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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11987C433EF for ; Tue, 15 Feb 2022 18:57:57 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6054449ED7; Tue, 15 Feb 2022 13:57:57 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id CVfpSBtUU05E; Tue, 15 Feb 2022 13:57:55 -0500 (EST) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A702749ED2; Tue, 15 Feb 2022 13:57:55 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 83DAC49ECF for ; Tue, 15 Feb 2022 13:57:54 -0500 (EST) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id NpY9GeMz8Uje for ; Tue, 15 Feb 2022 13:57:53 -0500 (EST) Received: from mail-io1-f54.google.com (mail-io1-f54.google.com [209.85.166.54]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 3853A49EBF for ; Tue, 15 Feb 2022 13:57:53 -0500 (EST) Received: by mail-io1-f54.google.com with SMTP id h5so1390132ioj.3 for ; Tue, 15 Feb 2022 10:57:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=xYfVux+CIlABTBnGP+1TuKUKEth7AQ/+EngXOD7SJRc=; b=c0Itl5iwd/n5gn0l5gRQjED/Gm+0SUMu0QvAZlzu6Uunay0OCCnebIYN2QLWE/vgr0 b1SRkggvbPIBirN3uR9G5/FqbZZKRlx3HIl6zHi42iNs9pE++n4yCWMnWxJsWqTcwU97 y2RWZMGWmQAMWgWTGZH6Hw6PF/jimIW8xqlfEhLrp3ruxE/g8+tVDBosnyy5nZH+16bF RyFh4PQA5cMTq7MPRu9GGizYCvIm5yOLfVSYyjfCM01wVqZged3cV+8o2n2goyKDU05h E2Rf2bZhDgmsgls83iQbHlO7n8aKBGV3ARfKHLKQIIYuZ5+qtEwnDjS8agz5x+/My3w8 OQfA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=xYfVux+CIlABTBnGP+1TuKUKEth7AQ/+EngXOD7SJRc=; b=TANFNP91yjtLh6TnXozXmFyzS0qOr8vQuH9aKtawchRTczdKiEQndjQOOyDEXf9GmJ HtwoQFsQc3l8TzCpSc6O/r5S9Q3ctViyOjYZ8O9Uf8n/R2yb8E6c2yLnMYSl8FpawtIs GhPgHlsw+QZWna7WhrjDp6v71ikRPNxpNftK9DKbOWXM3Pu+vAixTzMy/LNV01IsVLVI ZXb8MD0Vw66saCKRiOUgkEgtZLQwzw8aM0LbwUd2buqfS0aS45GvPoy1Ztpu6b/Q+E01 OG5e82eIpny9kltCxSubSV+dK036tcf43qIu4yRJG9rbnTjXfJA0kkGIapVxuNTKFGb/ vFBg== X-Gm-Message-State: AOAM5320gQaMJjcFDYfklcGKX4WTPvYureGpdwNGMLdnLq6P8wtO/J39 jBGutAzTR6gLcJA4a4uQOZYzdw== X-Google-Smtp-Source: ABdhPJwBqvknVuwUJVoIKC4yoStt6Wy8q4gp/ncMH7iNUF6wTE+Enpcr3H0D3NZSs3azu2iT2aFs3Q== X-Received: by 2002:a02:c90a:: with SMTP id t10mr220027jao.142.1644951472295; Tue, 15 Feb 2022 10:57:52 -0800 (PST) Received: from google.com (194.225.68.34.bc.googleusercontent.com. [34.68.225.194]) by smtp.gmail.com with ESMTPSA id t195sm16834393iof.47.2022.02.15.10.57.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Feb 2022 10:57:51 -0800 (PST) Date: Tue, 15 Feb 2022 18:57:47 +0000 From: Oliver Upton To: Reiji Watanabe Subject: Re: [PATCH v5 10/27] KVM: arm64: Hide IMPLEMENTATION DEFINED PMU support for the guest Message-ID: References: <20220214065746.1230608-1-reijiw@google.com> <20220214065746.1230608-11-reijiw@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220214065746.1230608-11-reijiw@google.com> Cc: kvm@vger.kernel.org, Marc Zyngier , Peter Shier , Will Deacon , Paolo Bonzini , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Reiji, On Sun, Feb 13, 2022 at 10:57:29PM -0800, Reiji Watanabe wrote: > When ID_AA64DFR0_EL1.PMUVER or ID_DFR0_EL1.PERFMON is 0xf, which > means IMPLEMENTATION DEFINED PMU supported, KVM unconditionally > expose the value for the guest as it is. Since KVM doesn't support > IMPLEMENTATION DEFINED PMU for the guest, in that case KVM should > expose 0x0 (PMU is not implemented) instead. > > Change cpuid_feature_cap_perfmon_field() to update the field value > to 0x0 when it is 0xf. Definitely agree with the change in this patch. Do we need to tolerate writes of 0xf for ABI compatibility (even if it is nonsensical)? Otherwise a guest with IMP_DEF PMU cannot be migrated to a newer kernel. -- Thanks, Oliver _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm