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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 DC93EC433F5 for ; Thu, 23 Sep 2021 13:11:31 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 5570C61152 for ; Thu, 23 Sep 2021 13:11:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 5570C61152 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D59634B0B8; Thu, 23 Sep 2021 09:11:30 -0400 (EDT) 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 dZyrxsKdCQ-D; Thu, 23 Sep 2021 09:11:26 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id EB5FE4B15B; Thu, 23 Sep 2021 09:11:26 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8582F4B11C for ; Thu, 23 Sep 2021 09:11:25 -0400 (EDT) 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 VVmrFy0tCr5u for ; Thu, 23 Sep 2021 09:11:21 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 077944B0B8 for ; Thu, 23 Sep 2021 09:11:21 -0400 (EDT) Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0F0786103D; Thu, 23 Sep 2021 13:11:20 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mTOVS-00CXQj-2g; Thu, 23 Sep 2021 14:11:18 +0100 Date: Thu, 23 Sep 2021 14:11:17 +0100 Message-ID: <87y27ntp1m.wl-maz@kernel.org> From: Marc Zyngier To: Will Deacon Subject: Re: [PATCH 5/5] KVM: arm64: Disable privileged hypercalls after pKVM finalisation In-Reply-To: <20210923130211.GB15934@willie-the-truck> References: <20210923112256.15767-1-will@kernel.org> <20210923112256.15767-6-will@kernel.org> <87zgs3tpqi.wl-maz@kernel.org> <20210923130211.GB15934@willie-the-truck> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: will@kernel.org, linux-arm-kernel@lists.infradead.org, qperret@google.com, catalin.marinas@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, kvmarm@lists.cs.columbia.edu X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: Catalin Marinas , 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 On Thu, 23 Sep 2021 14:02:11 +0100, Will Deacon wrote: > > On Thu, Sep 23, 2021 at 01:56:21PM +0100, Marc Zyngier wrote: > > On Thu, 23 Sep 2021 12:22:56 +0100, > > Will Deacon wrote: [...] > > > static void handle_host_hcall(struct kvm_cpu_context *host_ctxt) > > > { > > > DECLARE_REG(unsigned long, id, host_ctxt, 0); > > > + unsigned long hcall_min = 0; > > > hcall_t hfn; > > > > > > + if (static_branch_unlikely(&kvm_protected_mode_initialized)) > > > + hcall_min = __KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize; > > > + > > > id -= KVM_HOST_SMCCC_ID(0); > > > > > > - if (unlikely(id >= ARRAY_SIZE(host_hcall))) > > > + if (unlikely(id < hcall_min || id >= ARRAY_SIZE(host_hcall))) > > > > So I can still issue a pkvm_prot_finalize after finalisation? Seems > > odd. As hcall_min has to be inclusive, you probably want it to be set > > to __KVM_HOST_SMCCC_FUNC___pkvm_host_share_hyp once protected. > > Yeah, I ended up addresing that one in the previous patch. The problem is > that we need to allow pkvm_prot_finalize to be called on each CPU, so I > think we'd end up having an extra "really finalize damnit!" call to be > issued _once_ after each CPU is done with the finalisation if we want > to lock it down. > > The approach I took instead is to make pkvm_prot_finalize return -EBUSY > if it's called on a CPU where it's already been called. Ah, I see. Serves me right for reading patches out of order. Finalise is of course per-CPU, and the static key global. Epic fail. Probably deserves a comment, because I'm surely going to jump at that again in three months. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm