Robin R

WORKING NOW! Thank you @SimonF
 
Actually, @SimonF was correct. I misunderstood the instructions and blindly added <feature policy='require' name='vmx'/> which is not correct for two reasons. First, that is an Intel CPU feature whereas amd is 'svm'. Second, specifying 'svm' is not compatible with `host-passthrough` which does not work on my AM5/Ryzen 7950x system.
 
Once I changed my CPU section inside the XML from:
<cpu mode='host-passthrough' check='none' migratable='on'> <topology sockets='1' dies='1' cores='11' threads='2'/> <cache mode='passthrough'/> <feature policy='require' name='topoext'/> </cpu>  
To:
<cpu mode='host-model' check='partial'> <topology sockets='1' dies='1' cores='11' threads='2'/> <feature policy='require' name='topoext'/> </cpu>  
And started my VM, the XML below was auto-generated and modeled my CPU's features and created a custom XML CPU specification of:
<cpu mode='custom' match='exact' check='full'> <model fallback='forbid'>EPYC-Milan</model> <vendor>AMD</vendor> <topology sockets='1' dies='1' cores='11' threads='2'/> <feature policy='require' name='x2apic'/> <feature policy='require' name='tsc-deadline'/> <feature policy='require' name='hypervisor'/> <feature policy='require' name='tsc_adjust'/> <feature policy='require' name='avx512f'/> <feature policy='require' name='avx512dq'/> <feature policy='require' name='avx512ifma'/> <feature policy='require' name='avx512cd'/> <feature policy='require' name='avx512bw'/> <feature policy='require' name='avx512vl'/> <feature policy='require' name='avx512vbmi'/> <feature policy='require' name='avx512vbmi2'/> <feature policy='require' name='gfni'/> <feature policy='require' name='vaes'/> <feature policy='require' name='vpclmulqdq'/> <feature policy='require' name='avx512vnni'/> <feature policy='require' name='avx512bitalg'/> <feature policy='require' name='avx512-vpopcntdq'/> <feature policy='require' name='spec-ctrl'/> <feature policy='require' name='stibp'/> <feature policy='require' name='arch-capabilities'/> <feature policy='require' name='ssbd'/> <feature policy='require' name='avx512-bf16'/> <feature policy='require' name='cmp_legacy'/> <feature policy='require' name='virt-ssbd'/> <feature policy='disable' name='lbrv'/> <feature policy='disable' name='tsc-scale'/> <feature policy='disable' name='vmcb-clean'/> <feature policy='disable' name='pause-filter'/> <feature policy='disable' name='pfthreshold'/> <feature policy='require' name='rdctl-no'/> <feature policy='require' name='skip-l1dfl-vmentry'/> <feature policy='require' name='mds-no'/> <feature policy='require' name='pschange-mc-no'/> <feature policy='disable' name='pcid'/> <feature policy='require' name='topoext'/> <feature policy='disable' name='svm'/> <feature policy='disable' name='npt'/> <feature policy='disable' name='nrip-save'/> <feature policy='disable' name='svme-addr-chk'/> </cpu> WARNING: DO NOT COPY ABOVE "custom" CPU SPECIFICATION. It's auto-generated specifically for my CPU chipset. This is my CPU's model and may or may not model other system's CPUs correctly.
 
So the correct steps in my case were:
1) extract the vbios from the GPU using Spaceinvader One's process
2) bind VFIO at boot to the GPU(s)
3) pass the vbios to the GPU in the virtual machine (in my case I had to remove the nvidia bios header as per Spaceinvader One's videos)
4) Set my bios to boot my system in Legacy mode (non-UEFI mode)
5) Enable SVM in my bios (since I'm AMD)
6) Enable nested virtualization, in my case by adding kvm_amd.nested=1 (since I'm AMD) into my flash drive's boot settings
 
kernel /bzimage append kvm_amd.nested=1 initrd=/bzroot and changing CPU 'host-passthrough' to 'host-model'
<cpu mode='host-passthrough' check='none' migratable='on'> To:
<cpu mode='host-model' check='partial'>  
And removed this line inside the cpu tag (since it's not compatible with 'host-model'):
<cache mode='passthrough'/>