What were you trying to do that didn't work?
SNP guest can't boot with -cpu host

Please provide the package NVR for which bug is seen:
kernel-5.14.0-479.el9
qemu-kvm-9.0.0-6.el9.7337546923.x86_64
edk2-ovmf-20240524-1.el9.noarch

How reproducible:
100%

Steps to reproduce
1. Boot SNP guest with -cpu host
/usr/libexec/qemu-kvm -enable-kvm \
-cpu host \
-machine q35,confidential-guest-support=sev0,vmport=off \
-smp 4 \
-no-reboot \
-bios /usr/share/edk2/ovmf/OVMF.amdsev.fd \
-m 20480 \
-drive file=/home/kvm_autotest_root/images/snA.qcow2,if=none,id=disk0,format=qcow2 \
-device virtio-scsi-pci,id=scsi0,disable-legacy=on,iommu_platform=true \
-device scsi-hd,drive=disk0 \
-object memory-backend-ram,id=ram1,size=2048M \
-object sev-snp-guest,id=sev0,cbitpos=51,reduced-phys-bits=1 \
-nographic \
-netdev user,id=vmnic \
-device virtio-net-pci,disable-legacy=on,iommu_platform=true,netdev=vmnic,romfile=

qemu-kvm: SNP_LAUNCH_UPDATE ret=-5 fw_error=22 'Invalid parameter'
qemu-kvm: SEV-SNP: CPUID validation failed for function 0x1, index: 0x0provided: eax:0x00a10f11, ebx: 0x00040800, ecx: 0xf7fa3203, edx: 0x178bfbffexpected: eax:0x00a10f11, ebx: 0x00040800, ecx: 0xf6fa3203, edx: 0x178bfbff
qemu-kvm: SEV-SNP: CPUID validation failed for function 0x7, index: 0x0provided: eax:0x00000001, ebx: 0xf1bf07ab, ecx: 0x00415f4e, edx: 0xbc000010expected: eax:0x00000001, ebx: 0xf1bf07a9, ecx: 0x00415f4e, edx: 0x00000000
qemu-kvm: SEV-SNP: CPUID validation failed for function 0x80000008, index: 0x0provided: eax:0x00003930, ebx: 0x1302d205, ecx: 0x00002003, edx: 0x00000000expected: eax:0x00003930, ebx: 0x1102d205, ecx: 0x00002003, edx: 0x00000000
qemu-kvm: SEV-SNP: CPUID validation failed for function 0x8000001d, index: 0x3provided: eax:0x0000c163, ebx: 0x03c0003f, ecx: 0x00003fff, edx: 0x00000006expected: eax:0x0000c163, ebx: 0x03c0003f, ecx: 0x00003fff, edx: 0x00000002
qemu-kvm: SEV-SNP: failed update CPUID page

Expected results
SNP guest can boot

Actual results
Fail to boot SNP guest with host model