On 17/01/2019 10:23, Shameerali Kolothum Thodi wrote:
Hi Pierre,
-----Original Message-----
From: Pierre Morel [mailto:pmorel@xxxxxxxxxxxxx]
Sent: 15 January 2019 17:37
To: gerald.schaefer@xxxxxxxxxx
Cc: joro@xxxxxxxxxx; linux-s390@xxxxxxxxxxxxxxx;
iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
alex.williamson@xxxxxxxxxx; Shameerali Kolothum Thodi
<shameerali.kolothum.thodi@xxxxxxxxxx>; walling@xxxxxxxxxxxxx
Subject: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions
The s390 iommu can only allow DMA transactions between the zPCI device
entries start_dma and end_dma.
Let's declare the regions before start_dma and after end_dma as
reserved regions using the appropriate callback in iommu_ops.
The reserved region may later be retrieved from sysfs or from
the vfio iommu internal interface.
Just in case you are planning to use the sysfs interface to retrieve the valid
regions, and intend to use that in Qemu vfio path, please see the discussion
here [1] (If you haven't seen this already)
Thanks,
Shameer
[1] https://lists.gnu.org/archive/html/qemu-devel/2017-11/msg03651.html
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(+)
--
2.7.4
Thanks Shameer,
Interesting discussion indeed.
AFAIK the patch series you are working on will provide a way to retrieve
the reserved region through the VFIO IOMMU interface, using capabilities
in the VFIO_IOMMU_GET_INFO.
Before this patch, the iommu_type1 was not able to retrieve the
forbidden region from the s390_iommu.
See this patch is a contribution, so that these regions will appear in
the reserved list when the VFIO_IOMM_GET_INFO will be able to report the
information.
I am expecting to be able to to retrieve this information from the
VFIO_IOMMU_GET_INFO syscall as soon as it is available.
Regards,
Pierre
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
