arm/arm64: KVM: Fix set_clear_sgi_pend_reg offset

The sgi values calculated in read_set_clear_sgi_pend_reg() and
write_set_clear_sgi_pend_reg() were horribly incorrectly multiplied by 4
with catastrophic results in that subfunctions ended up overwriting
memory not allocated for the expected purpose.

This showed up as bugs in kfree() and the kernel complaining a lot of
you turn on memory debugging.

This addresses: http://marc.info/?l=kvm&m=141164910007868&w=2

Reported-by: Shannon Zhao <[email protected]>
Signed-off-by: Christoffer Dall <[email protected]>

virt/kvm/arm/vgic.c

@@ -816,7 +816,7 @@ static bool read_set_clear_sgi_pend_reg(struct kvm_vcpu *vcpu,
 {
 	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
 	int sgi;
-	int min_sgi = (offset & ~0x3) * 4;
+	int min_sgi = (offset & ~0x3);
 	int max_sgi = min_sgi + 3;
 	int vcpu_id = vcpu->vcpu_id;
 	u32 reg = 0;
@@ -837,7 +837,7 @@ static bool write_set_clear_sgi_pend_reg(struct kvm_vcpu *vcpu,
 {
 	struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
 	int sgi;
-	int min_sgi = (offset & ~0x3) * 4;
+	int min_sgi = (offset & ~0x3);
 	int max_sgi = min_sgi + 3;
 	int vcpu_id = vcpu->vcpu_id;
 	u32 reg;