[PATCH] x86/sev-es: Fix SEV-ES OUT/IN immediate opcode vc handling
From: Peter Gonda
Date: Wed Dec 16 2020 - 20:05:18 EST
The IN and OUT immediate instructions only use an 8-bit immediate. The
current VC handler uses the entire 32-bit immediate value. These
instructions only set the first bytes.
Tested with a loop back port with "outb %0,$0xe0". Before the port seen
by KVM was 0xffffffffffffffe0 instead of 0xe0. After the correct port
was seen by KVM and the guests loop back OUT then IN were equal.
Signed-off-by: Peter Gonda <pgonda@xxxxxxxxxx>
Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
---
arch/x86/kernel/sev-es-shared.c | 8 ++++++--
drivers/Makefile | 1 +
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c
index 7d04b356d44d..6c790377c55c 100644
--- a/arch/x86/kernel/sev-es-shared.c
+++ b/arch/x86/kernel/sev-es-shared.c
@@ -305,14 +305,14 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
case 0xe4:
case 0xe5:
*exitinfo |= IOIO_TYPE_IN;
- *exitinfo |= (u64)insn->immediate.value << 16;
+ *exitinfo |= insn->immediate.bytes[0] << 16;
break;
/* OUT immediate opcodes */
case 0xe6:
case 0xe7:
*exitinfo |= IOIO_TYPE_OUT;
- *exitinfo |= (u64)insn->immediate.value << 16;
+ *exitinfo |= insn->immediate.bytes[0] << 16;
break;