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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by MWH0EPF000971E8.mail.protection.outlook.com (10.167.243.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7228.16 via Frontend Transport; Fri, 26 Jan 2024 04:42:55 +0000 Received: from localhost (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.34; Thu, 25 Jan 2024 22:42:54 -0600 From: Michael Roth To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: [PATCH v2 15/25] x86/sev: Introduce snp leaked pages list Date: Thu, 25 Jan 2024 22:11:15 -0600 Message-ID: <20240126041126.1927228-16-michael.roth@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20240126041126.1927228-1-michael.roth@amd.com> References: <20240126041126.1927228-1-michael.roth@amd.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: MWH0EPF000971E8:EE_|SA0PR12MB4543:EE_ X-MS-Office365-Filtering-Correlation-Id: b8048db2-57b5-4e12-66fd-08dc1e2943cc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Jan 2024 04:42:55.8323 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: b8048db2-57b5-4e12-66fd-08dc1e2943cc X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: MWH0EPF000971E8.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4543 From: Ashish Kalra Pages are unsafe to be released back to the page-allocator, if they have been transitioned to firmware/guest state and can't be reclaimed or transitioned back to hypervisor/shared state. In this case add them to an internal leaked pages list to ensure that they are not freed or touched/accessed to cause fatal page faults. Suggested-by: Vlastimil Babka Signed-off-by: Ashish Kalra [mdr: relocate to arch/x86/virt/svm/sev.c] Signed-off-by: Michael Roth Reviewed-by: Vlastimil Babka --- arch/x86/include/asm/sev.h | 2 ++ arch/x86/virt/svm/sev.c | 34 ++++++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index d3ccb7a0c7e9..435ba9bc4510 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -264,6 +264,7 @@ void snp_dump_hva_rmpentry(unsigned long address); int psmash(u64 pfn); int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable); int rmp_make_shared(u64 pfn, enum pg_level level); +void snp_leak_pages(u64 pfn, unsigned int npages); #else static inline bool snp_probe_rmptable_info(void) { return false; } static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return -ENODEV; } @@ -275,6 +276,7 @@ static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int as return -ENODEV; } static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } +static inline void snp_leak_pages(u64 pfn, unsigned int npages) {} #endif #endif diff --git a/arch/x86/virt/svm/sev.c b/arch/x86/virt/svm/sev.c index 1a13eff78c9d..649ac1bb6b0e 100644 --- a/arch/x86/virt/svm/sev.c +++ b/arch/x86/virt/svm/sev.c @@ -65,6 +65,11 @@ static u64 probed_rmp_base, probed_rmp_size; static struct rmpentry *rmptable __ro_after_init; static u64 rmptable_max_pfn __ro_after_init; +static LIST_HEAD(snp_leaked_pages_list); +static DEFINE_SPINLOCK(snp_leaked_pages_list_lock); + +static unsigned long snp_nr_leaked_pages; + #undef pr_fmt #define pr_fmt(fmt) "SEV-SNP: " fmt @@ -505,3 +510,32 @@ int rmp_make_shared(u64 pfn, enum pg_level level) return rmpupdate(pfn, &state); } EXPORT_SYMBOL_GPL(rmp_make_shared); + +void snp_leak_pages(u64 pfn, unsigned int npages) +{ + struct page *page = pfn_to_page(pfn); + + pr_warn("Leaking PFN range 0x%llx-0x%llx\n", pfn, pfn + npages); + + spin_lock(&snp_leaked_pages_list_lock); + while (npages--) { + /* + * Reuse the page's buddy list for chaining into the leaked + * pages list. This page should not be on a free list currently + * and is also unsafe to be added to a free list. + */ + if (likely(!PageCompound(page)) || + (PageHead(page) && compound_nr(page) <= npages)) + /* + * Skip inserting tail pages of compound page as + * page->buddy_list of tail pages is not usable. + */ + list_add_tail(&page->buddy_list, &snp_leaked_pages_list); + dump_rmpentry(pfn); + snp_nr_leaked_pages++; + pfn++; + page++; + } + spin_unlock(&snp_leaked_pages_list_lock); +} +EXPORT_SYMBOL_GPL(snp_leak_pages);