From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from NAM11-CO1-obe.outbound.protection.outlook.com (mail-co1nam11on2040.outbound.protection.outlook.com [40.107.220.40]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D5F4572 for ; Fri, 16 Jul 2021 22:16:39 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=X0YH3+c2jWryI6DLAK2rya7qCXAtaKSei+AStFUltHMgFIQgTEXPk+s9csMFHs/NC5iA2in3UgM5npDACVHG96yYAQk4+D4ILHcYvjajTyxB9jomAFJTIEoOtdoeA1WFBeNCOY0Gdt99OPDx0X6obuigmB5usKF+m4jhWGxvHG9se6n+I0eFljJkABkGDSC5pIgWiTImoh5VM3niuSQhYk8jA9/G9EDJxX5/k1RGg99AZ+z33maCfOgcmChWlPVqXcdo0kLq15DIH3hyMHEDLRPq5Ydy6sx+vjCpE3nQH00GL69Mvjil4ShpoPc6g6VOKZGUvYD56497uZeOVHYK3w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=E/YQYG6JqQIqOkv5V1oUhlxOWa3jAAjt7lq47pIlx/U=; b=FfCTrjFbrUgbw5mGL/DAfG4C1PV2ivLolMe3U9V0lIpGN0oB4ZxADfs/7nrYLyRVeJjJvrUH8cBUdRfFjJzrkoTp+3QPzq3CTC1h+wtxHGY6mrVflYpmp5kFi/q0+fHWmZ4sXf/jkhd6bCE9vklwf5ClsPFFGFeIet9GGK0JIHImNRtFQJmTszx7ok10kB/XMsjr+QLDsazU6Nvnd+jVBXm3HLDe6MkjrF2DD9O+Qbo8mVpKMsqAobSD3p4LoMTJEO/7VtItqPgN6mKppO4QcxOd8uSHWDxFFcEtv72jxBMTmusiE0mZawXzlivJGy34SGGs/OX9Bmo6i6a1gnA45w== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=amd.com; dmarc=pass action=none header.from=amd.com; dkim=pass header.d=amd.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=E/YQYG6JqQIqOkv5V1oUhlxOWa3jAAjt7lq47pIlx/U=; b=Qk3QEibpJK1puS0jTCfzYZ7XBksX62LF1EVyuKEGSXLTsNx9UezczQ3bBJpIRM6JhWvgSS8zu5XxcWL61mUf+sjnjmiAf5F7vu1pFdt4QA9V6RVfS0jXXPghons06lHYP7zLSy6j1E25P5qPJ2up5IwKN5dFGiCbu667YiesOlg= Authentication-Results: gmail.com; dkim=none (message not signed) header.d=none;gmail.com; dmarc=none action=none header.from=amd.com; Received: from SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) by SN6PR12MB2768.namprd12.prod.outlook.com (2603:10b6:805:72::11) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4331.21; Fri, 16 Jul 2021 22:16:37 +0000 Received: from SN6PR12MB2718.namprd12.prod.outlook.com ([fe80::a8a9:2aac:4fd1:88fa]) by SN6PR12MB2718.namprd12.prod.outlook.com ([fe80::a8a9:2aac:4fd1:88fa%3]) with mapi id 15.20.4331.024; Fri, 16 Jul 2021 22:16:37 +0000 Cc: brijesh.singh@amd.com, 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, linux-crypto@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , 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 , tony.luck@intel.com, npmccallum@redhat.com, brijesh.ksingh@gmail.com Subject: Re: [PATCH Part2 RFC v4 25/40] KVM: SVM: Reclaim the guest pages when SEV-SNP VM terminates To: Sean Christopherson References: <20210707183616.5620-1-brijesh.singh@amd.com> <20210707183616.5620-26-brijesh.singh@amd.com> From: Brijesh Singh Message-ID: <2711d9f9-21a0-7baa-d0ff-2c0f69ca6949@amd.com> Date: Fri, 16 Jul 2021 17:16:30 -0500 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-ClientProxiedBy: SN4PR0501CA0100.namprd05.prod.outlook.com (2603:10b6:803:42::17) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from Brijeshs-MacBook-Pro.local (70.112.153.56) by SN4PR0501CA0100.namprd05.prod.outlook.com (2603:10b6:803:42::17) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4352.9 via Frontend Transport; Fri, 16 Jul 2021 22:16:31 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 55d761ab-7b05-45ed-049b-08d948a760e7 X-MS-TrafficTypeDiagnostic: SN6PR12MB2768: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN6PR12MB2718.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(4636009)(346002)(136003)(39860400002)(376002)(366004)(396003)(8936002)(52116002)(31686004)(5660300002)(86362001)(2906002)(66946007)(26005)(6916009)(6512007)(66556008)(66476007)(83380400001)(44832011)(36756003)(186003)(956004)(6486002)(478600001)(2616005)(7406005)(6506007)(7416002)(8676002)(54906003)(316002)(31696002)(53546011)(38100700002)(38350700002)(4326008)(43740500002)(45980500001);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?OTRjanRJTXRsMXp4emZWUkpiZFNTaXBpSlpzYnNuRVpzL3FjY0ZPUEYrUGJv?= =?utf-8?B?bjZHc2dtdXZTbGhiTTNwT3ROYmY2SHNFVEozQnR3RzFXM2piOHVTYU1jYlJj?= =?utf-8?B?bnJZRnNGbGYyNmtYellNUFVWTkRQOEpVcEdQVllpRkpLalkyTi9OT3hrc0Ez?= =?utf-8?B?R2hQNDJBTUgxZ0YyNHdicTFRdXErbjZ3U2pxNXBPZ1MraVdreTJwUk4wbUNN?= =?utf-8?B?aWF6dmdEZmJUTTNKV2J5NlUvRDJic1B2aXdSK3c3VU5DZ0RPY0c5ZS84NDhv?= =?utf-8?B?bGlzOTRjNWkzMXVpNkNTTTlMaDZwWGxESXA0UVA0ODFrQU5LTDUvZUxYYjZ3?= =?utf-8?B?dnpBb1NJT2F2WTFETWVtT3hTT2d3MTV6MmZuVkoxbk5lbmZvaDh6dk9jcmR0?= =?utf-8?B?bWtqQXRia0RlVDAzcWFDWWhiNDR6RVpjeE5qeEZLdTFNQnV0OE5sRkRubnhz?= =?utf-8?B?NUw3alJ3UnJrQXVCa0J3M3BaaVlTc1JJdEZnUkM4NStQRE1aTHVlWFN5ZEpy?= =?utf-8?B?dDhWcmpFcUU1aTdDTmpuY3JVc3cwYndVS1NDRDczd05jTkZRbG8rRUpFK05v?= =?utf-8?B?QkVxSEpqREk2Nm0wR3pvSnJrL3RERFcrWHVMVE5DRndMT1lOU1hkZjQwelEx?= =?utf-8?B?YnRaZnlOdHhPWDN0UHE3LzFIMkpPSGIyNzVJUjdsZ29tcjV3VkNHKzBpWkFH?= =?utf-8?B?NGxQM1N6aHlqd0pNcFpxMHVHcm1XQlZWUUsxVUg1TW1pWGlIcGx6YkhScVVN?= =?utf-8?B?QmVBN0JyWUFscW1Jck9GZXdVcUxFclBZa3pjVHRCVlh0cjNrTnFWSUNGM2hr?= =?utf-8?B?MjA5ZW9FMnRnTURWTWc4WGRJUDA0K2pEOUJOVjVFTWR6OWVNcFlPcE80dHV2?= =?utf-8?B?a1BIN3piN0diU3pnajBra2RtNVpBRmljQUhZNHFydkpnNlNoZ1VDVVM4Mitn?= =?utf-8?B?K2h2aXhmQnYraDJaa21LbkMwSnFyRFlKNnpYNTBacmJKcHgrdlJid1ZuK29H?= =?utf-8?B?WU1ieG1kZGhMQnBrWlNaeXE5cTk4czcySnFNZVJ1RllRSnNSNVNxNHh6Uytn?= =?utf-8?B?S2FBZTVZZXNsU1JSU3NQVThTWktPQmtmRGYyTlN4Ui92Zm91YWVnSzBCVHFJ?= =?utf-8?B?a25MakY4djVzRmtrUWlEUWMzMzFNT0dUdU9tYTlLRi9pVzhLWUdFMEpmR1ZY?= =?utf-8?B?TkhSNmdzL0Yxa3g5RUFIdFhFZko4b0h1b1JEMU92MTNHaWpRNTBDOEcyODNC?= =?utf-8?B?UE1HRytMU21VNUdEZTlEdjN6YjFKRG9LMjhWa3VWNXpESG9ETGFIaVllSkY3?= =?utf-8?B?elQ1YnlUOFcrNEZWVllVSE5EVDV5Vk4zL0ZRYnM1V3NkNk1RSThMR2FYQ0s2?= =?utf-8?B?a2NraXQ3L1ZjTzNPUnpsV2RhTE4yZkFNM1NGejJyU25WWGN1aTJuTUxMWklY?= =?utf-8?B?VFFkaW9iTHo5cUNTR2E3dkFzTjdRejhkZlhFcWpLVkdVZ3F6dzZTSmZVWmNK?= =?utf-8?B?R01vdGM0a2lkb0w4alpNYno5V3QzSHFTNlBJTXBxaDJZNk05dWN4ektteVNC?= =?utf-8?B?amRkTnkrQ3hrb1o5a0s5WGx0MkgwckZKL0p3UzdJWWNYd2FvUFJQSnNXemZI?= =?utf-8?B?VDArSmFmQ0NGNmM3Ni9rUWFpSStTZ0Y0cjV1YmtQdkdCUk9wRWlQOUUyWWh0?= =?utf-8?B?QjJtaEt2REViTGlPbVJ6ZzB4V0xrdEtsVUVlcUxROEd3Umc0R0FQcUZJd2lQ?= =?utf-8?Q?mSD6dExPVUldHAzKrOc1eJsbpiXHlsKAyVlH3x0?= X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-Network-Message-Id: 55d761ab-7b05-45ed-049b-08d948a760e7 X-MS-Exchange-CrossTenant-AuthSource: SN6PR12MB2718.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Jul 2021 22:16:37.3915 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: cv3SINbz63D4R5p71+vTdSG2QauU4fOlKTdQZVS3Clx/oUKshw737zO1fuJ2i5qfEjFnrWrmUrwNO+XkjOgNsg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SN6PR12MB2768 On 7/16/21 3:09 PM, Sean Christopherson wrote: > On Wed, Jul 07, 2021, Brijesh Singh wrote: >> The guest pages of the SEV-SNP VM maybe added as a private page in the >> RMP entry (assigned bit is set). The guest private pages must be >> transitioned to the hypervisor state before its freed. > Isn't this patch needed much earlier in the series, i.e. when the first RMPUPDATE > usage goes in? Yes, the first RMPUPDATE usage is in the LAUNCH_UPDATE patch and this should be squashed in that patch. >> Signed-off-by: Brijesh Singh >> --- >> arch/x86/kvm/svm/sev.c | 39 +++++++++++++++++++++++++++++++++++++++ >> 1 file changed, 39 insertions(+) >> >> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >> index 1f0635ac9ff9..4468995dd209 100644 >> --- a/arch/x86/kvm/svm/sev.c >> +++ b/arch/x86/kvm/svm/sev.c >> @@ -1940,6 +1940,45 @@ find_enc_region(struct kvm *kvm, struct kvm_enc_region *range) >> static void __unregister_enc_region_locked(struct kvm *kvm, >> struct enc_region *region) >> { >> + struct rmpupdate val = {}; >> + unsigned long i, pfn; >> + struct rmpentry *e; >> + int level, rc; >> + >> + /* >> + * The guest memory pages are assigned in the RMP table. Unassign it >> + * before releasing the memory. >> + */ >> + if (sev_snp_guest(kvm)) { >> + for (i = 0; i < region->npages; i++) { >> + pfn = page_to_pfn(region->pages[i]); >> + >> + if (need_resched()) >> + schedule(); > This can simply be "cond_resched();" Yes. > >> + >> + e = snp_lookup_page_in_rmptable(region->pages[i], &level); >> + if (unlikely(!e)) >> + continue; >> + >> + /* If its not a guest assigned page then skip it. */ >> + if (!rmpentry_assigned(e)) >> + continue; >> + >> + /* Is the page part of a 2MB RMP entry? */ >> + if (level == PG_LEVEL_2M) { >> + val.pagesize = RMP_PG_SIZE_2M; >> + pfn &= ~(KVM_PAGES_PER_HPAGE(PG_LEVEL_2M) - 1); >> + } else { >> + val.pagesize = RMP_PG_SIZE_4K; > This raises yet more questions (for me) as to the interaction between Page-Size > and Hyperivsor-Owned flags in the RMP. It also raises questions on the correctness > of zeroing the RMP entry if KVM_SEV_SNP_LAUNCH_START (in the previous patch). I assume you mean the LAUNCH_UPDATE because that's when we need to perform the RMPUPDATE. The hypervisor owned means all zero in the RMP entry. >> + } >> + >> + /* Transition the page to hypervisor owned. */ >> + rc = rmpupdate(pfn_to_page(pfn), &val); >> + if (rc) >> + pr_err("Failed to release pfn 0x%lx ret=%d\n", pfn, rc); > This is not robust, e.g. KVM will unpin the memory and release it back to the > kernel with a stale RMP entry. Shouldn't this be a WARN+leak situation? Yes. Maybe we should increase the page refcount to ensure that this page is not reused after the process is terminated ? >> + } >> + } >> + >> sev_unpin_memory(kvm, region->pages, region->npages); >> list_del(®ion->list); >> kfree(region); >> -- >> 2.17.1 >>