Re: [PATCH 3/5] vhost: support upto 509 memory regions

Michael S. Tsirkin
2015-06-16T21:14:28Z

On Tue, Jun 16, 2015 at 06:33:37PM +0200, Igor Mammedov wrote:
> since commit
> 1d4e7e3 kvm: x86: increase user memory slots to 509
>
> it became possible to use a bigger amount of memory
> slots, which is used by memory hotplug for
> registering hotplugged memory.
> However QEMU crashes if it's used with more than ~60
> pc-dimm devices and vhost-net since host kernel
> in module vhost-net refuses to accept more than 65
> memory regions.
>
> Increase VHOST_MEMORY_MAX_NREGIONS from 65 to 509

It was 64, not 65.

> to match KVM_USER_MEM_SLOTS fixes issue for vhost-net.
>
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

Still thinking about this: can you reorder this to
be the last patch in the series please?

Also - 509?
I think if we are changing this, it'd be nice to
create a way for userspace to discover the support
and the # of regions supported.

> ---
> drivers/vhost/vhost.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 99931a0..6a18c92 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -30,7 +30,7 @@
> #include "vhost.h"
>
> enum {
> - VHOST_MEMORY_MAX_NREGIONS = 64,
> + VHOST_MEMORY_MAX_NREGIONS = 509,
> VHOST_MEMORY_F_LOG = 0x1,
> };
>
> --
> 1.8.3.1