From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf1-f198.google.com (mail-pf1-f198.google.com [209.85.210.198]) by kanga.kvack.org (Postfix) with ESMTP id 89A866B6D91 for ; Tue, 4 Dec 2018 02:37:26 -0500 (EST) Received: by mail-pf1-f198.google.com with SMTP id i3so13366863pfj.4 for ; Mon, 03 Dec 2018 23:37:26 -0800 (PST) Received: from mga01.intel.com (mga01.intel.com. [192.55.52.88]) by mx.google.com with ESMTPS id 28si21308808pfm.50.2018.12.03.23.37.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Dec 2018 23:37:25 -0800 (PST) From: Alison Schofield Subject: [RFC v2 07/13] x86/mm: Add helpers for reference counting encrypted VMAs Date: Mon, 3 Dec 2018 23:39:54 -0800 Message-Id: In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: dhowells@redhat.com, tglx@linutronix.de Cc: jmorris@namei.org, mingo@redhat.com, hpa@zytor.com, bp@alien8.de, luto@kernel.org, peterz@infradead.org, kirill.shutemov@linux.intel.com, dave.hansen@intel.com, kai.huang@intel.com, jun.nakajima@intel.com, dan.j.williams@intel.com, jarkko.sakkinen@intel.com, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org In order to safely manage the usage of memory encryption keys, VMAs using each KeyID need to be counted. This count allows the MKTME (Multi-Key Total Memory Encryption) Key Service to know when the KeyID resource is actually in use, or when it is idle and may be considered for reuse. Define a global refcount_t array and provide helper functions to manipulate the counts. Signed-off-by: Alison Schofield Signed-off-by: Kirill A. Shutemov --- arch/x86/include/asm/mktme.h | 9 +++++++ arch/x86/mm/mktme.c | 58 ++++++++++++++++++++++++++++++++++++++++++++ include/linux/mm.h | 2 ++ 3 files changed, 69 insertions(+) diff --git a/arch/x86/include/asm/mktme.h b/arch/x86/include/asm/mktme.h index de3e529f3ab0..22d52635562c 100644 --- a/arch/x86/include/asm/mktme.h +++ b/arch/x86/include/asm/mktme.h @@ -28,6 +28,15 @@ extern int mktme_map_get_free_keyid(void); extern void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid, unsigned long start, unsigned long end); +/* Manage the MTKME encrypt_count references */ +extern int mktme_alloc_encrypt_array(void); +extern void mktme_free_encrypt_array(void); +extern int mktme_read_encrypt_ref(int keyid); +extern void vma_get_encrypt_ref(struct vm_area_struct *vma); +extern void vma_put_encrypt_ref(struct vm_area_struct *vma); +extern void key_get_encrypt_ref(int keyid); +extern void key_put_encrypt_ref(int keyid); + DECLARE_STATIC_KEY_FALSE(mktme_enabled_key); static inline bool mktme_enabled(void) { diff --git a/arch/x86/mm/mktme.c b/arch/x86/mm/mktme.c index e3fdf7b48173..facf08f9cb74 100644 --- a/arch/x86/mm/mktme.c +++ b/arch/x86/mm/mktme.c @@ -157,6 +157,64 @@ void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid, unlink_anon_vmas(vma); } +/* + * Helper functions manage the encrypt_count[] array that counts + * references on each MKTME hardware keyid. The gets & puts are + * used in core mm code that allocates and free's VMA's. The alloc, + * free, and read functions are used by the MKTME key service to + * manage key allocation and programming. + */ +refcount_t *encrypt_count; + +int mktme_alloc_encrypt_array(void) +{ + encrypt_count = kvcalloc(mktme_nr_keyids, sizeof(refcount_t), + GFP_KERNEL); + if (!encrypt_count) + return -ENOMEM; + return 0; +} + +void mktme_free_encrypt_array(void) +{ + kvfree(encrypt_count); +} + +int mktme_read_encrypt_ref(int keyid) +{ + return refcount_read(&encrypt_count[keyid]); +} + +void vma_get_encrypt_ref(struct vm_area_struct *vma) +{ + if (vma_keyid(vma)) + refcount_inc(&encrypt_count[vma_keyid(vma)]); +} + +void vma_put_encrypt_ref(struct vm_area_struct *vma) +{ + if (vma_keyid(vma)) + if (refcount_dec_and_test(&encrypt_count[vma_keyid(vma)])) { + mktme_map_lock(); + mktme_map_free_keyid(vma_keyid(vma)); + mktme_map_unlock(); + } +} + +void key_get_encrypt_ref(int keyid) +{ + refcount_inc(&encrypt_count[keyid]); +} + +void key_put_encrypt_ref(int keyid) +{ + if (refcount_dec_and_test(&encrypt_count[keyid])) { + mktme_map_lock(); + mktme_map_free_keyid(keyid); + mktme_map_unlock(); + } +} + /* Prepare page to be used for encryption. Called from page allocator. */ void __prep_encrypted_page(struct page *page, int order, int keyid, bool zero) { diff --git a/include/linux/mm.h b/include/linux/mm.h index 09182d78e7b7..453d675dd116 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2812,6 +2812,8 @@ static inline void mprotect_set_encrypt(struct vm_area_struct *vma, int newkeyid, unsigned long start, unsigned long end) {} +static inline void vma_get_encrypt_ref(struct vm_area_struct *vma) {} +static inline void vma_put_encrypt_ref(struct vm_area_struct *vma) {} #endif /* CONFIG_X86_INTEL_MKTME */ #endif /* __KERNEL__ */ #endif /* _LINUX_MM_H */ -- 2.14.1