On 29/01/16 02:31, Andy Lutomirski wrote:
> Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_ring.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
> index c169c6444637..305c05cc249a 100644
> --- a/drivers/virtio/virtio_ring.c
> +++ b/drivers/virtio/virtio_ring.c
> @@ -47,6 +47,18 @@
>
> static bool vring_use_dma_api(void)
> {
> +#if defined(CONFIG_X86) && defined(CONFIG_XEN)
> + /*
> + * In theory, it's possible to have a buggy QEMU-supposed
> + * emulated Q35 IOMMU and Xen enabled at the same time. On
> + * such a configuration, virtio has never worked and will
> + * not work without an even larger kludge. Instead, enable
> + * the DMA API if we're a Xen guest, which at least allows
> + * all of the sensible Xen configurations to work correctly.
> + */
> + return static_cpu_has(X86_FEATURE_XENPV);
You want:
if (xen_domain())
return true;
Without the #if so we use the DMA API for all types of Xen guest on all
architectures.
David
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