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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 92489C433EF for ; Sun, 13 Mar 2022 20:21:09 +0000 (UTC) Received: from localhost ([::1]:45032 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nTUiB-00046r-Hh for qemu-devel@archiver.kernel.org; Sun, 13 Mar 2022 16:21:07 -0400 Received: from eggs.gnu.org ([209.51.188.92]:50858) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nTUh6-0003OJ-SB for qemu-devel@nongnu.org; Sun, 13 Mar 2022 16:20:00 -0400 Received: from [2607:f8b0:4864:20::433] (port=33295 helo=mail-pf1-x433.google.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1nTUh5-0002Im-DY for qemu-devel@nongnu.org; Sun, 13 Mar 2022 16:20:00 -0400 Received: by mail-pf1-x433.google.com with SMTP id s42so12569754pfg.0 for ; Sun, 13 Mar 2022 13:19:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=message-id:date:mime-version:user-agent:subject:content-language:to :cc:references:from:in-reply-to:content-transfer-encoding; bh=C4zw8O51UZ+SbP7OlGrSn4pAiNhhd9TFG5m/m0/zj0k=; b=vy+/Nlpt+wsAIkfQ1XfXlO9zb86NMFhO6nCM7AoCnuUq2qVveGb3y5Uj0Cim7oxdXI WUwCUTyQOvM7pEbrfw4MW6rMCSjfIuFLX2z18c38SbbZ9ea1YjwDl2NLUxtN73vnGmph qfgGCahw2lZpwCJcKjkHAIYt43T7o5Kbdjc2E9mkbsIe1WELCS2kNeDGd4PJjNb7/HZH KCjpqvIMlkM9jYxDKFhWPjNEo8OB4aLAl7ckUSFqrW1KEibg60peMcV17Pwl92Fyk6Iz cGwZz5w00bW5NoS5Cjz5oT8iO+x6jo3KwT61kEmCLSx2ycYNJWzPry+6+LkJhQZW9RpZ 5MhQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=C4zw8O51UZ+SbP7OlGrSn4pAiNhhd9TFG5m/m0/zj0k=; b=vL0AGDGvqvopiDcfTV2JpiBuzoWw9eNi5VBDXrzS63ASxLVhg//RATG/1l3CJ5CrSn Adw7spCzZ/gLo4ugAOxCGHjqq4RovAOoLque/XuOoP0iBDLAIT4Z12KfAZ5HYg8CnTwu x3aJ1UKu1Ehi66mA7F1FXeTQeAkQqflwRHyr5NIEh9juq7y2mBR1fmOXDkp1our9Vkg/ rCBPzUMP2GD31c+EALMivRiPvTH5QIgbfX/YuCLwp8Xe0UD9nIsRkmrrulBNEVZzqpsh nvRPz6pQj5puGiGyVpUkb9YXhElp88OePyS94CmAOWBc38Zd8o3txbfcTDipAJo08x5l QNeQ== X-Gm-Message-State: AOAM531fZYrGLuupQ684tn7hzFJcURBJhczPlQksazmYvRfBOx5qUf4B 8rGmnM7MUhchP+pX2SpSQwpBdQ== X-Google-Smtp-Source: ABdhPJxRoaUGoiP7ljxao9cboHfNbw168h3K37dWFKOiht2CtwT59beDbuS2H37js66E1bHHFsMzOQ== X-Received: by 2002:a63:6bc8:0:b0:380:4fc1:f1ef with SMTP id g191-20020a636bc8000000b003804fc1f1efmr17617449pgc.451.1647202797744; Sun, 13 Mar 2022 13:19:57 -0700 (PDT) Received: from [192.168.1.6] (174-21-142-130.tukw.qwest.net. [174.21.142.130]) by smtp.gmail.com with ESMTPSA id 16-20020a056a00073000b004dfe2217090sm17718354pfm.200.2022.03.13.13.19.56 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 13 Mar 2022 13:19:57 -0700 (PDT) Message-ID: Date: Sun, 13 Mar 2022 13:19:55 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: Question about atomics Content-Language: en-US To: Warner Losh References: <5bb620d4-96f0-cf7f-5530-af529a32c78d@linaro.org> <45371f77-cae6-bf96-802d-6a3e70d5e334@linaro.org> From: Richard Henderson In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::433 (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::433; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x433.google.com X-Spam_score_int: -6 X-Spam_score: -0.7 X-Spam_bar: / X-Spam_report: (-0.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, PDS_HP_HELO_NORDNS=0.659, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Paolo Bonzini , QEMU Developers Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 3/13/22 11:29, Warner Losh wrote: > So I was assuming that the cas instructions for arm use start/end_exclsive under the covers. > Is that the case? Nope. The store exclusive guest insn is implemented with a host cmpxchg. Oh, I'd forgotten about the old arm cmpxchg64 syscall, which is still implemented with start/end_exclusive. That should get fixed... r~