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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id p5sm3698498wrt.79.2020.01.08.02.13.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 08 Jan 2020 02:13:49 -0800 (PST) From: Vitaly Kuznetsov To: Sean Christopherson Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Paolo Bonzini Subject: Re: [PATCH] KVM: x86/mmu: Fix a benign Bitwise vs. Logical OR mixup In-Reply-To: <20200108001859.25254-1-sean.j.christopherson@intel.com> References: <20200108001859.25254-1-sean.j.christopherson@intel.com> Date: Wed, 08 Jan 2020 11:13:48 +0100 Message-ID: <87d0bus1b7.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Sean Christopherson writes: > Use a Logical OR in __is_rsvd_bits_set() to combine the two reserved bit > checks, which are obviously intended to be logical statements. Switching > to a Logical OR is functionally a nop, but allows the compiler to better > optimize the checks. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/mmu/mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 7269130ea5e2..72e845709027 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3970,7 +3970,7 @@ __is_rsvd_bits_set(struct rsvd_bits_validate *rsvd_check, u64 pte, int level) > { > int bit7 = (pte >> 7) & 1, low6 = pte & 0x3f; > > - return (pte & rsvd_check->rsvd_bits_mask[bit7][level-1]) | > + return (pte & rsvd_check->rsvd_bits_mask[bit7][level-1]) || > ((rsvd_check->bad_mt_xwr & (1ull << low6)) != 0); Redundant parentheses detected! > } Reviewed-by: Vitaly Kuznetsov -- Vitaly