On 19/07/17 10:33, Anup Patel wrote:
> Some of the IOMMUs (such as ARM SMMU) are capable of bypassing
> transactions for which no IOMMU domain is configured.
>
> This patch adds IOMMU_CAP_BYPASS which can be used by IOMMU
> drivers to advertise transation bypass capability of an IOMMU.
Whatever the intended semantics of this are, I can't help thinking it
would be better served by allowing callers to explicitly allocate their
own IOMMU_DOMAIN_IDENTITY domains. That would also be useful for the
problem we have with legacy virtio devices behind real IOMMUs.
Robin.
> Signed-off-by: Anup Patel <anup.patel@xxxxxxxxxxxx>
> ---
> include/linux/iommu.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 2cb54ad..6bbb4cc 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -101,6 +101,10 @@ enum iommu_cap {
> transactions */
> IOMMU_CAP_INTR_REMAP, /* IOMMU supports interrupt isolation */
> IOMMU_CAP_NOEXEC, /* IOMMU_NOEXEC flag */
> + IOMMU_CAP_BYPASS, /*
> + * IOMMU can bypass transactions for
> + * which domain is not configured
> + */
> };
>
> /*
>
