Re: [PATCH v3 05/19] backends/host_iommu_device: Introduce HostIOMMUDeviceCaps

[Cédric Le Goater]

On 4/30/24 11:55, Duan, Zhenzhong wrote:

-----Original Message-----
From: Cédric Le Goater <c...@redhat.com>
Subject: Re: [PATCH v3 05/19] backends/host_iommu_device: Introduce
HostIOMMUDeviceCaps

On 4/29/24 08:50, 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 .check_cap() handler to check if

HOST_IOMMU_DEVICE_CAP_XXX

is supported.

Introduce a HostIOMMUDevice API host_iommu_device_check_cap()

which

is a wrapper of .check_cap().

Introduce a HostIOMMUDevice API

host_iommu_device_check_cap_common()

to check common capabalities of different host platform IOMMUs.

Suggested-by: Cédric Le Goater <c...@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
   include/sysemu/host_iommu_device.h | 44

++++++++++++++++++++++++++++++

   backends/host_iommu_device.c       | 29 ++++++++++++++++++++
   2 files changed, 73 insertions(+)

diff --git a/include/sysemu/host_iommu_device.h

b/include/sysemu/host_iommu_device.h

index 2b58a94d62..12b6afb463 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 +62,34 @@ struct HostIOMMUDeviceClass {
        * Returns: true on success, false on failure.
        */
       bool (*realize)(HostIOMMUDevice *hiod, void *opaque, Error **errp);
+    /**
+     * @check_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 (*check_cap)(HostIOMMUDevice *hiod, int cap, Error **errp);
   };
+
+/*
+ * Host IOMMU device capability list.
+ */
+#define HOST_IOMMU_DEVICE_CAP_IOMMUFD       0
+#define HOST_IOMMU_DEVICE_CAP_IOMMU_TYPE    1
+#define HOST_IOMMU_DEVICE_CAP_AW_BITS       2
+
+
+int host_iommu_device_check_cap(HostIOMMUDevice *hiod, int cap,

Error **errp);

+int host_iommu_device_check_cap_common(HostIOMMUDevice *hiod,

int cap,

+                                       Error **errp);
   #endif
diff --git a/backends/host_iommu_device.c

b/backends/host_iommu_device.c

index 41f2fdce20..b97d008cc7 100644
--- a/backends/host_iommu_device.c
+++ b/backends/host_iommu_device.c
@@ -28,3 +28,32 @@ static void host_iommu_device_init(Object *obj)
   static void host_iommu_device_finalize(Object *obj)
   {
   }
+
+/* Wrapper of HostIOMMUDeviceClass:check_cap */
+int host_iommu_device_check_cap(HostIOMMUDevice *hiod, int cap,

Error **errp)

Since we have an 'Error **errp', we could return a bool instead,
unless this is a 'get_cap' routine ?

Maybe better to name it host_iommu_device_get_cap()?
Because not all results are bool, some are integer, i.e., aw_bits.

LGTM.


Thanks,

C.