[PATCH v3 03/15] hw/pci: Add a pci_device_iommu_memory_region() helper

[Joao Martins <joao.m.martins@oracle.com>]

Today's VFIO model of understanding if an IOMMU is behind the PCIDevice
is to check whether the address space backing the device is memory or
not, which is done via pci_device_iommu_address_space(pdev).

On the other hand, the IOMMU MR is used for example to fetch attributes,
or when doing an vIOMMU map and figuring out if it's under the vIOMMU.
However, such object is only available today by the time the IOMMU map
notifier is called which depends on the guest doing a DMA map or not.
Thus there's no way to get access to the IOMMU memory region early i.e.
at vfio device initialization where we attest migration support and
impose LM blockers or not.

Much like pci_device_iommu_address_space() fetches the IOMMU AS, add a
pci_device_iommu_memory_region() which lets it return an the IOMMU MR
associated with it. The IOMMU MR is returned correctly for vIOMMUs using
pci_setup_iommu_info(). Note that today most vIOMMUs create the address
space and IOMMU MR at the same time, it's just mainly that there's API
to make the latter available.

This is in preparation for VFIO to track both the AS and IOMMU MR into
VFIOSpace without being tied to a map taking place by the guest. The
IOMMU MR will then provide access to upper layers about various IOMMU
attributes.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 include/hw/pci/pci.h | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index d2c87d87a24e..0177f50e96a3 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -365,13 +365,14 @@ void pci_device_deassert_intx(PCIDevice *dev);
 
 typedef struct PCIAddressSpace {
     AddressSpace *as;
+    IOMMUMemoryRegion *iommu_mr;
 } PCIAddressSpace;
 
 typedef AddressSpace *(*PCIIOMMUFunc)(PCIBus *, void *, int);
 typedef PCIAddressSpace (*PCIIOMMUASFunc)(PCIBus *, void *, int);
 static inline PCIAddressSpace as_to_pci_as(AddressSpace *as)
 {
-    PCIAddressSpace ret = { .as = as };
+    PCIAddressSpace ret = { .as = as, .iommu_mr = NULL };
 
     return ret;
 }
@@ -379,6 +380,13 @@ static inline AddressSpace *pci_as_to_as(PCIAddressSpace pci_as)
 {
     return pci_as.as;
 }
+static inline PCIAddressSpace to_pci_as(AddressSpace *as,
+                                        IOMMUMemoryRegion *iommu_mr)
+{
+    PCIAddressSpace ret = { .as = as, .iommu_mr = iommu_mr };
+
+    return ret;
+}
 
 PCIAddressSpace pci_device_iommu_info(PCIDevice *dev);
 static inline AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
@@ -386,6 +394,13 @@ static inline AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
     return pci_as_to_as(pci_device_iommu_info(dev));
 }
 
+static inline IOMMUMemoryRegion *pci_device_iommu_memory_region(PCIDevice *dev)
+{
+    PCIAddressSpace ret = pci_device_iommu_info(dev);
+
+    return ret.iommu_mr;
+}
+
 void pci_setup_iommu(PCIBus *bus, PCIIOMMUFunc fn, void *opaque);
 void pci_setup_iommu_info(PCIBus *bus, PCIIOMMUASFunc fn, void *opaque);
 
-- 
2.39.3