2018-04-20 22:21 GMT+08:00 Cornelia Huck <coh...@redhat.com>: > On Fri, 20 Apr 2018 21:51:13 +0800 > Wanpeng Li <kernel...@gmail.com> wrote: > >> 2018-04-20 15:15 GMT+08:00 Cornelia Huck <coh...@redhat.com>: >> > On Thu, 19 Apr 2018 17:47:28 -0700 >> > Wanpeng Li <kernel...@gmail.com> wrote: >> > >> >> From: Wanpeng Li <wanpen...@tencent.com> >> >> >> >> 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 <pbonz...@redhat.com> >> >> Cc: Radim Krčmář <rkrc...@redhat.com> >> >> Cc: Tonny Lu <tonn...@tencent.com> >> >> Cc: Cornelia Huck <coh...@redhat.com> >> >> Signed-off-by: Wanpeng Li <wanpen...@tencent.com> >> >> Signed-off-by: Tonny Lu <tonn...@tencent.com> >> >> --- >> >> 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? Regards, Wanpeng Li
