Messages in this thread | | | Date | Fri, 4 Dec 2015 12:49:49 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 2/2] x86_64: enable SWIOTLB if system has SRAT memory regions above MAX_DMA32_PFN |
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* Igor Mammedov <imammedo@redhat.com> 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 <imammedo@redhat.com> > --- > 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).
Thanks,
Ingo
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