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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 49843C282DD for ; Thu, 9 Jan 2020 17:25:28 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 16C5F206ED for ; Thu, 9 Jan 2020 17:25:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="pUg7oCiF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 16C5F206ED Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=hePyl4h+UPokvMb6lDwpZ4b1OMFzO6gLy0NQIUcelIc=; b=pUg7oCiFI1Vm4Z xWMg/m0wBSbiYOUmWldjDgZcSZrVeFY1mND0oKlpGvBgabrASknO12BOqNRLLMYIk9Dzl0clsfouK Ly2re6kvNz+AEivPgKn2wF0CdbO0VpDHi7LPIK5MFS5SFoEQQwuhL1PYySxqO0xmHtQs4KXDtcFv5 Fu1OwU2bBJwQGZ4XKCERHkHDZn7U9SC5kM+rpqa8g08/3ce3ZcPZavZg7ds576kpVfsuLY2ipzvM4 KNbuavelppSBldPHLvKT/wzA0A5bGR1fvu7fOT2yG+AmVwyj6CiuSPab0He8ZekDRUNydNhhndV9w ucliP/Nzw5iY48ao8DBg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipbYe-00011Y-Um; Thu, 09 Jan 2020 17:25:20 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1ipbYY-00010J-SY for linux-arm-kernel@lists.infradead.org; Thu, 09 Jan 2020 17:25:18 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 320E7328; Thu, 9 Jan 2020 09:25:14 -0800 (PST) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A75BE3F703; Thu, 9 Jan 2020 09:25:13 -0800 (PST) Date: Thu, 9 Jan 2020 17:25:12 +0000 From: Andrew Murray To: Marc Zyngier Subject: Re: [PATCH v2 11/18] KVM: arm64: don't trap Statistical Profiling controls to EL2 Message-ID: <20200109172511.GA42593@e119886-lin.cambridge.arm.com> References: <20191220143025.33853-1-andrew.murray@arm.com> <20191220143025.33853-12-andrew.murray@arm.com> <86bls0iqv6.wl-maz@kernel.org> <20191223115651.GA42593@e119886-lin.cambridge.arm.com> <1bb190091362262021dbaf41b5fe601e@www.loen.fr> <20191223121042.GC42593@e119886-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191223121042.GC42593@e119886-lin.cambridge.arm.com> User-Agent: Mutt/1.10.1+81 (426a6c1) (2018-08-26) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200109_092515_013633_06738C89 X-CRM114-Status: GOOD ( 26.48 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, Catalin Marinas , linux-kernel@vger.kernel.org, Sudeep Holla , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Dec 23, 2019 at 12:10:42PM +0000, Andrew Murray wrote: > On Mon, Dec 23, 2019 at 12:05:12PM +0000, Marc Zyngier wrote: > > On 2019-12-23 11:56, Andrew Murray wrote: > > > On Sun, Dec 22, 2019 at 10:42:05AM +0000, Marc Zyngier wrote: > > > > On Fri, 20 Dec 2019 14:30:18 +0000, > > > > Andrew Murray wrote: > > > > > > > > > > As we now save/restore the profiler state there is no need to trap > > > > > accesses to the statistical profiling controls. Let's unset the > > > > > _TPMS bit. > > > > > > > > > > Signed-off-by: Andrew Murray > > > > > --- > > > > > arch/arm64/kvm/debug.c | 2 -- > > > > > 1 file changed, 2 deletions(-) > > > > > > > > > > diff --git a/arch/arm64/kvm/debug.c b/arch/arm64/kvm/debug.c > > > > > index 43487f035385..07ca783e7d9e 100644 > > > > > --- a/arch/arm64/kvm/debug.c > > > > > +++ b/arch/arm64/kvm/debug.c > > > > > @@ -88,7 +88,6 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu > > > > *vcpu) > > > > > * - Performance monitors (MDCR_EL2_TPM/MDCR_EL2_TPMCR) > > > > > * - Debug ROM Address (MDCR_EL2_TDRA) > > > > > * - OS related registers (MDCR_EL2_TDOSA) > > > > > - * - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB) > > > > > * > > > > > * Additionally, KVM only traps guest accesses to the debug > > > > registers if > > > > > * the guest is not actively using them (see the > > > > KVM_ARM64_DEBUG_DIRTY > > > > > @@ -111,7 +110,6 @@ void kvm_arm_setup_debug(struct kvm_vcpu > > > > *vcpu) > > > > > */ > > > > > vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & > > > > MDCR_EL2_HPMN_MASK; > > > > > vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM | > > > > > - MDCR_EL2_TPMS | > > > > > > > > No. This is an *optional* feature (the guest could not be presented > > > > with the SPE feature, or the the support simply not be compiled in). > > > > > > > > If the guest is not allowed to see the feature, for whichever > > > > reason, > > > > the traps *must* be enabled and handled. > > > > > > I'll update this (and similar) to trap such registers when we don't > > > support > > > SPE in the guest. > > > > > > My original concern in the cover letter was in how to prevent the guest > > > from attempting to use these registers in the first place - I think the > > > solution I was looking for is to trap-and-emulate ID_AA64DFR0_EL1 such > > > that > > > the PMSVer bits indicate that SPE is not emulated. > > > > That, and active trapping of the SPE system registers resulting in injection > > of an UNDEF into the offending guest. > > Yes that's no problem. The spec says that 'direct access to [these registers] are UNDEFINED' - is it not more correct to handle this with trap_raz_wi than an undefined instruction? Thanks, Andrew Murray > > Thanks, > > Andrew Murray > > > > > Thanks, > > > > M. > > -- > > Jazz is not dead. It just smells funny... > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel