linux-kernel - Re: [PATCH v4 4/7] s390/pci: Use dma-iommu layer

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: <50c22529-e0f4-9124-fdc0-c8da49300b18@linux.ibm.com>
Date:   Thu, 19 Jan 2023 10:59:02 -0500
From:   Matthew Rosato <mjrosato@...ux.ibm.com>
To:     Niklas Schnelle <schnelle@...ux.ibm.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Wenjia Zhang <wenjia@...ux.ibm.com>
Cc:     Gerd Bayer <gbayer@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>, iommu@...ts.linux.dev,
        linux-s390@...r.kernel.org, borntraeger@...ux.ibm.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com,
        gerald.schaefer@...ux.ibm.com, agordeev@...ux.ibm.com,
        svens@...ux.ibm.com, linux-kernel@...r.kernel.org,
        Julian Ruess <julianr@...ux.ibm.com>
Subject: Re: [PATCH v4 4/7] s390/pci: Use dma-iommu layer

On 1/19/23 6:03 AM, Niklas Schnelle wrote:
>>>>>>>>>>>>>>>>>  
>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>  static char *pci_sw_names[] = {
>>>>>>>>>>>>>>>>> - "Allocated pages",
>>>>>>>>>>>>>>>>> +/* TODO "Allocated pages", */
>>>>>>>>>
>>>>>>>>> ? Forgot to finish this?
> 
> Definitely forgot to remove the TODO. I think my latest plan was to
> just remove this counter. With the DMA API conversion the
> dma_map_ops.alloc and dma_map_ops.free move to common code and I don't
> see how we could differentiate these from map/unmap on our side. I'm
> not sure how helpful this counter really is either. If you're
> interested in how many pages are mapped long term I think it makes more
> sense to look at the difference between mapped and unmapped pages. What
> do you think?
>>>>>>>>

Sounds reasonable to me, but I also note that without this series, when viewing statistics for a device, mapped - unmapped != allocated.  Maybe allocated pages was already broken, or is it taking into account something else that mapped - unmapped would not (maybe mapping the same page multiple times)?