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 <[email protected]>
Acked-by: Rik van Riel <[email protected]> -- All rights reversed -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
