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Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH Part2 v5 08/45] x86/fault: Add support to handle the RMP fault for user address To: Dave Hansen , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org References: <20210820155918.7518-1-brijesh.singh@amd.com> <20210820155918.7518-9-brijesh.singh@amd.com> From: Brijesh Singh Message-ID: <19599ede-9fc5-25e1-dcb3-98aafd8b7e87@amd.com> Date: Mon, 23 Aug 2021 09:36:05 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SN6PR01CA0034.prod.exchangelabs.com (2603:10b6:805:b6::47) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [10.236.31.95] (165.204.77.1) by SN6PR01CA0034.prod.exchangelabs.com (2603:10b6:805:b6::47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4436.19 via Frontend Transport; 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>> + >> + __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL); >> + return 0; >> +} > > We had a whole conversation the last time this was posted about huge > page types *other* than THP. I don't see any comprehension of those > types or what would happen if one of those was used with SEV-SNP. > > What was the result of those review comments? > Based on previous review comments Sean was not keen on KVM having perform this detection and abort the guest SEV-SNP VM launch. So, I didn't implemented the check and waiting for more discussion before going at it. SEV-SNP guest requires the VMM to register the guest backing pages before the VM launch. Personally, I would prefer KVM to check the backing page type during the registration and fail to register if its hugetlbfs (and others) to avoid us get into situation where we could not split the hugepage. thanks > I'm still worried that hugetlbfs (and others) are not properly handled > by this series. >