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David Alan Gilbert" , , , , , Brijesh Singh Subject: [PATCH v11 15/45] x86/compressed: Add helper for validating pages in the decompression stage Date: Thu, 24 Feb 2022 10:55:55 -0600 Message-ID: <20220224165625.2175020-16-brijesh.singh@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220224165625.2175020-1-brijesh.singh@amd.com> References: <20220224165625.2175020-1-brijesh.singh@amd.com> MIME-Version: 1.0 Content-Type: text/plain 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-Office365-Filtering-Correlation-Id: 2ee92988-b8c3-4312-93b6-08d9f7b6dfcb X-MS-TrafficTypeDiagnostic: CY4PR1201MB0006:EE_ X-Microsoft-Antispam-PRVS: 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:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230001)(4636009)(46966006)(40470700004)(36840700001)(5660300002)(4326008)(110136005)(2906002)(7406005)(44832011)(8676002)(70206006)(54906003)(40460700003)(70586007)(82310400004)(7416002)(8936002)(316002)(83380400001)(86362001)(36860700001)(36756003)(26005)(81166007)(356005)(47076005)(7696005)(16526019)(186003)(336012)(2616005)(1076003)(6666004)(508600001)(426003)(2101003)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Feb 2022 16:58:25.9311 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 2ee92988-b8c3-4312-93b6-08d9f7b6dfcb 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: DM6NAM11FT046.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR1201MB0006 X-Rspamd-Queue-Id: 853C5120009 X-Stat-Signature: ar9qb6tfzfeqawkmrz7s7k6j4rg7giiu Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=amd.com header.s=selector1 header.b=y6DT2wry; dmarc=pass (policy=quarantine) header.from=amd.com; spf=pass (imf29.hostedemail.com: domain of brijesh.singh@amd.com designates 40.107.94.67 as permitted sender) smtp.mailfrom=brijesh.singh@amd.com X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1645721909-547163 Content-Transfer-Encoding: quoted-printable 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: Many of the integrity guarantees of SEV-SNP are enforced through the Reverse Map Table (RMP). Each RMP entry contains the GPA at which a particular page of DRAM should be mapped. The VMs can request the hypervisor to add pages in the RMP table via the Page State Change VMGEXI= T defined in the GHCB specification. Inside each RMP entry is a Validated flag; this flag is automatically cleared to 0 by the CPU hardware when a new RMP entry is created for a guest. Each VM page can be either validated or invalidated, as indicated by the Validated flag in the RMP entry. Memory access to a private page that is not validated generates a #VC. A VM must use PVALIDATE instruction to validate the private page before using it. To maintain the security guarantee of SEV-SNP guests, when transitioning pages from private to shared, the guest must invalidate the pages before asking the hypervisor to change the page state to shared in the RMP table= . After the pages are mapped private in the page table, the guest must issu= e a page state change VMGEXIT to make the pages private in the RMP table an= d validate it. On boot, BIOS should have validated the entire system memory. During the kernel decompression stage, the early_setup_ghcb() uses the set_page_decrypted() to make the GHCB page shared (i.e clear encryption attribute). And while exiting from the decompression, it calls the set_page_encrypted() to make the page private. Add snp_set_page_{private,shared}() helpers that are used by the set_page_{decrypted,encrypted}() to change the page state in the RMP tabl= e. Signed-off-by: Brijesh Singh --- arch/x86/boot/compressed/ident_map_64.c | 18 +++++++++- arch/x86/boot/compressed/misc.h | 4 +++ arch/x86/boot/compressed/sev.c | 46 +++++++++++++++++++++++++ arch/x86/include/asm/sev-common.h | 26 ++++++++++++++ 4 files changed, 93 insertions(+), 1 deletion(-) diff --git a/arch/x86/boot/compressed/ident_map_64.c b/arch/x86/boot/comp= ressed/ident_map_64.c index f7213d0943b8..3d566964b829 100644 --- a/arch/x86/boot/compressed/ident_map_64.c +++ b/arch/x86/boot/compressed/ident_map_64.c @@ -275,15 +275,31 @@ static int set_clr_page_flags(struct x86_mapping_in= fo *info, * Changing encryption attributes of a page requires to flush it from * the caches. */ - if ((set | clr) & _PAGE_ENC) + if ((set | clr) & _PAGE_ENC) { clflush_page(address); =20 + /* + * If the encryption attribute is being cleared, then change + * the page state to shared in the RMP table. + */ + if (clr) + snp_set_page_shared(__pa(address & PAGE_MASK)); + } + /* Update PTE */ pte =3D *ptep; pte =3D pte_set_flags(pte, set); pte =3D pte_clear_flags(pte, clr); set_pte(ptep, pte); =20 + /* + * If the encryption attribute is being set, then change the page state= to + * private in the RMP entry. The page state change must be done after t= he PTE + * is updated. + */ + if (set & _PAGE_ENC) + snp_set_page_private(__pa(address & PAGE_MASK)); + /* Flush TLB after changing encryption attribute */ write_cr3(top_level_pgt); =20 diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/m= isc.h index 23e0e395084a..01cc13c12059 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -124,6 +124,8 @@ static inline void console_init(void) void sev_enable(struct boot_params *bp); void sev_es_shutdown_ghcb(void); extern bool sev_es_check_ghcb_fault(unsigned long address); +void snp_set_page_private(unsigned long paddr); +void snp_set_page_shared(unsigned long paddr); #else static inline void sev_enable(struct boot_params *bp) { } static inline void sev_es_shutdown_ghcb(void) { } @@ -131,6 +133,8 @@ static inline bool sev_es_check_ghcb_fault(unsigned l= ong address) { return false; } +static inline void snp_set_page_private(unsigned long paddr) { } +static inline void snp_set_page_shared(unsigned long paddr) { } #endif =20 /* acpi.c */ diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/se= v.c index 84e7d45afa9e..23978d858297 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -116,6 +116,52 @@ static enum es_result vc_read_mem(struct es_em_ctxt = *ctxt, /* Include code for early handlers */ #include "../../kernel/sev-shared.c" =20 +static inline bool sev_snp_enabled(void) +{ + return sev_status & MSR_AMD64_SEV_SNP_ENABLED; +} + +static void __page_state_change(unsigned long paddr, enum psc_op op) +{ + u64 val; + + if (!sev_snp_enabled()) + return; + + /* + * If private -> shared then invalidate the page before requesting the + * state change in the RMP table. + */ + if (op =3D=3D SNP_PAGE_STATE_SHARED && pvalidate(paddr, RMP_PG_SIZE_4K,= 0)) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); + + /* Issue VMGEXIT to change the page state in RMP table. */ + sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op)); + VMGEXIT(); + + /* Read the response of the VMGEXIT. */ + val =3D sev_es_rd_ghcb_msr(); + if ((GHCB_RESP_CODE(val) !=3D GHCB_MSR_PSC_RESP) || GHCB_MSR_PSC_RESP_V= AL(val)) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); + + /* + * Now that page state is changed in the RMP table, validate it so that= it is + * consistent with the RMP entry. + */ + if (op =3D=3D SNP_PAGE_STATE_PRIVATE && pvalidate(paddr, RMP_PG_SIZE_4K= , 1)) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PVALIDATE); +} + +void snp_set_page_private(unsigned long paddr) +{ + __page_state_change(paddr, SNP_PAGE_STATE_PRIVATE); +} + +void snp_set_page_shared(unsigned long paddr) +{ + __page_state_change(paddr, SNP_PAGE_STATE_SHARED); +} + static bool early_setup_ghcb(void) { if (set_page_decrypted((unsigned long)&boot_ghcb_page)) diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev= -common.h index 7ac5842e32b6..fe7fe16e5fd5 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -57,6 +57,32 @@ #define GHCB_MSR_AP_RESET_HOLD_REQ 0x006 #define GHCB_MSR_AP_RESET_HOLD_RESP 0x007 =20 +/* + * SNP Page State Change Operation + * + * GHCBData[55:52] - Page operation: + * 0x0001 Page assignment, Private + * 0x0002 Page assignment, Shared + */ +enum psc_op { + SNP_PAGE_STATE_PRIVATE =3D 1, + SNP_PAGE_STATE_SHARED, +}; + +#define GHCB_MSR_PSC_REQ 0x014 +#define GHCB_MSR_PSC_REQ_GFN(gfn, op) \ + /* GHCBData[55:52] */ \ + (((u64)((op) & 0xf) << 52) | \ + /* GHCBData[51:12] */ \ + ((u64)((gfn) & GENMASK_ULL(39, 0)) << 12) | \ + /* GHCBData[11:0] */ \ + GHCB_MSR_PSC_REQ) + +#define GHCB_MSR_PSC_RESP 0x015 +#define GHCB_MSR_PSC_RESP_VAL(val) \ + /* GHCBData[63:32] */ \ + (((u64)(val) & GENMASK_ULL(63, 32)) >> 32) + /* GHCB Hypervisor Feature Request/Response */ #define GHCB_MSR_HV_FT_REQ 0x080 #define GHCB_MSR_HV_FT_RESP 0x081 --=20 2.25.1