From b662e6fd7169f31ef664ecd0b0b45547462e1e31 Mon Sep 17 00:00:00 2001
From: Stefan Berger <stefanb@linux.ibm.com>
Date: Tue, 4 Jan 2022 14:45:31 -0500
Subject: [PATCH] tpm2: When writing state initialize s_ContextSlotMask if not
 set

If s_ContextSlotMask was not set since the TPM 2 was not initialized
by a call to TPM_Manufacture() or the state was not resumed, then
initialize the s_ContextSlotMask to 0xffff.

This situation can occur if a VM with an attached swtpm was started
and the VM's firmware either doesn't support TPM or didn't get to
initialize the vTPM.

The following commands recreated the issue with a SeaBIOS-only VM that
had no attached hard disk but an attached TPM 2:

virsh start BIOS-only-VM ; virsh save BIOS-only-VM save.bin ; \
 virsh restore save.bin

Error: Failed to restore domain from save.bin
error: internal error: qemu unexpectedly closed the monitor: \
2022-01-04T19:26:18.835851Z qemu-system-x86_64: tpm-emulator: Setting the stateblob (type 2) failed with a TPM error 0x3 a parameter is bad
2022-01-04T19:26:18.835899Z qemu-system-x86_64: error while loading state for instance 0x0 of device 'tpm-emulator'
2022-01-04T19:26:18.835929Z qemu-system-x86_64: load of migration failed: Input/output error

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2035731
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 src/tpm2/NVMarshal.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/tpm2/NVMarshal.c b/src/tpm2/NVMarshal.c
index 996c73c..c7cd1e0 100644
--- a/src/tpm2/NVMarshal.c
+++ b/src/tpm2/NVMarshal.c
@@ -1422,6 +1422,11 @@ STATE_RESET_DATA_Marshal(STATE_RESET_DATA *data, BYTE **buffer, INT32 *size)
     written += UINT16_Marshal(&array_size, buffer, size);
     for (i = 0; i < array_size; i++)
         written += UINT16_Marshal(&data->contextArray[i], buffer, size);
+
+    if (s_ContextSlotMask != 0x00ff && s_ContextSlotMask != 0xffff) {
+        /* TPM wasn't initialized, so s_ContextSlotMask wasn't set */
+        s_ContextSlotMask = 0xffff;
+    }
     written += UINT16_Marshal(&s_ContextSlotMask, buffer, size);
 
     written += UINT64_Marshal(&data->contextCounter, buffer, size);
-- 
2.36.1