linux-kernel - Re: [PATCH] KVM: x86: fix WARN_ON check of an unsigned less than zero

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Message-ID: <65768baced1c4d9e87555c9057c2c488@huawei.com>
Date:   Wed, 12 Feb 2020 12:47:37 +0000
From:   linmiaohe <linmiaohe@...wei.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
CC:     "colin.king@...onical.com" <colin.king@...onical.com>,
        "sean.j.christopherson@...el.com" <sean.j.christopherson@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH] KVM: x86: fix WARN_ON check of an unsigned less than zero

Paolo Bonzini <pbonzini@...hat.com> writes:
> 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 <colin.king@...onical.com>
>Suggested-by: Sean Christopherson <sean.j.christopherson@...el.com>
>Addresses-Coverity: ("Macro compares unsigned to 0")
>Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
>---

Reviewed-by: Miaohe Lin <linmiaohe@...wei.com>