https://bugzilla.kernel.org/show_bug.cgi?id=107561 schefister@xxxxxxxxx changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |schefister@xxxxxxxxx --- Comment #4 from schefister@xxxxxxxxx --- I narrowed it down earlier to "simplify kvm_mtrr_get_guest_memory_type". Actually this was the commit to break it, but it is only a small part of the feauture set implementing vMTRR. To my knowledge 4.1.x versions didn't have this code set at all. It was introduced in 4.2. What kvm_mtrr_get_guest_memory_type() does is basically decides what cache type to use (Uncachable, Write-Back, or Write-Through) based on the function mtrr_for_each_mem_type(). This kvm_mtrr_get_guest_memory_type function is only called by vmx_get_mt_mask. This is all related to how the hardware is set up regarding IOMMU, MMIO, VT-d and EPT andress translation. For experimenting purposes I simply modified kvm_mtrr_get_guest_memory_type to always return MTRR_TYPE_WRBACK and that fixed the issue. Guest boots correctly. Although I know, that hardcoding Write-back mode is not a viable long-term solution. It seems as the new function (in 4.2 and onward) does not return the proper cache type in case of pci passthrough configurations. I would also like to point out, that https://bugzilla.kernel.org/show_bug.cgi?id=107921 may be related. The other bug mentions very similar hardware to mine, and issues started the same time (upgrading to 4.2.x) with a pci passthrough configuration. -- You are receiving this mail because: You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
