On 2018-11-02 16:11, Jarkko Sakkinen wrote:
> diff --git a/arch/x86/kernel/cpu/intel_sgx.c b/arch/x86/kernel/cpu/intel_sgx.c
> new file mode 100644
> index 000000000000..b86aa4111592
> --- /dev/null
> +++ b/arch/x86/kernel/cpu/intel_sgx.c
> 
> ...
> 
> +static __init int sgx_page_cache_init(void)
> +{
> +	u32 eax, ebx, ecx, edx, type;
> +	u64 pa, size;
> +	int ret;
> +	int i;
> +
> +	BUILD_BUG_ON(SGX_MAX_EPC_SECTIONS > (SGX_EPC_SECTION_MASK + 1));
> +
> +	for (i = 0; i < SGX_MAX_EPC_SECTIONS; i++) {

Perhaps print a warning if there are more than SGX_MAX_EPC_SECTIONS 
sections reported by CPUID.

> +		cpuid_count(SGX_CPUID, i + SGX_CPUID_FIRST_VARIABLE_SUB_LEAF,
> +			    &eax, &ebx, &ecx, &edx);
> +
> +		type = eax & SGX_CPUID_SUB_LEAF_TYPE_MASK;
> +		if (type == SGX_CPUID_SUB_LEAF_INVALID)
> +			break;
> +		if (type != SGX_CPUID_SUB_LEAF_EPC_SECTION) {
> +			pr_err_once("sgx: Unknown sub-leaf type: %u\n", type);
> +			continue;
> +		}
> +
> +		pa = sgx_calc_section_metric(eax, ebx);
> +		size = sgx_calc_section_metric(ecx, edx);
> +		pr_info("sgx: EPC section 0x%llx-0x%llx\n", pa, pa + size - 1);
> +
> +		ret = sgx_init_epc_section(pa, size, i, &sgx_epc_sections[i]);
> +		if (ret) {
> +			sgx_page_cache_teardown();
> +			return ret;
> +		}
> +
> +		sgx_nr_epc_sections++;
> +	}
> +
> +	if (!sgx_nr_epc_sections) {
> +		pr_err("sgx: There are zero EPC sections.\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}

--
Jethro Beekman | Fortanix