On 04/21/2018 02:38 AM, Wanpeng Li wrote: > 2018-04-20 22:21 GMT+08:00 Cornelia Huck <cohuck@xxxxxxxxxx>: >> On Fri, 20 Apr 2018 21:51:13 +0800 >> Wanpeng Li <kernellwp@xxxxxxxxx> wrote: >> >>> 2018-04-20 15:15 GMT+08:00 Cornelia Huck <cohuck@xxxxxxxxxx>: >>>> On Thu, 19 Apr 2018 17:47:28 -0700 >>>> Wanpeng Li <kernellwp@xxxxxxxxx> wrote: >>>> >>>>> From: Wanpeng Li <wanpengli@xxxxxxxxxxx> >>>>> >>>>> Our virtual machines make use of device assignment by configuring >>>>> 12 NVMe disks for high I/O performance. Each NVMe device has 129 >>>>> MSI-X Table entries: >>>>> Capabilities: [50] MSI-X: Enable+ Count=129 Masked-Vector table: BAR=0 offset=00002000 >>>>> The windows virtual machines fail to boot since they will map the number of >>>>> MSI-table entries that the NVMe hardware reported to the bus to msi routing >>>>> table, this will exceed the 1024. This patch extends MAX_IRQ_ROUTES to 4096 >>>>> for all archs, in the future this might be extended again if needed. >>>>> >>>>> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> >>>>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> >>>>> Cc: Tonny Lu <tonnylu@xxxxxxxxxxx> >>>>> Cc: Cornelia Huck <cohuck@xxxxxxxxxx> >>>>> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx> >>>>> Signed-off-by: Tonny Lu <tonnylu@xxxxxxxxxxx> >>>>> --- >>>>> v1 -> v2: >>>>> * extend MAX_IRQ_ROUTES to 4096 for all archs >>>>> >>>>> include/linux/kvm_host.h | 6 ------ >>>>> 1 file changed, 6 deletions(-) >>>>> >>>>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >>>>> index 6930c63..0a5c299 100644 >>>>> --- a/include/linux/kvm_host.h >>>>> +++ b/include/linux/kvm_host.h >>>>> @@ -1045,13 +1045,7 @@ static inline int mmu_notifier_retry(struct kvm *kvm, unsigned long mmu_seq) >>>>> >>>>> #ifdef CONFIG_HAVE_KVM_IRQ_ROUTING >>>>> >>>>> -#ifdef CONFIG_S390 >>>>> #define KVM_MAX_IRQ_ROUTES 4096 //FIXME: we can have more than that... >>>> >>>> What about /* might need extension/rework in the future */ instead of >>>> the FIXME? >>> >>> Yeah, I guess the maintainers can help to fix it when applying. :) >>> >>>> >>>> As far as I understand, 4096 should cover most architectures and the >>>> sane end of s390 configurations, but will not be enough at the scarier >>>> end of s390. (I'm not sure how much it matters in practice.) >>>> >>>> Do we want to make this a tuneable in the future? Do some kind of >>>> dynamic allocation? Not sure whether it is worth the trouble. >>> >>> I think keep as it is currently. >> >> My main question here is how long this is enough... the number of >> virtqueues per device is up to 1K from the initial 64, which makes it >> possible to hit the 4K limit with fewer virtio devices than before (on >> s390, each virtqueue uses a routing table entry). OTOH, we don't want >> giant tables everywhere just to accommodate s390. > > I suspect there is no real scenario to futher extend for s390 since no > guys report. > >> If the s390 maintainers tell me that nobody is doing the really insane >> stuff, I'm happy as well :) > > Christian, any thoughts? For now this patch is a no-op for s390 so as long as nobody complains today we are good. If it turns out to be "not enough" we can then add a configurable number or whatever.
