linux-kernel - Re: [PATCH 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <e874b4c3-1d09-8d2a-bd59-80bae7e554d6@gmail.com>
Date:   Fri, 26 Nov 2021 19:39:03 +0800
From:   Tianyu Lan <ltykernel@...il.com>
To:     Christoph Hellwig <hch@....de>
Cc:     dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org,
        hpa@...or.com, jgross@...e.com, sstabellini@...nel.org,
        boris.ostrovsky@...cle.com, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, wei.liu@...nel.org,
        decui@...rosoft.com, joro@...tes.org, will@...nel.org,
        davem@...emloft.net, kuba@...nel.org, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, m.szyprowski@...sung.com,
        robin.murphy@....com, xen-devel@...ts.xenproject.org,
        michael.h.kelley@...rosoft.com,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>,
        iommu@...ts.linux-foundation.org, linux-hyperv@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
        netdev@...r.kernel.org, vkuznets@...hat.com, brijesh.singh@....com,
        konrad.wilk@...cle.com, parri.andrea@...il.com,
        thomas.lendacky@....com, dave.hansen@...el.com
Subject: Re: [PATCH 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for
 Isolation VM

On 11/26/2021 3:40 PM, Christoph Hellwig wrote:
> On Wed, Nov 17, 2021 at 10:00:08PM +0800, Tianyu Lan wrote:
>> On 11/17/2021 6:01 PM, Christoph Hellwig wrote:
>>> This doesn't really have much to do with normal DMA mapping,
>>> so why does this direct through the dma ops?
>>>
>>
>> According to the previous discussion, dma_alloc_noncontigous()
>> and dma_vmap_noncontiguous() may be used to handle the noncontigous
>> memory alloc/map in the netvsc driver. So add alloc/free and vmap/vunmap
>> callbacks here to handle the case. The previous patch v4 & v5 handles
>> the allocation and map in the netvsc driver. If this should not go though
>> dma ops, We also may make it as vmbus specific function and keep
>> the function in the vmbus driver.
> 
> But that only makes sense if they can actually use the normal DMA ops.
> If you implement your own incomplete ops and require to use them you
> do nothing but adding indirect calls to your fast path and making the
> code convoluted.
> 

Because the generic part implementation can't meet the netvsc driver
requests that allocate 16M memory and map pages via vmap_pfn(). So add 
Hyperv alloc_noncontiguous and vmap_noncontiguous callbacks. If this is
not a right way. we should call these hyper-V functions in the netvsc
driver directly, right?

Could you have a look at Michael summary about this series we made and
give some guides?

https://www.mail-archive.com/xen-devel@lists.xenproject.org/msg109284.html

Thanks.