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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DAFDC6FD18 for ; Tue, 28 Mar 2023 20:05:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229655AbjC1UFg (ORCPT ); Tue, 28 Mar 2023 16:05:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54328 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229487AbjC1UFe (ORCPT ); Tue, 28 Mar 2023 16:05:34 -0400 Received: from mail-ot1-x332.google.com (mail-ot1-x332.google.com [IPv6:2607:f8b0:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A380D8 for ; Tue, 28 Mar 2023 13:05:33 -0700 (PDT) Received: by mail-ot1-x332.google.com with SMTP id l39-20020a9d1b2a000000b006a121324abdso5461919otl.7 for ; Tue, 28 Mar 2023 13:05:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1680033933; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=G6FEViEm4gU8JFCJ2RcfK27b9/P3kvs8pk7ugYHZuE0=; b=CAj5fUeBt+P1MSKUzcuWRJjggwGGZ+vYKqnFK/a54Ju3lhtya1J1ugBJg02KobtzFt 8OHDRLAGnK49Hx7QJTS0AVwRdX7Fgmdsd4TKdXNs+tRx1/ptmc6RczIfzfYG5/SQfgj8 3yEn2AMT2wn8RXg4V5X8ikI0vD9BjMhzdr7BJJg7VppGmJsLlEeQtJNrMNW3YiQ7MhWw I9lc1/2rFeHVLoby+T7rDtcRu/PIILyndSj2r3Mg1YHb38qobpZ6Tb053+pUuG1NTrX1 HLs+ndyMV9XKJWk5lFtVD7mB4GS/LBjge8IN4uOyqfEQB43z9Rh8ajNCDdxjM5Irm013 ut7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680033933; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=G6FEViEm4gU8JFCJ2RcfK27b9/P3kvs8pk7ugYHZuE0=; b=lIzaAZ2aUKPl5zN4Lg0cVGrH+G3aoZgye8br8xKKG1iWWH6dYJLWigXPZ/DIPoLcJt QxUV/bILqAVJAR8mCqutocvOanXu96uec80lm3uEF4MsK31Y5Md82dJLxc9e8AH/L1Xc +PJFXz65scNocedsuFz5lFlXB4A8UyY5uCA5aSVa0kHOOVXAjXFgq1jPWJOs7rZHYZVu FqxhkzUJcLmqUGtjyWSGUsr0F250Gz601jPdIQo4WKtp6r9iAFBbq4W/8iWZzgo3O0H7 ionjvk42Q7N+sP9PqwEhJ6bpOcrMsH1I3jf3ez7ihoj2K4k1InbK4ObKxIZlf7h7TrPx HG0Q== X-Gm-Message-State: AO0yUKVUpF3QYEHkXWjt+jL26BpMyG5KlyYqxgd8cdePvlsmxjhQaeml 6rJGsSGepN/8VgGT396ahgTaQ8hbpqw2fizhoLKZlg== X-Google-Smtp-Source: AK7set+9cVCFolZRcf/HkeMdzjRC+qu7Oe4WvcGrY+CXjpOPVRzgrslvflHbt6aKN8UoutEzxgbN5k5tngkpn/CeRpA= X-Received: by 2002:a9d:7998:0:b0:694:3b4e:d8d7 with SMTP id h24-20020a9d7998000000b006943b4ed8d7mr8972612otm.0.1680033932848; Tue, 28 Mar 2023 13:05:32 -0700 (PDT) MIME-Version: 1.0 References: <20230317050637.766317-1-jingzhangos@google.com> <20230317050637.766317-3-jingzhangos@google.com> <861qlaxzyw.wl-maz@kernel.org> <87y1ngr89q.wl-maz@kernel.org> In-Reply-To: <87y1ngr89q.wl-maz@kernel.org> From: Jing Zhang Date: Tue, 28 Mar 2023 13:05:21 -0700 Message-ID: Subject: Re: [PATCH v4 2/6] KVM: arm64: Save ID registers' sanitized value per guest To: Marc Zyngier Cc: KVM , KVMARM , ARMLinux , Oliver Upton , Will Deacon , Paolo Bonzini , James Morse , Alexandru Elisei , Suzuki K Poulose , Fuad Tabba , Reiji Watanabe , Ricardo Koller , Raghavendra Rao Ananta Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Mar 28, 2023 at 12:22=E2=80=AFPM Marc Zyngier wrot= e: > > On Tue, 28 Mar 2023 18:36:58 +0100, > Jing Zhang wrote: > > > > Hi Marc, > > [...] > > > IIUC, usually we don't need a specific locking to update idregs here. > > All idregs are 64 bit and can be read/written atomically. The only > > case that may need a locking is to keep the consistency for PMUVer in > > AA64DFR0_EL1 and PerfMon in DFR0_EL1. If there is no use case for two > > VCPU threads in a VM to update PMUVer and PerfMon concurrently, then > > we don't need the locking as in later patch by using the kvm lock. > > WDTY? > > I think we generally need locking for any writable id-reg, the goal > being that they will ultimately *all* be writable. As you found out, > there is this need for the PMU fields, and I'm willing to bet that > there will be more of those. > > And given that the locking you have used in some of the later patches > violates the locking order (don't worry, you're not alone!), we need > to use something else. Which is where Oliver's series comes into play. Got it. Thanks for the details. I'll add locking based on Oliver's series. > > Thanks, > > M. > > -- > Without deviation from the norm, progress is not possible. Thanks, Jing 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 4F219C76196 for ; Tue, 28 Mar 2023 20:06:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From: In-Reply-To:References:MIME-Version:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=R9uCmW/TaAWtxQm1tEnEl5BlmfYLHwlONeejF1D/ShI=; b=JrQqLxeZdCJfNc ge9bIywwjdxiLW6Lq2cKMJWWj6DaGwKiIanD9Ln1fhixxfZsgddQjothkTlWhISbLJZmKo+bDN6ld gaCZ6f4H+gKl4hWhQ3JwUtMHzWcAGH40JVVqEyR0ZG27E4vYc2nzFEvqmocVLWzfxW8FKCEBCq+JF h5hqIoAXACpQ0DlSI4KvHw1t2DKjO7HUc8JYzWwuVU8Rc26AzClkYlrzfKAjwqA4m6KyVFlqUFCXt NfwfXo25pnjQcs8UgGrYa7N6DSOMXDmCGD2aDL2eLITn5ozgUJKmbY+dM/OhlfDgWsyPe26qU0Rw0 kdqXFIpLnkM5WSIVQTDw==; 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Tue, 28 Mar 2023 13:05:32 -0700 (PDT) MIME-Version: 1.0 References: <20230317050637.766317-1-jingzhangos@google.com> <20230317050637.766317-3-jingzhangos@google.com> <861qlaxzyw.wl-maz@kernel.org> <87y1ngr89q.wl-maz@kernel.org> In-Reply-To: <87y1ngr89q.wl-maz@kernel.org> From: Jing Zhang Date: Tue, 28 Mar 2023 13:05:21 -0700 Message-ID: Subject: Re: [PATCH v4 2/6] KVM: arm64: Save ID registers' sanitized value per guest To: Marc Zyngier Cc: KVM , KVMARM , ARMLinux , Oliver Upton , Will Deacon , Paolo Bonzini , James Morse , Alexandru Elisei , Suzuki K Poulose , Fuad Tabba , Reiji Watanabe , Ricardo Koller , Raghavendra Rao Ananta X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230328_130534_314630_728BBD6C X-CRM114-Status: GOOD ( 21.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gVHVlLCBNYXIgMjgsIDIwMjMgYXQgMTI6MjLigK9QTSBNYXJjIFp5bmdpZXIgPG1hekBrZXJu ZWwub3JnPiB3cm90ZToKPgo+IE9uIFR1ZSwgMjggTWFyIDIwMjMgMTg6MzY6NTggKzAxMDAsCj4g SmluZyBaaGFuZyA8amluZ3poYW5nb3NAZ29vZ2xlLmNvbT4gd3JvdGU6Cj4gPgo+ID4gSGkgTWFy YywKPgo+IFsuLi5dCj4KPiA+IElJVUMsIHVzdWFsbHkgd2UgZG9uJ3QgbmVlZCBhIHNwZWNpZmlj IGxvY2tpbmcgdG8gdXBkYXRlIGlkcmVncyBoZXJlLgo+ID4gQWxsIGlkcmVncyBhcmUgNjQgYml0 IGFuZCBjYW4gYmUgcmVhZC93cml0dGVuIGF0b21pY2FsbHkuIFRoZSBvbmx5Cj4gPiBjYXNlIHRo YXQgbWF5IG5lZWQgYSBsb2NraW5nIGlzIHRvIGtlZXAgdGhlIGNvbnNpc3RlbmN5IGZvciBQTVVW ZXIgaW4KPiA+IEFBNjRERlIwX0VMMSBhbmQgUGVyZk1vbiBpbiBERlIwX0VMMS4gSWYgdGhlcmUg aXMgbm8gdXNlIGNhc2UgZm9yIHR3bwo+ID4gVkNQVSB0aHJlYWRzIGluIGEgVk0gdG8gdXBkYXRl IFBNVVZlciBhbmQgUGVyZk1vbiBjb25jdXJyZW50bHksIHRoZW4KPiA+IHdlIGRvbid0IG5lZWQg dGhlIGxvY2tpbmcgYXMgaW4gbGF0ZXIgcGF0Y2ggYnkgdXNpbmcgdGhlIGt2bSBsb2NrLgo+ID4g V0RUWT8KPgo+IEkgdGhpbmsgd2UgZ2VuZXJhbGx5IG5lZWQgbG9ja2luZyBmb3IgYW55IHdyaXRh YmxlIGlkLXJlZywgdGhlIGdvYWwKPiBiZWluZyB0aGF0IHRoZXkgd2lsbCB1bHRpbWF0ZWx5ICph bGwqIGJlIHdyaXRhYmxlLiBBcyB5b3UgZm91bmQgb3V0LAo+IHRoZXJlIGlzIHRoaXMgbmVlZCBm b3IgdGhlIFBNVSBmaWVsZHMsIGFuZCBJJ20gd2lsbGluZyB0byBiZXQgdGhhdAo+IHRoZXJlIHdp bGwgYmUgbW9yZSBvZiB0aG9zZS4KPgo+IEFuZCBnaXZlbiB0aGF0IHRoZSBsb2NraW5nIHlvdSBo YXZlIHVzZWQgaW4gc29tZSBvZiB0aGUgbGF0ZXIgcGF0Y2hlcwo+IHZpb2xhdGVzIHRoZSBsb2Nr aW5nIG9yZGVyIChkb24ndCB3b3JyeSwgeW91J3JlIG5vdCBhbG9uZSEpLCB3ZSBuZWVkCj4gdG8g dXNlIHNvbWV0aGluZyBlbHNlLiBXaGljaCBpcyB3aGVyZSBPbGl2ZXIncyBzZXJpZXMgY29tZXMg aW50byBwbGF5LgpHb3QgaXQuIFRoYW5rcyBmb3IgdGhlIGRldGFpbHMuIEknbGwgYWRkIGxvY2tp bmcgYmFzZWQgb24gT2xpdmVyJ3Mgc2VyaWVzLgo+Cj4gVGhhbmtzLAo+Cj4gICAgICAgICBNLgo+ Cj4gLS0KPiBXaXRob3V0IGRldmlhdGlvbiBmcm9tIHRoZSBub3JtLCBwcm9ncmVzcyBpcyBub3Qg cG9zc2libGUuClRoYW5rcywKSmluZwoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxpc3QKbGludXgtYXJtLWtl cm5lbEBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRlYWQub3JnL21haWxt YW4vbGlzdGluZm8vbGludXgtYXJtLWtlcm5lbAo=