diff mbox series

[v2,16/16] KVM: selftests: Mark "guest_saw_irq" as volatile in xen_shinfo_test

Message ID 20221013211234.1318131-17-seanjc@google.com (mailing list archive)
State New, archived
Headers show
Series KVM: x86: gfn_to_pfn_cache fixes and cleanups | expand

Commit Message

Sean Christopherson Oct. 13, 2022, 9:12 p.m. UTC 
Tag "guest_saw_irq" as "volatile" to ensure that the compiler will never
optimize away lookups.  Relying on the compiler thinking that the flag
is global and thus might change also works, but it's subtle, less robust,
and looks like a bug at first glance, e.g. risks being "fixed" and
breaking the test.

Make the flag "static" as well since convincing the compiler it's global
is no longer necessary.

Alternatively, the flag could be accessed with {READ,WRITE}_ONCE(), but
literally every access would need the wrappers, and eking out performance
isn't exactly top priority for selftests.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
index caa3f5ab9e10..2a5727188c8d 100644
--- a/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
+++ b/tools/testing/selftests/kvm/x86_64/xen_shinfo_test.c
@@ -132,7 +132,7 @@  struct {
 	struct kvm_irq_routing_entry entries[2];
 } irq_routes;
 
-bool guest_saw_irq;
+static volatile bool guest_saw_irq;
 
 static void evtchn_handler(struct ex_regs *regs)
 {