Merge tag 'kvm-x86-selftests_utils-6.10' of https://github.com/kvm-x86/linux into HEAD

KVM selftests treewide updates for 6.10:

 - Define _GNU_SOURCE for all selftests to fix a warning that was introduced by
   a change to kselftest_harness.h late in the 6.9 cycle, and because forcing
   every test to #define _GNU_SOURCE is painful.

 - Provide a global psuedo-RNG instance for all tests, so that library code can
   generate random, but determinstic numbers.

 - Use the global pRNG to randomly force emulation of select writes from guest
   code on x86, e.g. to help validate KVM's emulation of locked accesses.

 - Rename kvm_util_base.h back to kvm_util.h, as the weird layer of indirection
   was added purely to avoid manually #including ucall_common.h in a handful of
   locations.

 - Allocate and initialize x86's GDT, IDT, TSS, segments, and default exception
   handlers at VM creation, instead of forcing tests to manually trigger the
   related setup.

1 files changed, 12 insertions, 1 deletions

diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index 68c899d27561..bb8002084f52 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -1,5 +1,4 @@
 // SPDX-License-Identifier: GPL-2.0
-#define _GNU_SOURCE /* for program_invocation_short_name */
 #include <fcntl.h>
 #include <pthread.h>
 #include <sched.h>
@@ -221,8 +220,20 @@ static void test_move_memory_region(void)
 
 static void guest_code_delete_memory_region(void)
 {
+	struct desc_ptr idt;
 	uint64_t val;
 
+	/*
+	 * Clobber the IDT so that a #PF due to the memory region being deleted
+	 * escalates to triple-fault shutdown.  Because the memory region is
+	 * deleted, there will be no valid mappings.  As a result, KVM will
+	 * repeatedly intercepts the state-2 page fault that occurs when trying
+	 * to vector the guest's #PF.  I.e. trying to actually handle the #PF
+	 * in the guest will never succeed, and so isn't an option.
+	 */
+	memset(&idt, 0, sizeof(idt));
+	__asm__ __volatile__("lidt %0" :: "m"(idt));
+
 	GUEST_SYNC(0);
 
 	/* Spin until the memory region is deleted. */