[PATCH 2/8] x86-iommu: Introduce x86_iommu_device_get() for x86-iommu retrieval

[Sairaj Kodilkar <sarunkod@amd.com>]

kvm_arch_fixup_msi_route() and kvm_arch_add_msi_route_post() use
x86_iommu_get_default() whenever an IOMMU is present. This selects the
correct unit only when a single IOMMU is attached to the system bus.

The following patches allow an IOMMU to attach to a different bus and
isolate the subset of devices below it. Each IOMMU then serves only part
of the PCI topology, so interrupt remapping must determine the IOMMU that
actually serves a given device.

Add x86_iommu_device_get() to locate the IOMMU bus for a PCI device and
retrieve its X86IOMMUState through a new get_x86_iommu callback.

Signed-off-by: Sairaj Kodilkar <sarunkod@amd.com>
---
 hw/i386/x86-iommu-stub.c    |  5 +++++
 hw/i386/x86-iommu.c         | 16 ++++++++++++++++
 include/hw/i386/x86-iommu.h |  6 ++++++
 include/hw/pci/pci.h        | 12 ++++++++++++
 4 files changed, 39 insertions(+)

diff --git a/hw/i386/x86-iommu-stub.c b/hw/i386/x86-iommu-stub.c
index 781b5ff92227..b0383d2290b1 100644
--- a/hw/i386/x86-iommu-stub.c
+++ b/hw/i386/x86-iommu-stub.c
@@ -32,6 +32,11 @@ X86IOMMUState *x86_iommu_get_default(void)
     return NULL;
 }
 
+X86IOMMUState *x86_iommu_device_get(PCIDevice *dev)
+{
+    return NULL;
+}
+
 bool x86_iommu_ir_supported(X86IOMMUState *s)
 {
     return false;
diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c
index a57445404ef8..601db5cfea09 100644
--- a/hw/i386/x86-iommu.c
+++ b/hw/i386/x86-iommu.c
@@ -26,6 +26,7 @@
 #include "qemu/error-report.h"
 #include "trace.h"
 #include "system/kvm.h"
+#include "hw/pci/pci_bus.h"
 
 void x86_iommu_iec_register_notifier(X86IOMMUState *iommu,
                                      iec_notify_fn fn, void *data)
@@ -90,6 +91,21 @@ X86IOMMUState *x86_iommu_get_default(void)
     return NULL;
 }
 
+X86IOMMUState *x86_iommu_device_get(PCIDevice *dev)
+{
+    PCIBus *iommu_bus;
+    X86IOMMUState *iommu = NULL;
+
+    pci_device_get_iommu_bus_devfn(dev, &iommu_bus, NULL, NULL);
+
+    if (iommu_bus && iommu_bus->iommu_ops->get_x86_iommu) {
+        iommu_bus->iommu_ops->get_x86_iommu(iommu_bus->iommu_opaque,
+                                            (void **)&iommu);
+    }
+
+    return iommu;
+}
+
 static void x86_iommu_realize(DeviceState *dev, Error **errp)
 {
     X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(dev);
diff --git a/include/hw/i386/x86-iommu.h b/include/hw/i386/x86-iommu.h
index 0a1e1ba72571..eb575271e9d7 100644
--- a/include/hw/i386/x86-iommu.h
+++ b/include/hw/i386/x86-iommu.h
@@ -134,6 +134,12 @@ struct X86IOMMU_MSIMessage {
  */
 X86IOMMUState *x86_iommu_get_default(void);
 
+/**
+ * x86_iommu_device_get - get IOMMU device for given PCI device
+ * @return: pointer to default IOMMU device
+ */
+X86IOMMUState *x86_iommu_device_get(PCIDevice *dev);
+
 /**
  * x86_iommu_iec_register_notifier - register IEC (Interrupt Entry
  *                                   Cache) notifiers
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index f2448e941a0b..f3c4c3a4db56 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -698,6 +698,18 @@ typedef struct PCIIOMMUOps {
      * Returns: the guest physical address of the MSI doorbell.
      */
     uint64_t (*get_msi_direct_gpa)(PCIBus *bus, void *opaque, int devfn);
+
+    /**
+     * @get_x86_iommu: get parent x86-iommu for given hardware (AMD/Intel)
+     *
+     * Callback is required if IOMMU defines x86->int_remap()
+     *
+     * @opaque: the data passed to pci_setup_iommu()
+     *
+     * @x86_iommu: A pointer to store the x86-iommu object
+     */
+    int (*get_x86_iommu)(void *opaque, void **x86_iommu);
+
 } PCIIOMMUOps;
 
 bool pci_device_get_iommu_bus_devfn(PCIDevice *dev, PCIBus **piommu_bus,
-- 
2.34.1