[PATCH v3 2/9] target/i386: SEV: Ensure SEV features are only set through qemu cli or IGVM

["Naveen N Rao (AMD)" <naveen@kernel.org>]

In preparation for qemu being able to set SEV features through the cli,
add a check to ensure that SEV features are not also set if using IGVM
files.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Naveen N Rao (AMD) <naveen@kernel.org>
---
 target/i386/sev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/target/i386/sev.c b/target/i386/sev.c
index 2fb1268ed788..7cfd15238703 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -1901,6 +1901,16 @@ static int sev_common_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
          * as SEV_STATE_UNINIT.
          */
         if (x86machine->igvm) {
+            /*
+             * Test only the user-set SEV features by masking out
+             * SVM_SEV_FEAT_SNP_ACTIVE which is set by default.
+             */
+            if (sev_common->sev_features & ~SVM_SEV_FEAT_SNP_ACTIVE) {
+                error_setg(errp,
+                           "%s: SEV features can't be specified when using IGVM files",
+                           __func__);
+                return -1;
+            }
             if (IGVM_CFG_GET_CLASS(x86machine->igvm)
                     ->process(x86machine->igvm, machine->cgs, true, errp) ==
                 -1) {
-- 
2.51.0