runtime: Enable choice between AMD SEV and SNP

This is based on a patch from @niteeshkd that adds a config
parameter to choose between AMD SEV and SEV-SNP VMs as the
confidential guest type in case both types are supported. SEV is
the default.

Signed-off-by: Joana Pecholt <joana.pecholt@aisec.fraunhofer.de>

src/runtime/pkg/katautils/config.go

@@ -149,6 +149,7 @@ type hypervisor struct {
 	DisableVhostNet                bool     `toml:"disable_vhost_net"`
 	GuestMemoryDumpPaging          bool     `toml:"guest_memory_dump_paging"`
 	ConfidentialGuest              bool     `toml:"confidential_guest"`
+	SevSnpGuest                    bool     `toml:"sev_snp_guest"`
 	GuestSwap                      bool     `toml:"enable_guest_swap"`
 	Rootless                       bool     `toml:"rootless"`
 	DisableSeccomp                 bool     `toml:"disable_seccomp"`
@@ -827,6 +828,7 @@ func newQemuHypervisorConfig(h hypervisor) (vc.HypervisorConfig, error) {
 		GuestMemoryDumpPath:     h.GuestMemoryDumpPath,
 		GuestMemoryDumpPaging:   h.GuestMemoryDumpPaging,
 		ConfidentialGuest:       h.ConfidentialGuest,
+		SevSnpGuest:             h.SevSnpGuest,
 		GuestSwap:               h.GuestSwap,
 		Rootless:                h.Rootless,
 		LegacySerial:            h.LegacySerial,
@@ -1221,6 +1223,7 @@ func GetDefaultHypervisorConfig() vc.HypervisorConfig {
 		TxRateLimiterMaxRate:    defaultTxRateLimiterMaxRate,
 		SGXEPCSize:              defaultSGXEPCSize,
 		ConfidentialGuest:       defaultConfidentialGuest,
+		SevSnpGuest:             defaultSevSnpGuest,
 		GuestSwap:               defaultGuestSwap,
 		Rootless:                defaultRootlessHypervisor,
 		DisableSeccomp:          defaultDisableSeccomp,