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Subject[PATCH v13 07/13] x86/sgx: Add data structures for tracking the EPC pages
Date
Add data structures to track Enclave Page Cache (EPC) pages.  EPC is
divided into multiple banks (1-N) of which addresses and sizes can be
enumerated with CPUID by the OS.

On NUMA systems a node can have at most bank. A bank can be at most part of
two nodes. SGX supports both nodes with a single memory controller and also
sub-cluster nodes with severals memory controllers on a single die.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Co-developed-by: Serge Ayoun <serge.ayoun@intel.com>
Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Serge Ayoun <serge.ayoun@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
arch/x86/include/asm/sgx.h | 60 ++++++++++++++++++
arch/x86/kernel/cpu/intel_sgx.c | 106 +++++++++++++++++++++++++++++++-
2 files changed, 164 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
index 2130e639ab49..17b7b3aa66bf 100644
--- a/arch/x86/include/asm/sgx.h
+++ b/arch/x86/include/asm/sgx.h
@@ -4,9 +4,69 @@
#ifndef _ASM_X86_SGX_H
#define _ASM_X86_SGX_H

+#include <linux/bitops.h>
+#include <linux/err.h>
+#include <linux/rwsem.h>
#include <linux/types.h>
+#include <asm/sgx_arch.h>
+#include <asm/asm.h>
+
+#define SGX_MAX_EPC_BANKS 8
+
+struct sgx_epc_page {
+ unsigned long desc;
+ struct list_head list;
+};
+
+struct sgx_epc_bank {
+ unsigned long pa;
+ void *va;
+ unsigned long size;
+ struct sgx_epc_page *pages_data;
+ struct sgx_epc_page **pages;
+ unsigned long free_cnt;
+ spinlock_t lock;
+};

extern bool sgx_enabled;
extern bool sgx_lc_enabled;
+extern struct sgx_epc_bank sgx_epc_banks[SGX_MAX_EPC_BANKS];
+
+/*
+ * enum sgx_epc_page_desc - defines bits and masks for an EPC page's desc
+ * @SGX_EPC_BANK_MASK: SGX allows a system to multiple EPC banks (at
+ * different physical locations). The index of a
+ * page's bank in its desc so that we can do a quick
+ * lookup of its virtual address (EPC is mapped via
+ * ioremap_cache() because it's non-standard memory).
+ * Current and near-future hardware defines at most
+ * eight banks, hence three bits to hold the bank.
+ * sgx_page_cache_init() asserts that the max bank
+ * index doesn't exceed SGX_EPC_BANK_MASK.
+ * @SGX_EPC_PAGE_RECLAIMABLE: When set, indicates a page is reclaimable. Used
+ * when freeing a page to know that we also need to
+ * remove the page from the active page list.
+ *
+ * Defines the layout of the desc field in the &struct sgx_epc_page, which
+ * contains EPC bank number, physical address of the page and the page status
+ * flag.
+ */
+enum sgx_epc_page_desc {
+ SGX_EPC_BANK_MASK = GENMASK_ULL(3, 0),
+ SGX_EPC_PAGE_RECLAIMABLE = BIT(4),
+ /* bits 12-63 are reserved for the physical page address of the page */
+};
+
+static inline struct sgx_epc_bank *sgx_epc_bank(struct sgx_epc_page *page)
+{
+ return &sgx_epc_banks[page->desc & SGX_EPC_BANK_MASK];
+}
+
+static inline void *sgx_epc_addr(struct sgx_epc_page *page)
+{
+ struct sgx_epc_bank *bank = sgx_epc_bank(page);
+
+ return (void *)(bank->va + (page->desc & PAGE_MASK) - bank->pa);
+}

#endif /* _ASM_X86_SGX_H */
diff --git a/arch/x86/kernel/cpu/intel_sgx.c b/arch/x86/kernel/cpu/intel_sgx.c
index 17b46bec9c54..53ac172e8006 100644
--- a/arch/x86/kernel/cpu/intel_sgx.c
+++ b/arch/x86/kernel/cpu/intel_sgx.c
@@ -1,23 +1,121 @@
// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
// Copyright(c) 2016-17 Intel Corporation.

-#include <asm/sgx.h>
-#include <asm/sgx_pr.h>
#include <linux/freezer.h>
#include <linux/highmem.h>
#include <linux/kthread.h>
+#include <linux/pagemap.h>
#include <linux/ratelimit.h>
#include <linux/sched/signal.h>
+#include <linux/shmem_fs.h>
#include <linux/slab.h>
+#include <asm/sgx.h>
+#include <asm/sgx_pr.h>

bool sgx_enabled __ro_after_init;
EXPORT_SYMBOL_GPL(sgx_enabled);
bool sgx_lc_enabled __ro_after_init;
EXPORT_SYMBOL_GPL(sgx_lc_enabled);
+struct sgx_epc_bank sgx_epc_banks[SGX_MAX_EPC_BANKS];
+EXPORT_SYMBOL_GPL(sgx_epc_banks);
+
+static int sgx_nr_epc_banks;
+
+static __init int sgx_init_epc_bank(u64 addr, u64 size, unsigned long index,
+ struct sgx_epc_bank *bank)
+{
+ unsigned long nr_pages = size >> PAGE_SHIFT;
+ struct sgx_epc_page *pages_data;
+ unsigned long i;
+ void *va;
+
+ va = ioremap_cache(addr, size);
+ if (!va)
+ return -ENOMEM;
+
+ pages_data = kcalloc(nr_pages, sizeof(struct sgx_epc_page), GFP_KERNEL);
+ if (!pages_data)
+ goto out_iomap;
+
+ bank->pages = kcalloc(nr_pages, sizeof(struct sgx_epc_page *),
+ GFP_KERNEL);
+ if (!bank->pages)
+ goto out_pdata;
+
+ for (i = 0; i < nr_pages; i++) {
+ bank->pages[i] = &pages_data[i];
+ bank->pages[i]->desc = (addr + (i << PAGE_SHIFT)) | index;
+ }
+
+ bank->pa = addr;
+ bank->size = size;
+ bank->va = va;
+ bank->free_cnt = nr_pages;
+ bank->pages_data = pages_data;
+ spin_lock_init(&bank->lock);
+ return 0;
+out_pdata:
+ kfree(pages_data);
+out_iomap:
+ iounmap(va);
+ return -ENOMEM;
+}
+
+static __init void sgx_page_cache_teardown(void)
+{
+ struct sgx_epc_bank *bank;
+ int i;
+
+ for (i = 0; i < sgx_nr_epc_banks; i++) {
+ bank = &sgx_epc_banks[i];
+ iounmap((void *)bank->va);
+ kfree(bank->pages);
+ kfree(bank->pages_data);
+ }
+}
+
+static inline u64 sgx_combine_bank_regs(u64 low, u64 high)
+{
+ return (low & 0xFFFFF000) + ((high & 0xFFFFF) << 32);
+}
+
+static __init int sgx_page_cache_init(void)
+{
+ u32 eax, ebx, ecx, edx;
+ u64 pa, size;
+ int ret;
+ int i;
+
+ for (i = 0; i < SGX_MAX_EPC_BANKS; i++) {
+ cpuid_count(SGX_CPUID, 2 + i, &eax, &ebx, &ecx, &edx);
+ if (!(eax & 0xF))
+ break;
+
+ pa = sgx_combine_bank_regs(eax, ebx);
+ size = sgx_combine_bank_regs(ecx, edx);
+ pr_info("EPC bank 0x%llx-0x%llx\n", pa, pa + size - 1);
+
+ ret = sgx_init_epc_bank(pa, size, i, &sgx_epc_banks[i]);
+ if (ret) {
+ sgx_page_cache_teardown();
+ return ret;
+ }
+
+ sgx_nr_epc_banks++;
+ }
+
+ if (!sgx_nr_epc_banks) {
+ pr_err("There are zero EPC banks.\n");
+ return -ENODEV;
+ }
+
+ return 0;
+}

static __init int sgx_init(void)
{
unsigned long fc;
+ int ret;

if (!boot_cpu_has(X86_FEATURE_SGX))
return false;
@@ -39,6 +137,10 @@ static __init int sgx_init(void)
if (!(fc & FEATURE_CONTROL_SGX_LE_WR))
pr_info("IA32_SGXLEPUBKEYHASHn MSRs are not writable\n");

+ ret = sgx_page_cache_init();
+ if (ret)
+ return ret;
+
sgx_enabled = true;
sgx_lc_enabled = !!(fc & FEATURE_CONTROL_SGX_LE_WR);
return 0;
--
2.17.1
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