KVM: selftests: dirty-log: Upgrade flag accesses to acquire/release semantics

In order to preserve ordering, make sure that the flag accesses
in the dirty log are done using acquire/release accessors.

Signed-off-by: Marc Zyngier <[email protected]>
Reviewed-by: Gavin Shan <[email protected]>
Reviewed-by: Peter Xu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: Marc Zyngier

tools/testing/selftests/kvm/dirty_log_test.c

@@ -17,6 +17,7 @@
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 #include <linux/atomic.h>
+#include <asm/barrier.h>
 
 #include "kvm_util.h"
 #include "test_util.h"
@@ -279,12 +280,12 @@ static void dirty_ring_create_vm_done(struct kvm_vm *vm)
 
 static inline bool dirty_gfn_is_dirtied(struct kvm_dirty_gfn *gfn)
 {
-	return gfn->flags == KVM_DIRTY_GFN_F_DIRTY;
+	return smp_load_acquire(&gfn->flags) == KVM_DIRTY_GFN_F_DIRTY;
 }
 
 static inline void dirty_gfn_set_collected(struct kvm_dirty_gfn *gfn)
 {
-	gfn->flags = KVM_DIRTY_GFN_F_RESET;
+	smp_store_release(&gfn->flags, KVM_DIRTY_GFN_F_RESET);
 }
 
 static uint32_t dirty_ring_collect_one(struct kvm_dirty_gfn *dirty_gfns,