Re: [PATCH] vhost: support upto 509 memory regions
From: "Michael S. Tsirkin" <mst@redhat.com>
Date: 2015-02-17 09:02:49
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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 <redacted>
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?
quoted hunk ↗ jump to hunk
--- 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