Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH 47/54] KVM: x86/mmu: Add helpers to do full reserved SPTE
 checks w/ generic MMU
To:     Sean Christopherson <seanjc@google.com>
Cc:     Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Yu Zhang <yu.c.zhang@linux.intel.com>,
        Maxim Levitsky <mlevitsk@redhat.com>
References: <20210622175739.3610207-1-seanjc@google.com>
 <20210622175739.3610207-48-seanjc@google.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <d79fe507-44a2-8051-63d3-09469e36bc49@redhat.com>
Date:   Wed, 23 Jun 2021 22:13:18 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.10.1
MIME-Version: 1.0
In-Reply-To: <20210622175739.3610207-48-seanjc@google.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 22/06/21 19:57, Sean Christopherson wrote:
> +	/*
> +	 * Use a bitwise-OR instead of a logical-OR to aggregate the reserved
> +	 * bits and EPT's invalid memtype/XWR checks to avoid an extra Jcc
> +	 * (this is used in hot paths).

Probably s/this is used in hot paths/this is extremely unlikely to be 
short-circuited as true/, since we are at it.

Paolo

> +	 */
> +	return __is_bad_mt_xwr(rsvd_check, spte) |
> +	       __is_rsvd_bits_set(rsvd_check, spte, level);