[PATCH] kvm: exclude ioeventfd from counting kvm_io_range limit

Previous Topic Next Topic
 
classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

[PATCH] kvm: exclude ioeventfd from counting kvm_io_range limit

Amos Kong
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 <[hidden email]>
---
 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


Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] kvm: exclude ioeventfd from counting kvm_io_range limit

Stefan Hajnoczi
On Sat, May 25, 2013 at 06:44:15AM +0800, Amos Kong wrote:

> 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 <[hidden email]>
> ---
>  include/linux/kvm_host.h | 3 ++-
>  virt/kvm/eventfd.c       | 2 ++
>  virt/kvm/kvm_main.c      | 3 ++-
>  3 files changed, 6 insertions(+), 2 deletions(-)

Reviewed-by: Stefan Hajnoczi <[hidden email]>

Reply | Threaded
Open this post in threaded view
|

Re: [PATCH] kvm: exclude ioeventfd from counting kvm_io_range limit

Gleb Natapov-4
In reply to this post by Amos Kong
On Sat, May 25, 2013 at 06:44:15AM +0800, Amos Kong wrote:

> 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 <[hidden email]>
Applied, thanks.

> ---
>  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

--
                        Gleb.