[PATCH 5.10 79/83] x86/sev: Return an error on a returned non-zero SW_EXITINFO1[31:0]

[Greg Kroah-Hartman]

From: Tom Lendacky <thomas.lendacky@xxxxxxx>

commit 06f2ac3d4219bbbfd93d79e01966a42053084f11 upstream.

After returning from a VMGEXIT NAE event, SW_EXITINFO1[31:0] is checked
for a value of 1, which indicates an error and that SW_EXITINFO2
contains exception information. However, future versions of the GHCB
specification may define new values for SW_EXITINFO1[31:0], so really
any non-zero value should be treated as an error.

Fixes: 597cfe48212a ("x86/boot/compressed/64: Setup a GHCB-based VC Exception handler")
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # 5.10+
Link: https://lkml.kernel.org/r/efc772af831e9e7f517f0439b13b41f56bad8784.1633063321.git.thomas.lendacky@xxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/kernel/sev-es-shared.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/kernel/sev-es-shared.c
+++ b/arch/x86/kernel/sev-es-shared.c
@@ -130,6 +130,8 @@ static enum es_result sev_es_ghcb_hv_cal
 		} else {
 			ret = ES_VMM_ERROR;
 		}
+	} else if (ghcb->save.sw_exit_info_1 & 0xffffffff) {
+		ret = ES_VMM_ERROR;
 	} else {
 		ret = ES_OK;
 	}