[PATCH v4 05/19] backends/host_iommu_device: Introduce HostIOMMUDeviceCaps

[Zhenzhong Duan]

HostIOMMUDeviceCaps's elements map to the host IOMMU's capabilities.
Different platform IOMMU can support different elements.

Currently only two elements, type and aw_bits, type hints the host
platform IOMMU type, i.e., INTEL vtd, ARM smmu, etc; aw_bits hints
host IOMMU address width.

Introduce .get_cap() handler to check if HOST_IOMMU_DEVICE_CAP_XXX
is supported.

Introduce a HostIOMMUDevice API host_iommu_device_get_cap() which
is a wrapper of .get_cap().

Suggested-by: Cédric Le Goater <c...@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 include/sysemu/host_iommu_device.h | 41 ++++++++++++++++++++++++++++++
 backends/host_iommu_device.c       | 12 +++++++++
 2 files changed, 53 insertions(+)

diff --git a/include/sysemu/host_iommu_device.h 
b/include/sysemu/host_iommu_device.h
index 2b58a94d62..680c2a311a 100644
--- a/include/sysemu/host_iommu_device.h
+++ b/include/sysemu/host_iommu_device.h
@@ -14,12 +14,27 @@
 
 #include "qom/object.h"
 #include "qapi/error.h"
+#include <linux/iommufd.h>
+
+/**
+ * struct HostIOMMUDeviceCaps - Define host IOMMU device capabilities.
+ *
+ * @type: host platform IOMMU type.
+ *
+ * @aw_bits: host IOMMU address width. 0xff if no limitation.
+ */
+typedef struct HostIOMMUDeviceCaps {
+    enum iommu_hw_info_type type;
+    uint8_t aw_bits;
+} HostIOMMUDeviceCaps;
 
 #define TYPE_HOST_IOMMU_DEVICE "host-iommu-device"
 OBJECT_DECLARE_TYPE(HostIOMMUDevice, HostIOMMUDeviceClass, HOST_IOMMU_DEVICE)
 
 struct HostIOMMUDevice {
     Object parent_obj;
+
+    HostIOMMUDeviceCaps caps;
 };
 
 /**
@@ -47,5 +62,31 @@ struct HostIOMMUDeviceClass {
      * Returns: true on success, false on failure.
      */
     bool (*realize)(HostIOMMUDevice *hiod, void *opaque, Error **errp);
+    /**
+     * @get_cap: check if a host IOMMU device capability is supported.
+     *
+     * Optional callback, if not implemented, hint not supporting query
+     * of @cap.
+     *
+     * @hiod: pointer to a host IOMMU device instance.
+     *
+     * @cap: capability to check.
+     *
+     * @errp: pass an Error out when fails to query capability.
+     *
+     * Returns: <0 on failure, 0 if a @cap is unsupported, or else
+     * 1 or some positive value for some special @cap,
+     * i.e., HOST_IOMMU_DEVICE_CAP_AW_BITS.
+     */
+    int (*get_cap)(HostIOMMUDevice *hiod, int cap, Error **errp);
 };
+
+/*
+ * Host IOMMU device capability list.
+ */
+#define HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE    0
+#define HOST_IOMMU_DEVICE_CAP_AW_BITS       1
+
+
+int host_iommu_device_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp);
 #endif
diff --git a/backends/host_iommu_device.c b/backends/host_iommu_device.c
index 41f2fdce20..0fcc201af3 100644
--- a/backends/host_iommu_device.c
+++ b/backends/host_iommu_device.c
@@ -28,3 +28,15 @@ static void host_iommu_device_init(Object *obj)
 static void host_iommu_device_finalize(Object *obj)
 {
 }
+
+/* Wrapper of HostIOMMUDeviceClass:get_cap */
+int host_iommu_device_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp)
+{
+    HostIOMMUDeviceClass *hiodc = HOST_IOMMU_DEVICE_GET_CLASS(hiod);
+    if (!hiodc->get_cap) {
+        error_setg(errp, ".get_cap() not implemented");
+        return -EINVAL;
+    }
+
+    return hiodc->get_cap(hiod, cap, errp);
+}
-- 
2.34.1