On Wed, Jul 19, 2017 at 4:27 PM, Robin Murphy <robin.murphy@xxxxxxx> wrote: > On 19/07/17 10:33, Anup Patel wrote: >> This patchset primarily adds Broadcom FlexRM reset module for >> VFIO platform driver. We also have minor improvments in IOMMU >> and VFIO driver to allow VFIO no-IOMMU mode access to FlexRM. > > I'm struggling to understand the IOMMU changes here - what's the > FlexRM's hardware relationship with the IOMMU, and how is it different > from any other device? Furthermore, if there *is* a relevant IOMMU > present, why would no-IOMMU mode need to be involved at all? We want to have FlexRM device accessible from user-space using VFIO platform with and without IOMMU. Currently, if IOMMU ops are available for platform bus then I cannot access FlexRM device using VFIO no-IOMMU mode. Since, SMMU can bypass transactions which do not match any SMRs, we should allow no-IOMMU mode for devices when IOMMU group is not available. Regards, Anup
