ARM: KVM: Bugfix: vgic_bytemap_get_reg per cpu regs

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: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

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;