Problem with random KVM error

[danko-miladinovic]

Hi,

I am using COCONUT-SVSM OVMF (with the Secure Boot patch; 52fa7e78d282 ("OvmfPkg/PlatformPei: Move NV vars init to after SEV-SNP memory acceptance")) and kernel (6.11). When I try to boot my VM with SNP and -smp 4, the VM boot stops, and I do not see the login prompt.
This is the last thing I see.

Memory Encryption Features active: AMD SEV SEV-ES SEV-SNP
SEV: Status: SEV SEV-ES SEV-SNP
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 65536 (order: 7, 524288 bytes, linear)
Mountpoint-cache hash table entries: 65536 (order: 7, 524288 bytes, linear)
smpboot: CPU0: AMD EPYC-v4 Processor (family: 0x17, model: 0x1, stepping: 0x2)
SEV: APIC: wakeup_secondary_cpu() replaced with wakeup_cpu_via_vmgexit()
Performance Events: Fam17h+ core perfctr, AMD PMU driver.
... version:                0
... bit width:              48
... generic registers:      6
... value mask:             0000ffffffffffff
... max period:             00007fffffffffff
... fixed-purpose events:   0
... event mask:             000000000000003f
signal: max sigframe size: 1360
rcu: Hierarchical SRCU implementation.
rcu:    Max phase no-delay instances is 1000.
smp: Bringing up secondary CPUs ...
smpboot: Parallel CPU startup disabled by the platform
smpboot: x86: Booting SMP configuration:
.... node  #0, CPUs:      #1 #2 #3
smp: Brought up 1 node, 4 CPUs
smpboot: Total of 4 processors activated (22757.23 BogoMIPS)

When I change the smp option to -smp 4,maxcpus=16, the VM boots, but sometimes I get the following error. On host:

[674643.810802] kvm_amd: kvm [3584985]: vcpu2, guest rIP: 0x0 vmgexit: exit code 0x0 input is not valid
[674643.810846] kvm_amd: set kvm_amd.dump_invalid_vmcb=1 to dump internal KVM state.
[674643.811418] kvm_amd: SEV-ES guest requested termination: 0x0:0x0

In guest:

KVM: unknown exit reason 24
EAX=00000000 EBX=00000000 ECX=00000000 EDX=00800f12
ESI=00000000 EDI=00000000 EBP=00000000 ESP=00000000
EIP=0000fff0 EFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=1
ES =0000 00000000 0000ffff 00009300
CS =f000 ffff0000 0000ffff 00009b00
SS =0000 00000000 0000ffff 00009300
DS =0000 00000000 0000ffff 00009300
FS =0000 00000000 0000ffff 00009300
GS =0000 00000000 0000ffff 00009300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 0000ffff
IDT=     00000000 0000ffff
CR0=60000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
DR6=00000000ffff0ff0 DR7=0000000000000400
EFER=0000000000000000
Code=c5 5a 08 2d 00 00 00 00 00 00 00 00 00 00 00 00 56 54 46 00 <0f> 20 c0 a8 01 74 05 e9 2c ff ff ff e9 11 ff 90 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Does anybody have an idea what is the cause of the error? Thank you for the help so far.

Kind regards,
Danko