On Mon, Jun 25, 2018 at 10:59:06AM +0100, Andre Przywara wrote: > Hi, > > On 24/06/18 23:10, Christoffer Dall wrote: > > This small series addresses a peculiarity of the current VGIC > > implementation, namely that we don't support interrupt grouping. > > Nice one and seems straight forward enough. > Just curious: Were there any complaints or even users of FIQs and/or > interrupt grouping? > No, but the behavior wasn't strictly architecturally compliant so it was on the table for the GICv2-on-GICv3 fixes that Marc was working on a while back. > > KVM either implements a GICv2 without support for the security > > extensions, or a GICv3 with DS=1. For GICv2, on systems without the > > security extensions, group 0 interrupts can be configured to be either > > signalled as FIQs or as IRQs by the VM, whereas group 1 interrupts are > > always IRQs. For GICv3, with DS=1, group 1 interrupts are always IRQs > > and group 0 interrupts are always FIQs, and there is no concept of > > secure vs. non-secure group 1 interrupts when DS=1. > > > > We were treating all interrupts on GICv2 as group 0, but yet telling the > > geust that they were group 1. The first patch changes this behavior, > > which seems to have no effect on no known guests, but still. > > > > The remaining patches introduce proper interrupt grouping support, along > > with MMIO accessors for the VM and userspace to retrieve and set the > > which group SGIs, PPIs, and SPIs belong to. LPIs are always group 1 > > interrupts as per the architecture, and there is no way to modify this > > configuration (no IGROUPR registers for LPIs or equivalent ITS > > commands). > > > > Lightly tested on Seattle, TX1, and the foundation model. I've run a > > GICv2 guest on a GICv3 host on the foundation model. > > I take it those were regression tests with Linux guests? > Do we have any means of testing this with guests which actually use > different groups or FIQs? Does kvm-unit-tests cover this? I don't think so. I did run kvm-unit-tests on a GICv3 system and didn't observe anything. I think I forgot to run it on a GICv2 system, I'll expand coverage for the next round. > > Did you do any tests on 32 bit? I am going to fire up something on my > Midway later today ... > Yes, I ran it on my cubietruck. Thanks, -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
