From patchwork Wed Jun 22 09:37:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Zhiquan Li X-Patchwork-Id: 12890406 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 637D9C433EF for ; Wed, 22 Jun 2022 09:37:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238701AbiFVJhC (ORCPT ); Wed, 22 Jun 2022 05:37:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235328AbiFVJhC (ORCPT ); Wed, 22 Jun 2022 05:37:02 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 937BC3526C for ; Wed, 22 Jun 2022 02:37:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655890621; x=1687426621; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=y9C9ZFYorJ9n6WzhRgeGq+dOf1V5wlOyDpU0Ni3qz+E=; b=WFIjY9XG8WeOgzNBzBip7K5h/l37WghMX2N3L8vAIJ5UDR+n8gXjh/1L IchIn5CKSE8Hm9RxInTZGNZVOLx8qhikjI8JbTidk7m2j4q9NLpXNkFZ2 iggpnmhQiAPMlpV7i2RtJMfq4mefo3WPUgb1k5/1ZHwbcIUFjrDFxw6IU KFeykKVLuyjgSGER2BM/bF7BjxAc+hO6E+G/uo21s6P589LEQfVfHnUj3 3HNl5w9TF2ncjVpE6uPj83r8azfGDnne/V4TXW2UGlKZ84hfYWXi679jh 973md21MJgUKeo+Q3NTzkssM1d5ZPlI3GMPjNQwU7bhGJSBTIbY9ohvQL A==; X-IronPort-AV: E=McAfee;i="6400,9594,10385"; a="281100613" X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="281100613" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 02:37:01 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,212,1650956400"; d="scan'208";a="677448860" Received: from zhiquan-linux-dev.bj.intel.com ([10.238.155.101]) by FMSMGA003.fm.intel.com with ESMTP; 22 Jun 2022 02:36:58 -0700 From: Zhiquan Li To: linux-sgx@vger.kernel.org, tony.luck@intel.com, jarkko@kernel.org, dave.hansen@linux.intel.com Cc: seanjc@google.com, kai.huang@intel.com, fan.du@intel.com, cathy.zhang@intel.com, zhiquan1.li@intel.com Subject: [PATCH v5 2/3] x86/sgx: Fine grained SGX MCA behavior for virtualization Date: Wed, 22 Jun 2022 17:37:04 +0800 Message-Id: <20220622093705.2891642-3-zhiquan1.li@intel.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220622093705.2891642-1-zhiquan1.li@intel.com> References: <20220622093705.2891642-1-zhiquan1.li@intel.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org When VM guest access a SGX EPC page with memory failure, current behavior will kill the guest, expected only kill the SGX application inside it. To fix it we send SIGBUS with code BUS_MCEERR_AR and some extra information for hypervisor to inject #MC information to guest, which is helpful in SGX case. The rest of things are guest side. Currently the hypervisor like Qemu already has mature facility to convert HVA to GPA and inject #MC to the guest OS. Unlike host enclaves, virtual EPC instance cannot be shared by multiple VMs. It is because how enclaves are created is totally up to the guest. Sharing virtual EPC instance will be very likely to unexpectedly break enclaves in all VMs. SGX virtual EPC driver doesn't explicitly prevent virtual EPC instance being shared by multiple VMs via fork(). However KVM doesn't support running a VM across multiple mm structures, and the de facto userspace hypervisor (Qemu) doesn't use fork() to create a new VM, so in practice this should not happen. Signed-off-by: Zhiquan Li Acked-by: Kai Huang Link: https://lore.kernel.org/linux-sgx/443cb425-009c-2784-56f4-5e707122de76@intel.com/T/#m1d1f4098f4fad78034e8706a60e4d79c119db407 --- Changes since V4: - Switch the order of the two variables so all of variables are in reverse Christmas style. - Do not initialize "ret" because it will be overridden by the return value of force_sig_mceerr() unconditionally. Changes since V2: - Retrieve virtual address from "owner" field of struct sgx_epc_page, instead of struct sgx_vepc_page. - Replace EPC page flag SGX_EPC_PAGE_IS_VEPC with SGX_EPC_PAGE_KVM_GUEST as they are duplicated. Changes since V1: - Add Acked-by from Kai Huang. - Add Kai’s excellent explanation regarding to why we no need to consider that one virtual EPC be shared by two guests. --- arch/x86/kernel/cpu/sgx/main.c | 24 ++++++++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c index ab4ec54bbdd9..4507c2302348 100644 --- a/arch/x86/kernel/cpu/sgx/main.c +++ b/arch/x86/kernel/cpu/sgx/main.c @@ -715,6 +715,8 @@ int arch_memory_failure(unsigned long pfn, int flags) struct sgx_epc_page *page = sgx_paddr_to_page(pfn << PAGE_SHIFT); struct sgx_epc_section *section; struct sgx_numa_node *node; + unsigned long vaddr; + int ret; /* * mm/memory-failure.c calls this routine for all errors @@ -731,8 +733,26 @@ int arch_memory_failure(unsigned long pfn, int flags) * error. The signal may help the task understand why the * enclave is broken. */ - if (flags & MF_ACTION_REQUIRED) - force_sig(SIGBUS); + if (flags & MF_ACTION_REQUIRED) { + /* + * Provide extra info to the task so that it can make further + * decision but not simply kill it. This is quite useful for + * virtualization case. + */ + if (page->flags & SGX_EPC_PAGE_KVM_GUEST) { + /* + * The "owner" field is repurposed as the virtual address + * of virtual EPC page. + */ + vaddr = (unsigned long)page->owner & PAGE_MASK; + ret = force_sig_mceerr(BUS_MCEERR_AR, (void __user *)vaddr, + PAGE_SHIFT); + if (ret < 0) + pr_err("Memory failure: Error sending signal to %s:%d: %d\n", + current->comm, current->pid, ret); + } else + force_sig(SIGBUS); + } section = &sgx_epc_sections[page->section]; node = section->node;