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=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 44360C433E0 for ; Mon, 15 Mar 2021 11:10:04 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id AEED164E89 for ; Mon, 15 Mar 2021 11:10:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AEED164E89 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1C19E4B501; Mon, 15 Mar 2021 07:10:03 -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 4kGX5iVnBQRD; Mon, 15 Mar 2021 07:10:02 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id F3D764B50B; Mon, 15 Mar 2021 07:10:01 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id D79A94B501 for ; Mon, 15 Mar 2021 07:10:00 -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 uFXwabbOVaTN for ; Mon, 15 Mar 2021 07:09:59 -0400 (EDT) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 927864B161 for ; Mon, 15 Mar 2021 07:09:59 -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 A87F164E83; Mon, 15 Mar 2021 11:09:57 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.lan) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lLl6h-001dZy-OX; Mon, 15 Mar 2021 11:09:55 +0000 From: Marc Zyngier To: gregkh@linuxfoundation.org Subject: [PATCH][stable-5.4] KVM: arm64: Reject VM creation when the default IPA size is unsupported Date: Mon, 15 Mar 2021 11:09:52 +0000 Message-Id: <20210315110952.4136142-1-maz@kernel.org> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: gregkh@linuxfoundation.org, kvmarm@lists.cs.columbia.edu, kernel-team@android.com, stable@vger.kernel.org, drjones@redhat.com, eric.auger@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Cc: kernel-team@android.com, kvmarm@lists.cs.columbia.edu, stable@vger.kernel.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 Commit 7d717558dd5ef10d28866750d5c24ff892ea3778 upstream. KVM/arm64 has forever used a 40bit default IPA space, partially due to its 32bit heritage (where the only choice is 40bit). However, there are implementations in the wild that have a *cough* much smaller *cough* IPA space, which leads to a misprogramming of VTCR_EL2, and a guest that is stuck on its first memory access if userspace dares to ask for the default IPA setting (which most VMMs do). Instead, blundly reject the creation of such VM, as we can't satisfy the requirements from userspace (with a one-off warning). Also clarify the boot warning, and document that the VM creation will fail when an unsupported IPA size is provided. Although this is an ABI change, it doesn't really change much for userspace: - the guest couldn't run before this change, but no error was returned. At least userspace knows what is happening. - a memory slot that was accepted because it did fit the default IPA space now doesn't even get a chance to be registered. The other thing that is left doing is to convince userspace to actually use the IPA space setting instead of relying on the antiquated default. Fixes: 233a7cb23531 ("kvm: arm64: Allow tuning the physical address size for VM") Signed-off-by: Marc Zyngier Cc: stable@vger.kernel.org Reviewed-by: Andrew Jones Reviewed-by: Eric Auger Link: https://lore.kernel.org/r/20210311100016.3830038-2-maz@kernel.org --- Documentation/virt/kvm/api.txt | 3 +++ arch/arm64/kvm/reset.c | 11 ++++++++--- 2 files changed, 11 insertions(+), 3 deletions(-) diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt index 7064efd3b5ea..fd22224853e5 100644 --- a/Documentation/virt/kvm/api.txt +++ b/Documentation/virt/kvm/api.txt @@ -172,6 +172,9 @@ is dependent on the CPU capability and the kernel configuration. The limit can be retrieved using KVM_CAP_ARM_VM_IPA_SIZE of the KVM_CHECK_EXTENSION ioctl() at run-time. +Creation of the VM will fail if the requested IPA size (whether it is +implicit or explicit) is unsupported on the host. + Please note that configuring the IPA size does not affect the capability exposed by the guest CPUs in ID_AA64MMFR0_EL1[PARange]. It only affects size of the address translated by the stage2 level (guest physical to diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index 784d485218ca..a3105ae464be 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -378,10 +378,10 @@ void kvm_set_ipa_limit(void) pr_info("kvm: Limiting the IPA size due to kernel %s Address limit\n", (va_max < pa_max) ? "Virtual" : "Physical"); - WARN(ipa_max < KVM_PHYS_SHIFT, - "KVM IPA limit (%d bit) is smaller than default size\n", ipa_max); kvm_ipa_limit = ipa_max; - kvm_info("IPA Size Limit: %dbits\n", kvm_ipa_limit); + kvm_info("IPA Size Limit: %d bits%s\n", kvm_ipa_limit, + ((kvm_ipa_limit < KVM_PHYS_SHIFT) ? + " (Reduced IPA size, limited VM/VMM compatibility)" : "")); } /* @@ -408,6 +408,11 @@ int kvm_arm_setup_stage2(struct kvm *kvm, unsigned long type) return -EINVAL; } else { phys_shift = KVM_PHYS_SHIFT; + if (phys_shift > kvm_ipa_limit) { + pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n", + current->comm); + return -EINVAL; + } } parange = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1) & 7; -- 2.29.2 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm