Re: [RFC PATCH 2/2] hw/i386/sgx: Attach SGX-EPC to its memory backend

[Yang Zhong <yang.zhong@intel.com>]

On Mon, Jan 17, 2022 at 12:48:10PM +0100, Paolo Bonzini wrote:
> On 1/17/22 00:53, Philippe Mathieu-Daudé via wrote:
> >We have one SGX-EPC address/size/node per memory backend,
> >make it child of the backend in the QOM composition tree.
> >
> >Cc: Yang Zhong <yang.zhong@intel.com>
> >Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> >---
> >  hw/i386/sgx.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> >diff --git a/hw/i386/sgx.c b/hw/i386/sgx.c
> >index 5de5dd08936..6362e5e9d02 100644
> >--- a/hw/i386/sgx.c
> >+++ b/hw/i386/sgx.c
> >@@ -300,6 +300,9 @@ void pc_machine_init_sgx_epc(PCMachineState *pcms)
> >          /* set the memdev link with memory backend */
> >          object_property_parse(obj, SGX_EPC_MEMDEV_PROP, list->value->memdev,
> >                                &error_fatal);
> >+        object_property_add_child(OBJECT(list->value->memdev), "sgx-epc",
> >+                                  OBJECT(obj));
> >+
> >          /* set the numa node property for sgx epc object */
> >          object_property_set_uint(obj, SGX_EPC_NUMA_NODE_PROP, list->value->node,
> >                               &error_fatal);
> 
> I don't think this is a good idea; only list->value->memdev should
> add something below itself in the tree.
> 
> However, I think obj can be added under the machine itself as
> /machine/sgx-epc-device[*].
> 

  Philippe, Sorry I can't receive all Qemu mails from my mutt tool.

  https://lists.nongnu.org/archive/html/qemu-devel/2022-01/msg03535.html
  I verified this patch, and the issue was reported as below:

  Unexpected error in object_property_try_add() at ../qom/object.c:1224:
  qemu-system-x86_64: attempt to add duplicate property 'sgx-epc' to object (type 'pc-q35-7.0-machine')
  Aborted (core dumped)

  Even I changed it to another name, which still reported same kind of issue.

  I tried below patch as my previous patch, and it can work
  diff --git a/hw/i386/sgx.c b/hw/i386/sgx.c
  index d60485fc422..66444745b47 100644
  --- a/hw/i386/sgx.c
  +++ b/hw/i386/sgx.c
  @@ -281,6 +281,7 @@ void pc_machine_init_sgx_epc(PCMachineState *pcms)
       SGXEPCState *sgx_epc = &pcms->sgx_epc;
       X86MachineState *x86ms = X86_MACHINE(pcms);
       SgxEPCList *list = NULL;
  +    int sgx_count = 0;
       Object *obj;

       memset(sgx_epc, 0, sizeof(SGXEPCState));
  @@ -297,7 +298,9 @@ void pc_machine_init_sgx_epc(PCMachineState *pcms)
       for (list = x86ms->sgx_epc_list; list; list = list->next) {
           obj = object_new("sgx-epc");

  -        object_property_add_child(OBJECT(pcms), "sgx-epc", OBJECT(obj));
  +        gchar *name = g_strdup_printf("device[%d]", sgx_count++);
  +        object_property_add_child(container_get(qdev_get_machine(), "/sgx-epc-device"),
  +                                      name, obj);
  
           /* set the memdev link with memory backend */
           object_property_parse(obj, SGX_EPC_MEMDEV_PROP, list->value->memdev,


  From the monitor, 
  (qemu) qom-list /machine/sgx-epc-device
  type (string)
  device[0] (child<sgx-epc>)
  device[1] (child<sgx-epc>)
  
  This can normally show two sgx epc section devices.
  
  If you have new patch, I can help verify, thanks!

  Yang

> Paolo