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Date:   Fri, 22 Apr 2022 16:00:53 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@kernel.org>
To:     Oleksandr Tyshchenko <olekstysh@gmail.com>
cc:     xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Julien Grall <julien@xen.org>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Christoph Hellwig <hch@infradead.org>
Subject: Re: [PATCH V1 6/6] arm/xen: Assign xen-grant DMA ops for xen-grant
 DMA devices
In-Reply-To: <1650646263-22047-7-git-send-email-olekstysh@gmail.com>
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References: <1650646263-22047-1-git-send-email-olekstysh@gmail.com> <1650646263-22047-7-git-send-email-olekstysh@gmail.com>
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On Fri, 22 Apr 2022, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
> 
> As the main (and single at the moment) purpose of xen-grant
> DMA devices is to enable using virtio devices in Xen guests
> in a safe manner, assign xen-grant DMA ops only if restricted
> access to the guest memory is enabled.
> 
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>

Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>


> ---
> Changes RFC -> V1:
>    - update commit subject/description
>    - remove #ifdef CONFIG_XEN_VIRTIO
>    - re-organize the check taking into the account that
>      swiotlb and virtio cases are mutually exclusive
>    - update according to the new naming scheme:
>      s/virtio/grant_dma
> ---
>  include/xen/arm/xen-ops.h | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/include/xen/arm/xen-ops.h b/include/xen/arm/xen-ops.h
> index 288deb1..26954e5 100644
> --- a/include/xen/arm/xen-ops.h
> +++ b/include/xen/arm/xen-ops.h
> @@ -2,12 +2,17 @@
>  #ifndef _ASM_ARM_XEN_OPS_H
>  #define _ASM_ARM_XEN_OPS_H
>  
> +#include <linux/virtio_config.h>
>  #include <xen/swiotlb-xen.h>
> +#include <xen/xen-ops.h>
>  
>  static inline void xen_setup_dma_ops(struct device *dev)
>  {
>  #ifdef CONFIG_XEN
> -	if (xen_swiotlb_detect())
> +	if (arch_has_restricted_virtio_memory_access() &&
> +			xen_is_grant_dma_device(dev))
> +		xen_grant_setup_dma_ops(dev);
> +	else if (xen_swiotlb_detect())
>  		dev->dma_ops = &xen_swiotlb_dma_ops;
>  #endif
>  }
> -- 
> 2.7.4
> 
> 
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