x86/sev-es: Fix SEV-ES OUT/IN immediate opcode vc handling

The IN and OUT instructions with port address as an immediate operand
only use an 8-bit immediate (imm8). The current VC handler uses the
entire 32-bit immediate value but these instructions only set the first
bytes.

Cast the operand to an u8 for that.

 [ bp: Massage commit message. ]

Fixes: 25189d0 ("x86/sev-es: Add support for handling IOIO exceptions")
Signed-off-by: Peter Gonda <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Acked-by: David Rientjes <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]

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 |= (u8)insn->immediate.value << 16;
 		break;
 
 	/* OUT immediate opcodes */
 	case 0xe6:
 	case 0xe7:
 		*exitinfo |= IOIO_TYPE_OUT;
-		*exitinfo |= (u64)insn->immediate.value << 16;
+		*exitinfo |= (u8)insn->immediate.value << 16;
 		break;
 
 	/* IN register opcodes */