On 2016/12/7 16:10, Marc Zyngier wrote: > On 07/12/16 07:45, Shannon Zhao wrote: >> >> >> On 2016/12/6 19:47, Marc Zyngier wrote: >>> On 06/12/16 06:41, Shannon Zhao wrote: >>>> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx> >>>> >>>> Commit 50926d8(KVM: arm/arm64: The GIC is dead, long live the GIC) >>>> removes the old vgic and commit 9097773(KVM: arm/arm64: vgic-new: >>>> vgic_init: implement kvm_vgic_hyp_init) doesn't reset LRs for new-vgic >>>> when probing GIC. These two patches add the missing part. >>>> >>>> BTW, here is a strange problem on Huawei D03 board when using >>>> upstream kernel that android guest with a goldfish_fb will hang with >>>> rcu_stall and interrupt timeout for goldfish_fb. We apply these patches >>>> but the problem still exists, while if we revert the commit >>>> b40c489(arm64: KVM: vgic-v3: Only wipe LRs on vcpu exit) the guest runs >>>> well. >>>> >>>> We add a trace in kvm_vgic_flush_hwstate() to print the value of >>>> compute_ap_list_depth(vcpu) and the value of vgic_lr before calling >>>> vgic_flush_lr_state(). The first output shows that the ap_list_depth is zero >>>> but the first one in vgic_lr is 10a0000000002001. I don't understand why >>>> there is a valued one in vgic_lr since the memory of vgic_lr is zero >>>> allocated. I think It should be zero when the vcpu first run and first >>>> call kvm_vgic_flush_hwstate(). >>>> >>>> qemu-system-aar-6673 [016] .... 501.969251: kvm_vgic_flush_hwstate: VCPU: 0, lits-count: 0, LR: 10a0000000002001, 0, 0, 0 >>>> >>>> I also add a trace at the end of vgic_flush_lr_state() which shows the >>>> kvm_vgic_global_state.nr_lr is 4, used_lrs is 0 and all LRs in vgic_lr >>>> are zero. >>>> >>>> qemu-system-aar-6673 [016] .... 501.969254: vgic_flush_lr_state_nuke: kvm_vgic_global_state.nr_lr is :4, irq1:0, irq2:0, irq3:0, irq4:0 >>>> >>>> But the trace at the beginning of kvm_vgic_sync_hwstate() shows the >>>> first one of vgic_lr is 10a0000000002001. >>>> >>>> qemu-system-aar-6673 [016] .... 501.969261: kvm_vgic_sync_hwstate_vgic_lr: VCPU: 0, used_lrs: 0, LR: 10a0000000002001, 0, 0, 0 >>>> >>>> The above three trace outputs are printed by the first KVM_ENTRY/EXIT of VCPU 0. >>> >>> Decoding this LR value is interesting: >>> >>> 10a0000000002001 >>> | | | LPI 8193 >>> | | >>> | Priority 0xa0 >>> | >>> Group1 >>> >>> Someone is injecting an LPI behind your back. If nobody populates this, >>> then you may want to investigate what is happening on the host side. Is >>> there anyone using this interrupt? >>> >> >> For this guest, I think nobody populates this LR, but on the host, there >> is a LPI interrupt 8193. It's a interrupt of eth2 >> >> MBIGEN-V2 8193 Edge eth2-tx0 >> >> It's a little confused to me that the LR registers should only be used >> for VM, right? Why does the interrupt on host would affect the LRs? > > It should never have an impact, but I'm worried that this could be a HW > bug where the physical side of the ITS leaks into the virtual one. You > have a GICv4, right? Yes, the hardware supports GICv4 but I think current kernel doesn't enable it. > > It'd be interesting to find out what happens if you leave this interrupt > disabled (don't enable eth2) and see if that interrupt magically appears > or not. > Ah, I found the guest uses ITS and there is a irq number 8193. If I use a qemu without ITS feature then there is no such irq in trace output. But there is still unexpected LR in vgic_lr[] array of irq 27. Nobody calls vgic_update_irq_pending for irq 27 before below trace outputs. qemu-system-aar-6681 [021] .... 1081.718849: kvm_vgic_flush_hwstate: VCPU: 0, lits-count: 0, LR: 0, 0, 0 qemu-system-aar-6681 [021] .... 1081.718849: vgic_flush_lr_state: used lr count is :0, irq1:0, irq2:0, irq3:0, irq4:0 qemu-system-aar-6681 [021] d... 1081.718850: kvm_entry: PC: 0xffffff8008432940 qemu-system-aar-6681 [021] .... 1081.718852: kvm_exit: TRAP: HSR_EC: 0x0024 (DABT_LOW), PC: 0xffffff8008432954 qemu-system-aar-6681 [021] .... 1081.718852: kvm_vgic_sync_hwstate_vgic_lr: VCPU: 0, used_lrs: 0, LR: 0, 0, 0, 0 qemu-system-aar-6681 [021] .... 1081.718855: kvm_vgic_flush_hwstate: VCPU: 0, lits-count: 0, LR: 50a002000000001b, 0, 0, 0 qemu-system-aar-6681 [021] .... 1081.718855: vgic_flush_lr_state: used lr count is :0, irq1:0, irq2:0, irq3:0, irq4:0 qemu-system-aar-6681 [021] d... 1081.718856: kvm_entry: PC: 0xffffff8008432958 qemu-system-aar-6681 [021] .... 1081.718858: kvm_exit: TRAP: HSR_EC: 0x0024 (DABT_LOW), PC: 0xffffff800843291c Thanks, -- Shannon _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
