Hi Zenghui, On 9/19/20 1:15 PM, Zenghui Yu wrote: > Hi folks, > > I had booted a guest with an assigned virtual function, with GICv4 > (direct MSI injection) enabled on my arm64 server. I got the following > QEMU error message on its shutdown: > > "qemu-system-aarch64: KVM_SET_DEVICE_ATTR failed: Group 4 attr > 0x0000000000000001: Permission denied" > > The problem is that the KVM_DEV_ARM_ITS_SAVE_TABLES ioctl failed while > stopping the VM. > > As for the kernel side, it turned out that an LPI with irq->hw=true was > observed while saving ITT for the device. KVM simply failed the save > operation by returning -EACCES to user-space. The reason is explained in > the comment block of vgic_its_save_itt(), though I think the HW bit > should actually be checked in the KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES > ioctl rather than in the ITT saving, well, it isn't much related to this > problem... > > I had noticed that some vectors had been masked by guest VF-driver on > shutdown, the correspond VLPIs had therefore been unmapped and irq->hw > was cleared. But some other vectors were un-handled. I *guess* that VFIO > released these vectors *after* the KVM_DEV_ARM_ITS_SAVE_TABLES ioctl so > that we end-up trying to save the VLPI's state. > > It may not be a big problem as the guest is going to shutdown anyway and > the whole guest save/restore on the GICv4.x system is not supported for > the time being... I'll look at how VFIO would release these vectors but > post it early in case this is an already known issue (and this might be > one thing need to be considered if one wants to implement migration on > the GICv4.x system). Thanks for reporting the issue. I will have a look at the QEMU sequence too Eric > > > Thanks, > Zenghui > _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
