x86/sgx: Initialize metadata for Enclave Page Cache (EPC) sections (e7e05452) · Commits · EulixOS / Software / Kernel

arch/x86/Kconfig

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		@@ -1930,6 +1930,23 @@ config X86_INTEL_TSX_MODE_AUTO
		side channel attacks- equals the tsx=auto command line parameter.
		endchoice

		config X86_SGX
		bool "Software Guard eXtensions (SGX)"
		depends on X86_64 && CPU_SUP_INTEL
		depends on CRYPTO=y
		depends on CRYPTO_SHA256=y
		select SRCU
		select MMU_NOTIFIER
		help
		Intel(R) Software Guard eXtensions (SGX) is a set of CPU instructions
		that can be used by applications to set aside private regions of code
		and data, referred to as enclaves. An enclave's private memory can
		only be accessed by code running within the enclave. Accesses from
		outside the enclave, including other enclaves, are disallowed by
		hardware.

		If unsure, say N.

		config EFI
		bool "EFI runtime service support"
		depends on ACPI

arch/x86/kernel/cpu/Makefile

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		@@ -48,6 +48,7 @@ obj-$(CONFIG_X86_MCE) += mce/
		obj-$(CONFIG_MTRR) += mtrr/
		obj-$(CONFIG_MICROCODE) += microcode/
		obj-$(CONFIG_X86_CPU_RESCTRL) += resctrl/
		obj-$(CONFIG_X86_SGX) += sgx/

		obj-$(CONFIG_X86_LOCAL_APIC) += perfctr-watchdog.o

arch/x86/kernel/cpu/sgx/Makefile

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		obj-y += \
		main.o

arch/x86/kernel/cpu/sgx/main.c

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		// SPDX-License-Identifier: GPL-2.0
		/* Copyright(c) 2016-20 Intel Corporation. */

		#include <linux/freezer.h>
		#include <linux/highmem.h>
		#include <linux/kthread.h>
		#include <linux/pagemap.h>
		#include <linux/ratelimit.h>
		#include <linux/sched/mm.h>
		#include <linux/sched/signal.h>
		#include <linux/slab.h>
		#include "encls.h"

		struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
		static int sgx_nr_epc_sections;
		static struct task_struct *ksgxd_tsk;

		/*
		* Reset dirty EPC pages to uninitialized state. Laundry can be left with SECS
		* pages whose child pages blocked EREMOVE.
		*/
		static void sgx_sanitize_section(struct sgx_epc_section *section)
		{
		struct sgx_epc_page *page;
		LIST_HEAD(dirty);
		int ret;

		while (!list_empty(&section->laundry_list)) {
		if (kthread_should_stop())
		return;

		spin_lock(&section->lock);

		page = list_first_entry(&section->laundry_list,
		struct sgx_epc_page, list);

		ret = __eremove(sgx_get_epc_virt_addr(page));
		if (!ret)
		list_move(&page->list, &section->page_list);
		else
		list_move_tail(&page->list, &dirty);

		spin_unlock(&section->lock);

		cond_resched();
		}

		list_splice(&dirty, &section->laundry_list);
		}

		static int ksgxd(void *p)
		{
		int i;

		set_freezable();

		/*
		* Sanitize pages in order to recover from kexec(). The 2nd pass is
		* required for SECS pages, whose child pages blocked EREMOVE.
		*/
		for (i = 0; i < sgx_nr_epc_sections; i++)
		sgx_sanitize_section(&sgx_epc_sections[i]);

		for (i = 0; i < sgx_nr_epc_sections; i++) {
		sgx_sanitize_section(&sgx_epc_sections[i]);

		/* Should never happen. */
		if (!list_empty(&sgx_epc_sections[i].laundry_list))
		WARN(1, "EPC section %d has unsanitized pages.\n", i);
		}

		return 0;
		}

		static bool __init sgx_page_reclaimer_init(void)
		{
		struct task_struct *tsk;

		tsk = kthread_run(ksgxd, NULL, "ksgxd");
		if (IS_ERR(tsk))
		return false;

		ksgxd_tsk = tsk;

		return true;
		}

		static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
		unsigned long index,
		struct sgx_epc_section *section)
		{
		unsigned long nr_pages = size >> PAGE_SHIFT;
		unsigned long i;

		section->virt_addr = memremap(phys_addr, size, MEMREMAP_WB);
		if (!section->virt_addr)
		return false;

		section->pages = vmalloc(nr_pages * sizeof(struct sgx_epc_page));
		if (!section->pages) {
		memunmap(section->virt_addr);
		return false;
		}

		section->phys_addr = phys_addr;
		spin_lock_init(&section->lock);
		INIT_LIST_HEAD(&section->page_list);
		INIT_LIST_HEAD(&section->laundry_list);

		for (i = 0; i < nr_pages; i++) {
		section->pages[i].section = index;
		list_add_tail(&section->pages[i].list, &section->laundry_list);
		}

		return true;
		}

		/**
		* A section metric is concatenated in a way that @low bits 12-31 define the
		* bits 12-31 of the metric and @high bits 0-19 define the bits 32-51 of the
		* metric.
		*/
		static inline u64 __init sgx_calc_section_metric(u64 low, u64 high)
		{
		return (low & GENMASK_ULL(31, 12)) +
		((high & GENMASK_ULL(19, 0)) << 32);
		}

		static bool __init sgx_page_cache_init(void)
		{
		u32 eax, ebx, ecx, edx, type;
		u64 pa, size;
		int i;

		for (i = 0; i < ARRAY_SIZE(sgx_epc_sections); i++) {
		cpuid_count(SGX_CPUID, i + SGX_CPUID_EPC, &eax, &ebx, &ecx, &edx);

		type = eax & SGX_CPUID_EPC_MASK;
		if (type == SGX_CPUID_EPC_INVALID)
		break;

		if (type != SGX_CPUID_EPC_SECTION) {
		pr_err_once("Unknown EPC section type: %u\n", type);
		break;
		}

		pa = sgx_calc_section_metric(eax, ebx);
		size = sgx_calc_section_metric(ecx, edx);

		pr_info("EPC section 0x%llx-0x%llx\n", pa, pa + size - 1);

		if (!sgx_setup_epc_section(pa, size, i, &sgx_epc_sections[i])) {
		pr_err("No free memory for an EPC section\n");
		break;
		}

		sgx_nr_epc_sections++;
		}

		if (!sgx_nr_epc_sections) {
		pr_err("There are zero EPC sections.\n");
		return false;
		}

		return true;
		}

		static void __init sgx_init(void)
		{
		int i;

		if (!boot_cpu_has(X86_FEATURE_SGX))
		return;

		if (!sgx_page_cache_init())
		return;

		if (!sgx_page_reclaimer_init())
		goto err_page_cache;

		return;

		err_page_cache:
		for (i = 0; i < sgx_nr_epc_sections; i++) {
		vfree(sgx_epc_sections[i].pages);
		memunmap(sgx_epc_sections[i].virt_addr);
		}
		}

		device_initcall(sgx_init);

arch/x86/kernel/cpu/sgx/sgx.h

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		/* SPDX-License-Identifier: GPL-2.0 */
		#ifndef _X86_SGX_H
		#define _X86_SGX_H

		#include <linux/bitops.h>
		#include <linux/err.h>
		#include <linux/io.h>
		#include <linux/rwsem.h>
		#include <linux/types.h>
		#include <asm/asm.h>
		#include "arch.h"

		#undef pr_fmt
		#define pr_fmt(fmt) "sgx: " fmt

		#define SGX_MAX_EPC_SECTIONS 8

		struct sgx_epc_page {
		unsigned int section;
		struct list_head list;
		};

		/*
		* The firmware can define multiple chunks of EPC to the different areas of the
		* physical memory e.g. for memory areas of the each node. This structure is
		* used to store EPC pages for one EPC section and virtual memory area where
		* the pages have been mapped.
		*/
		struct sgx_epc_section {
		unsigned long phys_addr;
		void *virt_addr;
		struct list_head page_list;
		struct list_head laundry_list;
		struct sgx_epc_page *pages;
		spinlock_t lock;
		};

		extern struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];

		static inline unsigned long sgx_get_epc_phys_addr(struct sgx_epc_page *page)
		{
		struct sgx_epc_section *section = &sgx_epc_sections[page->section];
		unsigned long index;

		index = ((unsigned long)page - (unsigned long)section->pages) / sizeof(*page);

		return section->phys_addr + index * PAGE_SIZE;
		}

		static inline void sgx_get_epc_virt_addr(struct sgx_epc_page page)
		{
		struct sgx_epc_section *section = &sgx_epc_sections[page->section];
		unsigned long index;

		index = ((unsigned long)page - (unsigned long)section->pages) / sizeof(*page);

		return section->virt_addr + index * PAGE_SIZE;
		}

		#endif /* _X86_SGX_H */