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 <akong@xxxxxxxxxx>
---
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 f0eea07..ef261ab 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -144,7 +144,8 @@ 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 302681c..c6d9baf 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2926,7 +2926,8 @@ 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) *
--
1.8.1.4
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