On 2/29/24 13:15, Gianluca Cecchi wrote:
Hello,
I'm trying to use AMX in my virtual machines.
More info on AMX:
https://www.intel.com/content/www/us/en/products/docs/accelerator-engines/advanced-matrix-extensions/overview.html <https://www.intel.com/content/www/us/en/products/docs/accelerator-engines/advanced-matrix-extensions/overview.html>
My system in test is currently SLES 15 SP5.
I'm also verifying in parallel with Suse (especially regarding the backported
features in their 5.14 based kernel), but in the meantime I would like to
understand implication, if any, of libvirt in the certification loop I have to
analyse.
From what I see we have in upstream:
. support in the KVM kernel module since 5.17
. support of cpu model SapphireRapids, the first offering AMX as an ISA
extension, in QEMU since 7.0
Is there any dependance to check on libvirt too?
Yes, support for the SapphireRapids CPU model was added in libvirt 9.4.0
https://gitlab.com/libvirt/libvirt/-/commit/96c8d39af007000daf3d5dfa845365f66379aaac
When I run
virsh cpu-models x86_64
Is libvirt sw stack querying qemu directly? Or the kvm kernel module? Or any
internal "database" file?
From man page it is not clear to me what "known" means:
"
cpu-models
Syntax:
cpu-models arch
Print the list of CPU models known by libvirt for the specified
architecture. Whether a specific hypervisor is able to create a domain which
uses any of the printed CPU models is a separate question which can be answered
by looking at the domain capabilities XML returned by domcapabilities
command. Moreover, for some architectures libvirt does not know any CPU models
and the usable CPU models are only limited by the hypervisor. This command will
print that all CPU models are accepted for these architectures and the actual
list of supported CPU models can be checked in the domain capabilities XML.
"
In SLES 15 SP5 with:
qemu-7.1.0-150500.49.9.2.x86_64
kernel-default-5.14.21-150500.55.49.1.x86_64
libvirtd-*-9.0.0-150500.6.11.1.x86_64
There are other requests to support SapphireRapids in SLES15 SP5, but it will
take some time to backport patches for all these components and release updated
packages.
Regards,
Jim
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