On December 5, 2015 at 20:38:17, Hristo Iliev (hristo hiliev eu) wrote:
Actually the 100% CPU usage issue reside on the changes on the kernel linux starting 4.2.x and the implementation of OVMF. Since the latest linux-vfio is based on linux 4.2.x, the issue also reside on that kernel. There’s a patch  for linux 4.3-mainline if you want to upgrade your kernel, I’ve tried it out myself on Z87 platform, but I haven’t found a patch for linux 4.2.x. If you want stableness, linux-lts-4.1.13 seems the latest stable right now.
I just upgraded my rig to a Haswell-E platform (Intel Core i7-5820K also, plus ASUS X99-A) last weekend, and I found no issues running pure linux-lts-4.1.13 (even the config is from lts). Though, I recompiled the kernel again with ABS and native CFLAGS hoping to have even better performance. Are you sure you meant linux-lts not linux-vfio (4.2.x)?
Hmm, that’s weird. Haswell-E platform should not need any PCIe ACS workaround patch. Its IOMMU groups are separated nicely for each device. Can you try using linux-vfio-lts’ config and recompile linux-lts using the config with ABS and try booting the guest again?
Recompiling on your machine probably just took around 10 minutes actually. :D