From patchwork Wed Sep 1 20:30:25 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12470249 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-21.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10672C4320A for ; Wed, 1 Sep 2021 20:30:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DF17D6101B for ; Wed, 1 Sep 2021 20:30:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231301AbhIAUbf (ORCPT ); Wed, 1 Sep 2021 16:31:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57624 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231268AbhIAUbc (ORCPT ); Wed, 1 Sep 2021 16:31:32 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99867C061575 for ; Wed, 1 Sep 2021 13:30:35 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id z15-20020a25868f000000b0059c56f47e94so635384ybk.21 for ; Wed, 01 Sep 2021 13:30:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:message-id:mime-version:subject:from:to:cc; bh=W1dxeMSnjrWamgGdUCD0sYJfSJN9IbPKQnQHF6ba9Zk=; b=IQ3nzeVkBaQ3+GaVFpdDRiwa1F5iA/5Zp/cm/bF8X3UWxA4Toc92TTI+eIn+naxoj4 ET+Zt+Rvu2Fr2/xquoH0yyIu1XZMcmT6cboCyI5rR64pNT2lIrUM9xsZrqNNRFzptE9I wsjHcW+VBGjjK0s1f/t7DFUqU3PrzpUZIO7H21qkNMgtq3NBIoSIXL8a6Wi2vk1qkqG1 BaUOcKIMQ08Iy5Y7BqvrFMwn+huvKoc2AWIhhSBz+VoHhzJ2fNfVJZIWBlgZKOH4ctt1 0w2Bp1svSX94Jl0zODWdtTreSksXnGqUiHiy/S7N6hf8RY5t4uNFQqLBoR2dt7fhnNYr B6yg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:message-id:mime-version:subject :from:to:cc; bh=W1dxeMSnjrWamgGdUCD0sYJfSJN9IbPKQnQHF6ba9Zk=; b=Y6E/W/t7VrkqWGsmvbYciBp++wupLSUpKI1QiK9OUNTYy2D3ZMnf/Dm88yPJaKd9je otKCiHjdS2184XjXXw8HOeURZGyseqJunBvOQSieM/QVpQa2aEnBFXIc5ZUgiZQhmMJc 5NfyTNNMQreDfPFTg5z4p7OLYf4P8/hxql70ae2jG+ZNFo4ncecZyc5mSRiLLpSFBNXd BWvM2sdBa5wwQXPO1rQD4RPDQsYum6McMnTOAhWSD6IigxcdVfWia7qMYg2rvS2cXZdc IH5yz4YpIW0ERzRzRA61HwNb29N1grT3jzLWCBG4thA1qLPg+P3QzKp3dH5xUIxzWVcT LrGA== X-Gm-Message-State: AOAM53141Xr1eZo8sySZLaefzJRFR4nEba5JLI+sPrOwGGYmayTCN/pA coQMihwG4/0RgVXrP0kZaf97QvD6F5E= X-Google-Smtp-Source: ABdhPJztMghe8pf2r0RN3BmnZkigpSEdqe6AO5tWh0SkJaCpcvF1MtRyRWIuMac/iI8RQmjvTQ8oDXGaxcw= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:90:200:9935:5a5e:c7b6:e649]) (user=seanjc job=sendgmr) by 2002:a05:6902:513:: with SMTP id x19mr1875181ybs.90.1630528234743; Wed, 01 Sep 2021 13:30:34 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 1 Sep 2021 13:30:25 -0700 Message-Id: <20210901203030.1292304-1-seanjc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.33.0.153.gba50c8fa24-goog Subject: [PATCH v3 0/5] KVM: rseq: Fix and a test for a KVM+rseq bug From: Sean Christopherson To: Russell King , Catalin Marinas , Will Deacon , Guo Ren , Thomas Bogendoerfer , Michael Ellerman , Steven Rostedt , Ingo Molnar , Oleg Nesterov , Thomas Gleixner , Peter Zijlstra , Andy Lutomirski , Mathieu Desnoyers , "Paul E. McKenney" , Boqun Feng , Paolo Bonzini , Shuah Khan Cc: Benjamin Herrenschmidt , Paul Mackerras , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Peter Foley , Shakeel Butt , Sean Christopherson , Ben Gardon Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Patch 1 fixes a KVM+rseq bug where KVM's handling of TIF_NOTIFY_RESUME, e.g. for task migration, clears the flag without informing rseq and leads to stale data in userspace's rseq struct. Patch 2 is a cleanup to try and make future bugs less likely. It's also a baby step towards moving and renaming tracehook_notify_resume() since it has nothing to do with tracing. Patch 3 is a fix/cleanup to stop overriding x86's unistd_{32,64}.h when the include path (intentionally) omits tools' uapi headers. KVM's selftests do exactly that so that they can pick up the uapi headers from the installed kernel headers, and still use various tools/ headers that mirror kernel code, e.g. linux/types.h. This allows the new test in patch 4 to reference __NR_rseq without having to manually define it. Patch 4 is a regression test for the KVM+rseq bug. Patch 5 is a cleanup made possible by patch 3. Based on commit 835d31d319d9 ("Merge tag 'media/v5.15-1' of ..."). v3: - Collect Ack/Review. [Mathieu, Ben] - Add explicit smp_wmb() instead of relying on atomic_inc() to do a full barrier. [Mathieu] - Add lots and lots of comments in the selftest, especially around why the migration thread needs a udelay(). [Mathieu] - Delay between 1us and 10us to reduce the odds of having a hard dependency on arch/kernel behavior. [Mathieu] - Dropped an s390 change in patch 2 after a rebase to upstream master. v2: - https://lkml.kernel.org/r/20210820225002.310652-1-seanjc@google.com - Don't touch rseq_cs when handling KVM case so that rseq_syscall() will still detect a naughty userspace. [Mathieu] - Use a sequence counter + retry in the test to ensure the process isn't migrated between sched_getcpu() and reading rseq.cpu_id, i.e. to avoid a flaky test. [Mathieu] - Add Mathieu's ack for patch 2. - Add more comments in the test. v1: https://lkml.kernel.org/r/20210818001210.4073390-1-seanjc@google.com Sean Christopherson (5): KVM: rseq: Update rseq when processing NOTIFY_RESUME on xfer to KVM guest entry: rseq: Call rseq_handle_notify_resume() in tracehook_notify_resume() tools: Move x86 syscall number fallbacks to .../uapi/ KVM: selftests: Add a test for KVM_RUN+rseq to detect task migration bugs KVM: selftests: Remove __NR_userfaultfd syscall fallback arch/arm/kernel/signal.c | 1 - arch/arm64/kernel/signal.c | 1 - arch/csky/kernel/signal.c | 4 +- arch/mips/kernel/signal.c | 4 +- arch/powerpc/kernel/signal.c | 4 +- include/linux/tracehook.h | 2 + kernel/entry/common.c | 4 +- kernel/rseq.c | 14 +- .../x86/include/{ => uapi}/asm/unistd_32.h | 0 .../x86/include/{ => uapi}/asm/unistd_64.h | 3 - tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 3 + tools/testing/selftests/kvm/rseq_test.c | 236 ++++++++++++++++++ 13 files changed, 257 insertions(+), 20 deletions(-) rename tools/arch/x86/include/{ => uapi}/asm/unistd_32.h (100%) rename tools/arch/x86/include/{ => uapi}/asm/unistd_64.h (83%) create mode 100644 tools/testing/selftests/kvm/rseq_test.c