Re: [Xen-devel] [PATCH v8 16/19] arm, arm64: do not always merge biovec if we are running on Xen

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Russell, Catalin,
are you OK with this patch?

It shouldn't have any impact when running on native, only on Xen.


On Thu, 17 Oct 2013, Stefano Stabellini wrote:
> This is similar to what it is done on X86: biovecs are prevented from merging
> otherwise every dma requests would be forced to bounce on the swiotlb buffer.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> 
> Changes in v7:
> - remove the extra autotranslate check in biomerge.c.
> ---
>  arch/arm/include/asm/io.h   |    8 ++++++++
>  arch/arm64/include/asm/io.h |    9 +++++++++
>  2 files changed, 17 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/include/asm/io.h b/arch/arm/include/asm/io.h
> index d070741..c45effc 100644
> --- a/arch/arm/include/asm/io.h
> +++ b/arch/arm/include/asm/io.h
> @@ -24,9 +24,11 @@
>  #ifdef __KERNEL__
>  
>  #include <linux/types.h>
> +#include <linux/blk_types.h>
>  #include <asm/byteorder.h>
>  #include <asm/memory.h>
>  #include <asm-generic/pci_iomap.h>
> +#include <xen/xen.h>
>  
>  /*
>   * ISA I/O bus memory addresses are 1:1 with the physical address.
> @@ -372,6 +374,12 @@ extern void pci_iounmap(struct pci_dev *dev, void 
> __iomem *addr);
>  #define BIOVEC_MERGEABLE(vec1, vec2) \
>       ((bvec_to_phys((vec1)) + (vec1)->bv_len) == bvec_to_phys((vec2)))
>  
> +extern bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
> +                                   const struct bio_vec *vec2);
> +#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)                            \
> +     (__BIOVEC_PHYS_MERGEABLE(vec1, vec2) &&                         \
> +      (!xen_domain() || xen_biovec_phys_mergeable(vec1, vec2)))
> +
>  #ifdef CONFIG_MMU
>  #define ARCH_HAS_VALID_PHYS_ADDR_RANGE
>  extern int valid_phys_addr_range(phys_addr_t addr, size_t size);
> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h
> index 1d12f89..c163287b 100644
> --- a/arch/arm64/include/asm/io.h
> +++ b/arch/arm64/include/asm/io.h
> @@ -22,11 +22,14 @@
>  #ifdef __KERNEL__
>  
>  #include <linux/types.h>
> +#include <linux/blk_types.h>
>  
>  #include <asm/byteorder.h>
>  #include <asm/barrier.h>
>  #include <asm/pgtable.h>
>  
> +#include <xen/xen.h>
> +
>  /*
>   * Generic IO read/write.  These perform native-endian accesses.
>   */
> @@ -263,5 +266,11 @@ extern int devmem_is_allowed(unsigned long pfn);
>   */
>  #define xlate_dev_kmem_ptr(p)        p
>  
> +extern bool xen_biovec_phys_mergeable(const struct bio_vec *vec1,
> +                                   const struct bio_vec *vec2);
> +#define BIOVEC_PHYS_MERGEABLE(vec1, vec2)                            \
> +     (__BIOVEC_PHYS_MERGEABLE(vec1, vec2) &&                         \
> +      (!xen_domain() || xen_biovec_phys_mergeable(vec1, vec2)))
> +
>  #endif       /* __KERNEL__ */
>  #endif       /* __ASM_IO_H */
> -- 
> 1.7.2.5
> 

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