KVM: MMU: Reset mmu->pkru_mask to avoid stale data

When updating mmu->pkru_mask, the value can only be added but it isn't
reset in advance. This will make mmu->pkru_mask keep the stale data.
Fix this issue.

Fixes: 2d34410 ("KVM, pkeys: introduce pkru_mask to cache conditions")
Signed-off-by: Chenyi Qiang <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Sean Christopherson <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Author: Qiangcy

arch/x86/kvm/mmu/mmu.c

@@ -4596,10 +4596,10 @@ static void update_pkru_bitmask(struct kvm_mmu *mmu)
 	unsigned bit;
 	bool wp;
 
-	if (!is_cr4_pke(mmu)) {
-		mmu->pkru_mask = 0;
+	mmu->pkru_mask = 0;
+
+	if (!is_cr4_pke(mmu))
 		return;
-	}
 
 	wp = is_cr0_wp(mmu);