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 422EAC4332F for ; Sun, 13 Nov 2022 10:21:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235248AbiKMKVJ (ORCPT ); Sun, 13 Nov 2022 05:21:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231972AbiKMKVH (ORCPT ); Sun, 13 Nov 2022 05:21:07 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7F20911807 for ; Sun, 13 Nov 2022 02:21:06 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E2ADF60B46 for ; Sun, 13 Nov 2022 10:21:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3F5F7C433C1; Sun, 13 Nov 2022 10:21:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668334865; bh=bAJllN46EPAoI4gsSpHJ8M3EPpj3jJg9OxPG1MEqQGU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=f/2fqifuG1M7A6Z1OoNTm5evuC9kytJ96vnnCcLxjISUV6M2tb8Q3ZHZq/krY1zFF XtLIOQvUqtszAZNN7M9LKtvS8CUK6rA0xfahPNnR28FVoEF8ueWSvaRGtTjQDpueoV HZGZ39sWZWiJJ+WOlbg+W9xZGHhfVrMcCo77eAfHn9BB6Bm9+Ki18QppuaHEOnRHmb 0+RrUPSoyh/cZE+q3P6fo8HvOBUEVt5rjQnQhHU/uln1tGhYsBydlswsLY84WXPHtK +FJmq+apzfdcgphjmNNKZoDYXAh52892zNWfandT7T5pOVGe6J6jKwMlplFWd0Jobw dh4QEhWOb1Y9g== Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1ouA6o-005mZw-T8; Sun, 13 Nov 2022 10:21:02 +0000 MIME-Version: 1.0 Date: Sun, 13 Nov 2022 10:21:02 +0000 From: Marc Zyngier To: Reiji Watanabe Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev, kvm@vger.kernel.org, James Morse , Suzuki K Poulose , Alexandru Elisei , Oliver Upton , Ricardo Koller Subject: Re: [PATCH v3 11/14] KVM: arm64: PMU: Allow ID_AA64DFR0_EL1.PMUver to be set from userspace In-Reply-To: References: <20221107085435.2581641-1-maz@kernel.org> <20221107085435.2581641-12-maz@kernel.org> User-Agent: Roundcube Webmail/1.4.13 Message-ID: <136ee516118c97b8f3e4792b8ec9752a@kernel.org> X-Sender: maz@kernel.org Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: reijiw@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvmarm@lists.linux.dev, kvm@vger.kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, oliver.upton@linux.dev, ricarkol@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2022-11-08 05:38, Reiji Watanabe wrote: > Hi Marc, > > On Mon, Nov 7, 2022 at 1:16 AM Marc Zyngier wrote: >> >> Allow userspace to write ID_AA64DFR0_EL1, on the condition that only >> the PMUver field can be altered and be at most the one that was >> initially computed for the guest. >> >> Signed-off-by: Marc Zyngier >> --- >> arch/arm64/kvm/sys_regs.c | 40 >> ++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 39 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c >> index 7a4cd644b9c0..47c882401f3c 100644 >> --- a/arch/arm64/kvm/sys_regs.c >> +++ b/arch/arm64/kvm/sys_regs.c >> @@ -1247,6 +1247,43 @@ static int set_id_aa64pfr0_el1(struct kvm_vcpu >> *vcpu, >> return 0; >> } >> >> +static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, >> + const struct sys_reg_desc *rd, >> + u64 val) >> +{ >> + u8 pmuver, host_pmuver; >> + bool valid_pmu; >> + >> + host_pmuver = kvm_arm_pmu_get_pmuver_limit(); >> + >> + /* >> + * Allow AA64DFR0_EL1.PMUver to be set from userspace as long >> + * as it doesn't promise more than what the HW gives us. We >> + * allow an IMPDEF PMU though, only if no PMU is supported >> + * (KVM backward compatibility handling). >> + */ >> + pmuver = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer), >> val); >> + if ((pmuver != ID_AA64DFR0_EL1_PMUVer_IMP_DEF && pmuver > >> host_pmuver) || >> + (pmuver != 0 && pmuver < ID_AA64DFR0_EL1_PMUVer_IMP)) > > Nit: Since this second condition cannot be true (right?), perhaps it > might > be rather confusing? I wasn't able to understand what it meant until > I see the equivalent check in set_id_dfr0_el1() (Maybe just me > though:). Ah, that's just me being tainted with the AArch32 version which doesn't start at 1 for PMUv3. I'll drop it. Thanks, M. -- Jazz is not dead. It just smells funny...