From patchwork Fri Mar 11 00:15:47 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: thermal-bot for Julien Panis X-Patchwork-Id: 550752 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB3F4C433EF for ; Fri, 11 Mar 2022 00:15:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344882AbiCKAQ4 (ORCPT ); Thu, 10 Mar 2022 19:16:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238512AbiCKAQz (ORCPT ); Thu, 10 Mar 2022 19:16:55 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0EDAAB44E; Thu, 10 Mar 2022 16:15:53 -0800 (PST) Date: Fri, 11 Mar 2022 00:15:47 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1646957749; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yt3MkfBwVR8zjm6WcsY98Muh80Kn70Hk+yeL0BKwiYA=; b=e4K6j03iGP91fXsy3bOvYKrUe12hzhw/9oAb1Ereto6MLLKwlXfMMhoeqxB5X7E2hLY2i8 bakmTl7ZJcFUypvhmSDrCdxENe4GTzXNe4RZp7MRabq6uBesdl1eB5ESProx6SzHTSU9Tl el0nhvtvf/Qp0uTt7Mm+z2wtDbkkTRR/9iwQEcTSViB2K6nsvwQS3jQIPX42dHs84tihGK pp0D4W6A0ZlVYXQkncXBkaQj8tBsE7YpcpRVWqmHBq9WHFW+toCFJFmd3OMChouC8IXuHw x/EC46OqfWoJPcFgoy4s3v/P2EKKLZ7SFlC528Tq5tOeZjxCxrMjmfqlFkEUuA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1646957749; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=yt3MkfBwVR8zjm6WcsY98Muh80Kn70Hk+yeL0BKwiYA=; b=+UpFYVAxgUBIrhbEjkm9etTDLnwDnNPfynQ03jhhGlFWrs9f0Gyj/ZzQ5pnJzIN3V5LA/r bKjb4GV0qJPGfGAg== From: "tip-bot2 for Jarkko Sakkinen" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/sgx] x86/sgx: Free backing memory after faulting the enclave page Cc: stable@vger.kernel.org, Dave Hansen , Jarkko Sakkinen , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20220303223859.273187-1-jarkko@kernel.org> References: <20220303223859.273187-1-jarkko@kernel.org> MIME-Version: 1.0 Message-ID: <164695774789.16921.7875752361736095667.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The following commit has been merged into the x86/sgx branch of tip: Commit-ID: ed83935a9af088439462ef3f2efcf1ef62b05dfd Gitweb: https://git.kernel.org/tip/ed83935a9af088439462ef3f2efcf1ef62b05dfd Author: Jarkko Sakkinen AuthorDate: Fri, 04 Mar 2022 00:38:58 +02:00 Committer: Dave Hansen CommitterDate: Thu, 10 Mar 2022 16:09:40 -08:00 x86/sgx: Free backing memory after faulting the enclave page There is a limited amount of SGX memory (EPC) on each system. When that memory is used up, SGX has its own swapping mechanism which is similar in concept but totally separate from the core mm/* code. Instead of swapping to disk, SGX swaps from EPC to normal RAM. That normal RAM comes from a shared memory pseudo-file and can itself be swapped by the core mm code. There is a hierarchy like this: EPC <-> shmem <-> disk After data is swapped back in from shmem to EPC, the shmem backing storage needs to be freed. Currently, the backing shmem is not freed. This effectively wastes the shmem while the enclave is running. The memory is recovered when the enclave is destroyed and the backing storage freed. Sort this out by freeing memory with shmem_truncate_range(), as soon as a page is faulted back to the EPC. In addition, free the memory for PCMD pages as soon as all PCMD's in a page have been marked as unused by zeroing its contents. Cc: stable@vger.kernel.org Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer") Reported-by: Dave Hansen Signed-off-by: Jarkko Sakkinen Signed-off-by: Dave Hansen Link: https://lkml.kernel.org/r/20220303223859.273187-1-jarkko@kernel.org --- arch/x86/kernel/cpu/sgx/encl.c | 57 +++++++++++++++++++++++++++------ 1 file changed, 48 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c index 001808e..6fa3d0a 100644 --- a/arch/x86/kernel/cpu/sgx/encl.c +++ b/arch/x86/kernel/cpu/sgx/encl.c @@ -13,6 +13,30 @@ #include "sgx.h" /* + * Calculate byte offset of a PCMD struct associated with an enclave page. PCMD's + * follow right after the EPC data in the backing storage. In addition to the + * visible enclave pages, there's one extra page slot for SECS, before PCMD + * structs. + */ +static inline pgoff_t sgx_encl_get_backing_page_pcmd_offset(struct sgx_encl *encl, + unsigned long page_index) +{ + pgoff_t epc_end_off = encl->size + sizeof(struct sgx_secs); + + return epc_end_off + page_index * sizeof(struct sgx_pcmd); +} + +/* + * Free a page from the backing storage in the given page index. + */ +static inline void sgx_encl_truncate_backing_page(struct sgx_encl *encl, unsigned long page_index) +{ + struct inode *inode = file_inode(encl->backing); + + shmem_truncate_range(inode, PFN_PHYS(page_index), PFN_PHYS(page_index) + PAGE_SIZE - 1); +} + +/* * ELDU: Load an EPC page as unblocked. For more info, see "OS Management of EPC * Pages" in the SDM. */ @@ -22,9 +46,11 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page, { unsigned long va_offset = encl_page->desc & SGX_ENCL_PAGE_VA_OFFSET_MASK; struct sgx_encl *encl = encl_page->encl; + pgoff_t page_index, page_pcmd_off; struct sgx_pageinfo pginfo; struct sgx_backing b; - pgoff_t page_index; + bool pcmd_page_empty; + u8 *pcmd_page; int ret; if (secs_page) @@ -32,14 +58,16 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page, else page_index = PFN_DOWN(encl->size); + page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index); + ret = sgx_encl_get_backing(encl, page_index, &b); if (ret) return ret; pginfo.addr = encl_page->desc & PAGE_MASK; pginfo.contents = (unsigned long)kmap_atomic(b.contents); - pginfo.metadata = (unsigned long)kmap_atomic(b.pcmd) + - b.pcmd_offset; + pcmd_page = kmap_atomic(b.pcmd); + pginfo.metadata = (unsigned long)pcmd_page + b.pcmd_offset; if (secs_page) pginfo.secs = (u64)sgx_get_epc_virt_addr(secs_page); @@ -55,11 +83,24 @@ static int __sgx_encl_eldu(struct sgx_encl_page *encl_page, ret = -EFAULT; } - kunmap_atomic((void *)(unsigned long)(pginfo.metadata - b.pcmd_offset)); + memset(pcmd_page + b.pcmd_offset, 0, sizeof(struct sgx_pcmd)); + + /* + * The area for the PCMD in the page was zeroed above. Check if the + * whole page is now empty meaning that all PCMD's have been zeroed: + */ + pcmd_page_empty = !memchr_inv(pcmd_page, 0, PAGE_SIZE); + + kunmap_atomic(pcmd_page); kunmap_atomic((void *)(unsigned long)pginfo.contents); sgx_encl_put_backing(&b, false); + sgx_encl_truncate_backing_page(encl, page_index); + + if (pcmd_page_empty) + sgx_encl_truncate_backing_page(encl, PFN_DOWN(page_pcmd_off)); + return ret; } @@ -577,7 +618,7 @@ static struct page *sgx_encl_get_backing_page(struct sgx_encl *encl, int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index, struct sgx_backing *backing) { - pgoff_t pcmd_index = PFN_DOWN(encl->size) + 1 + (page_index >> 5); + pgoff_t page_pcmd_off = sgx_encl_get_backing_page_pcmd_offset(encl, page_index); struct page *contents; struct page *pcmd; @@ -585,7 +626,7 @@ int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index, if (IS_ERR(contents)) return PTR_ERR(contents); - pcmd = sgx_encl_get_backing_page(encl, pcmd_index); + pcmd = sgx_encl_get_backing_page(encl, PFN_DOWN(page_pcmd_off)); if (IS_ERR(pcmd)) { put_page(contents); return PTR_ERR(pcmd); @@ -594,9 +635,7 @@ int sgx_encl_get_backing(struct sgx_encl *encl, unsigned long page_index, backing->page_index = page_index; backing->contents = contents; backing->pcmd = pcmd; - backing->pcmd_offset = - (page_index & (PAGE_SIZE / sizeof(struct sgx_pcmd) - 1)) * - sizeof(struct sgx_pcmd); + backing->pcmd_offset = page_pcmd_off & (PAGE_SIZE - 1); return 0; }