[kvm-unit-tests PATCH v3 13/20] x86/vmx: Initialize test stage in SIPI test *before* launching AP thread

[Sean Christopherson <seanjc@google.com>]

From: Mathias Krause <minipli@grsecurity.net>

Initialize the VMX test stage in the SIPI test *before* spawning the AP
thread, as setting the stage after waking the AP can result in the BSP's
write of '0' clobbering the AP's write of '1', ultimately causing the test
to hang because the BSP thinks the AP hasn't yet entered guest mode.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
[sean: write changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 x86/vmx_tests.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index effd0c59..6161f451 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -10285,11 +10285,11 @@ static void vmx_sipi_signal_test(void)
 	/* update CR3 on AP */
 	on_cpu(1, update_cr3, (void *)read_cr3());
 
+	vmx_set_test_stage(0);
+
 	/* start AP */
 	on_cpu_async(1, sipi_test_ap_thread, NULL);
 
-	vmx_set_test_stage(0);
-
 	/* BSP enter guest */
 	enter_guest();
 }
-- 
2.54.0.563.g4f69b47b94-goog