[v5,12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC

Message ID	20230923030657.16148-13-haitao.huang@linux.intel.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-sgx-owner@vger.kernel.org> From: Haitao Huang <haitao.huang@linux.intel.com> To: jarkko@kernel.org, dave.hansen@linux.intel.com, tj@kernel.org, linux-kernel@vger.kernel.org, linux-sgx@vger.kernel.org, x86@kernel.org, cgroups@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, sohil.mehta@intel.com Cc: zhiquan1.li@intel.com, kristen@linux.intel.com, seanjc@google.com, zhanb@microsoft.com, anakrish@microsoft.com, mikko.ylinen@linux.intel.com, yangjie@microsoft.com Subject: [PATCH v5 12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC Date: Fri, 22 Sep 2023 20:06:51 -0700 Message-Id: <20230923030657.16148-13-haitao.huang@linux.intel.com> In-Reply-To: <20230923030657.16148-1-haitao.huang@linux.intel.com> References: <20230923030657.16148-1-haitao.huang@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	Add Cgroup support for SGX EPC memory \| expand [v5,00/18] Add Cgroup support for SGX EPC memory [v5,01/18] cgroup/misc: Add per resource callbacks for CSS events [v5,02/18] cgroup/misc: Add SGX EPC resource type and export APIs for SGX driver [v5,03/18] x86/sgx: Add sgx_epc_lru_lists to encapsulate LRU lists [v5,04/18] x86/sgx: Use sgx_epc_lru_lists for existing active page list [v5,05/18] x86/sgx: Store reclaimable EPC pages in sgx_epc_lru_lists [v5,06/18] x86/sgx: Introduce EPC page states [v5,07/18] x86/sgx: Introduce RECLAIM_IN_PROGRESS state [v5,08/18] x86/sgx: Use a list to track to-be-reclaimed pages [v5,09/18] x86/sgx: Store struct sgx_encl when allocating new VA pages [v5,10/18] x86/sgx: Add EPC page flags to identify owner types [v5,11/18] x86/sgx: store unreclaimable pages in LRU lists [v5,12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC [v5,13/18] x86/sgx: Expose sgx_reclaim_pages() for use by EPC cgroup [v5,14/18] x86/sgx: Add helper to grab pages from an arbitrary EPC LRU [v5,15/18] x86/sgx: Prepare for multiple LRUs [v5,16/18] x86/sgx: Limit process EPC usage with misc cgroup controller [v5,17/18] Docs/x86/sgx: Add description for cgroup support [v5,18/18] selftests/sgx: Add scripts for EPC cgroup testing

diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c index 262f5fb18d74..ff42d649c7b6 100644 --- a/arch/x86/kernel/cpu/sgx/driver.c +++ b/arch/x86/kernel/cpu/sgx/driver.c @@ -44,7 +44,6 @@ static int sgx_open(struct inode *inode, struct file *file) static int sgx_release(struct inode *inode, struct file *file) { struct sgx_encl *encl = file->private_data; - struct sgx_encl_mm *encl_mm; /* * Drain the remaining mm_list entries. At this point the list contains @@ -52,31 +51,7 @@ static int sgx_release(struct inode *inode, struct file *file) * not exited yet. The processes, which have exited, are gone from the * list by sgx_mmu_notifier_release(). */ - for ( ; ; ) { - spin_lock(&encl->mm_lock); - - if (list_empty(&encl->mm_list)) { - encl_mm = NULL; - } else { - encl_mm = list_first_entry(&encl->mm_list, - struct sgx_encl_mm, list); - list_del_rcu(&encl_mm->list); - } - - spin_unlock(&encl->mm_lock); - - /* The enclave is no longer mapped by any mm. */ - if (!encl_mm) - break; - - synchronize_srcu(&encl->srcu); - mmu_notifier_unregister(&encl_mm->mmu_notifier, encl_mm->mm); - kfree(encl_mm); - - /* 'encl_mm' is gone, put encl_mm->encl reference: */ - kref_put(&encl->refcount, sgx_encl_release); - } - + sgx_encl_mm_drain(encl); kref_put(&encl->refcount, sgx_encl_release); return 0; } diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index a8617e6a4b4e..3c91a705e720 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -451,6 +451,9 @@ static vm_fault_t sgx_vma_fault(struct vm_fault *vmf) if (unlikely(!encl)) return VM_FAULT_SIGBUS; + if (test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) + return VM_FAULT_SIGBUS; + /* * The page_array keeps track of all enclave pages, whether they * are swapped out or not. If there is no entry for this page and @@ -649,7 +652,8 @@ static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr, if (!encl) return -EFAULT; - if (!test_bit(SGX_ENCL_DEBUG, &encl->flags)) + if (!test_bit(SGX_ENCL_DEBUG, &encl->flags) || + test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) return -EFAULT; for (i = 0; i < len; i += cnt) { @@ -774,6 +778,45 @@ void sgx_encl_release(struct kref *ref) kfree(encl); } +/** + * sgx_encl_mm_drain - drain all mm_list entries + * @encl: address of the sgx_encl to drain + * + * Used during oom kill to empty the mm_list entries after they have been + * zapped. Or used by sgx_release to drain the remaining mm_list entries when + * the enclave fd is closing. After this call, sgx_encl_release will be called + * with kref_put. + */ +void sgx_encl_mm_drain(struct sgx_encl *encl) +{ + struct sgx_encl_mm *encl_mm; + + for ( ; ; ) { + spin_lock(&encl->mm_lock); + + if (list_empty(&encl->mm_list)) { + encl_mm = NULL; + } else { + encl_mm = list_first_entry(&encl->mm_list, + struct sgx_encl_mm, list); + list_del_rcu(&encl_mm->list); + } + + spin_unlock(&encl->mm_lock); + + /* The enclave is no longer mapped by any mm. */ + if (!encl_mm) + break; + + synchronize_srcu(&encl->srcu); + mmu_notifier_unregister(&encl_mm->mmu_notifier, encl_mm->mm); + kfree(encl_mm); + + /* 'encl_mm' is gone, put encl_mm->encl reference: */ + kref_put(&encl->refcount, sgx_encl_release); + } +} + /* * 'mm' is exiting and no longer needs mmu notifications. */ @@ -845,6 +888,9 @@ int sgx_encl_mm_add(struct sgx_encl *encl, struct mm_struct *mm) struct sgx_encl_mm *encl_mm; int ret; + if (test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) + return -ENOMEM; + /* * Even though a single enclave may be mapped into an mm more than once, * each 'mm' only appears once on encl->mm_list. This is guaranteed by diff --git a/arch/x86/kernel/cpu/sgx/encl.h b/arch/x86/kernel/cpu/sgx/encl.h index 831d63f80f5a..cdb57ecb05c8 100644 --- a/arch/x86/kernel/cpu/sgx/encl.h +++ b/arch/x86/kernel/cpu/sgx/encl.h @@ -39,6 +39,7 @@ enum sgx_encl_flags { SGX_ENCL_DEBUG = BIT(1), SGX_ENCL_CREATED = BIT(2), SGX_ENCL_INITIALIZED = BIT(3), + SGX_ENCL_NO_MEMORY = BIT(4), }; struct sgx_encl_mm { @@ -125,5 +126,6 @@ struct sgx_encl_page *sgx_encl_load_page(struct sgx_encl *encl, unsigned long addr); struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim); void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page); +void sgx_encl_mm_drain(struct sgx_encl *encl); #endif /* _X86_ENCL_H */ diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 50ddd8988452..e1209e2cf6a3 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -420,6 +420,9 @@ static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg) test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) return -EINVAL; + if (test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) + return -ENOMEM; + if (copy_from_user(&add_arg, arg, sizeof(add_arg))) return -EFAULT; @@ -605,6 +608,9 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) return -EINVAL; + if (test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) + return -ENOMEM; + if (copy_from_user(&init_arg, arg, sizeof(init_arg))) return -EFAULT; @@ -681,6 +687,9 @@ static int sgx_ioc_sgx2_ready(struct sgx_encl *encl) if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags)) return -EINVAL; + if (test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) + return -ENOMEM; + return 0; } diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index f3a3ed894616..3b875ab4dcd0 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -621,6 +621,146 @@ void sgx_free_epc_page(struct sgx_epc_page *page) atomic_long_inc(&sgx_nr_free_pages); } +static bool sgx_oom_get_ref(struct sgx_epc_page *epc_page) +{ + struct sgx_encl *encl; + + if (epc_page->flags & SGX_EPC_OWNER_PAGE) + encl = epc_page->encl_page->encl; + else if (epc_page->flags & SGX_EPC_OWNER_ENCL) + encl = epc_page->encl; + else + return false; + + return kref_get_unless_zero(&encl->refcount); +} + +static struct sgx_epc_page *sgx_oom_get_victim(struct sgx_epc_lru_lists *lru) +{ + struct sgx_epc_page *epc_page, *tmp; + + if (list_empty(&lru->unreclaimable)) + return NULL; + + list_for_each_entry_safe(epc_page, tmp, &lru->unreclaimable, list) { + list_del_init(&epc_page->list); + + if (sgx_oom_get_ref(epc_page)) + return epc_page; + } + return NULL; +} + +static void sgx_epc_oom_zap(void *owner, struct mm_struct *mm, unsigned long start, + unsigned long end, const struct vm_operations_struct *ops) +{ + VMA_ITERATOR(vmi, mm, start); + struct vm_area_struct *vma; + + /** + * Use end because start can be zero and not mapped into + * enclave even if encl->base = 0. + */ + for_each_vma_range(vmi, vma, end) { + if (vma->vm_ops == ops && vma->vm_private_data == owner && + vma->vm_start < end) { + zap_vma_pages(vma); + } + } +} + +static bool sgx_oom_encl(struct sgx_encl *encl) +{ + unsigned long mm_list_version; + struct sgx_encl_mm *encl_mm; + bool ret = false; + int idx; + + if (!test_bit(SGX_ENCL_CREATED, &encl->flags)) + goto out_put; + + /* Done OOM on this enclave previously, do not redo it. + * This may happen when the SECS page is still UNRECLAIMABLE because + * another page is in RECLAIM_IN_PROGRESS. Still return true so OOM + * killer can wait until the reclaimer done with the hold-up page and + * SECS before it move on to find another victim. + */ + if (test_bit(SGX_ENCL_NO_MEMORY, &encl->flags)) + goto out; + + set_bit(SGX_ENCL_NO_MEMORY, &encl->flags); + + do { + mm_list_version = encl->mm_list_version; + + /* Pairs with smp_rmb() in sgx_encl_mm_add(). */ + smp_rmb(); + + idx = srcu_read_lock(&encl->srcu); + + list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) { + if (!mmget_not_zero(encl_mm->mm)) + continue; + + mmap_read_lock(encl_mm->mm); + + sgx_epc_oom_zap(encl, encl_mm->mm, encl->base, + encl->base + encl->size, &sgx_vm_ops); + + mmap_read_unlock(encl_mm->mm); + + mmput_async(encl_mm->mm); + } + + srcu_read_unlock(&encl->srcu, idx); + } while (WARN_ON_ONCE(encl->mm_list_version != mm_list_version)); + + sgx_encl_mm_drain(encl); +out: + ret = true; + +out_put: + /* + * This puts the refcount we took when we identified this enclave as + * an OOM victim. + */ + kref_put(&encl->refcount, sgx_encl_release); + return ret; +} + +static inline bool sgx_oom_encl_page(struct sgx_encl_page *encl_page) +{ + return sgx_oom_encl(encl_page->encl); +} + +/** + * sgx_epc_oom() - invoke EPC out-of-memory handling on target LRU + * @lru: LRU that is low + * + * Return: %true if a victim was found and kicked. + */ +bool sgx_epc_oom(struct sgx_epc_lru_lists *lru) +{ + struct sgx_epc_page *victim; + + spin_lock(&lru->lock); + victim = sgx_oom_get_victim(lru); + spin_unlock(&lru->lock); + + if (!victim) + return false; + + if (victim->flags & SGX_EPC_OWNER_PAGE) + return sgx_oom_encl_page(victim->encl_page); + + if (victim->flags & SGX_EPC_OWNER_ENCL) + return sgx_oom_encl(victim->encl); + + /*Will never happen unless we add more owner types in future */ + WARN_ON_ONCE(1); + return false; +} + static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size, unsigned long index, struct sgx_epc_section *section) diff --git a/arch/x86/kernel/cpu/sgx/sgx.h b/arch/x86/kernel/cpu/sgx/sgx.h index 337747bef7c2..6c0bfdc209c0 100644 --- a/arch/x86/kernel/cpu/sgx/sgx.h +++ b/arch/x86/kernel/cpu/sgx/sgx.h @@ -178,6 +178,7 @@ void sgx_reclaim_direct(void); void sgx_record_epc_page(struct sgx_epc_page *page, unsigned long flags); int sgx_drop_epc_page(struct sgx_epc_page *page); struct sgx_epc_page *sgx_alloc_epc_page(void *owner, bool reclaim); +bool sgx_epc_oom(struct sgx_epc_lru_lists *lrus); void sgx_ipi_cb(void *info);

[v5,12/18] x86/sgx: Add EPC OOM path to forcefully reclaim EPC

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