For bytemaps each IRQ field is 1 byte wide, so we pack 4 irq fields in one word and since there are 32 private (per cpu) irqs, we have 8 private u32 fields on the vgic_bytemap struct. We shift the offset from the base of the register group right by 2, giving us the word index instead of the field index. But then there are 8 private words, not 4, which is also why we subtract 8 words from the offset of the shared words.

Signed-off-by: Christoffer Dall christoffer.dall@linaro.org --- virt/kvm/arm/vgic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index 17c5ac7..96d7aa4 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -149,7 +149,7 @@ static u32 *vgic_bytemap_get_reg(struct vgic_bytemap *x, int cpuid, u32 offset) { offset >>= 2; BUG_ON(offset > (VGIC_NR_IRQS / 4)); - if (offset < 4) + if (offset < 8) return x->percpu[cpuid] + offset; else return x->shared + offset - 8;