Re: [PATCH v6 05/19] backends/host_iommu_device: Introduce HostIOMMUDeviceCaps

[Cédric Le Goater]

On 6/3/24 08:10, Zhenzhong Duan wrote:

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.

Suggested-by: Cédric Le Goater <c...@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
  include/sysemu/host_iommu_device.h | 37 ++++++++++++++++++++++++++++++
  1 file changed, 37 insertions(+)

diff --git a/include/sysemu/host_iommu_device.h 
b/include/sysemu/host_iommu_device.h
index 2b58a94d62..d47d1034b1 100644
--- a/include/sysemu/host_iommu_device.h
+++ b/include/sysemu/host_iommu_device.h
@@ -15,11 +15,25 @@
  #include "qom/object.h"
  #include "qapi/error.h"

+/**

+ * struct HostIOMMUDeviceCaps - Define host IOMMU device capabilities.
+ *
+ * @type: host platform IOMMU type.
+ *
+ * @aw_bits: host IOMMU address width. 0xff if no limitation.

Could we introduce a define for the special value 0xff ? This would answer
Eric's question.


Thanks,

C.

+ */
+typedef struct HostIOMMUDeviceCaps {
+    uint32_t 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 +61,28 @@ 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
  #endif