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 X-Spam-Level: X-Spam-Status: No, score=-13.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 53115C48BCD for ; Wed, 9 Jun 2021 16:13:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3326B613AC for ; Wed, 9 Jun 2021 16:13:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236302AbhFIQO6 (ORCPT ); Wed, 9 Jun 2021 12:14:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33884 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233896AbhFIQO5 (ORCPT ); Wed, 9 Jun 2021 12:14:57 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22D0EC06175F for ; Wed, 9 Jun 2021 09:12:48 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id k15so18738453pfp.6 for ; Wed, 09 Jun 2021 09:12:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=B80WuFTp3m8SwecqT3IfJ//IoK5UJC0lbvLHibfCmx8=; b=FWVZCG644MLckCLl4nD1KJzI72GQEbRGPhQm6FEHnfs/bflCedBZIU/WTxM6oDPOkt 98dy/fmo83KtIU4f4k6lfCKV73LxZP4D3hl/mx3tEcyZEMl3jyXhvUJkO+Lmfk94UwoB Ue8HOtSn0aj86hr91DQOz8gVsETP2ZR7af+/2Dw6Mm5Ga993W8n5WamXKxTRKNtjmttd UOUD/hJM0CrF1ETOrP9ld+91UwFgLsk3Ooqn7i6werfSXPKazJOmHooOiZIFXIsCJtKv YTc5QJuoa2w4474990DrcXsbBrQtWyEdf7cv2U2gjrWUuXvDPitimB9E4KZkONlXRh8N pICg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=B80WuFTp3m8SwecqT3IfJ//IoK5UJC0lbvLHibfCmx8=; b=uicYxPEOJcGMo9R6/QKKYFDPPpYfizlCBvO+/CbWoaDFU+kmeyifXJewYKwhQdqNUN tl/N2nHmgFixbxKBQF5dd5Hd0VH8SU5H+20LZl3q0aTqEf02Tif/tdhNRi5FMhFUhrqI fiXcUm9YQLzjqIMeP9tuh+RbT/V+FY9DPqhTdpdNcD7kwu0LJ8I2+Ya3zimBtdVzmqq0 s3qtuwxYWvALsaeyZl6+088GgAhkzofPwgSNGru24MfQoHFRWywGUN3RkLr/nKbMG/H1 bqrY9IRRuuq6oHgSPSpWQ9DSUyTngdwFHpEULtaXszprrZr6l1MwWQFC+Pq5fP4YqDl3 fF5Q== X-Gm-Message-State: AOAM53143o4D9ZbCnz14lWr4poWPD2/EPmlfrMZJ/2Qd9N+XHS6Pn0gE DSKJ37mBE9Rq7FsGnfxruYn/1Q== X-Google-Smtp-Source: ABdhPJxvlWFsnIlVWfNlW143h1l1tU2YoUyMXelmM/SalweFWK2m0qPlPzphjNaD0OiHDM8Sb/hzZg== X-Received: by 2002:a62:2581:0:b029:2ea:228e:5a37 with SMTP id l123-20020a6225810000b02902ea228e5a37mr524454pfl.63.1623255167466; Wed, 09 Jun 2021 09:12:47 -0700 (PDT) Received: from google.com ([2620:15c:f:10:bfdc:c2e5:77b1:8ef3]) by smtp.gmail.com with ESMTPSA id z22sm92340pfa.157.2021.06.09.09.12.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 09 Jun 2021 09:12:46 -0700 (PDT) Date: Wed, 9 Jun 2021 09:12:40 -0700 From: Sean Christopherson To: Wanpeng Li Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm , LKML , Steven Rostedt Subject: Re: [PATCH] KVM: x86: Ensure liveliness of nested VM-Enter fail tracepoint message Message-ID: References: <20210607175748.674002-1-seanjc@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Jun 09, 2021, Wanpeng Li wrote: > On Tue, 8 Jun 2021 at 02:00, Sean Christopherson wrote: > > > > Use the __string() machinery provided by the tracing subystem to make a > > copy of the string literals consumed by the "nested VM-Enter failed" > > tracepoint. A complete copy is necessary to ensure that the tracepoint > > can't outlive the data/memory it consumes and deference stale memory. > > > > Because the tracepoint itself is defined by kvm, if kvm-intel and/or > > kvm-amd are built as modules, the memory holding the string literals > > defined by the vendor modules will be freed when the module is unloaded, > > whereas the tracepoint and its data in the ring buffer will live until > > kvm is unloaded (or "indefinitely" if kvm is built-in). > > > > This bug has existed since the tracepoint was added, but was recently > > exposed by a new check in tracing to detect exactly this type of bug. > > > > fmt: '%s%s > > ' current_buffer: ' vmx_dirty_log_t-140127 [003] .... kvm_nested_vmenter_failed: ' > > WARNING: CPU: 3 PID: 140134 at kernel/trace/trace.c:3759 trace_check_vprintf+0x3be/0x3e0 > > CPU: 3 PID: 140134 Comm: less Not tainted 5.13.0-rc1-ce2e73ce600a-req #184 > > Hardware name: ASUS Q87M-E/Q87M-E, BIOS 1102 03/03/2014 > > RIP: 0010:trace_check_vprintf+0x3be/0x3e0 > > Code: <0f> 0b 44 8b 4c 24 1c e9 a9 fe ff ff c6 44 02 ff 00 49 8b 97 b0 20 > > RSP: 0018:ffffa895cc37bcb0 EFLAGS: 00010282 > > RAX: 0000000000000000 RBX: ffffa895cc37bd08 RCX: 0000000000000027 > > RDX: 0000000000000027 RSI: 00000000ffffdfff RDI: ffff9766cfad74f8 > > RBP: ffffffffc0a041d4 R08: ffff9766cfad74f0 R09: ffffa895cc37bad8 > > R10: 0000000000000001 R11: 0000000000000001 R12: ffffffffc0a041d4 > > R13: ffffffffc0f4dba8 R14: 0000000000000000 R15: ffff976409f2c000 > > FS: 00007f92fa200740(0000) GS:ffff9766cfac0000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000559bd11b0000 CR3: 000000019fbaa002 CR4: 00000000001726e0 > > Call Trace: > > trace_event_printf+0x5e/0x80 > > trace_raw_output_kvm_nested_vmenter_failed+0x3a/0x60 [kvm] > > print_trace_line+0x1dd/0x4e0 > > s_show+0x45/0x150 > > seq_read_iter+0x2d5/0x4c0 > > seq_read+0x106/0x150 > > vfs_read+0x98/0x180 > > ksys_read+0x5f/0xe0 > > do_syscall_64+0x40/0xb0 > > entry_SYSCALL_64_after_hwframe+0x44/0xae > > I can observe tons of other kvm tracepoints warning like this after > commit 9a6944fee68e25 (tracing: Add a verifier to check string > pointers for trace events), just echo 1 > > /sys/kernel/tracing/events/kvm/enable and boot a linux guest. Can you provide your .config? With all of events/kvm and events/kvmmmu enabled I don't get any warnings running a Linux guest, a nested Linux guest, and kvm-unit-tests. Do you see the behavior with other tracepoints? E.g. enabling all events on my systems yields warnings for a USB module, but everything else is clean.