On 06/10/2015 05:21 PM, Joerg Roedel wrote: > On Tue, Jun 09, 2015 at 01:55:50PM +0100, David Woodhouse wrote: >> On Mon, 2015-06-08 at 18:13 +0200, Joerg Roedel wrote: >>> So I think we need to read out that bit when we find translation enabled >>> and if it is different from what we would set it to, we bail out of any >>> copying, disable translation and proceed as in a normal boot. >> >> Given that this is only for kdump and not the general case of kexec, >> that's probably tolerable. Of course we do still need to make it *not* >> broken for the case where DMA_RTADDR_RTT is set, as it is at the >> moment. > > Yes, I just sent a patch for this and will include it into my x86/vt-d > branch if not objections come in. > >> And I suspect if we're doing that, it might be simple enough to make it >> convert to/from the extended page tables. I don't think we want to >> preserve PASID tables; only the "second level" (i.e. traditional) >> translation. So we could happily pull the page table pointer out of >> either kind of context entry, and install it into either kind. I think >> there's a simple mapping of translation types too. I need to sort out >> the translation types when adding the real PASID support (imminently!) >> anyway. > > What happens when we take away the PASID tables from a device? Can it > also go into some failure state? > When doing this, we need at least setup the page request queue before we > copy over anything and change the root-entry. Then we can handle any > faults that are caused by this and tell the device to not try further. > > > Joerg > Is PASID part of new specs? Is there any plan to upgrade the driver to support the latest vt-d specs? Zhenhua
