Re: [PATCH 1/2] xen/arm, arm64: fix xen_dma_ops after 815dd18 "Consolidate get_dma_ops..."

[Stefano Stabellini <sstabellini@kernel.org>]

Hello Russell,

Can I have your acked-by on the following fix (original patch is
1492117462-19886-1-git-send-email-sstabellini@kernel.org)?

Thanks,

Stefano


On Tue, 18 Apr 2017, Catalin Marinas wrote:
> On Thu, Apr 13, 2017 at 02:04:21PM -0700, Stefano Stabellini wrote:
> > The following commit:
> > 
> >   commit 815dd18788fe0d41899f51b91d0560279cf16b0d
> >   Author: Bart Van Assche <bart.vanassche@sandisk.com>
> >   Date:   Fri Jan 20 13:04:04 2017 -0800
> > 
> >       treewide: Consolidate get_dma_ops() implementations
> > 
> > rearranges get_dma_ops in a way that xen_dma_ops are not returned when
> > running on Xen anymore, dev->dma_ops is returned instead (see
> > arch/arm/include/asm/dma-mapping.h:get_arch_dma_ops and
> > include/linux/dma-mapping.h:get_dma_ops).
> > 
> > Fix the problem by storing dev->dma_ops in dev_archdata, and setting
> > dev->dma_ops to xen_dma_ops. This way, xen_dma_ops is returned naturally
> > by get_dma_ops. The Xen code can retrieve the original dev->dma_ops from
> > dev_archdata when needed. It also allows us to remove __generic_dma_ops
> > from common headers.
> > 
> > Signed-off-by: Stefano Stabellini <sstabellini@kernel.org>
> > Tested-by: Julien Grall <julien.grall@arm.com>
> > Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> > CC: linux@armlinux.org.uk
> > CC: catalin.marinas@arm.com
> > CC: will.deacon@arm.com
> > CC: boris.ostrovsky@oracle.com
> > CC: jgross@suse.com
> > CC: Julien Grall <julien.grall@arm.com>
> 
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> 
> 
> > diff --git a/arch/arm/include/asm/device.h b/arch/arm/include/asm/device.h
> > index 220ba20..36ec9c8 100644
> > --- a/arch/arm/include/asm/device.h
> > +++ b/arch/arm/include/asm/device.h
> > @@ -16,6 +16,9 @@ struct dev_archdata {
> >  #ifdef CONFIG_ARM_DMA_USE_IOMMU
> >  	struct dma_iommu_mapping	*mapping;
> >  #endif
> > +#ifdef CONFIG_XEN
> > +	const struct dma_map_ops *dev_dma_ops;
> > +#endif
> >  	bool dma_coherent;
> >  };
> >  
> > diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
> > index 7166569..680d3f3 100644
> > --- a/arch/arm/include/asm/dma-mapping.h
> > +++ b/arch/arm/include/asm/dma-mapping.h
> > @@ -16,19 +16,9 @@
> >  extern const struct dma_map_ops arm_dma_ops;
> >  extern const struct dma_map_ops arm_coherent_dma_ops;
> >  
> > -static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
> > -{
> > -	if (dev && dev->dma_ops)
> > -		return dev->dma_ops;
> > -	return &arm_dma_ops;
> > -}
> > -
> >  static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
> >  {
> > -	if (xen_initial_domain())
> > -		return xen_dma_ops;
> > -	else
> > -		return __generic_dma_ops(NULL);
> > +	return &arm_dma_ops;
> >  }
> >  
> >  #define HAVE_ARCH_DMA_SUPPORTED 1
> > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> > index 63eabb0..a614459 100644
> > --- a/arch/arm/mm/dma-mapping.c
> > +++ b/arch/arm/mm/dma-mapping.c
> > @@ -2396,6 +2396,13 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
> >  		dma_ops = arm_get_dma_map_ops(coherent);
> >  
> >  	set_dma_ops(dev, dma_ops);
> > +
> > +#ifdef CONFIG_XEN
> > +	if (xen_initial_domain()) {
> > +		dev->archdata.dev_dma_ops = dev->dma_ops;
> > +		dev->dma_ops = xen_dma_ops;
> > +	}
> > +#endif
> >  }
> >  
> >  void arch_teardown_dma_ops(struct device *dev)
> > diff --git a/arch/arm64/include/asm/device.h b/arch/arm64/include/asm/device.h
> > index 73d5bab..5a5fa47 100644
> > --- a/arch/arm64/include/asm/device.h
> > +++ b/arch/arm64/include/asm/device.h
> > @@ -20,6 +20,9 @@ struct dev_archdata {
> >  #ifdef CONFIG_IOMMU_API
> >  	void *iommu;			/* private IOMMU data */
> >  #endif
> > +#ifdef CONFIG_XEN
> > +	const struct dma_map_ops *dev_dma_ops;
> > +#endif
> >  	bool dma_coherent;
> >  };
> >  
> > diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h
> > index 505756c..5392dbe 100644
> > --- a/arch/arm64/include/asm/dma-mapping.h
> > +++ b/arch/arm64/include/asm/dma-mapping.h
> > @@ -27,11 +27,8 @@
> >  #define DMA_ERROR_CODE	(~(dma_addr_t)0)
> >  extern const struct dma_map_ops dummy_dma_ops;
> >  
> > -static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
> > +static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
> >  {
> > -	if (dev && dev->dma_ops)
> > -		return dev->dma_ops;
> > -
> >  	/*
> >  	 * We expect no ISA devices, and all other DMA masters are expected to
> >  	 * have someone call arch_setup_dma_ops at device creation time.
> > @@ -39,14 +36,6 @@ static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
> >  	return &dummy_dma_ops;
> >  }
> >  
> > -static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
> > -{
> > -	if (xen_initial_domain())
> > -		return xen_dma_ops;
> > -	else
> > -		return __generic_dma_ops(NULL);
> > -}
> > -
> >  void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
> >  			const struct iommu_ops *iommu, bool coherent);
> >  #define arch_setup_dma_ops	arch_setup_dma_ops
> > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> > index 81cdb2e..7f8b37e 100644
> > --- a/arch/arm64/mm/dma-mapping.c
> > +++ b/arch/arm64/mm/dma-mapping.c
> > @@ -977,4 +977,11 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
> >  
> >  	dev->archdata.dma_coherent = coherent;
> >  	__iommu_setup_dma_ops(dev, dma_base, size, iommu);
> > +
> > +#ifdef CONFIG_XEN
> > +	if (xen_initial_domain()) {
> > +		dev->archdata.dev_dma_ops = dev->dma_ops;
> > +		dev->dma_ops = xen_dma_ops;
> > +	}
> > +#endif
> >  }
> > diff --git a/include/xen/arm/page-coherent.h b/include/xen/arm/page-coherent.h
> > index 95ce6ac..b0a2bfc 100644
> > --- a/include/xen/arm/page-coherent.h
> > +++ b/include/xen/arm/page-coherent.h
> > @@ -2,8 +2,16 @@
> >  #define _ASM_ARM_XEN_PAGE_COHERENT_H
> >  
> >  #include <asm/page.h>
> > +#include <asm/dma-mapping.h>
> >  #include <linux/dma-mapping.h>
> >  
> > +static inline const struct dma_map_ops *__generic_dma_ops(struct device *dev)
> > +{
> > +	if (dev && dev->archdata.dev_dma_ops)
> > +		return dev->archdata.dev_dma_ops;
> > +	return get_arch_dma_ops(NULL);
> > +}
> > +
> >  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);