On Tue, Jun 18, 2013 at 11:09:28AM +0100, Marc Zyngier wrote:
> All the code in handle_mmio_cfg_reg() assumes the offset has
> been shifted right to accomodate for the 2:1 bit compression,
> but this is only done when getting the register addess.
I personally think this is a funky assumption. The offset is called
offset, because it's the offset, not a "compressed index" value, so I'd
prefer to fix the comparison values instead.
If not, put a comment and explain the assumption, because it's not
obvious.
>
> Shift the offset early so the code works mostly unchanged.
>
> Reported-by: Zhaobo (Bob, ERC) <zhaobo@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> arch/arm/kvm/vgic.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm/kvm/vgic.c b/arch/arm/kvm/vgic.c
> index a2d478a..902789f 100644
> --- a/arch/arm/kvm/vgic.c
> +++ b/arch/arm/kvm/vgic.c
> @@ -541,8 +541,12 @@ static bool handle_mmio_cfg_reg(struct kvm_vcpu *vcpu,
> struct kvm_exit_mmio *mmio, phys_addr_t offset)
> {
> u32 val;
> - u32 *reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_cfg,
> - vcpu->vcpu_id, offset >> 1);
> + u32 *reg;
> +
> + offset >>= 1;
> + reg = vgic_bitmap_get_reg(&vcpu->kvm->arch.vgic.irq_cfg,
> + vcpu->vcpu_id, offset);
> +
> if (offset & 2)
> val = *reg >> 16;
> else
> --
> 1.8.2.3
>
>
>
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