The long-deprecated use of <driver name='vfio|xen|kvm'/> in domain xml
for <hostdev> devices was only ever necessary during the period when
libvirt (and the Linux kernel) supported both VFIO and "legacy KVM"
styles of hostdev device assignment for QEMU. This became pointless
many years ago when legacy KVM device assignment was removed from the
kernel, and support for that style of device assignment was completely
disabled in the libvirt source in 2019 (commit
v5.6.0-316-g2e7225ea8c).
Nevertheless, there were instances of <driver name='vfio'/> in the
unit test data that were then (unnecessarily) propagated to several
more tests over the years. This patch cleans out those unnecessary
explicit settings of driver name='vfio' in all QEMU unit test data,
proving that the attribute is no longer (externally) needed. (A later
patch which adds a 2nd attribute to the <driver> element will include
a test case that explicitly exercises the driver name attribute).
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
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>
