On Mon, 24 Oct 2016 10:38:08 -0700 globalgorri...@fastmail.fm wrote: > On 24 Oct 2016, at 10:23, Alex Williamson wrote: > > > On Mon, 24 Oct 2016 10:20:08 -0700 > > globalgorri...@fastmail.fm wrote: > > > >> Hi, > >> > >> Pass-through works fine with the the same linux 4.8 VM and nouveau > >> and a > >> Quadro K2200. > >> > >> Passing-through both a R7 260X and and a R9 290 I get the same kernel > >> oops: > >> > >> IP: [<ffffffffc029efd9>] drm_pcie_get_speed_cap_mask+0x39/0xf0 [drm] > >> > >> More here: > >> http://pastebin.com/Waysyk2e > >> > >> Both the AMD cards work fine if I pass them through to a Windows VM. > >> > >> I'm supposing this might likely be then an issue with Radeon. > >> > >> However the oops makes me think perhaps it's breaking on unexpected > >> PCIE > >> information? > >> > >> Is it possible there some missing information in that radeon is > >> looking > >> for that's missing? What PCIE information is passed through by vfio > >> (lspci from both host and vm also in the pastebin)? > >> > >> Anybody using radeon with passthrough AMD cards and seen this? > > > > Radeon with a Linux guest is actually one of the few cases where you > > need to be running a Q35 machine with the GPU placed behind a PCIe > > downstream/root port. The code blindly assumes that an upstream PCIe > > bridge is present and tries to poke registers on it. > > Bingo. > > I'll have to clone and try with that. > > Alex, do you know if is enough to just simply passthrough the device but > with Q35? Or is a custom topology needed?
I would recommend a PCIe root port with the Radeon on the bus created by that. The Linux driver assumes this sort of topology. _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://www.redhat.com/mailman/listinfo/vfio-users