From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH] vhost: support upto 509 memory regions Date: Tue, 17 Feb 2015 10:02:42 +0100 Message-ID: <20150217090242.GA20254@redhat.com> References: <1423842599-5174-1-git-send-email-imammedo@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, netdev@vger.kernel.org, pbonzini@redhat.com To: Igor Mammedov Return-path: Content-Disposition: inline In-Reply-To: <1423842599-5174-1-git-send-email-imammedo@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, Feb 13, 2015 at 03:49:59PM +0000, 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 aborts 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. > > Increasing VHOST_MEMORY_MAX_NREGIONS from 65 to 509 > to match KVM_USER_MEM_SLOTS fixes issue for vhost-net. > > Signed-off-by: Igor Mammedov This scares me a bit: each region is 32byte, we are talking a 16K allocation that userspace can trigger. How does kvm handle this issue? > --- > 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 2ee2826..ecbd7a4 100644 > --- a/drivers/vhost/vhost.c > +++ b/drivers/vhost/vhost.c > @@ -29,7 +29,7 @@ > #include "vhost.h" > > enum { > - VHOST_MEMORY_MAX_NREGIONS = 64, > + VHOST_MEMORY_MAX_NREGIONS = 509, > VHOST_MEMORY_F_LOG = 0x1, > }; > > -- > 1.8.3.1