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=-18.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 D1DACC4338F for ; Tue, 27 Jul 2021 18:11:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3CB260F6C for ; Tue, 27 Jul 2021 18:11:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229809AbhG0SLv (ORCPT ); Tue, 27 Jul 2021 14:11:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:54742 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229453AbhG0SLv (ORCPT ); Tue, 27 Jul 2021 14:11:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BC23860238; Tue, 27 Jul 2021 18:11:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627409510; bh=q1CHfyk12vw4U1T20eDp/l4diZTpTmt1XveN+HsNvZc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=SCpJSpyuVKJ48axoUhFScqf5GQrNcRTW7Gtnaj1EJYMEX8Gb0MkvbRJtuQez0w5vG btoxnHcjX+fWlo643xBBvL7U5CIQUVUOk3c1XUal0tjMpLnr+xe0XyjEqy5/9sqfyL Pt9y9IdexKHL0V2Li9zb+qr6LGHm+8NnVQGy9n6uq4/jIbCKsJONjWpww/Qknz3jnp 2hZbxFoRzkPp18BGYNFxz+JqpUYzF0BYhpL/AfOZnh+Hit/ODIYCDjp2ROAQVw2onu 1ZHnF6cvqaf0ZkK1Kdl/sNHT1DBIQ8PrryiofhODctOwl9BWzfqnWUxI5AyTe79ooM HqVQ0KjFrDUxw== Date: Tue, 27 Jul 2021 19:11:46 +0100 From: Will Deacon To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, qperret@google.com, dbrazdil@google.com, Srivatsa Vaddagiri , Shanker R Donthineni , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: Re: [PATCH 07/16] KVM: arm64: Wire MMIO guard hypercalls Message-ID: <20210727181145.GF19173@willie-the-truck> References: <20210715163159.1480168-1-maz@kernel.org> <20210715163159.1480168-8-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210715163159.1480168-8-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, Jul 15, 2021 at 05:31:50PM +0100, Marc Zyngier wrote: > Plumb in the hypercall interface to allow a guest to discover, > enroll, map and unmap MMIO regions. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/kvm/hypercalls.c | 20 ++++++++++++++++++++ > include/linux/arm-smccc.h | 28 ++++++++++++++++++++++++++++ > 2 files changed, 48 insertions(+) > > diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c > index 30da78f72b3b..a3deeb907fdd 100644 > --- a/arch/arm64/kvm/hypercalls.c > +++ b/arch/arm64/kvm/hypercalls.c > @@ -5,6 +5,7 @@ > #include > > #include > +#include > > #include > #include > @@ -129,10 +130,29 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID: > val[0] = BIT(ARM_SMCCC_KVM_FUNC_FEATURES); > val[0] |= BIT(ARM_SMCCC_KVM_FUNC_PTP); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP); > + val[0] |= BIT(ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP); > break; > case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: > kvm_ptp_get_time(vcpu, val); > break; > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_INFO_FUNC_ID: > + val[0] = PAGE_SIZE; > + break; I get the nagging feeling that querying the stage-2 page-size outside of MMIO guard is going to be useful once we start looking at memory sharing, so perhaps rename this to something more generic? > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_ENROLL_FUNC_ID: > + set_bit(KVM_ARCH_FLAG_MMIO_GUARD, &vcpu->kvm->arch.flags); > + val[0] = SMCCC_RET_SUCCESS; > + break; > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_MAP_FUNC_ID: > + if (kvm_install_ioguard_page(vcpu, vcpu_get_reg(vcpu, 1))) > + val[0] = SMCCC_RET_SUCCESS; > + break; > + case ARM_SMCCC_VENDOR_HYP_KVM_MMIO_GUARD_UNMAP_FUNC_ID: > + if (kvm_remove_ioguard_page(vcpu, vcpu_get_reg(vcpu, 1))) > + val[0] = SMCCC_RET_SUCCESS; > + break; I think there's a slight discrepancy between MAP and UNMAP here in that calling UNMAP on something that hasn't been mapped will fail, whereas calling MAP on something that's already been mapped will succeed. I think that might mean you can't reason about the final state of the page if two vCPUs race to call these functions in some cases (and both succeed). Will