On Wed, Nov 01, 2017 at 03:23:50PM +0000, James Morse wrote: > Hi guys, > > On 31/10/17 10:08, Will Deacon wrote: > > On Tue, Oct 31, 2017 at 07:35:35AM +0100, Christoffer Dall wrote: > >> On Thu, Oct 19, 2017 at 03:57:46PM +0100, James Morse wrote: > >>> The aim of this series is to enable IESB and add ESB-instructions to let us > >>> kick any pending RAS errors into firmware to be handled by firmware-first. > >>> > >>> Not all systems will have this firmware, so these RAS errors will become > >>> pending SErrors. We should take these as quickly as possible and avoid > >>> panic()ing for errors where we could have continued. > >>> > >>> This first part of this series reworks the DAIF masking so that SError is > >>> unmasked unless we are handling a debug exception. > >>> > >>> The last part provides the same minimal handling for SError that interrupt > >>> KVM. KVM is currently unable to handle SErrors during world-switch, unless > >>> they occur during a magic single-instruction window, it hyp-panics. I suspect > >>> this will be easier to fix once the VHE world-switch is further optimised. > >>> > >>> KVMs kvm_inject_vabt() needs updating for v8.2 as now we can specify an ESR, > >>> and all-zeros has a RAS meaning. > >>> > >>> KVM's existing 'impdef SError to the guest' behaviour probably needs revisiting. > >>> These are errors where we don't know what they mean, they may not be > >>> synchronised by ESB. Today we blame the guest. > >>> My half-baked suggestion would be to make a virtual SError pending, but then > >>> exit to user-space to give Qemu the change to quit (for virtual machines that > >>> don't generate SError), pend an SError with a new Qemu-specific ESR, or blindly > >>> continue and take KVMs default all-zeros impdef ESR. > >> > >> The KVM side of this series is looking pretty good. > >> > >> What are the merge plans for this? I am fine if you will take this via > >> the arm64 tree with our acks from the KVM side. Alternatively, I > >> suppose you can apply all the arm64 patches and provide us with a stable > >> branch for that? > > > > I'll take a look this afternoon, but we haven't had a linux next release > > since the 18th so I'm starting to get nervous about conflicts if I end up > > pulling in new trees now. > > Will's 'what about mixed RAS support' comment will take me a while to get to > fix, and I don't think I can test that before the end of the week. > > Unless there is an rc8+linux-next I think this is too late, but I will split off > and repost the SError_rework bits as that seems uncontentious... > > It is indeed cutting it a bit close. We'll have the same challenge of either going via arm64 or using a stable branch we merge into the KVM side for the next merge window as well. I prefer the latter, since there's going to be some conflicts with my optimization series which I hope to get in for v4.16. Thanks, -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
