mirror of
https://gitlab.com/libvirt/libvirt.git
synced 2024-11-03 11:51:11 +00:00
5670c50ffb
When starting QEMU, or when hotplugging a PCI device QEMU might
lock some memory. How much? Well, that's an undecidable problem.
But despite that, we try to guess. And it more or less works,
until there's a counter example. This time, it's a guest with
both <hostdev/> and an NVMe <disk/>. I've started a simple guest
with 4GiB of memory:
# virsh dominfo fedora
Max memory: 4194304 KiB
Used memory: 4194304 KiB
And here are the amounts of memory that QEMU tried to lock,
obtained via:
grep VmLck /proc/$(pgrep qemu-kvm)/status
1) with just one <hostdev/>
VmLck: 4194308 kB
2) with just one NVMe <disk/>
VmLck: 4328544 kB
3) with one <hostdev/> and one NVMe <disk/>
VmLck: 8522852 kB
Now, what's surprising is case 2) where the locked memory exceeds
the VM memory. It almost resembles VDPA. Therefore, treat is as
such.
Unfortunately, I don't have a box with two or more spare NVMe-s
so I can't tell for sure. But setting limit too tight means QEMU
refuses to start.
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2014030
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>
25 lines
739 B
XML
25 lines
739 B
XML
<domain type='kvm'>
|
|
<name>guest</name>
|
|
<memory unit='KiB'>1048576</memory>
|
|
<vcpu placement='static'>1</vcpu>
|
|
<os>
|
|
<type arch='x86_64' machine='pc'>hvm</type>
|
|
</os>
|
|
<devices>
|
|
<emulator>/usr/bin/qemu-system-x86_64</emulator>
|
|
<disk type='nvme' device='disk'>
|
|
<driver name='qemu' type='raw'/>
|
|
<source type='pci' managed='yes' namespace='1'>
|
|
<address domain='0x0003' bus='0x02' slot='0x00' function='0x0'/>
|
|
</source>
|
|
<target dev='vda' bus='virtio'/>
|
|
</disk>
|
|
<hostdev mode='subsystem' type='pci' managed='yes'>
|
|
<driver name='vfio'/>
|
|
<source>
|
|
<address domain='0x0001' bus='0x01' slot='0x00' function='0x0'/>
|
|
</source>
|
|
</hostdev>
|
|
</devices>
|
|
</domain>
|