[PATCH v2 1/4] iommu: Disambiguate MSI region types

Joerg Roedel joro at 8bytes.org
Wed Mar 22 08:16:42 PDT 2017

On Thu, Mar 16, 2017 at 05:00:16PM +0000, Robin Murphy wrote:
> The introduction of reserved regions has left a couple of rough edges
> which we could do with sorting out sooner rather than later. Since we
> are not yet addressing the potential dynamic aspect of software-managed
> reservations and presenting them at arbitrary fixed addresses, it is
> incongruous that we end up displaying hardware vs. software-managed MSI
> regions to userspace differently, especially since ARM-based systems may
> actually require one or the other, or even potentially both at once,
> (which iommu-dma currently has no hope of dealing with at all). Let's
> resolve the former user-visible inconsistency ASAP before the ABI has
> been baked into a kernel release, in a way that also lays the groundwork
> for the latter shortcoming to be addressed by follow-up patches.
> For clarity, rename the software-managed type to IOMMU_RESV_SW_MSI, use
> IOMMU_RESV_MSI to describe the hardware type, and document everything a
> little bit. Since the x86 MSI remapping hardware falls squarely under
> this meaning of IOMMU_RESV_MSI, apply that type to their regions as well,
> so that we tell the same story to userspace across all platforms.
> Secondly, as the various region types require quite different handling,
> and it really makes little sense to ever try combining them, convert the
> bitfield-esque #defines to a plain enum in the process before anyone
> gets the wrong impression.
> Fixes: d30ddcaa7b02 ("iommu: Add a new type field in iommu_resv_region")
> Reviewed-by: Eric Auger <eric.auger at redhat.com>
> CC: Alex Williamson <alex.williamson at redhat.com>
> CC: David Woodhouse <dwmw2 at infradead.org>
> CC: kvm at vger.kernel.org
> Signed-off-by: Robin Murphy <robin.murphy at arm.com>

Applied this one to iommu/fixes.

More information about the linux-arm-kernel mailing list