linux-kernel - Re: [PATCH v15 16/23] x86/sgx: Enumerate and track EPC sections

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Date:   Sat, 3 Nov 2018 01:07:27 +0000
From:   Jethro Beekman <jethro@...tanix.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>
CC:     "dave.hansen@...el.com" <dave.hansen@...el.com>,
        "sean.j.christopherson@...el.com" <sean.j.christopherson@...el.com>,
        "nhorman@...hat.com" <nhorman@...hat.com>,
        "npmccallum@...hat.com" <npmccallum@...hat.com>,
        "serge.ayoun@...el.com" <serge.ayoun@...el.com>,
        "shay.katz-zamir@...el.com" <shay.katz-zamir@...el.com>,
        "haitao.huang@...el.com" <haitao.huang@...el.com>,
        "mark.shanahan@...el.com" <mark.shanahan@...el.com>,
        "andriy.shevchenko@...ux.intel.com" 
        <andriy.shevchenko@...ux.intel.com>,
        Suresh Siddha <suresh.b.siddha@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" 
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v15 16/23] x86/sgx: Enumerate and track EPC sections

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


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