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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 58EF3C43441 for ; Tue, 27 Nov 2018 07:46:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 17C0920873 for ; Tue, 27 Nov 2018 07:46:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 17C0920873 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729203AbeK0Snl (ORCPT ); Tue, 27 Nov 2018 13:43:41 -0500 Received: from mx2.suse.de ([195.135.220.15]:59884 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728267AbeK0Snl (ORCPT ); Tue, 27 Nov 2018 13:43:41 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 9F58AAEF5; Tue, 27 Nov 2018 07:46:39 +0000 (UTC) Subject: Re: [PATCH] xen/x86: add diagnostic printout to xen_mc_flush() in case of error To: Boris Ostrovsky , linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org Cc: sstabellini@kernel.org, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de References: <20181123162451.3351-1-jgross@suse.com> <0727da38-bfe8-f484-6b06-7205c1d953c1@oracle.com> From: Juergen Gross Openpgp: preference=signencrypt Autocrypt: addr=jgross@suse.com; prefer-encrypt=mutual; keydata= xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOB ycWxw3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJve dYm8Of8Zd621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJ NwQpd369y9bfIhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvx XP3FAp2pkW0xqG7/377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEB AAHNHkp1ZXJnZW4gR3Jvc3MgPGpncm9zc0BzdXNlLmRlPsLAeQQTAQIAIwUCU4xw6wIbAwcL CQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJELDendYovxMvi4UH/Ri+OXlObzqMANruTd4N zmVBAZgx1VW6jLc8JZjQuJPSsd/a+bNr3BZeLV6lu4Pf1Yl2Log129EX1KWYiFFvPbIiq5M5 kOXTO8Eas4CaScCvAZ9jCMQCgK3pFqYgirwTgfwnPtxFxO/F3ZcS8jovza5khkSKL9JGq8Nk czDTruQ/oy0WUHdUr9uwEfiD9yPFOGqp4S6cISuzBMvaAiC5YGdUGXuPZKXLpnGSjkZswUzY d9BVSitRL5ldsQCg6GhDoEAeIhUC4SQnT9SOWkoDOSFRXZ+7+WIBGLiWMd+yKDdRG5RyP/8f 3tgGiB6cyuYfPDRGsELGjUaTUq3H2xZgIPfOwE0EU4xwFgEIAMsx+gDjgzAY4H1hPVXgoLK8 B93sTQFN9oC6tsb46VpxyLPfJ3T1A6Z6MVkLoCejKTJ3K9MUsBZhxIJ0hIyvzwI6aYJsnOew cCiCN7FeKJ/oA1RSUemPGUcIJwQuZlTOiY0OcQ5PFkV5YxMUX1F/aTYXROXgTmSaw0aC1Jpo w7Ss1mg4SIP/tR88/d1+HwkJDVW1RSxC1PWzGizwRv8eauImGdpNnseneO2BNWRXTJumAWDD pYxpGSsGHXuZXTPZqOOZpsHtInFyi5KRHSFyk2Xigzvh3b9WqhbgHHHE4PUVw0I5sIQt8hJq 5nH5dPqz4ITtCL9zjiJsExHuHKN3NZsAEQEAAcLAXwQYAQIACQUCU4xwFgIbDAAKCRCw3p3W KL8TL0P4B/9YWver5uD/y/m0KScK2f3Z3mXJhME23vGBbMNlfwbr+meDMrJZ950CuWWnQ+d+ Ahe0w1X7e3wuLVODzjcReQ/v7b4JD3wwHxe+88tgB9byc0NXzlPJWBaWV01yB2/uefVKryAf AHYEd0gCRhx7eESgNBe3+YqWAQawunMlycsqKa09dBDL1PFRosF708ic9346GLHRc6Vj5SRA UTHnQqLetIOXZm3a2eQ1gpQK9MmruO86Vo93p39bS1mqnLLspVrL4rhoyhsOyh0Hd28QCzpJ wKeHTd0MAWAirmewHXWPco8p1Wg+V+5xfZzuQY0f4tQxvOpXpt4gQ1817GQ5/Ed/wsDtBBgB CAAgFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAlrd8NACGwIAgQkQsN6d1ii/Ey92IAQZFggA HRYhBFMtsHpB9jjzHji4HoBcYbtP2GO+BQJa3fDQAAoJEIBcYbtP2GO+TYsA/30H/0V6cr/W V+J/FCayg6uNtm3MJLo4rE+o4sdpjjsGAQCooqffpgA+luTT13YZNV62hAnCLKXH9n3+ZAgJ RtAyDWk1B/0SMDVs1wxufMkKC3Q/1D3BYIvBlrTVKdBYXPxngcRoqV2J77lscEvkLNUGsu/z W2pf7+P3mWWlrPMJdlbax00vevyBeqtqNKjHstHatgMZ2W0CFC4hJ3YEetuRBURYPiGzuJXU pAd7a7BdsqWC4o+GTm5tnGrCyD+4gfDSpkOT53S/GNO07YkPkm/8J4OBoFfgSaCnQ1izwgJQ jIpcG2fPCI2/hxf2oqXPYbKr1v4Z1wthmoyUgGN0LPTIm+B5vdY82wI5qe9uN6UOGyTH2B3p hRQUWqCwu2sqkI3LLbTdrnyDZaixT2T0f4tyF5Lfs+Ha8xVMhIyzNb1byDI5FKCb Message-ID: <04dc8206-d7ad-9438-2f68-c25bf5a10b96@suse.com> Date: Tue, 27 Nov 2018 08:46:38 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <0727da38-bfe8-f484-6b06-7205c1d953c1@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/11/2018 21:11, Boris Ostrovsky wrote: > On 11/23/18 11:24 AM, Juergen Gross wrote: >> Failure of an element of a Xen multicall is signalled via a WARN() >> only unless the kernel is compiled with MC_DEBUG. It is impossible to > > s/unless/if > > >> know which element failed and why it did so. >> >> Change that by printing the related information even without MC_DEBUG, >> even if maybe in some limited form (e.g. without information which >> caller produced the failing element). >> >> Move the printing out of the switch statement in order to have the >> same information for a single call. >> >> Signed-off-by: Juergen Gross >> --- >> arch/x86/xen/multicalls.c | 35 ++++++++++++++++++++--------------- >> 1 file changed, 20 insertions(+), 15 deletions(-) >> >> diff --git a/arch/x86/xen/multicalls.c b/arch/x86/xen/multicalls.c >> index 2bce7958ce8b..0766a08bdf45 100644 >> --- a/arch/x86/xen/multicalls.c >> +++ b/arch/x86/xen/multicalls.c >> @@ -69,6 +69,11 @@ void xen_mc_flush(void) >> >> trace_xen_mc_flush(b->mcidx, b->argidx, b->cbidx); >> >> +#if MC_DEBUG >> + memcpy(b->debug, b->entries, >> + b->mcidx * sizeof(struct multicall_entry)); >> +#endif >> + >> switch (b->mcidx) { >> case 0: >> /* no-op */ >> @@ -87,32 +92,34 @@ void xen_mc_flush(void) >> break; >> >> default: >> -#if MC_DEBUG >> - memcpy(b->debug, b->entries, >> - b->mcidx * sizeof(struct multicall_entry)); >> -#endif >> - >> if (HYPERVISOR_multicall(b->entries, b->mcidx) != 0) >> BUG(); >> for (i = 0; i < b->mcidx; i++) >> if (b->entries[i].result < 0) >> ret++; >> + } >> >> + if (WARN_ON(ret)) { >> + pr_err("%d of %d multicall(s) failed: cpu %d\n", >> + ret, b->mcidx, smp_processor_id()); >> + for (i = 0; i < b->mcidx; i++) { >> + if (b->entries[i].result < 0) { >> #if MC_DEBUG >> - if (ret) { >> - printk(KERN_ERR "%d multicall(s) failed: cpu %d\n", >> - ret, smp_processor_id()); >> - dump_stack(); >> - for (i = 0; i < b->mcidx; i++) { >> - printk(KERN_DEBUG " call %2d/%d: op=%lu arg=[%lx] result=%ld\t%pF\n", >> - i+1, b->mcidx, >> + pr_err(" call %2d: op=%lu arg=[%lx] result=%ld\t%pF\n", >> + i + 1, >> b->debug[i].op, >> b->debug[i].args[0], >> b->entries[i].result, >> b->caller[i]); >> +#else >> + pr_err(" call %2d: op=%lu arg=[%lx] result=%ld\n", >> + i + 1, >> + b->entries[i].op, >> + b->entries[i].args[0], >> + b->entries[i].result); >> +#endif > > Doesn't (non-debug) hypervisor corrupt op and args? No. Only debug hypervisor does so. See my patch (and rather lengthy discussion) on xen-devel: https://lists.xen.org/archives/html/xen-devel/2018-11/msg02714.html > > (Also, we don't really need to print anything when b->entries[i].result > == 0) Right. Did you miss the: + if (b->entries[i].result < 0) { above? Juergen