Hi Andre, On 23/08/2019 11:34, Andre Przywara wrote:
At the moment we initialise the target *mask* of a virtual IRQ to the VCPU it belongs to, even though this mask is only defined for GICv2 and quickly runs out of bits for many GICv3 guests. This behaviour triggers an UBSAN complaint for more than 32 VCPUs: ------ [ 5659.462377] UBSAN: Undefined behaviour in virt/kvm/arm/vgic/vgic-init.c:223:21 [ 5659.471689] shift exponent 32 is too large for 32-bit type 'unsigned int' ------ Also for GICv3 guests the reporting of TARGET in the "vgic-state" debugfs dump is wrong, due to this very same problem. Because there is no requirement to create the VGIC device before the VCPUs (and QEMU actually does it the other way round), we can't safely initialise mpidr or targets in kvm_vgic_vcpu_init(). But since we touch every private IRQ for each VCPU anyway later (in vgic_init()), we can just move the initialisation of those fields into there, where we definitely know the VGIC type. On the way make sure we really have either a VGICv2 or a VGICv3 device, since the existing code is just checking for "VGICv3 or not", silently ignoring the uninitialised case. Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx> Reported-by: Dave Martin <dave.martin@xxxxxxx>
I have tested with both a combination of GICv2/GICv3 and kvmtools/QEMU. I can confirm the UBSAN warning is not present anymore. Feel free to add my tested-by:
Tested-by: Julien Grall <julien.grall@xxxxxxx> Cheers, -- Julien Grall _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
