Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <8e2213fa-981a-11cd-5bcc-3338d3b2c5de@redhat.com>
Date:   Mon, 2 May 2022 13:52:10 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.8.0
Subject: Re: [PATCH] KVM: x86/mmu: Do not create SPTEs for GFNs that exceed
 host.MAXPHYADDR
Content-Language: en-US
To:     Kai Huang <kai.huang@intel.com>,
        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, Maxim Levitsky <mlevitsk@redhat.com>,
        Ben Gardon <bgardon@google.com>,
        David Matlack <dmatlack@google.com>
References: <20220428233416.2446833-1-seanjc@google.com>
 <2d10ff16d3f5fa03886721c24f2db10d79759ed2.camel@intel.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <2d10ff16d3f5fa03886721c24f2db10d79759ed2.camel@intel.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

On 5/2/22 13:12, Kai Huang wrote:
>> -		if (unlikely(!enable_mmio_caching)) {
>> +		if (unlikely(!enable_mmio_caching) ||
>> +		    unlikely(fault->gfn > kvm_mmu_max_gfn_host())) {
> Shouldn't we check fault->gfn against cpuid_maxphyaddr(vcpu) instead of
> kvm_mmu_max_gfn_host() here?

No, the point of this check is to handle the case where 
kvm_mmu_max_gfn_host() is smaller than cpuid_maxphyaddr().

Paolo