i386/sev: free existing launch update data and kernel hashes data on init

If there is existing launch update data and kernel hashes data, they need to be
freed when initialization code is executed. This is important for resettable
confidential guests where the initialization happens once every reset.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Link: https://lore.kernel.org/r/20260225035000.385950-22-anisinha@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/sev.c

@@ -1773,6 +1773,7 @@ static int sev_common_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
     uint32_t ebx;
     uint32_t host_cbitpos;
     struct sev_user_data_status status = {};
+    SevLaunchUpdateData *data, *next_elm;
     SevCommonState *sev_common = SEV_COMMON(cgs);
     SevCommonStateClass *klass = SEV_COMMON_GET_CLASS(cgs);
     X86ConfidentialGuestClass *x86_klass =
@@ -1780,6 +1781,11 @@ static int sev_common_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
 
     sev_common->state = SEV_STATE_UNINIT;
 
+    /* free existing launch update data if any */
+    QTAILQ_FOREACH_SAFE(data, &launch_update, next, next_elm) {
+        g_free(data);
+    }
+
     host_cpuid(0x8000001F, 0, NULL, &ebx, NULL, NULL);
     host_cbitpos = ebx & 0x3f;
 
@@ -1968,6 +1974,8 @@ static int sev_snp_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
 {
     MachineState *ms = MACHINE(qdev_get_machine());
     X86MachineState *x86ms = X86_MACHINE(ms);
+    SevCommonState *sev_common = SEV_COMMON(cgs);
+    SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(sev_common);
 
     if (x86ms->smm == ON_OFF_AUTO_AUTO) {
         x86ms->smm = ON_OFF_AUTO_OFF;
@@ -1976,6 +1984,10 @@ static int sev_snp_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
         return -1;
     }
 
+    /* free existing kernel hashes data if any */
+    g_free(sev_snp_guest->kernel_hashes_data);
+    sev_snp_guest->kernel_hashes_data = NULL;
+
     return 0;
 }