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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id x17sm5298087ilm.40.2021.02.26.13.55.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Feb 2021 13:55:17 -0800 (PST) Subject: Re: [PATCH] iommu/amd: Fix event counter availability check To: Paul Menzel , Alexander Monakov , Suravee Suthikulpanit Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, David Coe , Joerg Roedel , "Tj (Elloe Linux)" , Shuah Khan References: <20200529200738.1923-1-amonakov@ispras.ru> <4aba4c61-1878-3d4e-d52e-3ccac9715010@molgen.mpg.de> From: Shuah Khan Message-ID: Date: Fri, 26 Feb 2021 14:55:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <4aba4c61-1878-3d4e-d52e-3ccac9715010@molgen.mpg.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/26/21 2:44 PM, Paul Menzel wrote: > [cc: +suravee, +jörg] > > Dear Alex, dear Shuah, dear Suravee, dear Jörg, > > > Am 03.06.20 um 08:54 schrieb Alexander Monakov: >> On Tue, 2 Jun 2020, Shuah Khan wrote: >> >>> I changed the logic to read config to get max banks and counters >>> before checking if counters are writable and tried writing to all. >>> The result is the same and all of them aren't writable. However, >>> when disable the writable check and assume they are, I can run >> [snip] >> >> This is similar to what I did. I also noticed that counters can >> be successfully used with perf if the initial check is ignored. >> I was considering sending a patch to remove the check and adjust >> the event counting logic to use counters as read-only, but after >> a bit more investigation I've noticed how late pci_enable_device >> is done, and came up with this patch. It's a path of less resistance: >> I'd expect maintainers to be more averse to removing the check >> rather than fixing it so it works as intended (even though I think >> the check should not be there in the first place). >> >> However: >> >> The ability to modify the counters is needed only for sampling the >> events (getting an interrupt when a counter overflows). There's no >> code to do that for these AMD IOMMU counters. A solution I would >> prefer is to not write to those counters at all. It would simplify or >> even remove a bunch of code. I can submit a corresponding patch if >> there's general agreement this path is ok. >> >> What do you think? > > I like this idea. Suravee, Jörg, what do you think? > > Commit 6778ff5b21b (iommu/amd: Fix performance counter initialization) > delays the boot up to 100 ms, which is over 20 % on fast systems, and > also just a workaround, and does not seem to work always. The delay is > also not mentioned in the commit message. > > Sounds good to me. I can test this out on my system. thanks, -- Shuah 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=-5.4 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 353FCC433E0 for ; Fri, 26 Feb 2021 21:55:22 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9CB3464EFA for ; Fri, 26 Feb 2021 21:55:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9CB3464EFA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 49CA184399; Fri, 26 Feb 2021 21:55:21 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6zZ_noDcdqBZ; Fri, 26 Feb 2021 21:55:20 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp1.osuosl.org (Postfix) with ESMTP id 33B498439A; Fri, 26 Feb 2021 21:55:20 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 0A3A6C000A; Fri, 26 Feb 2021 21:55:20 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 795D2C0001 for ; Fri, 26 Feb 2021 21:55:19 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 5245943430 for ; Fri, 26 Feb 2021 21:55:19 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Authentication-Results: smtp2.osuosl.org (amavisd-new); dkim=pass (1024-bit key) header.d=linuxfoundation.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id oxSZ5QDJYF8o for ; Fri, 26 Feb 2021 21:55:18 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mail-io1-f45.google.com (mail-io1-f45.google.com [209.85.166.45]) by smtp2.osuosl.org (Postfix) with ESMTPS id A927C43421 for ; Fri, 26 Feb 2021 21:55:18 +0000 (UTC) Received: by mail-io1-f45.google.com with SMTP id p16so11224446ioj.4 for ; Fri, 26 Feb 2021 13:55:18 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=google; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=TbbG+K21OJksMSriRBsOnkJNEbaTjI1alnvlyWlecpQ=; b=PgkgDjZa97MDV9/Y8FaGFSjOFOKXBpNT06a5oxs2Czk9XCjecD+COXpqVKv844w6CB gAOfjg2mIaQFtRaW/ECx/j3YWKsMqhi7ev/2c8a6NMfX9hG+xl1eY+JBWSekfUsMVF1X eZZMhPhIMT57mfWIHBORF8HW0lTc+BQpQx7AA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TbbG+K21OJksMSriRBsOnkJNEbaTjI1alnvlyWlecpQ=; b=RClmrmfTyFnPKLkkZWeJCCQvnhGceDXQNDyP3I/m5GurUg8C+2iG+dFjtwAn4kMbF9 iw//QIW+RDlAzXqVI3c39XTv1f3GE1iy5x/NoMqNjwvvflab0cTlOHHtUBw3uRrkTeuC sCp0vze+DECJm91gkyaAqr2BjAtTda7TZ7DllQR4eBWH75YkYh0W1crlGovFq2pL2YpU Fi3tOONgapwHfiJxQfVxQCXiLpMzlOC0kZ1Y39tAcLCdBhhq2sZ3TMAV/9F/Inp6tBm/ DYf8AgVAruaAFqNsrUQ7QUbE6NDpJd7Y124uN4HiwFR7Mzmfwrrmm0aAfPfLb9U1XZs6 8eaQ== X-Gm-Message-State: AOAM530XysC4Y1nlxm5l/C6Nk26ru8J2JCGyni20INu+wZUZawmD+S6+ waRHNKQa6I7mNBdfxXB8N/V75Jlh X-Google-Smtp-Source: ABdhPJzu77gtIIuiUcz9cXqvS/WNpBNLjZbJf8JWOBHfSvJRNrkLY3fbuksgVXKop3px+qiLCwJylA== X-Received: by 2002:a02:4087:: with SMTP id n129mr5042155jaa.143.1614376517727; Fri, 26 Feb 2021 13:55:17 -0800 (PST) Received: from [192.168.1.112] (c-24-9-64-241.hsd1.co.comcast.net. [24.9.64.241]) by smtp.gmail.com with ESMTPSA id x17sm5298087ilm.40.2021.02.26.13.55.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Feb 2021 13:55:17 -0800 (PST) Subject: Re: [PATCH] iommu/amd: Fix event counter availability check To: Paul Menzel , Alexander Monakov , Suravee Suthikulpanit References: <20200529200738.1923-1-amonakov@ispras.ru> <4aba4c61-1878-3d4e-d52e-3ccac9715010@molgen.mpg.de> From: Shuah Khan Message-ID: Date: Fri, 26 Feb 2021 14:55:16 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <4aba4c61-1878-3d4e-d52e-3ccac9715010@molgen.mpg.de> Content-Language: en-US Cc: David Coe , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Shuah Khan , "Tj \(Elloe Linux\)" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" T24gMi8yNi8yMSAyOjQ0IFBNLCBQYXVsIE1lbnplbCB3cm90ZToKPiBbY2M6ICtzdXJhdmVlLCAr asO2cmddCj4gCj4gRGVhciBBbGV4LCBkZWFyIFNodWFoLCBkZWFyIFN1cmF2ZWUsIGRlYXIgSsO2 cmcsCj4gCj4gCj4gQW0gMDMuMDYuMjAgdW0gMDg6NTQgc2NocmllYiBBbGV4YW5kZXIgTW9uYWtv djoKPj4gT24gVHVlLCAyIEp1biAyMDIwLCBTaHVhaCBLaGFuIHdyb3RlOgo+Pgo+Pj4gSSBjaGFu Z2VkIHRoZSBsb2dpYyB0byByZWFkIGNvbmZpZyB0byBnZXQgbWF4IGJhbmtzIGFuZCBjb3VudGVy cwo+Pj4gYmVmb3JlIGNoZWNraW5nIGlmIGNvdW50ZXJzIGFyZSB3cml0YWJsZSBhbmQgdHJpZWQg d3JpdGluZyB0byBhbGwuCj4+PiBUaGUgcmVzdWx0IGlzIHRoZSBzYW1lIGFuZCBhbGwgb2YgdGhl bSBhcmVuJ3Qgd3JpdGFibGUuIEhvd2V2ZXIsCj4+PiB3aGVuIGRpc2FibGUgdGhlIHdyaXRhYmxl IGNoZWNrIGFuZCBhc3N1bWUgdGhleSBhcmUsIEkgY2FuIHJ1bgo+PiBbc25pcF0KPj4KPj4gVGhp cyBpcyBzaW1pbGFyIHRvIHdoYXQgSSBkaWQuIEkgYWxzbyBub3RpY2VkIHRoYXQgY291bnRlcnMg Y2FuCj4+IGJlIHN1Y2Nlc3NmdWxseSB1c2VkIHdpdGggcGVyZiBpZiB0aGUgaW5pdGlhbCBjaGVj ayBpcyBpZ25vcmVkLgo+PiBJIHdhcyBjb25zaWRlcmluZyBzZW5kaW5nIGEgcGF0Y2ggdG8gcmVt b3ZlIHRoZSBjaGVjayBhbmQgYWRqdXN0Cj4+IHRoZSBldmVudCBjb3VudGluZyBsb2dpYyB0byB1 c2UgY291bnRlcnMgYXMgcmVhZC1vbmx5LCBidXQgYWZ0ZXIKPj4gYSBiaXQgbW9yZSBpbnZlc3Rp Z2F0aW9uIEkndmUgbm90aWNlZCBob3cgbGF0ZSBwY2lfZW5hYmxlX2RldmljZQo+PiBpcyBkb25l LCBhbmQgY2FtZSB1cCB3aXRoIHRoaXMgcGF0Y2guIEl0J3MgYSBwYXRoIG9mIGxlc3MgcmVzaXN0 YW5jZToKPj4gSSdkIGV4cGVjdCBtYWludGFpbmVycyB0byBiZSBtb3JlIGF2ZXJzZSB0byByZW1v dmluZyB0aGUgY2hlY2sKPj4gcmF0aGVyIHRoYW4gZml4aW5nIGl0IHNvIGl0IHdvcmtzIGFzIGlu dGVuZGVkIChldmVuIHRob3VnaCBJIHRoaW5rCj4+IHRoZSBjaGVjayBzaG91bGQgbm90IGJlIHRo ZXJlIGluIHRoZSBmaXJzdCBwbGFjZSkuCj4+Cj4+IEhvd2V2ZXI6Cj4+Cj4+IFRoZSBhYmlsaXR5 IHRvIG1vZGlmeSB0aGUgY291bnRlcnMgaXMgbmVlZGVkIG9ubHkgZm9yIHNhbXBsaW5nIHRoZQo+ PiBldmVudHMgKGdldHRpbmcgYW4gaW50ZXJydXB0IHdoZW4gYSBjb3VudGVyIG92ZXJmbG93cyku IFRoZXJlJ3Mgbm8KPj4gY29kZSB0byBkbyB0aGF0IGZvciB0aGVzZSBBTUQgSU9NTVUgY291bnRl cnMuIEEgc29sdXRpb24gSSB3b3VsZAo+PiBwcmVmZXIgaXMgdG8gbm90IHdyaXRlIHRvIHRob3Nl IGNvdW50ZXJzIGF0IGFsbC4gSXQgd291bGQgc2ltcGxpZnkgb3IKPj4gZXZlbiByZW1vdmUgYSBi dW5jaCBvZiBjb2RlLiBJIGNhbiBzdWJtaXQgYSBjb3JyZXNwb25kaW5nIHBhdGNoIGlmCj4+IHRo ZXJlJ3MgZ2VuZXJhbCBhZ3JlZW1lbnQgdGhpcyBwYXRoIGlzIG9rLgo+Pgo+PiBXaGF0IGRvIHlv dSB0aGluaz8KPiAKPiBJIGxpa2UgdGhpcyBpZGVhLiBTdXJhdmVlLCBKw7ZyZywgd2hhdCBkbyB5 b3UgdGhpbms/Cj4gCj4gQ29tbWl0IDY3NzhmZjViMjFiIChpb21tdS9hbWQ6IEZpeCBwZXJmb3Jt YW5jZSBjb3VudGVyIGluaXRpYWxpemF0aW9uKSAKPiBkZWxheXMgdGhlIGJvb3QgdXAgdG8gMTAw IG1zLCB3aGljaCBpcyBvdmVyIDIwICUgb24gZmFzdCBzeXN0ZW1zLCBhbmQgCj4gYWxzbyBqdXN0 IGEgd29ya2Fyb3VuZCwgYW5kIGRvZXMgbm90IHNlZW0gdG8gd29yayBhbHdheXMuIFRoZSBkZWxh eSBpcyAKPiBhbHNvIG5vdCBtZW50aW9uZWQgaW4gdGhlIGNvbW1pdCBtZXNzYWdlLgo+IAo+CgpT b3VuZHMgZ29vZCB0byBtZS4gSSBjYW4gdGVzdCB0aGlzIG91dCBvbiBteSBzeXN0ZW0uCgp0aGFu a3MsCi0tIFNodWFoCgpfX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fXwppb21tdSBtYWlsaW5nIGxpc3QKaW9tbXVAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcK aHR0cHM6Ly9saXN0cy5saW51eGZvdW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vaW9tbXU=