This bug is cloned from qemu bug https://issues.redhat.com/browse/RHEL-29192
Qemu will support it in rhel 9.6, libvirt needs to add the support also as confirmed.

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We need AMD host support IOMMU with qemu-kvm downstream according to the latest windows security feature.

Current stats is the IOMMU does not be supported on AMD host with downstram qemu-kvm. Details as:

[root@hp-dl385g10-18 ~]# /usr/libexec/qemu-kvm -M q35,kernel-irqchip=split -device amd-iommu,,xtsup=on
qemu-kvm: warning: CPU model qemu64-x86_64-cpu is deprecated – use at least 'Nehalem' / 'Opteron_G4', or 'host' / 'max'
qemu-kvm: -device amd-iommu,,xtsup=on: 'amd-iommu,xtsup=on' is not a valid device model name

The AMD cpuinfo as:

# cat /proc/cpuinfo 
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 23
model           : 1
model name      : AMD EPYC 7301 16-Core Processor
stepping        : 2
microcode       : 0x800126e
cpu MHz         : 2200.000
cache size      : 512 KB
physical id     : 0
siblings        : 32
core id         : 0
cpu cores       : 16
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc cpuid extd_apicid amd_dcm aperfmperf rapl pni pclmulqdq monitor ssse3 fma cx16 sse4_1 sse4_2 movbe popcnt aes xsave avx f16c rdrand lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw skinit wdt tce topoext perfctr_core perfctr_nb bpext perfctr_llc mwaitx cpb hw_pstate ssbd ibpb vmmcall fsgsbase bmi1 avx2 smep bmi2 rdseed adx smap clflushopt sha_ni xsaveopt xsavec xgetbv1 xsaves clzero irperf xsaveerptr arat npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold avic v_vmsave_vmload vgif overflow_recov succor smca
bugs            : sysret_ss_attrs null_seg spectre_v1 spectre_v2 spec_store_bypass retbleed
bogomips        : 4391.92
TLB size        : 2560 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 48 bits physical, 48 bits virtual
power management: ts ttp tm hwpstate cpb eff_freq_ro [13] [14]