I've been trying to run VMs on a GICv3-based system that offers the GICv2 compatibility feature, and noticed that they would tend to slowly die under load.
It turned out that this is due to KVM not being exactly true to the architecture, and ends up injecting multiple SGI with the same vintid, which the architecture clearly outlines as a "don't do that". This bug has been there since the first days of the "new vgic". Another issue is that we don't use the right barriers when exiting from the guest, as we only synchronize stores, while the architecture requires to synchronize both loads and stores. And we miss an isb to force execution of the previous dsb. Unless someone shouts, I'm planning to take these patches into 4.16 as they directly affect my laptop (yes, I'm biased). Marc Zyngier (2): KVM: arm/arm64: vgic: Don't populate multiple LRs with the same vintid kvm: arm/arm64: vgic-v3: Tighten synchronization for guests using v2 on v3 virt/kvm/arm/hyp/vgic-v3-sr.c | 3 ++- virt/kvm/arm/vgic/vgic.c | 11 +---------- 2 files changed, 3 insertions(+), 11 deletions(-) -- 2.14.2 _______________________________________________ kvmarm mailing list firstname.lastname@example.org https://lists.cs.columbia.edu/mailman/listinfo/kvmarm