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Mon, 12 Jun 2023 04:29:58 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; 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 CY4PEPF0000E9CD.mail.protection.outlook.com (10.167.241.140) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.6500.21 via Frontend Transport; Mon, 12 Jun 2023 04:29:58 +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 15.1.2507.23; Sun, 11 Jun 2023 23:29:57 -0500 From: Michael Roth To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Brijesh Singh Subject: [PATCH RFC v9 14/51] x86/sev: Add helper functions for RMPUPDATE and PSMASH instruction Date: Sun, 11 Jun 2023 23:25:22 -0500 Message-ID: <20230612042559.375660-15-michael.roth@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230612042559.375660-1-michael.roth@amd.com> References: <20230612042559.375660-1-michael.roth@amd.com> MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] 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: CY4PEPF0000E9CD:EE_|DM6PR12MB4435:EE_ X-MS-Office365-Filtering-Correlation-Id: 39ba6556-3c53-4fa1-dc99-08db6afdae0d 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: 12 Jun 2023 04:29:58.1065 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 39ba6556-3c53-4fa1-dc99-08db6afdae0d 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: CY4PEPF0000E9CD.namprd03.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4435 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org From: Brijesh Singh The RMPUPDATE instruction writes a new RMP entry in the RMP Table. The hypervisor will use the instruction to add pages to the RMP table. See APM3 for details on the instruction operations. The PSMASH instruction expands a 2MB RMP entry into a corresponding set of contiguous 4KB-Page RMP entries. The hypervisor will use this instruction to adjust the RMP entry without invalidating the previous RMP entry. Add the following external interface API functions: psmash(): Used to smash a 2MB aligned page into 4K pages while preserving the Validated bit in the RMP. rmp_make_private(): Used to assign a page to guest using the RMPUPDATE instruction. rmp_make_shared(): Used to transition a page to hypervisor/shared state using the RMPUPDATE instruction. Signed-off-by: Ashish Kalra Signed-off-by: Brijesh Singh [mdr: add RMPUPDATE retry logic for transient FAIL_OVERLAP errors] Signed-off-by: Michael Roth --- arch/x86/coco/sev/host.c | 94 +++++++++++++++++++++++++++++++ arch/x86/include/asm/sev-common.h | 14 +++++ arch/x86/include/asm/sev-host.h | 10 ++++ 3 files changed, 118 insertions(+) diff --git a/arch/x86/coco/sev/host.c b/arch/x86/coco/sev/host.c index d766b3bc6647..9df690b0b263 100644 --- a/arch/x86/coco/sev/host.c +++ b/arch/x86/coco/sev/host.c @@ -338,3 +338,97 @@ void sev_dump_rmpentry(u64 pfn) } } EXPORT_SYMBOL_GPL(sev_dump_rmpentry); + +/* + * PSMASH a 2MB aligned page into 4K pages in the RMP table while preserving the + * Validated bit. + */ +int psmash(u64 pfn) +{ + unsigned long paddr = pfn << PAGE_SHIFT; + int ret; + + pr_debug("%s: PFN: 0x%llx\n", __func__, pfn); + + if (!pfn_valid(pfn)) + return -EINVAL; + + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + return -ENXIO; + + /* Binutils version 2.36 supports the PSMASH mnemonic. */ + asm volatile(".byte 0xF3, 0x0F, 0x01, 0xFF" + : "=a"(ret) + : "a"(paddr) + : "memory", "cc"); + + return ret; +} +EXPORT_SYMBOL_GPL(psmash); + +static int rmpupdate(u64 pfn, struct rmp_state *val) +{ + unsigned long paddr = pfn << PAGE_SHIFT; + int ret, level, npages; + int attempts = 0; + + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + return -ENXIO; + + do { + /* Binutils version 2.36 supports the RMPUPDATE mnemonic. */ + asm volatile(".byte 0xF2, 0x0F, 0x01, 0xFE" + : "=a"(ret) + : "a"(paddr), "c"((unsigned long)val) + : "memory", "cc"); + + attempts++; + } while (ret == RMPUPDATE_FAIL_OVERLAP); + + if (ret) { + pr_err("RMPUPDATE failed after %d attempts, ret: %d, pfn: %llx, npages: %d, level: %d\n", + attempts, ret, pfn, npages, level); + sev_dump_rmpentry(pfn); + dump_stack(); + return -EFAULT; + } + + return 0; +} + +/* + * Assign a page to guest using the RMPUPDATE instruction. + */ +int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable) +{ + struct rmp_state val; + + pr_debug("%s: GPA: 0x%llx, PFN: 0x%llx, level: %d, immutable: %d\n", + __func__, gpa, pfn, level, immutable); + + memset(&val, 0, sizeof(val)); + val.assigned = 1; + val.asid = asid; + val.immutable = immutable; + val.gpa = gpa; + val.pagesize = X86_TO_RMP_PG_LEVEL(level); + + return rmpupdate(pfn, &val); +} +EXPORT_SYMBOL_GPL(rmp_make_private); + +/* + * Transition a page to hypervisor/shared state using the RMPUPDATE instruction. + */ +int rmp_make_shared(u64 pfn, enum pg_level level) +{ + struct rmp_state val; + + pr_debug("%s: PFN: 0x%llx, level: %d\n", __func__, pfn, level); + + memset(&val, 0, sizeof(val)); + val.pagesize = X86_TO_RMP_PG_LEVEL(level); + + return rmpupdate(pfn, &val); +} +EXPORT_SYMBOL_GPL(rmp_make_shared); diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index bf0378136289..9eb20b416251 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -171,8 +171,22 @@ struct snp_psc_desc { #define GHCB_ERR_INVALID_INPUT 5 #define GHCB_ERR_INVALID_EVENT 6 +/* RMUPDATE detected 4K page and 2MB page overlap. */ +#define RMPUPDATE_FAIL_OVERLAP 4 + /* RMP page size */ #define RMP_PG_SIZE_4K 0 +#define RMP_PG_SIZE_2M 1 #define RMP_TO_X86_PG_LEVEL(level) (((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M) +#define X86_TO_RMP_PG_LEVEL(level) (((level) == PG_LEVEL_4K) ? RMP_PG_SIZE_4K : RMP_PG_SIZE_2M) + +struct rmp_state { + u64 gpa; + u8 assigned; + u8 pagesize; + u8 immutable; + u8 rsvd; + u32 asid; +} __packed; #endif diff --git a/arch/x86/include/asm/sev-host.h b/arch/x86/include/asm/sev-host.h index 85cfe577155c..753e80d16433 100644 --- a/arch/x86/include/asm/sev-host.h +++ b/arch/x86/include/asm/sev-host.h @@ -16,9 +16,19 @@ #ifdef CONFIG_KVM_AMD_SEV int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level); void sev_dump_rmpentry(u64 pfn); +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); #else static inline int snp_lookup_rmpentry(u64 pfn, bool *assigned, int *level) { return 0; } static inline void sev_dump_rmpentry(u64 pfn) {} +static inline int psmash(u64 pfn) { return -ENXIO; } +static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, + bool immutable) +{ + return -ENODEV; +} +static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } #endif #endif