From patchwork Thu Jul 24 19:27:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Will Deacon X-Patchwork-Id: 4619651 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id A7984C0514 for ; Thu, 24 Jul 2014 19:28:15 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id CE6C8201DC for ; Thu, 24 Jul 2014 19:28:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DB93C201D3 for ; Thu, 24 Jul 2014 19:28:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934551AbaGXT2J (ORCPT ); Thu, 24 Jul 2014 15:28:09 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:60796 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934311AbaGXT2H (ORCPT ); Thu, 24 Jul 2014 15:28:07 -0400 Received: from edgewater-inn.cambridge.arm.com (edgewater-inn.cambridge.arm.com [10.1.203.34]) by cam-admin0.cambridge.arm.com (8.12.6/8.12.6) with ESMTP id s6OJRlwo021306; Thu, 24 Jul 2014 20:27:47 +0100 (BST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id 2E49D1AE0AE4; Thu, 24 Jul 2014 20:27:50 +0100 (BST) From: Will Deacon To: pbonzini@redhat.com, gleb@kernel.org Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, Will Deacon , Christoffer Dall , Marc Zyngier , Joel Schopp , Don Dutile , Peter Maydell , Subject: [PATCH] kvm: arm64: vgic: fix hyp panic with 64k pages on juno platform Date: Thu, 24 Jul 2014 20:27:47 +0100 Message-Id: <1406230067-926-1-git-send-email-will.deacon@arm.com> X-Mailer: git-send-email 2.0.1 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP If the physical address of GICV isn't page-aligned, then we end up creating a stage-2 mapping of the page containing it, which causes us to map neighbouring memory locations directly into the guest. As an example, consider a platform with GICV at physical 0x2c02f000 running a 64k-page host kernel. If qemu maps this into the guest at 0x80010000, then guest physical addresses 0x80010000 - 0x8001efff will map host physical region 0x2c020000 - 0x2c02efff. Accesses to these physical regions may cause UNPREDICTABLE behaviour, for example, on the Juno platform this will cause an SError exception to EL3, which brings down the entire physical CPU resulting in RCU stalls / HYP panics / host crashing / wasted weeks of debugging. SBSA recommends that systems alias the 4k GICV across the bounding 64k region, in which case GICV physical could be described as 0x2c020000 in the above scenario. This patch fixes the problem by failing the vgic probe if the physical address of GICV isn't page-aligned. Note that this generated a warning in dmesg about freeing enabled IRQs, so I had to move the IRQ enabling later in the probe. Cc: Christoffer Dall Cc: Marc Zyngier Cc: Gleb Natapov Cc: Paolo Bonzini Cc: Joel Schopp Cc: Don Dutile Cc: Peter Maydell Cc: Signed-off-by: Will Deacon --- Paulo, Gleb, This fixes a *really* nasty bug with 64k-page hosts and KVM. I believe Marc and Christoffer are both on holiday at the moment (not together), so could you please take this as an urgent fix? Without it, I can trivially bring down machines using kvm. I've checked that it applies cleanly against -next, so you shouldn't see any conflicts during the merge window. Thanks, Will virt/kvm/arm/vgic.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c index 56ff9bebb577..fa9a95b3ed19 100644 --- a/virt/kvm/arm/vgic.c +++ b/virt/kvm/arm/vgic.c @@ -1526,17 +1526,25 @@ int kvm_vgic_hyp_init(void) goto out_unmap; } - kvm_info("%s@%llx IRQ%d\n", vgic_node->name, - vctrl_res.start, vgic_maint_irq); - on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1); - if (of_address_to_resource(vgic_node, 3, &vcpu_res)) { kvm_err("Cannot obtain VCPU resource\n"); ret = -ENXIO; goto out_unmap; } + + if (!PAGE_ALIGNED(vcpu_res.start)) { + kvm_err("GICV physical address 0x%llx not page aligned\n", + (unsigned long long)vcpu_res.start); + ret = -ENXIO; + goto out_unmap; + } + vgic_vcpu_base = vcpu_res.start; + kvm_info("%s@%llx IRQ%d\n", vgic_node->name, + vctrl_res.start, vgic_maint_irq); + on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1); + goto out; out_unmap: