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Date:   Wed, 2 Feb 2022 13:22:46 +0000
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Subject: Re: [PATCH 0/2] x86/hyperv/Swiotlb: Add swiotlb_alloc_from_low_pages
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To:     Christoph Hellwig <hch@infradead.org>,
        Tianyu Lan <ltykernel@gmail.com>
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        michael.h.kelley@microsoft.com,
        Tianyu Lan <Tianyu.Lan@microsoft.com>,
        iommu@lists.linux-foundation.org, linux-hyperv@vger.kernel.org,
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        brijesh.singh@amd.com, konrad.wilk@oracle.com, hch@lst.de,
        parri.andrea@gmail.com, thomas.lendacky@amd.com
References: <20220126161053.297386-1-ltykernel@gmail.com>
 <Yfo84XYBsV7tA6Xd@infradead.org>
From:   Robin Murphy <robin.murphy@arm.com>
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On 2022-02-02 08:12, Christoph Hellwig wrote:
> I think this interface is a little too hacky.  In the end all the
> non-trusted hypervisor schemes (including the per-device swiotlb one)
> can allocate the memory from everywhere and want for force use of
> swiotlb.  I think we need some kind of proper interface for that instead
> of setting all kinds of global variables.

Right, if platform/hypervisor code knows enough to be able to set magic 
non-standard allocation flags correctly, surely it could equally just 
perform whatever non-standard allocation it needs and call 
swiotlb_init_with_tbl() instead of swiotlb_init().

Robin.