From mboxrd@z Thu Jan 1 00:00:00 1970 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 9EC67ECAAD2 for ; Thu, 1 Sep 2022 22:31:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235082AbiIAWbI (ORCPT ); Thu, 1 Sep 2022 18:31:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48132 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235413AbiIAWan (ORCPT ); Thu, 1 Sep 2022 18:30:43 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B44D6D9D for ; Thu, 1 Sep 2022 15:29:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 49976B8293B for ; Thu, 1 Sep 2022 22:29:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1167C433D6; Thu, 1 Sep 2022 22:29:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662071370; bh=KQj3iNyASUtYcqldylh3JNvPEm1DfPVEBwQbarRbuKM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H4lIGqxpeAoh4w4ueucM8f26KxEWnPwnxrTmhYeP8Ce7kSpWnA2mKer1yPhvJ6CFx VRwnuvAJIx710JX1RzgxOpK/QWfcikge1tTVB0E0ya9Ux2rN3TlZ4TuPo7qGPQ68AX LOcadrVbvrQjDUeAhYKTIlS5wMLJFzZl34SyJfWSgxHr4+ye+wSttiNG3EAAW/UIM7 4EmwLNZunqBmwZnRzffPcqrllxXMHsCc44YdZXixIZvRg8HIBKEwiS6EapMPjJr/3g WNJZGWMBulurC6S8upQlzyh9mQsHZblRP4r9uaQZBi0iXBnNiGsuj79L/D4NxMl9Ak v5VE125Gby9yA== Date: Fri, 2 Sep 2022 01:29:25 +0300 From: Jarkko Sakkinen To: Zhiquan Li Cc: linux-sgx@vger.kernel.org, tony.luck@intel.com, dave.hansen@linux.intel.com, tglx@linutronix.de, bp@alien8.de, seanjc@google.com, kai.huang@intel.com, fan.du@intel.com, cathy.zhang@intel.com Subject: Re: [PATCH v7 0/3] x86/sgx: fine grained SGX MCA behavior Message-ID: References: <20220901003601.2048563-1-zhiquan1.li@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220901003601.2048563-1-zhiquan1.li@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-sgx@vger.kernel.org On Thu, Sep 01, 2022 at 08:35:58AM +0800, Zhiquan Li wrote: > V6: https://lore.kernel.org/linux-sgx/20220826160503.1576966-1-zhiquan1.li@intel.com/T/#t > > Changes since V6: > - Revise the commit message of patch 01 suggested by Jarkko. > - Fix build warning due to type changes. > > V5: https://lore.kernel.org/linux-sgx/Yrf27fugD7lkyaek@kernel.org/T/#t > > Changes since V5: > - Rename the 'owner' field as 'encl_owner' and update the references > as a separate patch. > - To prevent casting the 'encl_owner' field, introduce a union with > another field - "vepc_vaddr", suggested by Dave Hansen. > - Clean up the commit message of patch 02 suggested by Dave Hansen. > - Remove patch 03 unless we have better reason to keep it. > - Add Reviewed-by from Jarkko. > > V4: https://lore.kernel.org/linux-sgx/20220608032654.1764936-1-zhiquan1.li@intel.com/T/#t > > Changes since V4: > - Switch the order of the two variables at patch 02 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. > - Add Co-developed-by and Signed-off-by from Cathy Zhang at patch 01. > - Add Acked-by from Kai Huang at patch 01. > > V3: https://lore.kernel.org/linux-sgx/41704e5d4c03b49fcda12e695595211d950cfb08.camel@kernel.org/T/#t > > Changes since V3: > - Take the definition of EPC page flag SGX_EPC_PAGE_KVM_GUEST from > Cathy Zhang's third patch of SGX rebootless recovery patch set but > discard irrelevant portion, since it might need some time to re-forge > and these are two different features. > Link: https://lore.kernel.org/linux-sgx/41704e5d4c03b49fcda12e695595211d950cfb08.camel@kernel.org/T/#m9782d23496cacecb7da07a67daa79f4b322ae170 > > V2: https://lore.kernel.org/linux-sgx/694234d7-6a0d-e85f-f2f9-e52b4a61e1ec@intel.com/T/#t > > Changes since V2: > - Repurpose the owner field as the virtual address of virtual EPC page > - Remove struct sgx_vepc_page and relevant code. > - Remove patch 01 as the changes are not necessary in new design. > - Rework patch 02 suggested by Jarkko. > - Adapt patch 03 and 04 since struct sgx_vepc_page was discarded. > - Replace EPC page flag SGX_EPC_PAGE_IS_VEPC with > SGX_EPC_PAGE_KVM_GUEST as they are duplicated. > Link: https://lore.kernel.org/linux-sgx/eb95b32ecf3d44a695610cf7f2816785@intel.com/T/#u > > V1: https://lore.kernel.org/linux-sgx/443cb425-009c-2784-56f4-5e707122de76@intel.com/T/#t > > Changes since V1: > - Updated cover letter and commit messages, added valuable > information from Jarkko, Tony and Kai's comments. > - Added documentations for struct struct sgx_vepc and > struct sgx_vepc_page. > > Hi everyone, > > This series contains a few patches to fine grained SGX MCA behavior. > > Today, if a guest accesses an SGX EPC page with memory failure, > the kernel behavior will kill the entire guest. This blast radius is > too large. It would be idea to kill only the SGX application inside > the guest. > > To fix this, send a SIGBUS to host userspace (like QEMU) which can > follow up by injecting a #MC to the guest. > > However, when a page triggers a machine check, it only reports the > PFN. But in order to inject #MC into hypervisor, the virtual address > is required. The 'encl_owner' field is useless in virtualization > case, then repurpose it as 'vepc_vaddr' - the virtual address of the > virtual EPC page for such case so that arch_memory_failure() can easily > retrieve it. > > Suppose an enclave is shared by multiple processes, when an enclave > page triggers a machine check, the enclave will be disabled so that > it couldn't be entered again. Killing other processes with the same > enclave mapped would perhaps be overkill, but they are going to find > that the enclave is "dead" next time they try to use it. Thanks for > Jarkko’s head up and Tony’s clarification on this point. > > 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. > > This series is based on tip/x86/sgx. > > Tests: > 1. MCE injection test for SGX in VM. > As we expected, the application was killed and VM was alive. > 2. Kernel selftest/sgx: PASS > 3. Internal SGX stress test: PASS > 4. kmemleak test: No memory leakage detected. > > Much appreciate your feedback. > > Best Regards, > Zhiquan > > Zhiquan Li (3): > x86/sgx: Rename the owner field of struct sgx_epc_page as encl_owner > x86/sgx: Introduce union with vepc_vaddr field for virtualization case > x86/sgx: Fine grained SGX MCA behavior for virtualization > > arch/x86/kernel/cpu/sgx/main.c | 48 +++++++++++++++++++++++++--------- > arch/x86/kernel/cpu/sgx/sgx.h | 8 +++++- > arch/x86/kernel/cpu/sgx/virt.c | 4 ++- > 3 files changed, 46 insertions(+), 14 deletions(-) > > -- > 2.25.1 > Acked-by: Jarkko Sakkinen (all patches) BR, Jarkko