Add utilities for starting/stopping the swap kthread, and ensure that ksgxswapd_tsk is either NULL or valid. Attempt to run the swap thread if it is not running when when sgx_alloc_page wants to wake it. Return sgx_run_swap_kthread's error if both it and sgx_alloc_page_fast fail so the application sees the more critical error, e.g. -ENOMEM vs -EBUSY. Previously, sgx_pm_resume didn't check the return of kthread_run, which can fail with -ENOMEM. Upon failure, SGX applications would hang due to the lack of a kernel thread to perform EPC swapping, and the kernel would crash on the next system suspend due to passing an error pointer to kthread_stop. Signed-off-by: Sean Christopherson <sean.j.christopherson(a)intel.com&gt; --- drivers/platform/x86/intel_sgx/sgx.h | 4 +-- drivers/platform/x86/intel_sgx/sgx_main.c | 6 ++--- drivers/platform/x86/intel_sgx/sgx_page_cache.c | 34 ++++++++++++++++++++----- 3 files changed, 31 insertions(+), 13 deletions(-) diff --git a/drivers/platform/x86/intel_sgx/sgx.h b/drivers/platform/x86/intel_sgx/sgx.h index b5b21d4..b0fd1c8 100644 --- a/drivers/platform/x86/intel_sgx/sgx.h +++ b/drivers/platform/x86/intel_sgx/sgx.h @@ -215,9 +215,9 @@ void sgx_tgid_ctx_release(struct kref *ref); extern struct mutex sgx_tgid_ctx_mutex; extern struct list_head sgx_tgid_ctx_list; -extern struct task_struct *ksgxswapd_tsk; -int ksgxswapd(void *p); +int sgx_run_swap_kthread(void); +void sgx_stop_swap_kthread(void); int sgx_add_epc_bank(resource_size_t start, unsigned long size); int sgx_page_cache_init(void); void sgx_page_cache_teardown(void); diff --git a/drivers/platform/x86/intel_sgx/sgx_main.c b/drivers/platform/x86/intel_sgx/sgx_main.c index 8124d02..be012b7 100644 --- a/drivers/platform/x86/intel_sgx/sgx_main.c +++ b/drivers/platform/x86/intel_sgx/sgx_main.c @@ -163,8 +163,7 @@ static int sgx_pm_suspend(struct device *dev) struct sgx_tgid_ctx *ctx; struct sgx_encl *encl; - kthread_stop(ksgxswapd_tsk); - ksgxswapd_tsk = NULL; + sgx_stop_swap_kthread(); list_for_each_entry(ctx, &sgx_tgid_ctx_list, list) { list_for_each_entry(encl, &ctx->encl_list, encl_list) { @@ -179,8 +178,7 @@ static int sgx_pm_suspend(struct device *dev) static int sgx_pm_resume(struct device *dev) { - ksgxswapd_tsk = kthread_run(ksgxswapd, NULL, "kswapd"); - return 0; + return sgx_run_swap_kthread(); } static SIMPLE_DEV_PM_OPS(sgx_drv_pm, sgx_pm_suspend, sgx_pm_resume); diff --git a/drivers/platform/x86/intel_sgx/sgx_page_cache.c b/drivers/platform/x86/intel_sgx/sgx_page_cache.c index 356f2c2..cc4875e 100644 --- a/drivers/platform/x86/intel_sgx/sgx_page_cache.c +++ b/drivers/platform/x86/intel_sgx/sgx_page_cache.c @@ -78,7 +78,7 @@ static unsigned int sgx_nr_total_epc_pages; static unsigned int sgx_nr_free_pages; static unsigned int sgx_nr_low_pages = SGX_NR_LOW_EPC_PAGES_DEFAULT; static unsigned int sgx_nr_high_pages; -struct task_struct *ksgxswapd_tsk; +static struct task_struct *ksgxswapd_tsk; static DECLARE_WAIT_QUEUE_HEAD(ksgxswapd_waitq); @@ -368,7 +368,7 @@ static void sgx_swap_pages(unsigned long nr_to_scan) kref_put(&ctx->refcount, sgx_tgid_ctx_release); } -int ksgxswapd(void *p) +static int ksgxswapd(void *p) { while (!kthread_should_stop()) { wait_event_interruptible(ksgxswapd_waitq, @@ -383,6 +383,22 @@ int ksgxswapd(void *p) return 0; } +int sgx_run_swap_kthread(void) +{ + struct task_struct *tmp = kthread_run(ksgxswapd, NULL, "ksgxswapd"); + if (!IS_ERR(tmp)) + ksgxswapd_tsk = tmp; + return PTR_ERR_OR_ZERO(tmp); +} + +void sgx_stop_swap_kthread(void) +{ + if (ksgxswapd_tsk) { + kthread_stop(ksgxswapd_tsk); + ksgxswapd_tsk = NULL; + } +} + int sgx_add_epc_bank(resource_size_t start, unsigned long size) { unsigned long i; @@ -417,8 +433,7 @@ int sgx_add_epc_bank(resource_size_t start, unsigned long size) int sgx_page_cache_init(void) { sgx_nr_high_pages = 2 * sgx_nr_low_pages; - ksgxswapd_tsk = kthread_run(ksgxswapd, NULL, "ksgxswapd"); - return PTR_ERR_OR_ZERO(ksgxswapd_tsk); + return sgx_run_swap_kthread(); } void sgx_page_cache_teardown(void) @@ -426,8 +441,7 @@ void sgx_page_cache_teardown(void) struct sgx_epc_page *entry; struct list_head *parser, *temp; - if (ksgxswapd_tsk) - kthread_stop(ksgxswapd_tsk); + sgx_stop_swap_kthread(); spin_lock(&sgx_free_list_lock); list_for_each_safe(parser, temp, &sgx_free_list) { @@ -491,8 +505,14 @@ struct sgx_epc_page *sgx_alloc_page(unsigned int flags) schedule(); } - if (sgx_nr_free_pages < sgx_nr_low_pages) + if (sgx_nr_free_pages < sgx_nr_low_pages) { + if (!ksgxswapd_tsk) { + int ret = sgx_run_swap_kthread(); + if (ret && IS_ERR(entry)) + return ERR_PTR(ret); + } wake_up(&ksgxswapd_waitq); + } return entry; } -- 2.7.4