On Fri, 4 Dec 2015 12:49:49 +0100 Ingo Molnar <[email protected]> wrote:
> > * Igor Mammedov <[email protected]> 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. > > > > Signed-off-by: Igor Mammedov <[email protected]> > > --- > > arch/x86/kernel/pci-swiotlb.c | 2 +- > > arch/x86/mm/srat.c | 3 +++ > > 2 files changed, 4 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c > > index adf0392..7c577a1 100644 > > --- a/arch/x86/kernel/pci-swiotlb.c > > +++ b/arch/x86/kernel/pci-swiotlb.c > > @@ -88,7 +88,7 @@ int __init pci_swiotlb_detect_4gb(void) > > { > > /* don't initialize swiotlb if iommu=off (no_iommu=1) */ > > #ifdef CONFIG_X86_64 > > - if (!no_iommu && max_pfn > MAX_DMA32_PFN) > > + if (!no_iommu && max_possible_pfn > MAX_DMA32_PFN) > > swiotlb = 1; > > Ok, this series looks a lot better! > > > #endif > > return swiotlb; > > diff --git a/arch/x86/mm/srat.c b/arch/x86/mm/srat.c > > index c2aea63..a26bdbe 100644 > > --- a/arch/x86/mm/srat.c > > +++ b/arch/x86/mm/srat.c > > @@ -203,6 +203,9 @@ acpi_numa_memory_affinity_init(struct > > acpi_srat_mem_affinity *ma) > > pr_warn("SRAT: Failed to mark hotplug range [mem > > %#010Lx-%#010Lx] in memblock\n", > > (unsigned long long)start, (unsigned long long)end - 1); > > > > + if (max_possible_pfn < PFN_UP(end - 1)) > > + max_possible_pfn = PFN_UP(end - 1); > > Small nit, why not write this as something like: > > max_possible_pfn = max(max_possible_pfn, PFN_UP(end - 1)); > > ? > > I'd also move this second hunk to the first patch, because logically it > belongs > there (or into a third patch). sure, I'll move it to the 1st patch > > Thanks, > > Ingo -- 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/
