diff mbox

[v8,10/13] xen/arm/arm64: introduce xen_arch_need_swiotlb

Message ID 1415636045-24669-10-git-send-email-stefano.stabellini@eu.citrix.com (mailing list archive)
State New, archived
Headers show

Commit Message

Stefano Stabellini Nov. 10, 2014, 4:14 p.m. UTC 
Introduce an arch specific function to find out whether a particular dma
mapping operation needs to bounce on the swiotlb buffer.

On ARM and ARM64, if the page involved is a foreign page and the device
is not coherent, we need to bounce because at unmap time we cannot
execute any required cache maintenance operations (we don't know how to
find the pfn from the mfn).

No change of behaviour for x86.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

---

Changes in v6:
- fix ts.

Changes in v5:
- fix indentation.
---
 arch/arm/include/asm/xen/page.h |    4 ++++
 arch/arm/xen/mm.c               |    7 +++++++
 arch/x86/include/asm/xen/page.h |    7 +++++++
 drivers/xen/swiotlb-xen.c       |    5 ++++-
 4 files changed, 22 insertions(+), 1 deletion(-)

Comments

Catalin Marinas Nov. 10, 2014, 6:34 p.m. UTC | #1 
On Mon, Nov 10, 2014 at 04:14:02PM +0000, Stefano Stabellini wrote:
> --- a/arch/arm/include/asm/xen/page.h
> +++ b/arch/arm/include/asm/xen/page.h
> @@ -107,4 +107,8 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
>  #define xen_remap(cookie, size) ioremap_cache((cookie), (size))
>  #define xen_unmap(cookie) iounmap((cookie))
>  
> +bool xen_arch_need_swiotlb(struct device *dev,
> +			   unsigned long pfn,
> +			   unsigned long mfn);
> +
>  #endif /* _ASM_ARM_XEN_PAGE_H */
> diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> index 0e96023..1b087cd 100644
> --- a/arch/arm/xen/mm.c
> +++ b/arch/arm/xen/mm.c
> @@ -102,6 +102,13 @@ void __xen_dma_sync_single_for_device(struct device *hwdev,
>  	__xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
>  }
>  
> +bool xen_arch_need_swiotlb(struct device *dev,
> +			   unsigned long pfn,
> +			   unsigned long mfn)
> +{
> +	return ((pfn != mfn) && !is_device_dma_coherent(dev));
> +}

Why not a static inline? It doesn't look like a big function.
Stefano Stabellini Nov. 11, 2014, 11:52 a.m. UTC | #2 
On Mon, 10 Nov 2014, Catalin Marinas wrote:
> On Mon, Nov 10, 2014 at 04:14:02PM +0000, Stefano Stabellini wrote:
> > --- a/arch/arm/include/asm/xen/page.h
> > +++ b/arch/arm/include/asm/xen/page.h
> > @@ -107,4 +107,8 @@ static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
> >  #define xen_remap(cookie, size) ioremap_cache((cookie), (size))
> >  #define xen_unmap(cookie) iounmap((cookie))
> >  
> > +bool xen_arch_need_swiotlb(struct device *dev,
> > +			   unsigned long pfn,
> > +			   unsigned long mfn);
> > +
> >  #endif /* _ASM_ARM_XEN_PAGE_H */
> > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> > index 0e96023..1b087cd 100644
> > --- a/arch/arm/xen/mm.c
> > +++ b/arch/arm/xen/mm.c
> > @@ -102,6 +102,13 @@ void __xen_dma_sync_single_for_device(struct device *hwdev,
> >  	__xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
> >  }
> >  
> > +bool xen_arch_need_swiotlb(struct device *dev,
> > +			   unsigned long pfn,
> > +			   unsigned long mfn)
> > +{
> > +	return ((pfn != mfn) && !is_device_dma_coherent(dev));
> > +}
> 
> Why not a static inline? It doesn't look like a big function.

Because the next patch is going to make this change:

-   return ((pfn != mfn) && !is_device_dma_coherent(dev));
+   return (!hypercall_cflush && (pfn != mfn) && !is_device_dma_coherent(dev));

and I think it makes sense to keep hypercall_cflush as a static variable
within arch/arm/xen/mm.c (avoid exporting it in page.h).
diff mbox

Patch

diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index 135c24a..68c739b 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -107,4 +107,8 @@  static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 #define xen_remap(cookie, size) ioremap_cache((cookie), (size))
 #define xen_unmap(cookie) iounmap((cookie))
 
+bool xen_arch_need_swiotlb(struct device *dev,
+			   unsigned long pfn,
+			   unsigned long mfn);
+
 #endif /* _ASM_ARM_XEN_PAGE_H */
diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index 0e96023..1b087cd 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -102,6 +102,13 @@  void __xen_dma_sync_single_for_device(struct device *hwdev,
 	__xen_dma_page_cpu_to_dev(hwdev, handle, size, dir);
 }
 
+bool xen_arch_need_swiotlb(struct device *dev,
+			   unsigned long pfn,
+			   unsigned long mfn)
+{
+	return ((pfn != mfn) && !is_device_dma_coherent(dev));
+}
+
 int xen_create_contiguous_region(phys_addr_t pstart, unsigned int order,
 				 unsigned int address_bits,
 				 dma_addr_t *dma_handle)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index c949923..f58ef6c 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -236,4 +236,11 @@  void make_lowmem_page_readwrite(void *vaddr);
 #define xen_remap(cookie, size) ioremap((cookie), (size));
 #define xen_unmap(cookie) iounmap((cookie))
 
+static inline bool xen_arch_need_swiotlb(struct device *dev,
+					 unsigned long pfn,
+					 unsigned long mfn)
+{
+	return false;
+}
+
 #endif /* _ASM_X86_XEN_PAGE_H */
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index ad2c5eb..3725ee4 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -399,7 +399,9 @@  dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page,
 	 * buffering it.
 	 */
 	if (dma_capable(dev, dev_addr, size) &&
-	    !range_straddles_page_boundary(phys, size) && !swiotlb_force) {
+	    !range_straddles_page_boundary(phys, size) &&
+		!xen_arch_need_swiotlb(dev, PFN_DOWN(phys), PFN_DOWN(dev_addr)) &&
+		!swiotlb_force) {
 		/* we are not interested in the dma_addr returned by
 		 * xen_dma_map_page, only in the potential cache flushes executed
 		 * by the function. */
@@ -557,6 +559,7 @@  xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 		dma_addr_t dev_addr = xen_phys_to_bus(paddr);
 
 		if (swiotlb_force ||
+		    xen_arch_need_swiotlb(hwdev, PFN_DOWN(paddr), PFN_DOWN(dev_addr)) ||
 		    !dma_capable(hwdev, dev_addr, sg->length) ||
 		    range_straddles_page_boundary(paddr, sg->length)) {
 			phys_addr_t map = swiotlb_tbl_map_single(hwdev,