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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 039E6C4338F for ; Thu, 12 Aug 2021 10:00:31 +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 AF9DC61038 for ; Thu, 12 Aug 2021 10:00:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AF9DC61038 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc: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=DJg7jc7kRSyWrzhDpjvIHj+6gtpDO+j4oo/1WkyDj9U=; b=DAsZVuzm+W4N2V NtSln4sN4EcffghBW2zgpWC0KRgVb8MfCTY3VQeF/qReZunVpRH8ly4FknshhZu3U4Z1QeMeJQzY3 XVBYmPISepAsz3wV+fphJ+gyU5lFjrHh0dbbkzSf7EkZplQbuIIZN07Dt5SDX5+GR0piltOFMJ+b4 siX8QRXkWJE5slE5Clj526XmLBq57/9ViwkauaMbXq1RG+qbxRcjt13LYlUgdKYiM+xnNlwOWjm6k hWF3g9D9kWEcxrhk/Yiexhmdn9BuzxQKdHklArppIomRFBAsckJPb1jkseBxOH+XRrs4JOCRCqac7 Glr8TVROXmL3eNY+cUPw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mE7TJ-009aAX-7w; Thu, 12 Aug 2021 09:57:57 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mE7TD-009a9O-9u for linux-arm-kernel@lists.infradead.org; Thu, 12 Aug 2021 09:57:55 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9ED9960F57; Thu, 12 Aug 2021 09:57:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1628762269; bh=HxmpIxZ8vP71X/haLXmLN6MBqTPWJ4X2U98Wz3faOco=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qi3GtSC95NtI+T6MxxcNybLmWFslRHvRU4ZDmPgyAoXbqx4EgyXqEnLVndjdRYaUe /Wgt8tZ9n4FTy+sfler2nLtrTLmuML0Uoj/RttYKi+nE9x8SQJepidfJYmEemGOfgP UGRkBZqW/HX9AsEjDgBGf7hq1/A7IJsqTRL03YUn/hMtiY7hwctM+HqysiEQXlfqBJ ZHCWU+Qo1HSJE/NFdGC1ZsUTImBJZp7yHuEziSB43FNJN0XHeBIigL2okY/EjPR9ok sL1F0NCCNRHHUEcQ7PQ4eXre5RZGobzyfcWG5dsVno/9VK3AMkNHeTLHg4PxMHD8l1 izwVzHr89iTrg== Date: Thu, 12 Aug 2021 10:57:44 +0100 From: Will Deacon To: Fuad Tabba Cc: kvmarm@lists.cs.columbia.edu, maz@kernel.org, james.morse@arm.com, alexandru.elisei@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.com, christoffer.dall@arm.com, pbonzini@redhat.com, drjones@redhat.com, qperret@google.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com Subject: Re: [PATCH v3 14/15] KVM: arm64: Handle protected guests at 32 bits Message-ID: <20210812095743.GL5912@willie-the-truck> References: <20210719160346.609914-1-tabba@google.com> <20210719160346.609914-15-tabba@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210719160346.609914-15-tabba@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210812_025751_424432_17BCAF56 X-CRM114-Status: GOOD ( 24.18 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jul 19, 2021 at 05:03:45PM +0100, Fuad Tabba wrote: > Protected KVM does not support protected AArch32 guests. However, > it is possible for the guest to force run AArch32, potentially > causing problems. Add an extra check so that if the hypervisor > catches the guest doing that, it can prevent the guest from > running again by resetting vcpu->arch.target and returning > ARM_EXCEPTION_IL. > > Adapted from commit 22f553842b14 ("KVM: arm64: Handle Asymmetric > AArch32 systems") > > Signed-off-by: Fuad Tabba > --- > arch/arm64/kvm/hyp/include/hyp/switch.h | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h > index 8431f1514280..f09343e15a80 100644 > --- a/arch/arm64/kvm/hyp/include/hyp/switch.h > +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -477,6 +478,29 @@ static inline bool fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code) > write_sysreg_el2(read_sysreg_el2(SYS_ELR) - 4, SYS_ELR); > } > > + /* > + * Protected VMs might not be allowed to run in AArch32. The check below > + * is based on the one in kvm_arch_vcpu_ioctl_run(). > + * The ARMv8 architecture doesn't give the hypervisor a mechanism to > + * prevent a guest from dropping to AArch32 EL0 if implemented by the > + * CPU. If the hypervisor spots a guest in such a state ensure it is > + * handled, and don't trust the host to spot or fix it. > + */ > + if (unlikely(is_nvhe_hyp_code() && > + kvm_vm_is_protected(kern_hyp_va(vcpu->kvm)) && > + FIELD_GET(FEATURE(ID_AA64PFR0_EL0), > + PVM_ID_AA64PFR0_ALLOW) < > + ID_AA64PFR0_ELx_32BIT_64BIT && > + vcpu_mode_is_32bit(vcpu))) { > + /* > + * As we have caught the guest red-handed, decide that it isn't > + * fit for purpose anymore by making the vcpu invalid. > + */ > + vcpu->arch.target = -1; > + *exit_code = ARM_EXCEPTION_IL; > + goto exit; > + } Would this be better off inside the nvhe-specific run loop? Seems like we could elide fixup_guest_exit() altogether if we've detect that we're in AArch32 state when we shouldn't be and it would keep the code off the shared path. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel