Hi Jean, On 2019/1/31 22:55, Jean-Philippe Brucker wrote: > Hi, > > On 31/01/2019 13:52, Zhen Lei wrote: >> Currently, many peripherals are faster than before. For example, the top >> speed of the older netcard is 10Gb/s, and now it's more than 25Gb/s. But >> when iommu page-table mapping enabled, it's hard to reach the top speed >> in strict mode, because of frequently map and unmap operations. In order >> to keep abreast of the times, I think it's better to set non-strict as >> default. > > Most users won't be aware of this relaxation and will have their system > vulnerable to e.g. thunderbolt hotplug. See for example 4.3 Deferred > Invalidation in > http://www.cs.technion.ac.il/users/wwwb/cgi-bin/tr-get.cgi/2018/MSC/MSC-2018-21.pdf > > Why not keep the policy to secure by default, as we do for > iommu.passthrough? And maybe add something similar to > CONFIG_IOMMU_DEFAULT_PASSTRHOUGH? It's easy enough for experts to pass a > command-line argument or change the default config.
Sorry for the late reply, it was Chinese new year, and we had a long discussion internally, we are fine to add a Kconfig but not sure OS vendors will set it to default y. OS vendors seems not happy to pass a command-line argument, to be honest, this is our motivation to enable non-strict as default. Hope OS vendors can see this email thread, and give some input here. Thanks Hanjun _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
