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From: Paolo Bonzini <>
Subject: [PATCH] KVM: x86: fix WARN_ON check of an unsigned less than zero
Date: Wed, 12 Feb 2020 13:28:48 +0100	[thread overview]
Message-ID: <> (raw)

The check cpu->hv_clock.system_time < 0 is redundant since system_time
is a u64 and hence can never be less than zero.  But what was actually
meant is to check that the result is positive, since kernel_ns and
v->kvm->arch.kvmclock_offset are both s64.

Reported-by: Colin King <>
Suggested-by: Sean Christopherson <>
Addresses-Coverity: ("Macro compares unsigned to 0")
Signed-off-by: Paolo Bonzini <>
 arch/x86/kvm/x86.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 54e8142b15d0..359fcd395132 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2444,7 +2444,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
 	vcpu->hv_clock.tsc_timestamp = tsc_timestamp;
 	vcpu->hv_clock.system_time = kernel_ns + v->kvm->arch.kvmclock_offset;
 	vcpu->last_guest_tsc = tsc_timestamp;
-	WARN_ON(vcpu->hv_clock.system_time < 0);
+	WARN_ON((s64)vcpu->hv_clock.system_time < 0);
 	/* If the host uses TSC clocksource, then it is stable */
 	pvclock_flags = 0;

             reply	other threads:[~2020-02-12 12:28 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-12 12:28 Paolo Bonzini [this message]
2020-02-12 12:47 [PATCH] KVM: x86: fix WARN_ON check of an unsigned less than zero linmiaohe

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