Hi Igor, Shameer, On 2/27/19 11:10 AM, Igor Mammedov wrote: > On Tue, 26 Feb 2019 18:53:24 +0100 > Auger Eric <eric.au...@redhat.com> wrote: > >> Hi Igor, >> >> On 2/26/19 5:56 PM, Igor Mammedov wrote: >>> On Tue, 26 Feb 2019 14:11:58 +0100 >>> Auger Eric <eric.au...@redhat.com> wrote: >>> >>>> Hi Igor, >>>> >>>> On 2/26/19 9:40 AM, Auger Eric wrote: >>>>> Hi Igor, >>>>> >>>>> On 2/25/19 10:42 AM, Igor Mammedov wrote: >>>>>> On Fri, 22 Feb 2019 18:35:26 +0100 >>>>>> Auger Eric <eric.au...@redhat.com> wrote: >>>>>> >>>>>>> Hi Igor, >>>>>>> >>>>>>> On 2/22/19 5:27 PM, Igor Mammedov wrote: >>>>>>>> On Wed, 20 Feb 2019 23:39:46 +0100 >>>>>>>> Eric Auger <eric.au...@redhat.com> wrote: >>>>>>>> >>>>>>>>> This series aims to bump the 255GB RAM limit in machvirt and to >>>>>>>>> support device memory in general, and especially PCDIMM/NVDIMM. >>>>>>>>> >>>>>>>>> In machvirt versions < 4.0, the initial RAM starts at 1GB and can >>>>>>>>> grow up to 255GB. From 256GB onwards we find IO regions such as the >>>>>>>>> additional GICv3 RDIST region, high PCIe ECAM region and high PCIe >>>>>>>>> MMIO region. The address map was 1TB large. This corresponded to >>>>>>>>> the max IPA capacity KVM was able to manage. >>>>>>>>> >>>>>>>>> Since 4.20, the host kernel is able to support a larger and dynamic >>>>>>>>> IPA range. So the guest physical address can go beyond the 1TB. The >>>>>>>>> max GPA size depends on the host kernel configuration and physical >>>>>>>>> CPUs. >>>>>>>>> >>>>>>>>> In this series we use this feature and allow the RAM to grow without >>>>>>>>> any other limit than the one put by the host kernel. >>>>>>>>> >>>>>>>>> The RAM still starts at 1GB. First comes the initial ram (-m) of size >>>>>>>>> ram_size and then comes the device memory (,maxmem) of size >>>>>>>>> maxram_size - ram_size. The device memory is potentially hotpluggable >>>>>>>>> depending on the instantiated memory objects. >>>>>>>>> >>>>>>>>> IO regions previously located between 256GB and 1TB are moved after >>>>>>>>> the RAM. Their offset is dynamically computed, depends on ram_size >>>>>>>>> and maxram_size. Size alignment is enforced. >>>>>>>>> >>>>>>>>> In case maxmem value is inferior to 255GB, the legacy memory map >>>>>>>>> still is used. The change of memory map becomes effective from 4.0 >>>>>>>>> onwards. >>>>>>>>> >>>>>>>>> As we keep the initial RAM at 1GB base address, we do not need to do >>>>>>>>> invasive changes in the EDK2 FW. It seems nobody is eager to do >>>>>>>>> that job at the moment. >>>>>>>>> >>>>>>>>> Device memory being put just after the initial RAM, it is possible >>>>>>>>> to get access to this feature while keeping a 1TB address map. >>>>>>>>> >>>>>>>>> This series reuses/rebases patches initially submitted by Shameer >>>>>>>>> in [1] and Kwangwoo in [2] for the PC-DIMM and NV-DIMM parts. >>>>>>>>> >>>>>>>>> Functionally, the series is split into 3 parts: >>>>>>>>> 1) bump of the initial RAM limit [1 - 9] and change in >>>>>>>>> the memory map >>>>>>>> >>>>>>>>> 2) Support of PC-DIMM [10 - 13] >>>>>>>> Is this part complete ACPI wise (for coldplug)? I haven't noticed >>>>>>>> DSDT AML here no E820 changes, so ACPI wise pc-dimm shouldn't be >>>>>>>> visible to the guest. It might be that DT is masking problem >>>>>>>> but well, that won't work on ACPI only guests. >>>>>>> >>>>>>> guest /proc/meminfo or "lshw -class memory" reflects the amount of mem >>>>>>> added with the DIMM slots. >>>>>> Question is how does it get there? Does it come from DT or from firmware >>>>>> via UEFI interfaces? >>>>>> >>>>>>> So it looks fine to me. Isn't E820 a pure x86 matter? >>>>>> sorry for misleading, I've meant is UEFI GetMemoryMap(). >>>>>> On x86, I'm wary of adding PC-DIMMs to E802 which then gets exposed >>>>>> via UEFI GetMemoryMap() as guest kernel might start using it as normal >>>>>> memory early at boot and later put that memory into zone normal and hence >>>>>> make it non-hot-un-pluggable. The same concerns apply to DT based means >>>>>> of discovery. >>>>>> (That's guest issue but it's easy to workaround it not putting >>>>>> hotpluggable >>>>>> memory into UEFI GetMemoryMap() or DT and let DSDT describe it properly) >>>>>> That way memory doesn't get (ab)used by firmware or early boot kernel >>>>>> stages >>>>>> and doesn't get locked up. >>>>>> >>>>>>> What else would you expect in the dsdt? >>>>>> Memory device descriptions, look for code that adds PNP0C80 with _CRS >>>>>> describing memory ranges >>>>> >>>>> OK thank you for the explanations. I will work on PNP0C80 addition then. >>>>> Does it mean that in ACPI mode we must not output DT hotplug memory >>>>> nodes or assuming that PNP0C80 is properly described, it will "override" >>>>> DT description? >>>> >>>> After further investigations, I think the pieces you pointed out are >>>> added by Shameer's series, ie. through the build_memory_hotplug_aml() >>>> call. So I suggest we separate the concerns: this series brings support >>>> for DIMM coldplug. hotplug, including all the relevant ACPI structures >>>> will be added later on by Shameer. >>> >>> Maybe we should not put pc-dimms in DT for this series until it gets clear >>> if it doesn't conflict with ACPI in some way. >> >> I guess you mean removing the DT hotpluggable memory nodes only in ACPI >> mode? Otherwise you simply remove the DIMM feature, right? > Something like this so DT won't get in conflict with ACPI. > Only we don't have a switch for it something like, -machine fdt=on (with > default off) > >> I double checked and if you remove the hotpluggable memory DT nodes in >> ACPI mode: >> - you do not see the PCDIMM slots in guest /proc/meminfo anymore. So I >> guess you're right, if the DT nodes are available, that memory is >> considered as not unpluggable by the guest. >> - You can see the NVDIMM slots using ndctl list -u. You can mount a DAX >> system. >> >> Hotplug/unplug is clearly not supported by this series and any attempt >> results in "memory hotplug is not supported". Is it really an issue if >> the guest does not consider DIMM slots as not hot-unpluggable memory? I >> am not even sure the guest kernel would support to unplug that memory. >> >> In case we want all ACPI tables to be ready for making this memory seen >> as hot-unpluggable we need some Shameer's patches on top of this series. > May be we should push for this way (into 4.0), it's just a several patches > after all or even merge them in your series (I'd guess it would need to be > rebased on top of your latest work)
Shameer, would you agree if we merge PATCH 1 of your RFC hotplug series (without the reduced hw_reduced_acpi flag) in this series and isolate in a second PATCH the acpi_memory_hotplug_init() + build_memory_hotplug_aml called in virt code? Then would remain the GED/GPIO actual integration. Thanks Eric > >> Also don't DIMM slots already make sense in DT mode. Usually we accept >> to add one feature in DT and then in ACPI. For instance we can benefit > usually it doesn't conflict with each other (at least I'm not aware of it) > but I see a problem with in this case. > >> from nvdimm in dt mode right? So, considering an incremental approach I >> would be in favour of keeping the DT nodes. > I'd guess it is the same as for DIMMs, ACPI support for NVDIMMs is much > more versatile. > > I consider target application of arm/virt as a board that's used to > run in production generic ACPI capable guest in most use cases and > various DT only guests as secondary ones. It's hard to make > both usecases be happy with defaults (that's probably one of the > reasons why 'sbsa' board is being added). > > So I'd give priority to ACPI based arm/virt versus DT when defaults are > considered. > >> Thanks >> >> Eric >>> >>> >>> >>> >