From patchwork Thu Sep 8 09:48:28 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vitaly Kuznetsov X-Patchwork-Id: 9320783 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 033E760752 for ; Thu, 8 Sep 2016 09:50:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EDB472972C for ; Thu, 8 Sep 2016 09:50:36 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id E251929770; Thu, 8 Sep 2016 09:50:36 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 6B53D2972C for ; Thu, 8 Sep 2016 09:50:36 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1bhvx8-00008z-EW; Thu, 08 Sep 2016 09:49:02 +0000 Received: from casper.infradead.org ([2001:770:15f::2]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bhvx3-00008A-Ln for linux-arm-kernel@bombadil.infradead.org; Thu, 08 Sep 2016 09:48:57 +0000 Received: from mx1.redhat.com ([209.132.183.28]) by casper.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1bhvx1-00020S-Cg for linux-arm-kernel@lists.infradead.org; Thu, 08 Sep 2016 09:48:56 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D08E969187; Thu, 8 Sep 2016 09:48:31 +0000 (UTC) Received: from vitty.brq.redhat.com (vitty.brq.redhat.com [10.34.26.3]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u889mTPB025144; Thu, 8 Sep 2016 05:48:29 -0400 From: Vitaly Kuznetsov To: xen-devel@lists.xenproject.org Subject: [PATCH] arm/xen: fix SMP guests boot Date: Thu, 8 Sep 2016 11:48:28 +0200 Message-Id: <1473328108-30658-1-git-send-email-vkuznets@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Thu, 08 Sep 2016 09:48:32 +0000 (UTC) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20160908_104855_562955_38168B7A X-CRM114-Status: GOOD ( 20.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefano Stabellini , Wei Chen , linux-kernel@vger.kernel.org, Russell King , Julien Grall , David Vrabel , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP Commit 88e957d6e47f ("xen: introduce xen_vcpu_id mapping") broke SMP ARM guests on Xen. When FIFO-based event channels are in use (this is the default), evtchn_fifo_alloc_control_block() is called on CPU_UP_PREPARE event and this happens before we set up xen_vcpu_id mapping in xen_starting_cpu. Temporary fix the issue by setting direct Linux CPU id <-> Xen vCPU id mapping for all possible CPUs at boot. We don't currently support kexec/kdump on Xen/ARM so these ids always match. In future, we have several ways to solve the issue, e.g.: - Eliminate all hypercalls from CPU_UP_PREPARE, do them from the starting CPU. This can probably be done for both x86 and ARM and, if done, will allow us to get Xen's idea of vCPU id from CPUID/MPIDR on the starting CPU directly, no messing with ACPI/device tree required. - Save vCPU id information from ACPI/device tree on ARM and use it to initialize xen_vcpu_id mapping. This is the same trick we currently do on x86. Reported-by: Julien Grall Tested-by: Wei Chen Signed-off-by: Vitaly Kuznetsov Acked-by: Stefano Stabellini --- It would be nice if this patch could still make it to 4.8 as all SMP ARM/Xen guests are currently broken. --- arch/arm/xen/enlighten.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 3d2cef6..f193414 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -170,9 +170,6 @@ static int xen_starting_cpu(unsigned int cpu) pr_info("Xen: initializing cpu%d\n", cpu); vcpup = per_cpu_ptr(xen_vcpu_info, cpu); - /* Direct vCPU id mapping for ARM guests. */ - per_cpu(xen_vcpu_id, cpu) = cpu; - info.mfn = virt_to_gfn(vcpup); info.offset = xen_offset_in_page(vcpup); @@ -330,6 +327,7 @@ static int __init xen_guest_init(void) { struct xen_add_to_physmap xatp; struct shared_info *shared_info_page = NULL; + int cpu; if (!xen_domain()) return 0; @@ -380,7 +378,8 @@ static int __init xen_guest_init(void) return -ENOMEM; /* Direct vCPU id mapping for ARM guests. */ - per_cpu(xen_vcpu_id, 0) = 0; + for_each_possible_cpu(cpu) + per_cpu(xen_vcpu_id, cpu) = cpu; xen_auto_xlat_grant_frames.count = gnttab_max_grant_frames(); if (xen_xlate_map_ballooned_pages(&xen_auto_xlat_grant_frames.pfn,