On Mon, Sep 22, 2014 at 10:12:30PM +0100, Christoffer Dall wrote:
> We were using an atomic bitop on the vgic_v2.vgic_elrsr field which was
> not aligned to the natural size on 64-bit platforms. This bug showed up
> after QEMU correctly identifies the pl011 line as being level-triggered,
> and not edge-triggered.
>
> These data structures are protected by a spinlock so simply use a
> non-atomic version of the accessor instead.
>
> Tested-by: Joel Schopp <joel.schopp@xxxxxxx>
> Reported-by: Riku Voipio <riku.voipio@xxxxxxxxxx>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> ---
> virt/kvm/arm/vgic-v2.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c
> index 01124ef..416baed 100644
> --- a/virt/kvm/arm/vgic-v2.c
> +++ b/virt/kvm/arm/vgic-v2.c
> @@ -71,7 +71,7 @@ static void vgic_v2_sync_lr_elrsr(struct kvm_vcpu *vcpu, int lr,
> struct vgic_lr lr_desc)
> {
> if (!(lr_desc.state & LR_STATE_MASK))
> - set_bit(lr, (unsigned long *)vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr);
> + __set_bit(lr, (unsigned long *)vcpu->arch.vgic_cpu.vgic_v2.vgic_elrsr);
> }
Does this work for big-endian arm64 machines? Surely the bug is due to
casting a u32 * to an unsigned long *, and not specifically related to
atomics (which is where it happened to explode)?
Will
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