[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC 0/N] xen: arm: rework early bring up
On Wed, 2013-09-18 at 22:14 +0100, Julien Grall wrote: > On 09/18/2013 09:22 PM, Ian Campbell wrote: > > On Wed, 2013-09-18 at 21:00 +0100, Julien Grall wrote: > >> On 09/18/2013 08:24 PM, Ian Campbell wrote: > >>> On Wed, 2013-09-18 at 20:22 +0100, Ian Campbell wrote: > >>>> On Wed, 2013-09-18 at 18:33 +0100, Julien Grall wrote: > >>>>> On 09/17/2013 02:37 AM, Ian Campbell wrote: > >>>>>> Hi, > >>>>>> > >>>>>> The following reworks early bring up on ARM to use a separate set of > >>>>>> boot pagetables. This simplifies things by avoiding the need to bring > >>>>>> up > >>>>>> all CPUs in lock step, which in turn allows us to do secondary CPU > >>>>>> bringup in C code. > >>>>>> > >>>>>> Unfortunately the main bulk of this change is a single large patch > >>>>>> which > >>>>>> is hard to decompose any further since it is basically pulling on the > >>>>>> thread and then knitting a new jumper from it. > >>>>>> > >>>>>> With these changes Xen now absolutely requires that the bootloader > >>>>>> calls > >>>>>> the hypervisor in HYP mode, the previous workarounds have been removed. > >>>>>> For use on models a bootwrapper is now required. See > >>>>>> git://xenbits.xen.org/people/ianc/boot-wrapper.git xen-arm32 > >>>>>> git://xenbits.xen.org/people/ianc/boot-wrapper-aarch64.git > >>>>>> xen-arm64 > >>>>>> > >>>>>> I have implemented support for CPU bringup on the fastmodel vexpress > >>>>>> platforms (v7and v8) here, I suppose it should work OK on a real > >>>>>> vexpress too but I've not tried it. > >>>>> > >>>>> I have just tried the patch series on the versatile express and it > >>>>> doesn't work. I'm using the u-boot from Andre and all the cpus already > >>>>> boot in hyp mode (checked without this patch series). > >>>> > >>>> :-( > >>>> > >>>> The code should essentially the same as the old kick cpus, but > >>>> reimplemented in C. The only difference I can spot is that the C version > >>>> is kicking a single CPU at a time while the ASM version is kicking > >>>> everyone at once. Does using send_SGI_allbutself instead work as a hack? > >>>> > >>>> Perhaps our idea of the CPUID is wrong or something? Your patches to > >>>> fixup the logical CPU id stuff might help? > >> > >> I have found the issue, in send_SGI_mask we remove the offline CPUs with > >> the following line: > >> mask &= cpumask_bits(&cpu_online_map); > >> > >> As the secondary cpu (assuming we have a board with only 2 cores) is not > >> yet online, we can't send SGI with our code. > >> I'm very surprised that the code works on the fast models. > > > > So am I, now. > > > > OK. So online mask == 0x1 and we are trying to wake mask 0x2, so the > > actual target list we end up using is 0... > > > > The gic manual says "When TargetListFilter is 0b00, if the CPUTargetList > > field is 0x00 the Distributor does not forward the interrupt to any CPU > > interface." (footnote to table 4-21), so it shouldn't be waking > > anything... It may be a model bug > > > >> To solve the issue, I think we need to create another helper which will > >> send an SGI wihout removing offline CPUs. > > > > Looking briefly at the callchains leading to send_SGI_mask I don't see > > any which deliberately pass an offline CPU (which would be pretty > > non-sensical apart from this one case). So we could perhaps just remove > > this check and make it the caller's problem. > > Or maybe the right check is for cpu_possible mask or something similar > > instead of online? > > You are right, cpu_possible mask is better. > I can modify this patch http://patches.linaro.org/20437/ to add the > check in gic_cpu_mask. Sounds reasonable. > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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