[PATCH v2 09/10] hw/arm/smmu-common: Allow pxb-cxl as an SMMUv3 primary bus

[<mhonap@nvidia.com>]

From: Manish Honap <mhonap@nvidia.com>

The SMMUv3 primary-bus check only accepted pxb-pcie as a valid extra
root complex, so a CXL device behind a pxb-cxl could not reach the
IOMMU: attaching an arm-smmuv3 to a pxb-cxl bus failed at realize with
"SMMU should be attached to a default PCIe root complex (pcie.0) or a
pxb-pcie based root complex".

A pxb-cxl uses the same PCIe-compatible bus as a pxb-pcie, so accept it
too. A CXL Type-2 device passed through with vfio-pci sits behind a
pxb-cxl and needs SMMU translation for its DMA and ATS just like a
pxb-pcie device.

AI-used-for: code (prototype)
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
Signed-off-by: Manish Honap <mhonap@nvidia.com>
---
 hw/arm/smmu-common.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/hw/arm/smmu-common.c b/hw/arm/smmu-common.c
index 8e40ba603d..42fb098ab2 100644
--- a/hw/arm/smmu-common.c
+++ b/hw/arm/smmu-common.c
@@ -963,19 +963,20 @@ static void smmu_base_realize(DeviceState *dev, Error **errp)
         s->iommu_ops = &smmu_ops;
     }
     /*
-     * We only allow default PCIe Root Complex(pcie.0) or pxb-pcie based extra
-     * root complexes to be associated with SMMU.
+     * We only allow the default PCIe root complex (pcie.0) or pxb-pcie /
+     * pxb-cxl based extra root complexes to be associated with SMMU.
      */
     if (pci_bus_is_express(pci_bus) && pci_bus_is_root(pci_bus) &&
         object_dynamic_cast(OBJECT(pci_bus)->parent, TYPE_PCI_HOST_BRIDGE)) {
         /*
-         * This condition matches either the default pcie.0, pxb-pcie, or
-         * pxb-cxl. For both pxb-pcie and pxb-cxl, parent_dev will be set.
-         * Currently, we don't allow pxb-cxl as it requires further
-         * verification. Therefore, make sure this is indeed pxb-pcie.
+         * pcie.0 has no parent_dev; pxb-pcie and pxb-cxl do. Accept both bus
+         * types explicitly so other root complexes are still rejected. A
+         * pxb-cxl uses the same PCIe-compatible bus, so a CXL device behind it
+         * needs the SMMU just like a pxb-pcie one.
          */
         if (pci_bus->parent_dev) {
-            if (!object_dynamic_cast(OBJECT(pci_bus), TYPE_PXB_PCIE_BUS)) {
+            if (!object_dynamic_cast(OBJECT(pci_bus), TYPE_PXB_PCIE_BUS) &&
+                !object_dynamic_cast(OBJECT(pci_bus), TYPE_PXB_CXL_BUS)) {
                 goto out_err;
             }
         }
@@ -990,8 +991,8 @@ static void smmu_base_realize(DeviceState *dev, Error **errp)
         return;
     }
 out_err:
-    error_setg(errp, "SMMU should be attached to a default PCIe root complex"
-               "(pcie.0) or a pxb-pcie based root complex");
+    error_setg(errp, "SMMU should be attached to a default PCIe root complex "
+               "(pcie.0), a pxb-pcie, or a pxb-cxl based root complex");
 }
 
 /*
-- 
2.25.1