Re: [PATCH v4 23/33] sgx-epc: Add the reset interface for sgx-epc virt device

[Paolo Bonzini]

On 19/07/21 13:21, Yang Zhong wrote:
> +static void sgx_epc_del_subregion(DeviceState *dev)
> +{
> +    PCMachineState *pcms = PC_MACHINE(qdev_get_machine());
> +    SGXEPCState *sgx_epc = &pcms->sgx_epc;
> +    SGXEPCDevice *epc = SGX_EPC(dev);
> +
> +    /* del subregion and related operations */
> +    memory_region_del_subregion(&sgx_epc->mr,
> +                                host_memory_backend_get_memory(epc->hostmem));
> +    host_memory_backend_set_mapped(epc->hostmem, false);
> +    g_free(sgx_epc->sections);
> +    sgx_epc->sections = NULL;
> +
> +    /* multiple epc devices, only zero the first time */
> +    if (epc_num == sgx_epc->nr_sections) {
> +        sgx_epc->size = 0;
> +        sgx_epc->nr_sections = 0;
> +    }
> +}

Can it just invoke a method on the memory devices, without reusing the 
code in sgx_epc_realize?  In particular why is it necessary to update 
sgx_epc->size and sgx_epc->nr_sections?

Paolo