[PATCH 3.10 242/250] kvm: exclude ioeventfd from counting kvm_io_range limit
From: Willy Tarreau <w@1wt.eu>
Date: 2017-06-07 23:35:06
Also in:
lkml
Subsystem:
kernel virtual machine (kvm), the rest · Maintainers:
Paolo Bonzini, Linus Torvalds
From: Amos Kong <redacted> 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 <redacted> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Gleb Natapov <redacted> [wt: next patch depends on this one] Signed-off-by: Willy Tarreau <w@1wt.eu> --- 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