lkml.org 
[lkml]   [2018]   [Aug]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v13 10/13] x86/sgx: Add sgx_einit() for initializing enclaves
Date
From: Sean Christopherson <sean.j.christopherson@intel.com>

Add a function to perform ENCLS(EINIT), which initializes an enclave,
which can be used by a driver for running enclaves and VMMs.

Writing the LE hash MSRs is extraordinarily expensive, e.g. 3-4x slower
than normal MSRs, so we use a per-cpu cache to track the last known value
of the MSRs to avoid unnecessarily writing the MSRs with the current value.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
arch/x86/include/asm/sgx.h | 2 +
arch/x86/kernel/cpu/intel_sgx.c | 86 +++++++++++++++++++++++++++++++--
2 files changed, 85 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
index baf30d49b71f..c15c156436be 100644
--- a/arch/x86/include/asm/sgx.h
+++ b/arch/x86/include/asm/sgx.h
@@ -108,6 +108,8 @@ void sgx_free_page(struct sgx_epc_page *page);
void sgx_page_reclaimable(struct sgx_epc_page *page);
struct page *sgx_get_backing(struct file *file, pgoff_t index);
void sgx_put_backing(struct page *backing_page, bool write);
+int sgx_einit(struct sgx_sigstruct *sigstruct, struct sgx_einittoken *token,
+ struct sgx_epc_page *secs_page, u64 lepubkeyhash[4]);

#define ENCLS_FAULT_FLAG 0x40000000UL
#define ENCLS_FAULT_FLAG_ASM "$0x40000000"
diff --git a/arch/x86/kernel/cpu/intel_sgx.c b/arch/x86/kernel/cpu/intel_sgx.c
index 1046478a3ab9..fe25e6805680 100644
--- a/arch/x86/kernel/cpu/intel_sgx.c
+++ b/arch/x86/kernel/cpu/intel_sgx.c
@@ -9,6 +9,7 @@
#include <linux/sched/signal.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
+#include <linux/suspend.h>
#include <asm/sgx.h>
#include <asm/sgx_pr.h>

@@ -38,6 +39,18 @@ static LIST_HEAD(sgx_active_page_list);
static DEFINE_SPINLOCK(sgx_active_page_list_lock);
static struct task_struct *ksgxswapd_tsk;
static DECLARE_WAIT_QUEUE_HEAD(ksgxswapd_waitq);
+static struct notifier_block sgx_pm_notifier;
+static u64 sgx_pm_cnt;
+
+/* The cache for the last known values of IA32_SGXLEPUBKEYHASHx MSRs for each
+ * CPU. The entries are initialized when they are first used by sgx_einit().
+ */
+struct sgx_lepubkeyhash {
+ u64 msrs[4];
+ u64 pm_cnt;
+};
+
+static DEFINE_PER_CPU(struct sgx_lepubkeyhash *, sgx_lepubkeyhash_cache);

/**
* sgx_reclaim_pages - reclaim EPC pages from the consumers
@@ -328,6 +341,54 @@ void sgx_put_backing(struct page *backing_page, bool write)
}
EXPORT_SYMBOL_GPL(sgx_put_backing);

+/**
+ * sgx_einit - initialize an enclave
+ * @sigstruct: a pointer to the SIGSTRUCT
+ * @token: a pointer to the EINITTOKEN
+ * @secs_page: a pointer to the SECS EPC page
+ * @lepubkeyhash: the desired value for IA32_SGXLEPUBKEYHASHx MSRs
+ *
+ * Try to perform EINIT operation. If the MSRs are writable, they are updated
+ * according to @lepubkeyhash.
+ *
+ * Return:
+ * 0 on success,
+ * -errno on failure
+ * SGX error code if EINIT fails
+ */
+int sgx_einit(struct sgx_sigstruct *sigstruct, struct sgx_einittoken *token,
+ struct sgx_epc_page *secs_page, u64 lepubkeyhash[4])
+{
+ struct sgx_lepubkeyhash __percpu *cache;
+ bool cache_valid;
+ int i, ret;
+
+ if (!sgx_lc_enabled)
+ return __einit(sigstruct, token, sgx_epc_addr(secs_page));
+
+ cache = per_cpu(sgx_lepubkeyhash_cache, smp_processor_id());
+ if (!cache) {
+ cache = kzalloc(sizeof(struct sgx_lepubkeyhash), GFP_KERNEL);
+ if (!cache)
+ return -ENOMEM;
+ }
+
+ cache_valid = cache->pm_cnt == sgx_pm_cnt;
+ cache->pm_cnt = sgx_pm_cnt;
+ preempt_disable();
+ for (i = 0; i < 4; i++) {
+ if (cache_valid && lepubkeyhash[i] == cache->msrs[i])
+ continue;
+
+ wrmsrl(MSR_IA32_SGXLEPUBKEYHASH0 + i, lepubkeyhash[i]);
+ cache->msrs[i] = lepubkeyhash[i];
+ }
+ ret = __einit(sigstruct, token, sgx_epc_addr(secs_page));
+ preempt_enable();
+ return ret;
+}
+EXPORT_SYMBOL(sgx_einit);
+
static __init int sgx_init_epc_bank(u64 addr, u64 size, unsigned long index,
struct sgx_epc_bank *bank)
{
@@ -426,6 +487,15 @@ static __init int sgx_page_cache_init(void)
return 0;
}

+static int sgx_pm_notifier_cb(struct notifier_block *nb, unsigned long action,
+ void *data)
+{
+ if (action == PM_SUSPEND_PREPARE || action == PM_HIBERNATION_PREPARE)
+ sgx_pm_cnt++;
+
+ return NOTIFY_DONE;
+}
+
static __init int sgx_init(void)
{
struct task_struct *tsk;
@@ -452,20 +522,30 @@ 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();
+ sgx_pm_notifier.notifier_call = sgx_pm_notifier_cb;
+ ret = register_pm_notifier(&sgx_pm_notifier);
if (ret)
return ret;

+ ret = sgx_page_cache_init();
+ if (ret)
+ goto out_pm;
+
tsk = kthread_run(ksgxswapd, NULL, "ksgxswapd");
if (IS_ERR(tsk)) {
- sgx_page_cache_teardown();
- return PTR_ERR(tsk);
+ ret = PTR_ERR(tsk);
+ goto out_pcache;
}
ksgxswapd_tsk = tsk;

sgx_enabled = true;
sgx_lc_enabled = !!(fc & FEATURE_CONTROL_SGX_LE_WR);
return 0;
+out_pcache:
+ sgx_page_cache_teardown();
+out_pm:
+ unregister_pm_notifier(&sgx_pm_notifier);
+ return ret;
}

arch_initcall(sgx_init);
--
2.17.1
\
 
 \ /
  Last update: 2018-08-27 20:58    [W:0.346 / U:2.656 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site