[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] Fixing ATS enabling for device assignment
>>> "Han, Weidong" 05/19/10 4:37 AM >>> >Currently, Xen only enables ATS in Xen booting. When a ATS capable device is >assigned to guest, ATS is actually not enabled because FLR before assignment >causes it to be disabled. Thus ATS cannot be used in guest. This patch enables >ATS in domain_context_mapping. This ensures ATS is enabled in assignment >because FLR is earlier than domain_context_mapping call. Therefore ATS can be >used in guest. This patch also implements disable_ats_device to disable ATS >when the device is deassigned from a domain. Hmm, this looks inconsistent to me: Iirc FLR is being done from the tools, so unless it is technically impossible to do FLR after domain_context_mapping(), the patch creates a hypervisor dependency on the tools (if nothing else, a latent bug - to be introduced the moment operation ordering changes in the tools). Further, if ATS gets enabled at boot time, why would you want to disable it after de-assignment? Finally (only partially related) - why are {en,dis}able_ats_device() architecture specific? PCI config space accesses really aren't I would think. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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