From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35968) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dcerZ-0001Hn-WF for qemu-devel@nongnu.org; Tue, 01 Aug 2017 17:38:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dcerZ-0004px-5Z for qemu-devel@nongnu.org; Tue, 01 Aug 2017 17:38:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37774) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dcerY-0004pH-TP for qemu-devel@nongnu.org; Tue, 01 Aug 2017 17:38:01 -0400 Date: Wed, 2 Aug 2017 00:37:58 +0300 From: "Michael S. Tsirkin" Message-ID: <1501623438-31419-10-git-send-email-mst@redhat.com> References: <1501623438-31419-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1501623438-31419-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PULL 09/10] pc: make 'pc.rom' readonly when machine has PCI enabled List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , Igor Mammedov , Peng Hao , Paolo Bonzini , Richard Henderson , Eduardo Habkost From: Igor Mammedov looking at bios ROM mapping in QEMU it seems that only isapc (i.e. not PCI enabled machine) requires ROM being mapped as RW in other cases BIOS is mapped as RO. Do the same for option ROM 'pc.rom' when machine has PCI enabled. As useful side-effect pc.rom MemoryRegion stops being put in vhost memory map (filtered out by vhost_section()), which reduces number of entries by 1. Coincidentally it fixes migration failure reported in "[PATCH V2] vhost: fix a migration failed because of vhost region merge" where following destination CLI with /sys/module/vhost/parameters/max_mem_regions = 8 export DIMMSCOUNT=6 QEMU -enable-kvm \ -netdev type=tap,id=guest0,vhost=on,script=no,vhostforce \ -device virtio-net-pci,netdev=guest0 \ -m 256,slots=256,maxmem=2G \ `i=0; while [ $i -lt $DIMMSCOUNT ]; do echo \ "-object memory-backend-ram,id=m$i,size=128M \ -device pc-dimm,id=d$i,memdev=m$i"; i=$(($i + 1)); \ done` will fail to startup with error: "-device pc-dimm,id=d5,memdev=m5: a used vhost backend has no free memory slots left" while it's possible to add the 6th DIMM during hotplug on source. Issue is caused by the fact that number of entries in vhost map is bigger on 1 entry, when -device is processed, than after guest boots up, and that offending entry belongs to 'pc.rom', it's not like vhost intends to do IO in ROM range so making it RO hides region from vhost and makes number of entries in vhost memory map at -device/machine_done time match number of entries after guest boots. Signed-off-by: Igor Mammedov Reported-by: Peng Hao Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/i386/pc.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 22e1603..5943539 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -1443,6 +1443,9 @@ void pc_memory_init(PCMachineState *pcms, option_rom_mr = g_malloc(sizeof(*option_rom_mr)); memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE, &error_fatal); + if (pcmc->pci_enabled) { + memory_region_set_readonly(option_rom_mr, true); + } memory_region_add_subregion_overlap(rom_memory, PC_ROM_MIN_VGA, option_rom_mr, -- MST