Re: [PULL 05/33] i386: Add 'sgx-epc' device to expose EPC sections to guest

[Thomas Huth]

On 28/09/2021 14.50, Paolo Bonzini wrote:
> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> SGX EPC is enumerated through CPUID, i.e. EPC "devices" need to be
> realized prior to realizing the vCPUs themselves, which occurs long
> before generic devices are parsed and realized.  Because of this,
> do not allow 'sgx-epc' devices to be instantiated after vCPUS have
> been created.
>
> The 'sgx-epc' device is essentially a placholder at this time, it will
> be fully implemented in a future patch along with a dedicated command
> to create 'sgx-epc' devices.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> Message-Id: <20210719112136.57018-5-yang.zhong@intel.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>   hw/i386/meson.build       |   1 +
>   hw/i386/sgx-epc.c         | 167 ++++++++++++++++++++++++++++++++++++++
>   include/hw/i386/sgx-epc.h |  44 ++++++++++
>   3 files changed, 212 insertions(+)
>   create mode 100644 hw/i386/sgx-epc.c
>   create mode 100644 include/hw/i386/sgx-epc.h
...
> +static void sgx_epc_class_init(ObjectClass *oc, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(oc);
> +    MemoryDeviceClass *mdc = MEMORY_DEVICE_CLASS(oc);
> +
> +    dc->hotpluggable = false;
> +    dc->realize = sgx_epc_realize;
> +    dc->unrealize = sgx_epc_unrealize;
> +    dc->desc = "SGX EPC section";
> +    device_class_set_props(dc, sgx_epc_properties);
> +
> +    mdc->get_addr = sgx_epc_md_get_addr;
> +    mdc->set_addr = sgx_epc_md_set_addr;
> +    mdc->get_plugged_size = sgx_epc_md_get_plugged_size;
> +    mdc->get_memory_region = sgx_epc_md_get_memory_region;
> +    mdc->fill_device_info = sgx_epc_md_fill_device_info;
> +}

 Hi!

Our device-crash-test script reports that this new device can be used to 
crash QEMU:

$ ./qemu-system-x86_64 -M none -device sgx-epc
/home/thuth/devel/qemu/include/hw/i386/pc.h:128:PC_MACHINE: Object 
0x55c80d332290 is not an instance of type generic-pc-machine

Should it be marked with:

    dc->user_creatable = false

?

  Thomas