[PATCH v4 37/47] x86/pvclock: WARN if pvclock's valid_flags are overwritten

[Sean Christopherson <seanjc@xxxxxxxxxx>]

WARN if the common PV clock valid_flags are overwritten; all PV clocks
expect that they are the one and only PV clock, i.e. don't guard against
another PV clock having modified the flags.

Reviewed-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/kernel/pvclock.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index a51adce67f92..8d098841a225 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -21,6 +21,7 @@ static struct pvclock_vsyscall_time_info *pvti_cpu0_va 
__ro_after_init;
 
 void __init pvclock_set_flags(u8 flags)
 {
+       WARN_ON(valid_flags);
        valid_flags = flags;
 }
 
-- 
2.54.0.823.g6e5bcc1fc9-goog