linux-kernel - Re: [RFC PATCH V3 10/11] HV/Netvsc: Add Isolation VM support for netvsc driver

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

Message-ID: <20210614070903.GA29976@lst.de>
Date:   Mon, 14 Jun 2021 09:09:03 +0200
From:   Christoph Hellwig <hch@....de>
To:     Tianyu Lan <ltykernel@...il.com>
Cc:     Christoph Hellwig <hch@....de>, kys@...rosoft.com,
        haiyangz@...rosoft.com, sthemmin@...rosoft.com, wei.liu@...nel.org,
        decui@...rosoft.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, x86@...nel.org, hpa@...or.com, arnd@...db.de,
        dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org,
        akpm@...ux-foundation.org, kirill.shutemov@...ux.intel.com,
        rppt@...nel.org, hannes@...xchg.org, cai@....pw,
        krish.sadhukhan@...cle.com, saravanand@...com,
        Tianyu.Lan@...rosoft.com, konrad.wilk@...cle.com,
        m.szyprowski@...sung.com, robin.murphy@....com,
        boris.ostrovsky@...cle.com, jgross@...e.com,
        sstabellini@...nel.org, joro@...tes.org, will@...nel.org,
        xen-devel@...ts.xenproject.org, davem@...emloft.net,
        kuba@...nel.org, jejb@...ux.ibm.com, martin.petersen@...cle.com,
        iommu@...ts.linux-foundation.org, linux-arch@...r.kernel.org,
        linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-scsi@...r.kernel.org, netdev@...r.kernel.org,
        vkuznets@...hat.com, thomas.lendacky@....com,
        brijesh.singh@....com, sunilmut@...rosoft.com
Subject: Re: [RFC PATCH V3 10/11] HV/Netvsc: Add Isolation VM support for
 netvsc driver

On Mon, Jun 07, 2021 at 11:21:20PM +0800, Tianyu Lan wrote:
>> dma_map_single can only be used on page baked memory, and if this is
>> using page backed memory you wouldn't need to do thee phys_to_virt
>> tricks.  Can someone explain the mess here in more detail?
>
> Sorry. Could you elaborate the issue? These pages in the pb array are not 
> allocated by DMA API and using dma_map_single() here is to map these pages' 
> address to bounce buffer physical address.

dma_map_single just calls dma_map_page using virt_to_page.  So this
can't work on addresses not in the kernel linear mapping.