acd2d98833f9 Mon Sep 17 00:00:00 2001
> From: Roman Skakun <Roman_Skakun@epam.com>
> Date: Fri, 16 Jul 2021 11:39:34 +0300
> Subject: dma-mapping: handle vmalloc addresses in
>  dma_common_{mmap,get_sgtable}
>
> xen-swiotlb can use vmalloc backed addresses for dma coherent allocations
> and uses the common helpers.  Properly handle them to unbreak Xen on
> ARM platforms.
>
> Fixes: 1b65c4e5a9af ("swiotlb-xen: use xen_alloc/free_coherent_pages")
> Signed-off-by: Roman Skakun <roman_skakun@epam.com>
> Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>
> [hch: split the patch, renamed the helpers]
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  kernel/dma/ops_helpers.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
> index 910ae69cae77..af4a6ef48ce0 100644
> --- a/kernel/dma/ops_helpers.c
> +++ b/kernel/dma/ops_helpers.c
> @@ -5,6 +5,13 @@
>   */
>  #include <linux/dma-map-ops.h>
>
> +static struct page *dma_common_vaddr_to_page(void *cpu_addr)
> +{
> +       if (is_vmalloc_addr(cpu_addr))
> +               return vmalloc_to_page(cpu_addr);
> +       return virt_to_page(cpu_addr);
> +}
> +
>  /*
>   * Create scatter-list for the already allocated DMA buffer.
>   */
> @@ -12,7 +19,7 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
>                  void *cpu_addr, dma_addr_t dma_addr, size_t size,
>                  unsigned long attrs)
>  {
> -       struct page *page = virt_to_page(cpu_addr);
> +       struct page *page = dma_common_vaddr_to_page(cpu_addr);
>         int ret;
>
>         ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
> @@ -32,6 +39,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
>         unsigned long user_count = vma_pages(vma);
>         unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
>         unsigned long off = vma->vm_pgoff;
> +       struct page *page = dma_common_vaddr_to_page(cpu_addr);
>         int ret = -ENXIO;
>
>         vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
> @@ -43,7 +51,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
>                 return -ENXIO;
>
>         return remap_pfn_range(vma, vma->vm_start,
> -                       page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
> +                       page_to_pfn(page) + vma->vm_pgoff,
>                         user_count << PAGE_SHIFT, vma->vm_page_prot);
>  #else
>         return -ENXIO;
> --
> 2.30.2
>
Stefano Stabellini July 16, 2021, 3:29 p.m. UTC | #3
On Fri, 16 Jul 2021, Roman Skakun wrote:
> > Technically this looks good.  But given that exposing a helper
> > that does either vmalloc_to_page or virt_to_page is one of the
> > never ending MM discussions I don't want to get into that discussion
> > and just keep it local in the DMA code.
> >
> > Are you fine with me applying this version?
> 
> Looks good to me, thanks!
> But, Stefano asked me about using created helper in the
> xen_swiotlb_free_coherent()
> and I created a patch according to this mention.
> 
> We can merge this patch and create a new one for
> xen_swiotlb_free_coherent() later.

Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
was problematic.

This patch is fine by me.


> пт, 16 июл. 2021 г. в 12:35, Christoph Hellwig <hch@lst.de>:
> >
> > Technically this looks good.  But given that exposing a helper
> > that does either vmalloc_to_page or virt_to_page is one of the
> > never ending MM discussions I don't want to get into that discussion
> > and just keep it local in the DMA code.
> >
> > Are you fine with me applying this version?
> >
> > ---
> > From 40ac971eab89330d6153e7721e88acd2d98833f9 Mon Sep 17 00:00:00 2001
> > From: Roman Skakun <Roman_Skakun@epam.com>
> > Date: Fri, 16 Jul 2021 11:39:34 +0300
> > Subject: dma-mapping: handle vmalloc addresses in
> >  dma_common_{mmap,get_sgtable}
> >
> > xen-swiotlb can use vmalloc backed addresses for dma coherent allocations
> > and uses the common helpers.  Properly handle them to unbreak Xen on
> > ARM platforms.
> >
> > Fixes: 1b65c4e5a9af ("swiotlb-xen: use xen_alloc/free_coherent_pages")
> > Signed-off-by: Roman Skakun <roman_skakun@epam.com>
> > Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>
> > [hch: split the patch, renamed the helpers]
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > ---
> >  kernel/dma/ops_helpers.c | 12 ++++++++++--
> >  1 file changed, 10 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
> > index 910ae69cae77..af4a6ef48ce0 100644
> > --- a/kernel/dma/ops_helpers.c
> > +++ b/kernel/dma/ops_helpers.c
> > @@ -5,6 +5,13 @@
> >   */
> >  #include <linux/dma-map-ops.h>
> >
> > +static struct page *dma_common_vaddr_to_page(void *cpu_addr)
> > +{
> > +       if (is_vmalloc_addr(cpu_addr))
> > +               return vmalloc_to_page(cpu_addr);
> > +       return virt_to_page(cpu_addr);
> > +}
> > +
> >  /*
> >   * Create scatter-list for the already allocated DMA buffer.
> >   */
> > @@ -12,7 +19,7 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
> >                  void *cpu_addr, dma_addr_t dma_addr, size_t size,
> >                  unsigned long attrs)
> >  {
> > -       struct page *page = virt_to_page(cpu_addr);
> > +       struct page *page = dma_common_vaddr_to_page(cpu_addr);
> >         int ret;
> >
> >         ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
> > @@ -32,6 +39,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> >         unsigned long user_count = vma_pages(vma);
> >         unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> >         unsigned long off = vma->vm_pgoff;
> > +       struct page *page = dma_common_vaddr_to_page(cpu_addr);
> >         int ret = -ENXIO;
> >
> >         vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
> > @@ -43,7 +51,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> >                 return -ENXIO;
> >
> >         return remap_pfn_range(vma, vma->vm_start,
> > -                       page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
> > +                       page_to_pfn(page) + vma->vm_pgoff,
> >                         user_count << PAGE_SHIFT, vma->vm_page_prot);
> >  #else
> >         return -ENXIO;
> > --
> > 2.30.2
> >
> 
> 
> -- 
> Best Regards, Roman.
>
Roman Skakun July 17, 2021, 8:39 a.m. UTC | #4
> We can merge this patch and create a new one for
> xen_swiotlb_free_coherent() later.
> Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
> was problematic.
>
> This patch is fine by me.

Good. I'm agreed too. Waiting for Christoph.

пт, 16 июл. 2021 г. в 18:29, Stefano Stabellini <sstabellini@kernel.org>:
>
> On Fri, 16 Jul 2021, Roman Skakun wrote:
> > > Technically this looks good.  But given that exposing a helper
> > > that does either vmalloc_to_page or virt_to_page is one of the
> > > never ending MM discussions I don't want to get into that discussion
> > > and just keep it local in the DMA code.
> > >
> > > Are you fine with me applying this version?
> >
> > Looks good to me, thanks!
> > But, Stefano asked me about using created helper in the
> > xen_swiotlb_free_coherent()
> > and I created a patch according to this mention.
> >
> > We can merge this patch and create a new one for
> > xen_swiotlb_free_coherent() later.
>
> Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
> was problematic.
>
> This patch is fine by me.
>
>
> > пт, 16 июл. 2021 г. в 12:35, Christoph Hellwig <hch@lst.de>:
> > >
> > > Technically this looks good.  But given that exposing a helper
> > > that does either vmalloc_to_page or virt_to_page is one of the
> > > never ending MM discussions I don't want to get into that discussion
> > > and just keep it local in the DMA code.
> > >
> > > Are you fine with me applying this version?
> > >
> > > ---
> > > From 40ac971eab89330d6153e7721e88acd2d98833f9 Mon Sep 17 00:00:00 2001
> > > From: Roman Skakun <Roman_Skakun@epam.com>
> > > Date: Fri, 16 Jul 2021 11:39:34 +0300
> > > Subject: dma-mapping: handle vmalloc addresses in
> > >  dma_common_{mmap,get_sgtable}
> > >
> > > xen-swiotlb can use vmalloc backed addresses for dma coherent allocations
> > > and uses the common helpers.  Properly handle them to unbreak Xen on
> > > ARM platforms.
> > >
> > > Fixes: 1b65c4e5a9af ("swiotlb-xen: use xen_alloc/free_coherent_pages")
> > > Signed-off-by: Roman Skakun <roman_skakun@epam.com>
> > > Reviewed-by: Andrii Anisov <andrii_anisov@epam.com>
> > > [hch: split the patch, renamed the helpers]
> > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > > ---
> > >  kernel/dma/ops_helpers.c | 12 ++++++++++--
> > >  1 file changed, 10 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
> > > index 910ae69cae77..af4a6ef48ce0 100644
> > > --- a/kernel/dma/ops_helpers.c
> > > +++ b/kernel/dma/ops_helpers.c
> > > @@ -5,6 +5,13 @@
> > >   */
> > >  #include <linux/dma-map-ops.h>
> > >
> > > +static struct page *dma_common_vaddr_to_page(void *cpu_addr)
> > > +{
> > > +       if (is_vmalloc_addr(cpu_addr))
> > > +               return vmalloc_to_page(cpu_addr);
> > > +       return virt_to_page(cpu_addr);
> > > +}
> > > +
> > >  /*
> > >   * Create scatter-list for the already allocated DMA buffer.
> > >   */
> > > @@ -12,7 +19,7 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
> > >                  void *cpu_addr, dma_addr_t dma_addr, size_t size,
> > >                  unsigned long attrs)
> > >  {
> > > -       struct page *page = virt_to_page(cpu_addr);
> > > +       struct page *page = dma_common_vaddr_to_page(cpu_addr);
> > >         int ret;
> > >
> > >         ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
> > > @@ -32,6 +39,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> > >         unsigned long user_count = vma_pages(vma);
> > >         unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> > >         unsigned long off = vma->vm_pgoff;
> > > +       struct page *page = dma_common_vaddr_to_page(cpu_addr);
> > >         int ret = -ENXIO;
> > >
> > >         vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
> > > @@ -43,7 +51,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
> > >                 return -ENXIO;
> > >
> > >         return remap_pfn_range(vma, vma->vm_start,
> > > -                       page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
> > > +                       page_to_pfn(page) + vma->vm_pgoff,
> > >                         user_count << PAGE_SHIFT, vma->vm_page_prot);
> > >  #else
> > >         return -ENXIO;
> > > --
> > > 2.30.2
> > >
> >
> >
> > --
> > Best Regards, Roman.
> >
Christoph Hellwig July 19, 2021, 9:22 a.m. UTC | #5
On Sat, Jul 17, 2021 at 11:39:21AM +0300, Roman Skakun wrote:
> > We can merge this patch and create a new one for
> > xen_swiotlb_free_coherent() later.
> > Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
> > was problematic.
> >
> > This patch is fine by me.
> 
> Good. I'm agreed too. Waiting for Christoph.

Fine with.  I've queued up the modified patch.
Roman Skakun July 21, 2021, 6:39 p.m. UTC | #6
> Fine with.  I've queued up the modified patch.

Good. Thanks!

>
> On Sat, Jul 17, 2021 at 11:39:21AM +0300, Roman Skakun wrote:
> > > We can merge this patch and create a new one for
> > > xen_swiotlb_free_coherent() later.
> > > Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
> > > was problematic.
> > >
> > > This patch is fine by me.
> >
> > Good. I'm agreed too. Waiting for Christoph.
>
> Fine with.  I've queued up the modified patch.



--
Best Regards, Roman.
diff mbox series

Patch

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 92ee6eea30cd..c2f612a10a95 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -337,7 +337,7 @@  xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
 	int order = get_order(size);
 	phys_addr_t phys;
 	u64 dma_mask = DMA_BIT_MASK(32);
-	struct page *page;
+	struct page *page = cpu_addr_to_page(vaddr);
 
 	if (hwdev && hwdev->coherent_dma_mask)
 		dma_mask = hwdev->coherent_dma_mask;
@@ -349,11 +349,6 @@  xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
 	/* Convert the size to actually allocated. */
 	size = 1UL << (order + XEN_PAGE_SHIFT);
 
-	if (is_vmalloc_addr(vaddr))
-		page = vmalloc_to_page(vaddr);
-	else
-		page = virt_to_page(vaddr);
-
 	if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
 		     range_straddles_page_boundary(phys, size)) &&
 	    TestClearPageXenRemapped(page))
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index a5f89fc4d6df..ce0edb0bb603 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -226,6 +226,8 @@  struct page *dma_alloc_from_pool(struct device *dev, size_t size,
 		bool (*phys_addr_ok)(struct device *, phys_addr_t, size_t));
 bool dma_free_from_pool(struct device *dev, void *start, size_t size);
 
+struct page *cpu_addr_to_page(void *cpu_addr);
+
 #ifdef CONFIG_ARCH_HAS_DMA_COHERENCE_H
 #include <asm/dma-coherence.h>
 #elif defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
index 910ae69cae77..472e861750d3 100644
--- a/kernel/dma/ops_helpers.c
+++ b/kernel/dma/ops_helpers.c
@@ -5,6 +5,17 @@ 
  */
 #include <linux/dma-map-ops.h>
 
+/*
+ * This helper converts virtual address to page address.
+ */
+struct page *cpu_addr_to_page(void *cpu_addr)
+{
+	if (is_vmalloc_addr(cpu_addr))
+		return vmalloc_to_page(cpu_addr);
+	else
+		return virt_to_page(cpu_addr);
+}
+
 /*
  * Create scatter-list for the already allocated DMA buffer.
  */
@@ -12,7 +23,7 @@  int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
 		 void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		 unsigned long attrs)
 {
-	struct page *page = virt_to_page(cpu_addr);
+	struct page *page = cpu_addr_to_page(cpu_addr);
 	int ret;
 
 	ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
@@ -32,6 +43,7 @@  int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 	unsigned long user_count = vma_pages(vma);
 	unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
 	unsigned long off = vma->vm_pgoff;
+	struct page *page = cpu_addr_to_page(cpu_addr);
 	int ret = -ENXIO;
 
 	vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
@@ -43,7 +55,7 @@  int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
 		return -ENXIO;
 
 	return remap_pfn_range(vma, vma->vm_start,
-			page_to_pfn(virt_to_page(cpu_addr)) + vma->vm_pgoff,
+			page_to_pfn(page) + vma->vm_pgoff,
 			user_count << PAGE_SHIFT, vma->vm_page_prot);
 #else
 	return -ENXIO;