diff mbox series

[07/11] swiotlb-xen: provide a single page-coherent.h header

Message ID 20190816130013.31154-8-hch@lst.de
State Superseded
Headers show
Series [01/11] xen/arm: use dma-noncoherent.h calls for xen-swiotlb cache maintainance | expand

Commit Message

Christoph Hellwig Aug. 16, 2019, 1 p.m. UTC
Merge the various page-coherent.h files into a single one that either
provides prototypes or stubs depending on the need for cache
maintainance.

For extra benefits alo include <xen/page-coherent.h> in the file
actually implementing the interfaces provided.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/arm/include/asm/xen/page-coherent.h   |  2 --
 arch/arm/xen/mm.c                          |  1 +
 arch/arm64/include/asm/xen/page-coherent.h |  2 --
 arch/x86/include/asm/xen/page-coherent.h   | 22 ------------------
 drivers/xen/swiotlb-xen.c                  |  4 +---
 include/Kbuild                             |  2 +-
 include/xen/{arm => }/page-coherent.h      | 27 +++++++++++++++++++---
 7 files changed, 27 insertions(+), 33 deletions(-)
 delete mode 100644 arch/arm/include/asm/xen/page-coherent.h
 delete mode 100644 arch/arm64/include/asm/xen/page-coherent.h
 delete mode 100644 arch/x86/include/asm/xen/page-coherent.h
 rename include/xen/{arm => }/page-coherent.h (76%)

Comments

Julien Grall Aug. 16, 2019, 10:40 p.m. UTC | #1
Hi,

On 8/16/19 2:00 PM, Christoph Hellwig wrote:
> Merge the various page-coherent.h files into a single one that either
> provides prototypes or stubs depending on the need for cache
> maintainance.
> 
> For extra benefits alo include <xen/page-coherent.h> in the file
> actually implementing the interfaces provided.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>   arch/arm/include/asm/xen/page-coherent.h   |  2 --
>   arch/arm/xen/mm.c                          |  1 +
>   arch/arm64/include/asm/xen/page-coherent.h |  2 --
>   arch/x86/include/asm/xen/page-coherent.h   | 22 ------------------
>   drivers/xen/swiotlb-xen.c                  |  4 +---
>   include/Kbuild                             |  2 +-
>   include/xen/{arm => }/page-coherent.h      | 27 +++++++++++++++++++---

I am not sure I agree with this rename. The implementation of the 
helpers are very Arm specific as this is assuming Dom0 is 1:1 mapped.

This was necessary due to the lack of IOMMU on Arm platforms back then.
But this is now a pain to get rid of it on newer platform...

Cheers,
Christoph Hellwig Aug. 17, 2019, 6:50 a.m. UTC | #2
On Fri, Aug 16, 2019 at 11:40:43PM +0100, Julien Grall wrote:
> I am not sure I agree with this rename. The implementation of the helpers 
> are very Arm specific as this is assuming Dom0 is 1:1 mapped.
>
> This was necessary due to the lack of IOMMU on Arm platforms back then.
> But this is now a pain to get rid of it on newer platform...

So if you look at the final version of the header after the whole
series, what assumes a 1:1 mapping?  It all just is

	if (pfn_valid())
		local cache sync;
	else
		call into the arch code;

are you concerned that the local cache sync might have to be split
up more for a non-1:1 map in that case?  We could just move
the xen_dma_* routines into the arch instead of __xen_dma, but it
really helps to have a common interface header.
Julien Grall Aug. 17, 2019, 6:20 p.m. UTC | #3
Hi Christoph,

On 8/17/19 7:50 AM, Christoph Hellwig wrote:
> On Fri, Aug 16, 2019 at 11:40:43PM +0100, Julien Grall wrote:
>> I am not sure I agree with this rename. The implementation of the helpers
>> are very Arm specific as this is assuming Dom0 is 1:1 mapped.
>>
>> This was necessary due to the lack of IOMMU on Arm platforms back then.
>> But this is now a pain to get rid of it on newer platform...
> 
> So if you look at the final version of the header after the whole
> series, what assumes a 1:1 mapping?  It all just is
> 
> 	if (pfn_valid())
> 		local cache sync;
> 	else
> 		call into the arch code;

In the context of Xen Arm, the dev_addr is a host physical address. From 
my understanding pfn_valid() is dealing with a guest physical frame.

Therefore by passing PFN_DOWN(dev_addr) in argument you assume that the 
host and guest address spaces are the same.

> 
> are you concerned that the local cache sync might have to be split
> up more for a non-1:1 map in that case?  We could just movea
> the xen_dma_* routines into the arch instead of __xen_dma, but it
> really helps to have a common interface header.
Moving xen_dma_* routines into the arch would be a good option. 
Although, I would still consider a stub version for arch not requiring 
specific DMA.

Cheers,
diff mbox series

Patch

diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h
deleted file mode 100644
index 27e984977402..000000000000
--- a/arch/arm/include/asm/xen/page-coherent.h
+++ /dev/null
@@ -1,2 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <xen/arm/page-coherent.h>
diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
index a59980f1aa54..85482cdda1e5 100644
--- a/arch/arm/xen/mm.c
+++ b/arch/arm/xen/mm.c
@@ -15,6 +15,7 @@ 
 #include <xen/interface/grant_table.h>
 #include <xen/interface/memory.h>
 #include <xen/page.h>
+#include <xen/page-coherent.h>
 #include <xen/swiotlb-xen.h>
 
 #include <asm/cacheflush.h>
diff --git a/arch/arm64/include/asm/xen/page-coherent.h b/arch/arm64/include/asm/xen/page-coherent.h
deleted file mode 100644
index 27e984977402..000000000000
--- a/arch/arm64/include/asm/xen/page-coherent.h
+++ /dev/null
@@ -1,2 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0 */
-#include <xen/arm/page-coherent.h>
diff --git a/arch/x86/include/asm/xen/page-coherent.h b/arch/x86/include/asm/xen/page-coherent.h
deleted file mode 100644
index 8ee33c5edded..000000000000
--- a/arch/x86/include/asm/xen/page-coherent.h
+++ /dev/null
@@ -1,22 +0,0 @@ 
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _ASM_X86_XEN_PAGE_COHERENT_H
-#define _ASM_X86_XEN_PAGE_COHERENT_H
-
-#include <asm/page.h>
-#include <linux/dma-mapping.h>
-
-static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
-	     dma_addr_t dev_addr, unsigned long offset, size_t size,
-	     enum dma_data_direction dir, unsigned long attrs) { }
-
-static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
-		size_t size, enum dma_data_direction dir,
-		unsigned long attrs) { }
-
-static inline void xen_dma_sync_single_for_cpu(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir) { }
-
-static inline void xen_dma_sync_single_for_device(struct device *hwdev,
-		dma_addr_t handle, size_t size, enum dma_data_direction dir) { }
-
-#endif /* _ASM_X86_XEN_PAGE_COHERENT_H */
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index f9dd4cb6e4b3..7b23929854e7 100644
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -31,12 +31,10 @@ 
 #include <linux/export.h>
 #include <xen/swiotlb-xen.h>
 #include <xen/page.h>
+#include <xen/page-coherent.h>
 #include <xen/xen-ops.h>
 #include <xen/hvc-console.h>
 
-#include <asm/dma-mapping.h>
-#include <asm/xen/page-coherent.h>
-
 #include <trace/events/swiotlb.h>
 /*
  * Used to do a quick range check in swiotlb_tbl_unmap_single and
diff --git a/include/Kbuild b/include/Kbuild
index c38f0d46b267..e2ae52ef9e1e 100644
--- a/include/Kbuild
+++ b/include/Kbuild
@@ -1189,7 +1189,6 @@  header-test-			+= video/vga.h
 header-test-			+= video/w100fb.h
 header-test-			+= xen/acpi.h
 header-test-			+= xen/arm/hypercall.h
-header-test-			+= xen/arm/page-coherent.h
 header-test-			+= xen/arm/page.h
 header-test-			+= xen/balloon.h
 header-test-			+= xen/events.h
@@ -1231,6 +1230,7 @@  header-test-			+= xen/interface/xen.h
 header-test-			+= xen/interface/xenpmu.h
 header-test-			+= xen/mem-reservation.h
 header-test-			+= xen/page.h
+header-test-			+= xen/page-coherent.h
 header-test-			+= xen/platform_pci.h
 header-test-			+= xen/swiotlb-xen.h
 header-test-			+= xen/xen-front-pgdir-shbuf.h
diff --git a/include/xen/arm/page-coherent.h b/include/xen/page-coherent.h
similarity index 76%
rename from include/xen/arm/page-coherent.h
rename to include/xen/page-coherent.h
index 4294a31305ca..7c32944de051 100644
--- a/include/xen/arm/page-coherent.h
+++ b/include/xen/page-coherent.h
@@ -1,10 +1,12 @@ 
 /* SPDX-License-Identifier: GPL-2.0 */
-#ifndef _XEN_ARM_PAGE_COHERENT_H
-#define _XEN_ARM_PAGE_COHERENT_H
+#ifndef _XEN_PAGE_COHERENT_H
+#define _XEN_PAGE_COHERENT_H
 
 #include <linux/dma-mapping.h>
 #include <asm/page.h>
 
+#if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
+    defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU)
 void __xen_dma_map_page(struct device *hwdev, struct page *page,
 	     dma_addr_t dev_addr, unsigned long offset, size_t size,
 	     enum dma_data_direction dir, unsigned long attrs);
@@ -71,5 +73,24 @@  static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
 	else
 		__xen_dma_unmap_page(hwdev, handle, size, dir, attrs);
 }
+#else
+static inline void xen_dma_map_page(struct device *hwdev, struct page *page,
+	     dma_addr_t dev_addr, unsigned long offset, size_t size,
+	     enum dma_data_direction dir, unsigned long attrs)
+{
+}
+static inline void xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+}
+static inline void xen_dma_sync_single_for_cpu(struct device *hwdev,
+		dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+}
+static inline void xen_dma_sync_single_for_device(struct device *hwdev,
+		dma_addr_t handle, size_t size, enum dma_data_direction dir)
+{
+}
+#endif
 
-#endif /* _XEN_ARM_PAGE_COHERENT_H */
+#endif /* _XEN_PAGE_COHERENT_H */