linux-kernel - Re: [RFC PATCH 5/6] arm/xen: Introduce xen_setup_dma_ops()

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Message-ID: <alpine.DEB.2.22.394.2204151303340.915916@ubuntu-linux-20-04-desktop>
Date:   Fri, 15 Apr 2022 15:02:32 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     Oleksandr Tyshchenko <olekstysh@...il.com>
cc:     xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Logan Gunthorpe <logang@...tatee.com>,
        David Hildenbrand <david@...hat.com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Kees Cook <keescook@...omium.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Julien Grall <julien@....org>
Subject: Re: [RFC PATCH 5/6] arm/xen: Introduce xen_setup_dma_ops()

On Thu, 14 Apr 2022, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> 
> This patch introduces new helper and places it in new header.
> The helper's purpose is to assign any Xen specific DMA ops in
> a single place. For now, we deal with xen-swiotlb DMA ops only.
> The subsequent patch will add xen-virtio DMA ops case.
> 
> Also re-use the xen_swiotlb_detect() check on Arm32.

Thanks for the patch, this is good to have in any case. I would move it
to the beginning of the series.

> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> ---
>  arch/arm/include/asm/xen/xen-ops.h   |  1 +
>  arch/arm/mm/dma-mapping.c            |  5 ++---
>  arch/arm64/include/asm/xen/xen-ops.h |  1 +
>  arch/arm64/mm/dma-mapping.c          |  5 ++---
>  include/xen/arm/xen-ops.h            | 13 +++++++++++++
>  5 files changed, 19 insertions(+), 6 deletions(-)
>  create mode 100644 arch/arm/include/asm/xen/xen-ops.h
>  create mode 100644 arch/arm64/include/asm/xen/xen-ops.h
>  create mode 100644 include/xen/arm/xen-ops.h
> 
> diff --git a/arch/arm/include/asm/xen/xen-ops.h b/arch/arm/include/asm/xen/xen-ops.h
> new file mode 100644
> index 00000000..8d2fa24
> --- /dev/null
> +++ b/arch/arm/include/asm/xen/xen-ops.h
> @@ -0,0 +1 @@
> +#include <xen/arm/xen-ops.h>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index 82ffac6..a1bf9dd 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -33,7 +33,7 @@
>  #include <asm/dma-iommu.h>
>  #include <asm/mach/map.h>
>  #include <asm/system_info.h>
> -#include <xen/swiotlb-xen.h>
> +#include <asm/xen/xen-ops.h>
>  
>  #include "dma.h"
>  #include "mm.h"
> @@ -2288,8 +2288,7 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>  	set_dma_ops(dev, dma_ops);
>  
>  #ifdef CONFIG_XEN
> -	if (xen_initial_domain())
> -		dev->dma_ops = &xen_swiotlb_dma_ops;
> +	xen_setup_dma_ops(dev);
>  #endif

You can take this opportunity to also remove the #ifdef, by providing an
empty stub implemention of xen_setup_dma_ops for the !CONFIG_XEN case.

>  	dev->archdata.dma_ops_setup = true;
>  }
> diff --git a/arch/arm64/include/asm/xen/xen-ops.h b/arch/arm64/include/asm/xen/xen-ops.h
> new file mode 100644
> index 00000000..8d2fa24
> --- /dev/null
> +++ b/arch/arm64/include/asm/xen/xen-ops.h
> @@ -0,0 +1 @@
> +#include <xen/arm/xen-ops.h>
> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
> index 6719f9e..831e673 100644
> --- a/arch/arm64/mm/dma-mapping.c
> +++ b/arch/arm64/mm/dma-mapping.c
> @@ -9,9 +9,9 @@
>  #include <linux/dma-map-ops.h>
>  #include <linux/dma-iommu.h>
>  #include <xen/xen.h>
> -#include <xen/swiotlb-xen.h>
>  
>  #include <asm/cacheflush.h>
> +#include <asm/xen/xen-ops.h>
>  
>  void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>  		enum dma_data_direction dir)
> @@ -53,7 +53,6 @@ void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
>  		iommu_setup_dma_ops(dev, dma_base, dma_base + size - 1);
>  
>  #ifdef CONFIG_XEN
> -	if (xen_swiotlb_detect())
> -		dev->dma_ops = &xen_swiotlb_dma_ops;
> +	xen_setup_dma_ops(dev);
>  #endif

same here

>  }
> diff --git a/include/xen/arm/xen-ops.h b/include/xen/arm/xen-ops.h
> new file mode 100644
> index 00000000..621da05
> --- /dev/null
> +++ b/include/xen/arm/xen-ops.h
> @@ -0,0 +1,13 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _ASM_ARM_XEN_OPS_H
> +#define _ASM_ARM_XEN_OPS_H
> +
> +#include <xen/swiotlb-xen.h>
> +
> +static inline void xen_setup_dma_ops(struct device *dev)
> +{
> +	if (xen_swiotlb_detect())
> +		dev->dma_ops = &xen_swiotlb_dma_ops;
> +}
> +
> +#endif /* _ASM_ARM_XEN_OPS_H */
> -- 
> 2.7.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> 

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