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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 Singh Subject: [PATCH v8 29/40] x86/compressed/64: add support for SEV-SNP CPUID table in #VC handlers Date: Fri, 10 Dec 2021 09:43:21 -0600 Message-ID: <20211210154332.11526-30-brijesh.singh@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20211210154332.11526-1-brijesh.singh@amd.com> References: <20211210154332.11526-1-brijesh.singh@amd.com> MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB03.amd.com (10.181.40.144) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 02e073b3-9a8c-4d7a-d555-08d9bbf3f7e0 X-MS-TrafficTypeDiagnostic: DM6PR12MB4548:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:3383; 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:SATLEXMB03.amd.com; PTR:InfoDomainNonexistent; CAT:NONE; SFS:(4636009)(46966006)(36840700001)(40470700001)(16526019)(426003)(4326008)(44832011)(186003)(6666004)(7416002)(8676002)(7696005)(1076003)(336012)(2616005)(54906003)(47076005)(5660300002)(2906002)(110136005)(508600001)(356005)(83380400001)(70586007)(36756003)(70206006)(81166007)(26005)(7406005)(316002)(36860700001)(30864003)(86362001)(40460700001)(82310400004)(8936002)(36900700001)(2101003); DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 10 Dec 2021 15:44:35.9477 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 02e073b3-9a8c-4d7a-d555-08d9bbf3f7e0 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=[SATLEXMB03.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT036.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM6PR12MB4548 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org From: Michael Roth CPUID instructions generate a #VC exception for SEV-ES/SEV-SNP guests, for which early handlers are currently set up to handle. In the case of SEV-SNP, guests can use a configurable location in guest memory that has been pre-populated with a firmware-validated CPUID table to look up the relevant CPUID values rather than requesting them from hypervisor via a VMGEXIT. Add the various hooks in the #VC handlers to allow CPUID instructions to be handled via the table. The code to actually configure/enable the table will be added in a subsequent commit. Signed-off-by: Michael Roth Signed-off-by: Brijesh Singh --- arch/x86/boot/compressed/sev.c | 1 + arch/x86/include/asm/sev-common.h | 2 + arch/x86/kernel/sev-shared.c | 320 ++++++++++++++++++++++++++++++ arch/x86/kernel/sev.c | 1 + 4 files changed, 324 insertions(+) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 348f7711c3ea..3514feb5b226 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "error.h" diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index 38c14601ae4a..673e6778194b 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -152,6 +152,8 @@ struct snp_psc_desc { #define GHCB_TERM_PSC 1 /* Page State Change failure */ #define GHCB_TERM_PVALIDATE 2 /* Pvalidate failure */ #define GHCB_TERM_NOT_VMPL0 3 /* SNP guest is not running at VMPL-0 */ +#define GHCB_TERM_CPUID 4 /* CPUID-validation failure */ +#define GHCB_TERM_CPUID_HV 5 /* CPUID failure during hypervisor fallback */ #define GHCB_RESP_CODE(v) ((v) & GHCB_MSR_INFO_MASK) diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index d89481b31022..dabb425498e0 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -14,6 +14,41 @@ #define has_cpuflag(f) boot_cpu_has(f) #endif +/* + * Individual entries of the SEV-SNP CPUID table, as defined by the SEV-SNP + * Firmware ABI, Revision 0.9, Section 7.1, Table 14. Note that the XCR0_IN + * and XSS_IN are denoted here as __unused/__unused2, since they are not + * needed for the current guest implementation, where the size of the buffers + * needed to store enabled XSAVE-saved features are calculated rather than + * encoded in the CPUID table for each possible combination of XCR0_IN/XSS_IN + * to save space. + */ +struct snp_cpuid_fn { + u32 eax_in; + u32 ecx_in; + u64 __unused; + u64 __unused2; + u32 eax; + u32 ebx; + u32 ecx; + u32 edx; + u64 __reserved; +} __packed; + +/* + * SEV-SNP CPUID table header, as defined by the SEV-SNP Firmware ABI, + * Revision 0.9, Section 8.14.2.6. Also noted there is the SEV-SNP + * firmware-enforced limit of 64 entries per CPUID table. + */ +#define SNP_CPUID_COUNT_MAX 64 + +struct snp_cpuid_info { + u32 count; + u32 __reserved1; + u64 __reserved2; + struct snp_cpuid_fn fn[SNP_CPUID_COUNT_MAX]; +} __packed; + /* * Since feature negotiation related variables are set early in the boot * process they must reside in the .data section so as not to be zeroed @@ -23,6 +58,20 @@ */ static u16 ghcb_version __ro_after_init; +/* Copy of the SNP firmware's CPUID page. */ +static struct snp_cpuid_info cpuid_info_copy __ro_after_init; +static bool snp_cpuid_initialized __ro_after_init; + +/* + * These will be initialized based on CPUID table so that non-present + * all-zero leaves (for sparse tables) can be differentiated from + * invalid/out-of-range leaves. This is needed since all-zero leaves + * still need to be post-processed. + */ +u32 cpuid_std_range_max __ro_after_init; +u32 cpuid_hyp_range_max __ro_after_init; +u32 cpuid_ext_range_max __ro_after_init; + static bool __init sev_es_check_cpu_features(void) { if (!has_cpuflag(X86_FEATURE_RDRAND)) { @@ -246,6 +295,244 @@ static int sev_cpuid_hv(u32 func, u32 subfunc, u32 *eax, u32 *ebx, return 0; } +static const struct snp_cpuid_info * +snp_cpuid_info_get_ptr(void) +{ + void *ptr; + + /* + * This may be called early while still running on the initial identity + * mapping. Use RIP-relative addressing to obtain the correct address + * in both for identity mapping and after switch-over to kernel virtual + * addresses. + */ + asm ("lea cpuid_info_copy(%%rip), %0" + : "=r" (ptr) + : "p" (&cpuid_info_copy)); + + return ptr; +} + +static inline bool snp_cpuid_active(void) +{ + return snp_cpuid_initialized; +} + +static int snp_cpuid_calc_xsave_size(u64 xfeatures_en, u32 base_size, + u32 *xsave_size, bool compacted) +{ + const struct snp_cpuid_info *cpuid_info = snp_cpuid_info_get_ptr(); + u32 xsave_size_total = base_size; + u64 xfeatures_found = 0; + int i; + + for (i = 0; i < cpuid_info->count; i++) { + const struct snp_cpuid_fn *fn = &cpuid_info->fn[i]; + + if (!(fn->eax_in == 0xD && fn->ecx_in > 1 && fn->ecx_in < 64)) + continue; + if (!(xfeatures_en & (BIT_ULL(fn->ecx_in)))) + continue; + if (xfeatures_found & (BIT_ULL(fn->ecx_in))) + continue; + + xfeatures_found |= (BIT_ULL(fn->ecx_in)); + + if (compacted) + xsave_size_total += fn->eax; + else + xsave_size_total = max(xsave_size_total, + fn->eax + fn->ebx); + } + + /* + * Either the guest set unsupported XCR0/XSS bits, or the corresponding + * entries in the CPUID table were not present. This is not a valid + * state to be in. + */ + if (xfeatures_found != (xfeatures_en & GENMASK_ULL(63, 2))) + return -EINVAL; + + *xsave_size = xsave_size_total; + + return 0; +} + +static void snp_cpuid_hv(u32 func, u32 subfunc, u32 *eax, u32 *ebx, u32 *ecx, + u32 *edx) +{ + /* + * MSR protocol does not support fetching indexed subfunction, but is + * sufficient to handle current fallback cases. Should that change, + * make sure to terminate rather than ignoring the index and grabbing + * random values. If this issue arises in the future, handling can be + * added here to use GHCB-page protocol for cases that occur late + * enough in boot that GHCB page is available. + */ + if (cpuid_function_is_indexed(func) && subfunc) + sev_es_terminate(1, GHCB_TERM_CPUID_HV); + + if (sev_cpuid_hv(func, 0, eax, ebx, ecx, edx)) + sev_es_terminate(1, GHCB_TERM_CPUID_HV); +} + +static bool +snp_cpuid_find_validated_func(u32 func, u32 subfunc, u32 *eax, u32 *ebx, + u32 *ecx, u32 *edx) +{ + const struct snp_cpuid_info *cpuid_info = snp_cpuid_info_get_ptr(); + int i; + + for (i = 0; i < cpuid_info->count; i++) { + const struct snp_cpuid_fn *fn = &cpuid_info->fn[i]; + + if (fn->eax_in != func) + continue; + + if (cpuid_function_is_indexed(func) && fn->ecx_in != subfunc) + continue; + + *eax = fn->eax; + *ebx = fn->ebx; + *ecx = fn->ecx; + *edx = fn->edx; + + return true; + } + + return false; +} + +static bool snp_cpuid_check_range(u32 func) +{ + if (func <= cpuid_std_range_max || + (func >= 0x40000000 && func <= cpuid_hyp_range_max) || + (func >= 0x80000000 && func <= cpuid_ext_range_max)) + return true; + + return false; +} + +static int snp_cpuid_postprocess(u32 func, u32 subfunc, u32 *eax, u32 *ebx, + u32 *ecx, u32 *edx) +{ + u32 ebx2, ecx2, edx2; + + switch (func) { + case 0x1: + snp_cpuid_hv(func, subfunc, NULL, &ebx2, NULL, &edx2); + + /* initial APIC ID */ + *ebx = (ebx2 & GENMASK(31, 24)) | (*ebx & GENMASK(23, 0)); + /* APIC enabled bit */ + *edx = (edx2 & BIT(9)) | (*edx & ~BIT(9)); + + /* OSXSAVE enabled bit */ + if (native_read_cr4() & X86_CR4_OSXSAVE) + *ecx |= BIT(27); + break; + case 0x7: + /* OSPKE enabled bit */ + *ecx &= ~BIT(4); + if (native_read_cr4() & X86_CR4_PKE) + *ecx |= BIT(4); + break; + case 0xB: + /* extended APIC ID */ + snp_cpuid_hv(func, 0, NULL, NULL, NULL, edx); + break; + case 0xD: { + bool compacted = false; + u64 xcr0 = 1, xss = 0; + u32 xsave_size; + + if (subfunc != 0 && subfunc != 1) + return 0; + + if (native_read_cr4() & X86_CR4_OSXSAVE) + xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); + if (subfunc == 1) { + /* Get XSS value if XSAVES is enabled. */ + if (*eax & BIT(3)) { + unsigned long lo, hi; + + asm volatile("rdmsr" : "=a" (lo), "=d" (hi) + : "c" (MSR_IA32_XSS)); + xss = (hi << 32) | lo; + } + + /* + * The PPR and APM aren't clear on what size should be + * encoded in 0xD:0x1:EBX when compaction is not enabled + * by either XSAVEC (feature bit 1) or XSAVES (feature + * bit 3) since SNP-capable hardware has these feature + * bits fixed as 1. KVM sets it to 0 in this case, but + * to avoid this becoming an issue it's safer to simply + * treat this as unsupported for SEV-SNP guests. + */ + if (!(*eax & (BIT(1) | BIT(3)))) + return -EINVAL; + + compacted = true; + } + + if (snp_cpuid_calc_xsave_size(xcr0 | xss, *ebx, &xsave_size, + compacted)) + return -EINVAL; + + *ebx = xsave_size; + } + break; + case 0x8000001E: + /* extended APIC ID */ + snp_cpuid_hv(func, subfunc, eax, &ebx2, &ecx2, NULL); + /* compute ID */ + *ebx = (*ebx & GENMASK(31, 8)) | (ebx2 & GENMASK(7, 0)); + /* node ID */ + *ecx = (*ecx & GENMASK(31, 8)) | (ecx2 & GENMASK(7, 0)); + break; + default: + /* No fix-ups needed, use values as-is. */ + break; + } + + return 0; +} + +/* + * Returns -EOPNOTSUPP if feature not enabled. Any other return value should be + * treated as fatal by caller. + */ +static int snp_cpuid(u32 func, u32 subfunc, u32 *eax, u32 *ebx, u32 *ecx, + u32 *edx) +{ + if (!snp_cpuid_active()) + return -EOPNOTSUPP; + + if (!snp_cpuid_find_validated_func(func, subfunc, eax, ebx, ecx, edx)) { + /* + * Some hypervisors will avoid keeping track of CPUID entries + * where all values are zero, since they can be handled the + * same as out-of-range values (all-zero). This is useful here + * as well as it allows virtually all guest configurations to + * work using a single SEV-SNP CPUID table. + * + * To allow for this, there is a need to distinguish between + * out-of-range entries and in-range zero entries, since the + * CPUID table entries are only a template that may need to be + * augmented with additional values for things like + * CPU-specific information during post-processing. So if it's + * not in the table, but is still in the valid range, proceed + * with the post-processing. Otherwise, just return zeros. + */ + *eax = *ebx = *ecx = *edx = 0; + if (!snp_cpuid_check_range(func)) + return 0; + } + + return snp_cpuid_postprocess(func, subfunc, eax, ebx, ecx, edx); +} + /* * Boot VC Handler - This is the first VC handler during boot, there is no GHCB * page yet, so it only supports the MSR based communication with the @@ -253,16 +540,26 @@ static int sev_cpuid_hv(u32 func, u32 subfunc, u32 *eax, u32 *ebx, */ void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) { + unsigned int subfn = lower_bits(regs->cx, 32); unsigned int fn = lower_bits(regs->ax, 32); u32 eax, ebx, ecx, edx; + int ret; /* Only CPUID is supported via MSR protocol */ if (exit_code != SVM_EXIT_CPUID) goto fail; + ret = snp_cpuid(fn, subfn, &eax, &ebx, &ecx, &edx); + if (ret == 0) + goto cpuid_done; + + if (ret != -EOPNOTSUPP) + goto fail; + if (sev_cpuid_hv(fn, 0, &eax, &ebx, &ecx, &edx)) goto fail; +cpuid_done: regs->ax = eax; regs->bx = ebx; regs->cx = ecx; @@ -557,12 +854,35 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) return ret; } +static int vc_handle_cpuid_snp(struct pt_regs *regs) +{ + u32 eax, ebx, ecx, edx; + int ret; + + ret = snp_cpuid(regs->ax, regs->cx, &eax, &ebx, &ecx, &edx); + if (ret == 0) { + regs->ax = eax; + regs->bx = ebx; + regs->cx = ecx; + regs->dx = edx; + } + + return ret; +} + static enum es_result vc_handle_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct pt_regs *regs = ctxt->regs; u32 cr4 = native_read_cr4(); enum es_result ret; + int snp_cpuid_ret; + + snp_cpuid_ret = vc_handle_cpuid_snp(regs); + if (snp_cpuid_ret == 0) + return ES_OK; + if (snp_cpuid_ret != -EOPNOTSUPP) + return ES_VMM_ERROR; ghcb_set_rax(ghcb, regs->ax); ghcb_set_rcx(ghcb, regs->cx); diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 21926b094378..32f60602ec29 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -33,6 +33,7 @@ #include #include #include +#include #define DR7_RESET_VALUE 0x400