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Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , 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 , "Dr . David Alan Gilbert" , brijesh.ksingh@gmail.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH v11 42/45] virt: Add SEV-SNP guest driver Content-Language: en-US To: Dave Hansen , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org References: <20220224165625.2175020-1-brijesh.singh@amd.com> <20220224165625.2175020-43-brijesh.singh@amd.com> From: Brijesh Singh In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: SN7PR04CA0184.namprd04.prod.outlook.com (2603:10b6:806:126::9) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 0e8a7088-f709-4229-ef6e-08d9fde159d1 X-MS-TrafficTypeDiagnostic: CH0PR12MB5249:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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dkim=pass header.d=amd.com header.s=selector1 header.b="Djeg/Dyc"; spf=pass (imf07.hostedemail.com: domain of brijesh.singh@amd.com designates 40.107.223.85 as permitted sender) smtp.mailfrom=brijesh.singh@amd.com; dmarc=pass (policy=quarantine) header.from=amd.com X-Rspam-User: X-HE-Tag: 1646399859-50704 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 3/3/22 11:33 AM, Dave Hansen wrote: ... >> + */ >> + if (count >= UINT_MAX) { >> + pr_err_ratelimited("request message sequence counter overflow\n"); >> + return 0; >> + } >> + >> + return count; >> +} > I didn't see a pr_fmt defined anywhere. But, for a "driver", should > this be a dev_err()? Okay, I can switch to dev_err() and will define pr_fmt. > ... >> +static void free_shared_pages(void *buf, size_t sz) >> +{ >> + unsigned int npages = PAGE_ALIGN(sz) >> PAGE_SHIFT; >> + >> + if (!buf) >> + return; >> + >> + if (WARN_ONCE(set_memory_encrypted((unsigned long)buf, npages), >> + "failed to restore encryption mask (leak it)\n")) >> + return; >> + >> + __free_pages(virt_to_page(buf), get_order(sz)); >> +} > Nit: It's a bad practice to do important things inside a WARN_ON() _or_ > and if(). This should be: > > int ret; > > ... > > ret = set_memory_encrypted((unsigned long)buf, npages)); > > if (ret) { > WARN_ONCE(...); > return; > } > > BTW, this look like a generic allocator thingy. But it's only ever used > to allocate a 'struct snp_guest_msg'. Why all the trouble to allocate > and free one fixed-size structure? The changelog and comments don't > shed any light. The GHCB specification says that a guest must use shared memory for request, response, and certificate blob. In this patch, you are seeing that {alloc,free}_shared_pages() used only to alloc/free the request and response page. In the last patch, we used the same generic function to allocate the certificate blob with a different size (~16K) than 'struct snp_guest_msg.' thanks