From: Amos Kong <[email protected]> commit 6ea34c9b78c10289846db0abeebd6b84d5aca084 upstream.
We can easily reach the 1000 limit by start VM with a couple hundred I/O devices (multifunction=on). The hardcode limit already been adjusted 3 times (6 ~ 200 ~ 300 ~ 1000). In userspace, we already have maximum file descriptor to limit ioeventfd count. But kvm_io_bus devices also are used for pit, pic, ioapic, coalesced_mmio. They couldn't be limited by maximum file descriptor. Currently only ioeventfds take too much kvm_io_bus devices, so just exclude it from counting kvm_io_range limit. Also fixed one indent issue in kvm_host.h Signed-off-by: Amos Kong <[email protected]> Reviewed-by: Stefan Hajnoczi <[email protected]> Signed-off-by: Gleb Natapov <[email protected]> [wt: next patch depends on this one] Signed-off-by: Willy Tarreau <[email protected]> --- include/linux/kvm_host.h | 3 ++- virt/kvm/eventfd.c | 2 ++ virt/kvm/kvm_main.c | 3 ++- 3 files changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 8db53cf..cbe9083 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -145,7 +145,8 @@ struct kvm_io_range { #define NR_IOBUS_DEVS 1000 struct kvm_io_bus { - int dev_count; + int dev_count; + int ioeventfd_count; struct kvm_io_range range[]; }; diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c index 64ee720..1550637 100644 --- a/virt/kvm/eventfd.c +++ b/virt/kvm/eventfd.c @@ -753,6 +753,7 @@ kvm_assign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) if (ret < 0) goto unlock_fail; + kvm->buses[bus_idx]->ioeventfd_count++; list_add_tail(&p->list, &kvm->ioeventfds); mutex_unlock(&kvm->slots_lock); @@ -798,6 +799,7 @@ kvm_deassign_ioeventfd(struct kvm *kvm, struct kvm_ioeventfd *args) continue; kvm_io_bus_unregister_dev(kvm, bus_idx, &p->dev); + kvm->buses[bus_idx]->ioeventfd_count--; ioeventfd_release(p); ret = 0; break; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e9128725..36d14e5 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2936,7 +2936,8 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, struct kvm_io_bus *new_bus, *bus; bus = kvm->buses[bus_idx]; - if (bus->dev_count > NR_IOBUS_DEVS - 1) + /* exclude ioeventfd which is limited by maximum fd */ + if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1) return -ENOSPC; new_bus = kzalloc(sizeof(*bus) + ((bus->dev_count + 1) * -- 2.8.0.rc2.1.gbe9624a
