From patchwork Tue Sep 4 15:13:39 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cornelia Huck X-Patchwork-Id: 1403001 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id 4948BE00A6 for ; Tue, 4 Sep 2012 15:15:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932498Ab2IDPPS (ORCPT ); Tue, 4 Sep 2012 11:15:18 -0400 Received: from e06smtp15.uk.ibm.com ([195.75.94.111]:39904 "EHLO e06smtp15.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757225Ab2IDPNs (ORCPT ); Tue, 4 Sep 2012 11:13:48 -0400 Received: from /spool/local by e06smtp15.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 4 Sep 2012 16:13:47 +0100 Received: from b06cxnps4074.portsmouth.uk.ibm.com (9.149.109.196) by e06smtp15.uk.ibm.com (192.168.101.145) with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted; Tue, 4 Sep 2012 16:13:46 +0100 Received: from d06av07.portsmouth.uk.ibm.com (d06av07.portsmouth.uk.ibm.com [9.149.37.248]) by b06cxnps4074.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q84FDd0K54001860; Tue, 4 Sep 2012 15:13:39 GMT Received: from d06av07.portsmouth.uk.ibm.com (d06av07.portsmouth.uk.ibm.com [127.0.0.1]) by d06av07.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q84EibIo024701; Tue, 4 Sep 2012 10:44:39 -0400 Received: from tuxmaker.boeblingen.de.ibm.com (tuxmaker.boeblingen.de.ibm.com [9.152.85.9]) by d06av07.portsmouth.uk.ibm.com (8.14.4/8.13.1/NCO v10.0 AVin) with ESMTP id q84Eiajs024630; Tue, 4 Sep 2012 10:44:36 -0400 From: Cornelia Huck To: KVM , linux-s390 , qemu-devel Cc: Avi Kivity , Marcelo Tosatti , Anthony Liguori , Rusty Russell , Christian Borntraeger , Carsten Otte , Alexander Graf , Heiko Carstens , Martin Schwidefsky , Sebastian Ott Subject: [PATCH v2 1/4] s390/kvm: Handle hosts not supporting s390-virtio. Date: Tue, 4 Sep 2012 17:13:39 +0200 Message-Id: <1346771622-52763-2-git-send-email-cornelia.huck@de.ibm.com> X-Mailer: git-send-email 1.7.11.5 In-Reply-To: <1346771622-52763-1-git-send-email-cornelia.huck@de.ibm.com> References: <1346771622-52763-1-git-send-email-cornelia.huck@de.ibm.com> x-cbid: 12090415-0342-0000-0000-000002BFB337 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Running under a kvm host does not necessarily imply the presence of a page mapped above the main memory with the virtio information; however, the code includes a hard coded access to that page. Instead, check for the presence of the page and exit gracefully before we hit an addressing exception if it does not exist. Signed-off-by: Cornelia Huck --- Changes v1->v2: - check for the presence of the patch with lura - reorder init sequence - comments --- drivers/s390/kvm/kvm_virtio.c | 39 +++++++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 8 deletions(-) diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c index 47cccd5..76b95f3 100644 --- a/drivers/s390/kvm/kvm_virtio.c +++ b/drivers/s390/kvm/kvm_virtio.c @@ -419,6 +419,26 @@ static void kvm_extint_handler(struct ext_code ext_code, } /* + * For s390-virtio, we expect a page above main storage containing + * the virtio configuration. Try to actually load from this area + * in order to figure out if the host provides this page. + */ +static int __init test_devices_support(unsigned long addr) +{ + int ret = -EIO; + + asm volatile( + "0: lura 0,%1\n" + "1: xgr %0,%0\n" + "2:\n" + EX_TABLE(0b,2b) + EX_TABLE(1b,2b) + : "+d" (ret) + : "a" (addr) + : "0", "cc"); + return ret; +} +/* * Init function for virtio * devices are in a single page above top of "normal" mem */ @@ -429,21 +449,24 @@ static int __init kvm_devices_init(void) if (!MACHINE_IS_KVM) return -ENODEV; + if (test_devices_support(real_memory_size) < 0) + /* No error. */ + return 0; + + rc = vmem_add_mapping(real_memory_size, PAGE_SIZE); + if (rc) + return rc; + + kvm_devices = (void *) real_memory_size; + kvm_root = root_device_register("kvm_s390"); if (IS_ERR(kvm_root)) { rc = PTR_ERR(kvm_root); printk(KERN_ERR "Could not register kvm_s390 root device"); + vmem_remove_mapping(real_memory_size, PAGE_SIZE); return rc; } - rc = vmem_add_mapping(real_memory_size, PAGE_SIZE); - if (rc) { - root_device_unregister(kvm_root); - return rc; - } - - kvm_devices = (void *) real_memory_size; - INIT_WORK(&hotplug_work, hotplug_devices); service_subclass_irq_register();