On 18/01/2019 14:51, Jean-Philippe Brucker wrote:
Hi Pierre,
On 18/01/2019 13:29, Pierre Morel wrote:
On 17/01/2019 14:02, Robin Murphy wrote:
On 15/01/2019 17:37, Pierre Morel wrote:
The s390 iommu can only allow DMA transactions between the zPCI device
entries start_dma and end_dma.
...
I already posted a patch retrieving the geometry through
VFIO_IOMMU_GET_INFO using a specific capability for the geometry [1],
and AFAIU, Alex did not agree with this.
On arm we also need to report the IOMMU geometry to userspace (max IOVA
size in particular). Shameer has been working on a solution [2] that
presents a unified view of both geometry and reserved regions into the
VFIO_IOMMU_GET_INFO call, and I think we should go with that. If I
understand correctly it's currently blocked on the RMRR problem and
we're waiting for Jacob or Ashok to take a look at it, as Kevin pinged
them on thread [1]?
[2] https://lkml.org/lkml/2018/4/18/293
Thanks,
Jean
Hi Jean,
I hopped that this proposition went in the same direction based on the
following assumptions:
- The goal of the get_resv_region is defined in iommu.h as:
-----
* @get_resv_regions: Request list of reserved regions for a device
-----
- A iommu reserve region is a region which should not be mapped.
Isn't it exactly what happens outside the aperture?
Shouldn't it be reported by the iommu reserved region?
- If we use VFIO and want to get all reserved region we will have the
VFIO_IOMMU_GET_INFO call provided by Shameer and it can get all reserved
regions depending from the iommu driver itself at once by calling the
get_reserved_region callback instead of having to merge them with the
aperture.
- If there are other reserved region, depending on the system
configuration and not on the IOMMU itself, the VFIO_IOMMU_GET_INFO call
will have to merge them with the region gotten from the iommu driver.
- If we do not use QEMU nor VFIO at all, AFAIU, the standard way to
retrieve the reserved regions associated with a device is to call the
get_reserved_region callback from the associated iommu.
Please tell me were I am wrong.
Regards,
Pierre
What is different in what you propose?
@Alex: I was hoping that this patch goes in your direction. What do you
think?
Thanks,
Pierre
[1]: https://lore.kernel.org/patchwork/patch/1030369/
This seems to me related with the work Shameer has started on
vfio_iommu_type1 so I add Alex and Shameer to the CC list.
Pierre Morel (1):
iommu/s390: Declare s390 iommu reserved regions
drivers/iommu/s390-iommu.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
