Re: FSGSBASE seems to be busted on Xen PV

2020-07-03 Thread Thomas Gleixner
Andrew Cooper writes: > On 03/07/2020 18:10, Andy Lutomirski wrote: >> If you can't get this fixed in upstream Xen reasonably quickly, we may >> need to disable FSGSBASE in a Xen PV guest in Linux. > > This has come up several times before, but if its actually breaking > userspace then Xen needs

Re: FSGSBASE seems to be busted on Xen PV

2020-07-03 Thread Andrew Cooper
On 03/07/2020 18:10, Andy Lutomirski wrote: > Hi Xen folks- > > I did some testing of the upcoming Linux FSGSBASE support on Xen PV, > and I found what appears to be some significant bugs in the Xen > context switching code. These bugs are causing Linux selftest > failures, and they could easily

FSGSBASE seems to be busted on Xen PV

2020-07-03 Thread Andy Lutomirski
Hi Xen folks- I did some testing of the upcoming Linux FSGSBASE support on Xen PV, and I found what appears to be some significant bugs in the Xen context switching code. These bugs are causing Linux selftest failures, and they could easily cause random and hard-to-debug failures of user