[PATCH v2 08/19] intel_iommu: Fail passthrough device under PCI bridge if x-flts=on

[Zhenzhong Duan]

Currently we don't support nested translation for passthrough device
with emulated device under same PCI bridge.

Reason is for emulated devices, AS should switch to iommu MR, while for
passthrough devices, it needs the AS stick with the system MR hence be
able to keep the VFIO container IOAS as a GPA IOAS. To support this, let
AS switch to iommu MR and have a separate GPA IOAS is needed, but that
brings a new memory listener which duplicates with VFIO memory listener.

For trade off, we choose to not support this special scenario because
PCIE bridge is more popular than PCI bridge now.

Suggested-by: Yi Liu <yi.l....@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 hw/i386/intel_iommu.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
index 1c79efc1cb..9d4adc9458 100644
--- a/hw/i386/intel_iommu.c
+++ b/hw/i386/intel_iommu.c
@@ -4330,9 +4330,10 @@ VTDAddressSpace *vtd_find_add_as(IntelIOMMUState *s, 
PCIBus *bus,
     return vtd_dev_as;
 }
 
-static bool vtd_check_hiod(IntelIOMMUState *s, HostIOMMUDevice *hiod,
+static bool vtd_check_hiod(IntelIOMMUState *s, VTDHostIOMMUDevice *vtd_hiod,
                            Error **errp)
 {
+    HostIOMMUDevice *hiod = vtd_hiod->hiod;
     HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
     int ret;
 
@@ -4359,6 +4360,8 @@ static bool vtd_check_hiod(IntelIOMMUState *s, 
HostIOMMUDevice *hiod,
 #ifdef CONFIG_IOMMUFD
     struct HostIOMMUDeviceCaps *caps = &hiod->caps;
     struct iommu_hw_info_vtd *vtd = &caps->vendor_caps.vtd;
+    PCIBus *bus = vtd_hiod->bus;
+    PCIDevice *pdev = pci_find_device(bus, pci_bus_num(bus), vtd_hiod->devfn);
 
     /* Remaining checks are all stage-1 translation specific */
     if (!object_dynamic_cast(OBJECT(hiod), TYPE_HOST_IOMMU_DEVICE_IOMMUFD)) {
@@ -4381,6 +4384,12 @@ static bool vtd_check_hiod(IntelIOMMUState *s, 
HostIOMMUDevice *hiod,
         error_setg(errp, "Stage-1 1GB huge page is unsupported by host IOMMU");
         return false;
     }
+
+    if (pci_device_get_iommu_bus_devfn(pdev, &bus, NULL, NULL)) {
+        error_setg(errp, "Host device under PCI bridge is unsupported "
+                   "when x-flts=on");
+        return false;
+    }
 #endif
 
     error_setg(errp, "host device is uncompatible with stage-1 translation");
@@ -4414,7 +4423,7 @@ static bool vtd_dev_set_iommu_device(PCIBus *bus, void 
*opaque, int devfn,
     vtd_hiod->iommu_state = s;
     vtd_hiod->hiod = hiod;
 
-    if (!vtd_check_hiod(s, hiod, errp)) {
+    if (!vtd_check_hiod(s, vtd_hiod, errp)) {
         g_free(vtd_hiod);
         vtd_iommu_unlock(s);
         return false;
-- 
2.34.1