virt inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I401IF
CVE: NA

------------------------------

Up to now, when the type was UNMANAGED, we used to
allocate IOVA pages within a reserved IOVA MSI range.

If both the host and the guest are exposed with SMMUs, each
would allocate an IOVA. The guest allocates an IOVA (gIOVA)
to map onto the guest MSI doorbell (gDB). The Host allocates
another IOVA (hIOVA) to map onto the physical doorbell (hDB).

So we end up with 2 unrelated mappings, at S1 and S2:
         S1             S2
gIOVA    ->     gDB
               hIOVA    ->    hDB

The PCI device would be programmed with hIOVA.
No stage 1 mapping would existing, causing the MSIs to fault.

iommu_dma_bind_guest_msi() allows to pass gIOVA/gDB
to the host so that gIOVA can be used by the host instead of
re-allocating a new hIOVA.

         S1           S2
gIOVA    ->    gDB    ->    hDB

this time, the PCI device can be programmed with the gIOVA MSI
doorbell which is correctly mapped through both stages.

Nested mode is not compatible with HW MSI regions as in that
case gDB and hDB should have a 1-1 mapping. This check will
be done when attaching each device to the IOMMU domain.
Signed-off-by: NEric Auger <eric.auger@redhat.com>
Signed-off-by: Kunkun Jiang<jiangkunkun@huawei.com>
Reviewed-by: NKeqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>