From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: [PATCH] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN Date: Mon, 30 Nov 2015 21:45:29 -0500 Message-ID: <565D09C9.9000708@redhat.com> References: <1448904938-92922-1-git-send-email-imammedo@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41713 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751841AbbLACpd (ORCPT ); Mon, 30 Nov 2015 21:45:33 -0500 In-Reply-To: <1448904938-92922-1-git-send-email-imammedo@redhat.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Igor Mammedov , linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, konrad.wilk@oracle.com, rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org, akataria@vmware.com, fujita.tomonori@lab.ntt.co.jp, revers@redhat.com On 11/30/2015 12:35 PM, Igor Mammedov wrote: > when memory hotplug enabled system is booted with less > than 4GB of RAM and then later more RAM is hotplugged > 32-bit devices stop functioning with following error: > > nommu_map_single: overflow 327b4f8c0+1522 of device mask ffffffff > > the reason for this is that if x86_64 system were booted > with RAM less than 4GB, it doesn't enable SWIOTLB and > when memory is hotplugged beyond MAX_DMA32_PFN, devices > that expect 32-bit addresses can't handle 64-bit addresses. > > Fix it by tracking max possible PFN when parsing > memory affinity structures from SRAT ACPI table and > enable SWIOTLB if there is hotpluggable memory > regions beyond MAX_DMA32_PFN. > > It fixes KVM guests when they use emulated devices > (reproduces with ata_piix, e1000 and usb devices, > RHBZ: 1275941, 1275977, 1271527) > It also fixes the HyperV, VMWare with emulated devices > which are affected by this issue as well. > > Systems that have RAM less than 4GB and do not use > memory hotplug but still have hotplug regions in SRAT > (i.e. broken BIOS that can't disable mem hotplug) > can disable memory hotplug with 'acpi_no_memhotplug = 1' > to avoid automatic SWIOTLB initialization. > > Tested on QEMU/KVM and HyperV. > > Signed-off-by: Igor Mammedov Acked-by: Rik van Riel -- All rights reversed