On 4/26/23 12:06, Sabin Rapan wrote:
On 20.02.2023 20:38, Michael Roth wrote:
From: Brijesh Singh <brijesh.singh@xxxxxxx>
+static int snp_decommission_context(struct kvm *kvm)
+{
+ struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+ struct sev_data_snp_addr data = {};
+ int ret;
+
+ /* If context is not created then do nothing */
+ if (!sev->snp_context)
+ return 0;
+
+ data.gctx_paddr = __sme_pa(sev->snp_context);
+ ret = sev_do_cmd(SEV_CMD_SNP_DECOMMISSION, &data, NULL);
+ if (WARN_ONCE(ret, "failed to release guest context"))
+ return ret;
+
+ /* free the context page now */
+ snp_free_firmware_page(sev->snp_context);
+ sev->snp_context = NULL;
+
+ return 0;
+}
+
Even though it's not documented, SNP_DECOMMISSION seems to clear the
WBINVD indicator just like DEACTIVATE does for SEV.
Won't ASID recycling race with SNP_DECOMMISSION if the latter isn't
guarded with sev_deactivate_lock?
Good catch, yes, this needs to use the sev_deactivate_lock around the
DECOMMISSION command.
Thanks,
Tom
void sev_vm_destroy(struct kvm *kvm)
{
struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
@@ -2333,7 +2440,15 @@ void sev_vm_destroy(struct kvm *kvm)
}
}
- sev_unbind_asid(kvm, sev->handle);
+ if (sev_snp_guest(kvm)) {
+ if (snp_decommission_context(kvm)) {
+ WARN_ONCE(1, "Failed to free SNP guest context, leaking asid!\n");
+ return;
+ }
+ } else {
+ sev_unbind_asid(kvm, sev->handle);
+ }
+
sev_asid_free(sev);
}
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