From 87b0f241db1eba0e9db1fd233c5ab8a8d0115979 Mon Sep 17 00:00:00 2001
Message-Id: <87b0f241db1eba0e9db1fd233c5ab8a8d0115979@dist-git>
From: Michal Privoznik <mprivozn@redhat.com>
Date: Mon, 21 Mar 2022 13:33:06 +0100
Subject: [PATCH] qemu_tpm: Do async IO when starting swtpm emulator
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When vTPM is secured via virSecret libvirt passes the secret
value via an FD when swtpm is started (arguments --key and
--migration-key). The writing of the secret into the FDs is
handled via virCommand, specifically qemu_tpm calls
virCommandSetSendBuffer()) and then virCommandRunAsync() spawns a
thread to handle writing into the FD via
virCommandDoAsyncIOHelper. But the thread is not created unless
VIR_EXEC_ASYNC_IO flag is set, which it isn't. In order to fix
it, virCommandDoAsyncIO() must be called.

The credit goes to Marc-André Lureau
<marcandre.lureau@redhat.com> who has done all the debugging and
proposed fix in the bugzilla.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2064115
Fixes: a9c500d2b50c5c041a1bb6ae9724402cf1cec8fe
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
(cherry picked from commit 4d7bb0177a33c4e90fd001edfe27bc030354d875)
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2152188
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_tpm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/qemu/qemu_tpm.c b/src/qemu/qemu_tpm.c
index 9c5d1ffed4..29dcb2ac0f 100644
--- a/src/qemu/qemu_tpm.c
+++ b/src/qemu/qemu_tpm.c
@@ -923,6 +923,7 @@ qemuExtTPMStartEmulator(virQEMUDriver *driver,
     if (!(pidfile = qemuTPMEmulatorCreatePidFilename(cfg->swtpmStateDir, shortName)))
         return -1;
 
+    virCommandDoAsyncIO(cmd);
     virCommandDaemonize(cmd);
     virCommandSetPidFile(cmd, pidfile);
     virCommandSetErrorFD(cmd, &errfd);
-- 
2.39.0