From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: qemu-kvm: require 4K aligned resource size for memory Date: Tue, 20 Oct 2009 19:15:09 +0200 Message-ID: <20091020171508.GD13378@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Dor Laor , kvm@vger.kernel.org To: Chris Wright Return-path: Received: from mx1.redhat.com ([209.132.183.28]:27803 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751477AbZJTRRS (ORCPT ); Tue, 20 Oct 2009 13:17:18 -0400 Received: from int-mx08.intmail.prod.int.phx2.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.21]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id n9KHHMfA016384 for ; Tue, 20 Oct 2009 13:17:23 -0400 Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: KVM does not virtualize low address bits for memory accesses, so we must require that PCI BAR size is a multiple of 4K for passthrough to work (this also guarantees that address is 4K aligned). Users of recent linux kernels can force resource size up to 4K using: commit 32a9a682bef2f6fce7026bd94d1ce20028b0e52d Author: Yuji Shimada Date: Mon Mar 16 17:13:39 2009 +0900 PCI: allow assignment of memory resources with a specified alignment Signed-off-by: Michael S. Tsirkin --- diff --git a/hw/device-assignment.c b/hw/device-assignment.c index 237060f..c2ef31f 100644 --- a/hw/device-assignment.c +++ b/hw/device-assignment.c @@ -381,6 +381,14 @@ static int assigned_dev_register_regions(PCIRegion *io_regions, int t = cur_region->type & IORESOURCE_PREFETCH ? PCI_ADDRESS_SPACE_MEM_PREFETCH : PCI_ADDRESS_SPACE_MEM; + if (cur_region->size & 0xFFF) { + fprintf(stderr, "Unable to assign device: PCI region %d " + "at address 0x%llx has size 0x%x, " + " which is not a multiple of 4K\n", + i, (unsigned long long)cur_region->base_addr, + cur_region->size); + return -1; + } /* map physical memory */ pci_dev->v_addrs[i].e_physbase = cur_region->base_addr;