[PATCH 1/3] sev/i386: Allow launching with -kernel if no OVMF hashes table found

[Dov Murik <dovmurik@linux.ibm.com>]

Commit cff03145ed3c ("sev/i386: Introduce sev_add_kernel_loader_hashes
for measured linux boot", 2021-09-30) introduced measured direct boot
with -kernel, using an OVMF-designated hashes table which QEMU fills.

However, if OVMF doesn't designate such an area, QEMU would completely
abort the VM launch.  This breaks launching with -kernel using older
OVMF images which don't publish the SEV_HASH_TABLE_RV_GUID.

Instead, just warn the user that -kernel was supplied by OVMF doesn't
specify the GUID for the hashes table.  The following warning will be
displayed during VM launch:

    qemu-system-x86_64: warning: SEV: kernel specified but OVMF has no hash table guid

Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
Reported-by: Tom Lendacky <thomas.lendacky@amd.com>
---
 target/i386/sev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/i386/sev.c b/target/i386/sev.c
index eede07f11d..682b8ccf6c 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -1204,7 +1204,7 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderContext *ctx, Error **errp)
     int aligned_len;
 
     if (!pc_system_ovmf_table_find(SEV_HASH_TABLE_RV_GUID, &data, NULL)) {
-        error_setg(errp, "SEV: kernel specified but OVMF has no hash table guid");
+        warn_report("SEV: kernel specified but OVMF has no hash table guid");
         return false;
     }
     area = (SevHashTableDescriptor *)data;
-- 
2.25.1