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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 7A2C3C432C3 for ; Thu, 14 Nov 2019 05:12:29 +0000 (UTC) Received: from lists.ozlabs.org (lists.auug.org.au [203.11.71.3]) (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 3396E20659 for ; Thu, 14 Nov 2019 05:12:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b="A85mzLCe" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3396E20659 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=ozlabs.org Authentication-Results: mail.kernel.org; spf=fail smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 47D8k31kgjzF74S for ; Thu, 14 Nov 2019 16:12:27 +1100 (AEDT) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 47D8dS1HkqzF6lq for ; Thu, 14 Nov 2019 16:08:28 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=ozlabs.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; secure) header.d=ozlabs.org header.i=@ozlabs.org header.b="A85mzLCe"; dkim-atps=neutral Received: by ozlabs.org (Postfix, from userid 1003) id 47D8dR40m4z9s7T; Thu, 14 Nov 2019 16:08:27 +1100 (AEDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ozlabs.org; s=201707; t=1573708107; bh=kPRYQtgfmwdv40EbuZcqeYZToO/RlWVUa8XfGajWvEI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=A85mzLCe/m8AOIXYfoAJDqpK70LNQTu2NI6GpcGjIrL25sgnKF4HZRCR3kxRgBTf0 G172C2juWrJytAFkuaI+uojelB+dtpIJod2mwqc6bXxz5pU2EbAwmg0m4QNXU2clFC RDi0G4X+NjFnbjSk0g0YYXLGkjQDO1DMhXRKTSKGoPtCi+ueh2/hkbx+89sDFfLkZ6 HDL8rgIVAUeLPPowCl2fFbLv/u6yq0hhN57mTIl+TYgTxH3zcFaVwGlCWdBMs1vjn9 PfySVcQ910QyGD55HBHYIqO6ldJ2Nk64IK6NM/MF46bZWK22t6sZrm8aU2Q9l2vR2y xs13pE6bm/PlA== Date: Thu, 14 Nov 2019 16:08:25 +1100 From: Paul Mackerras To: Ram Pai Subject: Re: [PATCH v10 7/8] KVM: PPC: Implement H_SVM_INIT_ABORT hcall Message-ID: <20191114050825.GB28382@oak.ozlabs.ibm.com> References: <20191111041924.GA4017@oak.ozlabs.ibm.com> <20191112010158.GB5159@oc0525413822.ibm.com> <20191112053836.GB10885@oak.ozlabs.ibm.com> <20191112075215.GD5159@oc0525413822.ibm.com> <20191112113204.GA10178@blackberry> <20191112144555.GE5159@oc0525413822.ibm.com> <20191113001427.GA17829@oak.ozlabs.ibm.com> <20191113063233.GF5159@oc0525413822.ibm.com> <20191113211824.GA20535@blackberry> <20191113215042.GG5159@oc0525413822.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191113215042.GG5159@oc0525413822.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sukadev Bhattiprolu , cclaudio@linux.ibm.com, kvm-ppc@vger.kernel.org, Bharata B Rao , linux-mm@kvack.org, jglisse@redhat.com, Ram Pai , aneesh.kumar@linux.vnet.ibm.com, paulus@au1.ibm.com, sukadev@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, hch@lst.de Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, Nov 13, 2019 at 01:50:42PM -0800, Ram Pai wrote: > On Thu, Nov 14, 2019 at 08:18:24AM +1100, Paul Mackerras wrote: > > On Tue, Nov 12, 2019 at 10:32:33PM -0800, Ram Pai wrote: > > > On Wed, Nov 13, 2019 at 11:14:27AM +1100, Paul Mackerras wrote: > > > > On Tue, Nov 12, 2019 at 06:45:55AM -0800, Ram Pai wrote: > > > > > On Tue, Nov 12, 2019 at 10:32:04PM +1100, Paul Mackerras wrote: > > > > > > On Mon, Nov 11, 2019 at 11:52:15PM -0800, Ram Pai wrote: > > > > > > > There is subtle problem removing that code from the assembly. > > > > > > > > > > > > > > If the H_SVM_INIT_ABORT hcall returns to the ultravisor without clearing > > > > > > > kvm->arch.secure_guest, the hypervisor will continue to think that the > > > > > > > VM is a secure VM. However the primary reason the H_SVM_INIT_ABORT > > > > > > > hcall was invoked, was to inform the Hypervisor that it should no longer > > > > > > > consider the VM as a Secure VM. So there is a inconsistency there. > > > > > > > > > > > > Most of the checks that look at whether a VM is a secure VM use code > > > > > > like "if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)". Now > > > > > > since KVMPPC_SECURE_INIT_ABORT is 4, an if statement such as that will > > > > > > take the false branch once we have set kvm->arch.secure_guest to > > > > > > KVMPPC_SECURE_INIT_ABORT in kvmppc_h_svm_init_abort. So in fact in > > > > > > most places we will treat the VM as a normal VM from then on. If > > > > > > there are any places where we still need to treat the VM as a secure > > > > > > VM while we are processing the abort we can easily do that too. > > > > > > > > > > Is the suggestion -- KVMPPC_SECURE_INIT_ABORT should never return back > > > > > to the Ultravisor? Because removing that assembly code will NOT lead the > > > > > > > > No. The suggestion is that vcpu->arch.secure_guest stays set to > > > > KVMPPC_SECURE_INIT_ABORT until userspace calls KVM_PPC_SVM_OFF. > > > > > > In the fast_guest_return path, if it finds > > > (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_ABORT) is true, should it return to > > > UV or not? > > > > > > Ideally it should return back to the ultravisor the first time > > > KVMPPC_SECURE_INIT_ABORT is set, and not than onwards. > > > > What is ideal about that behavior? Why would that be a particularly > > good thing to do? > > It is following the rule -- "return back to the caller". That doesn't address the question of why vcpu->arch.secure_guest should be cleared at the point where we do that. Paul.