[RFC v7 09/25] hw/pci: introduce pci_device_set/unset_iommu_context()

[Liu Yi L <yi.l.liu@xxxxxxxxx>]

For nesting IOMMU translation capable platforms, vIOMMUs running on
such system could be implemented upon physical IOMMU nested paging
(VFIO case). vIOMMU advertises such implementation by "want_nested"
attribute to PCIe devices (e.g. VFIO PCI). Once "want_nested" is
satisfied, device (VFIO case) should set HostIOMMUContext to vIOMMU,
thus vIOMMU could manage stage-1 translation. DMAs out from such
devices would be protected through the stage-1 page tables owned by
guest together with stage-2 page tables owned by host.

This patch adds pci_device_set/unset_iommu_context() to set/unset
HostIOMMUContext for a given PCIe device (VFIO case). Caller of set
should fail if set operation failed.

Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Eric Auger <eric.auger@xxxxxxxxxx>
Cc: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx>
Cc: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
---
rfcv5 (v2) -> rfcv6:
*) pci_device_set_iommu_context() returns 0 if callback is not implemented.
---
 hw/pci/pci.c         | 28 ++++++++++++++++++++++++++++
 include/hw/pci/pci.h | 10 ++++++++++
 2 files changed, 38 insertions(+)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 3c27805..59864c6 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2743,6 +2743,34 @@ int pci_device_get_iommu_attr(PCIDevice *dev, IOMMUAttr attr, void *data)
     return -ENOENT;
 }
 
+int pci_device_set_iommu_context(PCIDevice *dev,
+                                 HostIOMMUContext *iommu_ctx)
+{
+    PCIBus *bus;
+    uint8_t devfn;
+
+    pci_device_get_iommu_bus_devfn(dev, &bus, &devfn);
+    if (bus && bus->iommu_ops &&
+        bus->iommu_ops->set_iommu_context) {
+        return bus->iommu_ops->set_iommu_context(bus,
+                              bus->iommu_opaque, devfn, iommu_ctx);
+    }
+    return 0;
+}
+
+void pci_device_unset_iommu_context(PCIDevice *dev)
+{
+    PCIBus *bus;
+    uint8_t devfn;
+
+    pci_device_get_iommu_bus_devfn(dev, &bus, &devfn);
+    if (bus && bus->iommu_ops &&
+        bus->iommu_ops->unset_iommu_context) {
+        bus->iommu_ops->unset_iommu_context(bus,
+                                 bus->iommu_opaque, devfn);
+    }
+}
+
 void pci_setup_iommu(PCIBus *bus, const PCIIOMMUOps *ops, void *opaque)
 {
     bus->iommu_ops = ops;
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index f74161b..0647d64 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -9,6 +9,8 @@
 
 #include "hw/pci/pcie.h"
 
+#include "hw/iommu/host_iommu_context.h"
+
 extern bool pci_available;
 
 /* PCI bus */
@@ -495,10 +497,18 @@ struct PCIIOMMUOps {
                                 void *opaque, int32_t devfn);
     int (*get_iommu_attr)(PCIBus *bus, void *opaque, int32_t devfn,
                            IOMMUAttr attr, void *data);
+    int (*set_iommu_context)(PCIBus *bus, void *opaque,
+                             int32_t devfn,
+                             HostIOMMUContext *iommu_ctx);
+    void (*unset_iommu_context)(PCIBus *bus, void *opaque,
+                                int32_t devfn);
 };
 
 AddressSpace *pci_device_iommu_address_space(PCIDevice *dev);
 int pci_device_get_iommu_attr(PCIDevice *dev, IOMMUAttr attr, void *data);
+int pci_device_set_iommu_context(PCIDevice *dev,
+                                 HostIOMMUContext *iommu_ctx);
+void pci_device_unset_iommu_context(PCIDevice *dev);
 void pci_setup_iommu(PCIBus *bus, const PCIIOMMUOps *iommu_ops, void *opaque);
 
 static inline void
-- 
2.7.4