David Gibson wrote: > On Tue, Apr 17, 2018 at 09:28:42AM +0530, Bharata B Rao wrote: >> On Mon, Apr 16, 2018 at 07:47:29PM +0300, Serhii Popovych wrote: >>> Bharata B Rao wrote: >>>> On Wed, Apr 11, 2018 at 02:41:59PM -0400, Serhii Popovych wrote: >>>>> Now recent kernels (i.e. since linux-stable commit a346137e9142 >>>>> ("powerpc/numa: Use ibm,max-associativity-domains to discover possible >>>>> nodes") >>>>> support this property to mark initially memory-less NUMA nodes as >>>>> "possible" >>>>> to allow further memory hot-add to them. >>>>> >>>>> Advertise this property for pSeries machines to let guest kernels detect >>>>> maximum supported node configuration and benefit from kernel side change >>>>> when hot-add memory to specific, possibly empty before, NUMA node. >>>>> >>>>> Signed-off-by: Serhii Popovych <spopo...@redhat.com> >>>>> --- >>>>> hw/ppc/spapr.c | 10 ++++++++++ >>>>> 1 file changed, 10 insertions(+) >>>>> >>>>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c >>>>> index a81570e..c05bbad 100644 >>>>> --- a/hw/ppc/spapr.c >>>>> +++ b/hw/ppc/spapr.c >>>>> @@ -910,6 +910,13 @@ static void spapr_dt_rtas(sPAPRMachineState *spapr, >>>>> void *fdt) >>>>> 0, cpu_to_be32(SPAPR_MEMORY_BLOCK_SIZE), >>>>> cpu_to_be32(max_cpus / smp_threads), >>>>> }; >>>>> + uint32_t maxdomains[] = { >>>>> + cpu_to_be32(4), >>>>> + cpu_to_be32(0), >>>>> + cpu_to_be32(0), >>>>> + cpu_to_be32(0), >>>>> + cpu_to_be32(nb_numa_nodes - 1), >>>>> + }; >>>>> >>>>> _FDT(rtas = fdt_add_subnode(fdt, 0, "rtas")); >>>>> >>>>> @@ -946,6 +953,9 @@ static void spapr_dt_rtas(sPAPRMachineState *spapr, >>>>> void *fdt) >>>>> _FDT(fdt_setprop(fdt, rtas, "ibm,associativity-reference-points", >>>>> refpoints, sizeof(refpoints))); >>>>> >>>>> + _FDT(fdt_setprop(fdt, rtas, "ibm,max-associativity-domains", >>>>> + maxdomains, sizeof(maxdomains))); >>>>> + >>>>> _FDT(fdt_setprop_cell(fdt, rtas, "rtas-error-log-max", >>>>> RTAS_ERROR_LOG_MAX)); >>>>> _FDT(fdt_setprop_cell(fdt, rtas, "rtas-event-scan-rate", >>>> >>>> This commit causes hash guest with latest guest kernel to hang at early >>>> boot. >>> >>> I use v4.16 tag from stable and can't reproduce on P8 machine reported >>> issue. >>> >>> Could you please share more details about your setup, kernel commit id >>> you spot problem? >> >> I am on 4.16.0-rc7 (commit id: 0b412605ef5f) >> >> BTW this happens only for non-NUMA guest. > > Ah, that might explain it. With no NUMA nodes specified, I think this > code will put a -1 into the max-associativity-domains property, which > is probably causing the mess. If we don't have NUMA (nb_numa_nodes == > 0) we probably want to either omit the property entirely, or clamp > that 5th cell to 0. > Ok, proposed fix already posted to qemu-devel. Sorry forgot to CC.
Mail subject contains (w/o quotas): "spapr: Correct max associativity domains value for non-NUMA configs" Tested with v4.16 tag: o Before : non-NUMA configs: able to reproduce, stall during boot o After : non-NUMA configs: not reproducible, boot is ok -- Thanks, Serhii
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