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[PULL 14/23] hw/pci/pci_host: Allow PCI host to bypass iommu


From: Michael S. Tsirkin
Subject: [PULL 14/23] hw/pci/pci_host: Allow PCI host to bypass iommu
Date: Tue, 13 Jul 2021 18:10:48 -0400

From: Xingang Wang <wangxingang5@huawei.com>

Add a new bypass_iommu property for PCI host and use it to check
whether devices attached to the PCI root bus will bypass iommu.
In pci_device_iommu_address_space(), check the property and
avoid getting iommu address space for devices bypass iommu.

Signed-off-by: Xingang Wang <wangxingang5@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <1625748919-52456-2-git-send-email-wangxingang5@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/pci/pci.h      |  1 +
 include/hw/pci/pci_host.h |  1 +
 hw/pci/pci.c              | 18 +++++++++++++++++-
 hw/pci/pci_host.c         |  1 +
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 6be4e0c460..f4d51b672b 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -480,6 +480,7 @@ void pci_for_each_bus(PCIBus *bus,
 
 PCIBus *pci_device_root_bus(const PCIDevice *d);
 const char *pci_root_bus_path(PCIDevice *dev);
+bool pci_bus_bypass_iommu(PCIBus *bus);
 PCIDevice *pci_find_device(PCIBus *bus, int bus_num, uint8_t devfn);
 int pci_qdev_find_device(const char *id, PCIDevice **pdev);
 void pci_bus_get_w64_range(PCIBus *bus, Range *range);
diff --git a/include/hw/pci/pci_host.h b/include/hw/pci/pci_host.h
index 52e038c019..c6f4eb4585 100644
--- a/include/hw/pci/pci_host.h
+++ b/include/hw/pci/pci_host.h
@@ -43,6 +43,7 @@ struct PCIHostState {
     uint32_t config_reg;
     bool mig_enabled;
     PCIBus *bus;
+    bool bypass_iommu;
 
     QLIST_ENTRY(PCIHostState) next;
 };
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 377084f1a8..27d588e268 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -416,6 +416,22 @@ const char *pci_root_bus_path(PCIDevice *dev)
     return rootbus->qbus.name;
 }
 
+bool pci_bus_bypass_iommu(PCIBus *bus)
+{
+    PCIBus *rootbus = bus;
+    PCIHostState *host_bridge;
+
+    if (!pci_bus_is_root(bus)) {
+        rootbus = pci_device_root_bus(bus->parent_dev);
+    }
+
+    host_bridge = PCI_HOST_BRIDGE(rootbus->qbus.parent);
+
+    assert(host_bridge->bus == rootbus);
+
+    return host_bridge->bypass_iommu;
+}
+
 static void pci_root_bus_init(PCIBus *bus, DeviceState *parent,
                               MemoryRegion *address_space_mem,
                               MemoryRegion *address_space_io,
@@ -2718,7 +2734,7 @@ AddressSpace *pci_device_iommu_address_space(PCIDevice 
*dev)
 
         iommu_bus = parent_bus;
     }
-    if (iommu_bus && iommu_bus->iommu_fn) {
+    if (!pci_bus_bypass_iommu(bus) && iommu_bus && iommu_bus->iommu_fn) {
         return iommu_bus->iommu_fn(bus, iommu_bus->iommu_opaque, devfn);
     }
     return &address_space_memory;
diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
index 8ca5fadcbd..cf02f0d6a5 100644
--- a/hw/pci/pci_host.c
+++ b/hw/pci/pci_host.c
@@ -222,6 +222,7 @@ const VMStateDescription vmstate_pcihost = {
 static Property pci_host_properties_common[] = {
     DEFINE_PROP_BOOL("x-config-reg-migration-enabled", PCIHostState,
                      mig_enabled, true),
+    DEFINE_PROP_BOOL("bypass-iommu", PCIHostState, bypass_iommu, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
-- 
MST




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