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Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , 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, Brijesh Singh Subject: [PATCH Part1 RFC v4 26/36] x86/compressed/64: enable SEV-SNP-validated CPUID in #VC handler Date: Wed, 7 Jul 2021 13:14:56 -0500 Message-Id: <20210707181506.30489-27-brijesh.singh@amd.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210707181506.30489-1-brijesh.singh@amd.com> References: <20210707181506.30489-1-brijesh.singh@amd.com> X-ClientProxiedBy: SA0PR11CA0104.namprd11.prod.outlook.com (2603:10b6:806:d1::19) To BYAPR12MB2711.namprd12.prod.outlook.com (2603:10b6:a03:63::10) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from sbrijesh-desktop.amd.com (165.204.77.1) by SA0PR11CA0104.namprd11.prod.outlook.com (2603:10b6:806:d1::19) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4308.19 via Frontend Transport; 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dkim=pass header.d=amd.com header.s=selector1 header.b=OMNIb6ei; spf=temperror (imf21.hostedemail.com: error in processing during lookup of brijesh.singh@amd.com: DNS error) smtp.mailfrom=brijesh.singh@amd.com X-Rspamd-Server: rspam05 X-Stat-Signature: 1q3oyzw6dw1s13n6iukw9n8wh1um9wkw X-Rspamd-Queue-Id: 27265D002861 X-Rspam-User: nil X-HE-Tag: 1625683783-71393 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: 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 special location in guest memory address space that has been pre-populated with firmware-validated CPUID information to look up the relevant CPUID values rather than requesting them from hypervisor via a VMGEXIT. Determine the location of the CPUID memory address in advance of any CPUID instructions/exceptions and, when available, use it to handle the CPUID lookup. Signed-off-by: Michael Roth Signed-off-by: Brijesh Singh --- arch/x86/boot/compressed/efi-config-table.c | 44 +++ arch/x86/boot/compressed/head_64.S | 1 + arch/x86/boot/compressed/idt_64.c | 7 +- arch/x86/boot/compressed/misc.h | 10 + arch/x86/boot/compressed/sev.c | 3 + arch/x86/include/asm/sev-common.h | 2 + arch/x86/include/asm/sev.h | 3 + arch/x86/kernel/sev-shared.c | 322 ++++++++++++++++++++ arch/x86/kernel/sev.c | 4 + 9 files changed, 394 insertions(+), 2 deletions(-) diff --git a/arch/x86/boot/compressed/efi-config-table.c b/arch/x86/boot/compressed/efi-config-table.c index d1a34aa7cefd..678fc4236030 100644 --- a/arch/x86/boot/compressed/efi-config-table.c +++ b/arch/x86/boot/compressed/efi-config-table.c @@ -178,3 +178,47 @@ efi_bp_get_conf_table(struct boot_params *boot_params, return 0; } + +/* + * Given boot_params, locate EFI system/config table from it and search for + * physical for the vendor table associated with GUID. + * + * @boot_params: pointer to boot_params + * @guid: GUID of vendor table + * @vendor_table_pa: location to store physical address of vendor table + * + * Returns 0 on success. On error, return params are left unchanged. + */ +int +efi_bp_find_vendor_table(struct boot_params *boot_params, efi_guid_t guid, + unsigned long *vendor_table_pa) +{ + unsigned long conf_table_pa = 0; + unsigned int conf_table_len = 0; + unsigned int i; + bool efi_64; + int ret; + + ret = efi_bp_get_conf_table(boot_params, &conf_table_pa, + &conf_table_len, &efi_64); + if (ret) + return ret; + + for (i = 0; i < conf_table_len; i++) { + unsigned long vendor_table_pa_tmp; + efi_guid_t vendor_table_guid; + int ret; + + if (get_vendor_table((void *)conf_table_pa, i, + &vendor_table_pa_tmp, + &vendor_table_guid, efi_64)) + return -EINVAL; + + if (!efi_guidcmp(guid, vendor_table_guid)) { + *vendor_table_pa = vendor_table_pa_tmp; + return 0; + } + } + + return -ENOENT; +} diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index a2347ded77ea..1c1658693fc9 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -441,6 +441,7 @@ SYM_CODE_START(startup_64) .Lon_kernel_cs: pushq %rsi + movq %rsi, %rdi /* real mode address */ call load_stage1_idt popq %rsi diff --git a/arch/x86/boot/compressed/idt_64.c b/arch/x86/boot/compressed/idt_64.c index 9b93567d663a..1f6511a6625d 100644 --- a/arch/x86/boot/compressed/idt_64.c +++ b/arch/x86/boot/compressed/idt_64.c @@ -3,6 +3,7 @@ #include #include #include "misc.h" +#include static void set_idt_entry(int vector, void (*handler)(void)) { @@ -28,13 +29,15 @@ static void load_boot_idt(const struct desc_ptr *dtr) } /* Setup IDT before kernel jumping to .Lrelocated */ -void load_stage1_idt(void) +void load_stage1_idt(void *rmode) { boot_idt_desc.address = (unsigned long)boot_idt; - if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { + sev_snp_cpuid_init(rmode); set_idt_entry(X86_TRAP_VC, boot_stage1_vc); + } load_boot_idt(&boot_idt_desc); } diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h index 522baf8ff04a..74c3cf3b982c 100644 --- a/arch/x86/boot/compressed/misc.h +++ b/arch/x86/boot/compressed/misc.h @@ -193,6 +193,10 @@ int efi_bp_get_conf_table(struct boot_params *boot_params, unsigned long *conf_table_pa, unsigned int *conf_table_len, bool *is_efi_64); + +int efi_bp_find_vendor_table(struct boot_params *boot_params, efi_guid_t guid, + unsigned long *vendor_table_pa); + #else static inline int efi_foreach_conf_entry(void *conf_table, unsigned int conf_table_len, @@ -222,6 +226,12 @@ efi_bp_get_conf_table(struct boot_params *boot_params, { return -ENOENT; } + +int efi_bp_find_vendor_table(struct boot_params *boot_params, efi_guid_t guid, + unsigned long *vendor_table_pa); +{ + return -ENOENT; +} #endif /* CONFIG_EFI */ #endif /* BOOT_COMPRESSED_MISC_H */ diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index d4cbadf80838..13a6ce74f320 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -20,6 +20,9 @@ #include #include #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 5da5f5147623..e14d24f0950c 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -132,5 +132,7 @@ struct __packed 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_HYP 5 /* CPUID failure during hypervisor fallback */ #endif diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index e41bd55dba5d..e403bd1fcb23 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -11,6 +11,7 @@ #include #include #include +#include #define GHCB_PROTOCOL_MIN 1ULL #define GHCB_PROTOCOL_MAX 2ULL @@ -127,6 +128,7 @@ void snp_set_memory_shared(unsigned long vaddr, unsigned int npages); void snp_set_memory_private(unsigned long vaddr, unsigned int npages); void snp_set_wakeup_secondary_cpu(void); +void sev_snp_cpuid_init(struct boot_params *bp); #else static inline void sev_es_ist_enter(struct pt_regs *regs) { } static inline void sev_es_ist_exit(void) { } @@ -143,6 +145,7 @@ static inline void snp_set_memory_shared(unsigned long vaddr, unsigned int npage static inline void snp_set_memory_private(unsigned long vaddr, unsigned int npages) { } static inline void snp_set_wakeup_secondary_cpu(void) { } +static inline void sev_snp_cpuid_init(struct boot_params *bp) { } #endif #endif diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index 4884de256a49..5e0e8e208a8c 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -14,6 +14,25 @@ #define has_cpuflag(f) boot_cpu_has(f) #endif +struct sev_snp_cpuid_fn { + u32 eax_in; + u32 ecx_in; + u64 unused; + u64 unused2; + u32 eax; + u32 ebx; + u32 ecx; + u32 edx; + u64 reserved; +} __packed; + +struct sev_snp_cpuid_info { + u32 count; + u32 reserved1; + u64 reserved2; + struct sev_snp_cpuid_fn fn[0]; +} __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 @@ -26,6 +45,15 @@ static u16 ghcb_version __section(".data..ro_after_init"); /* Bitmap of SEV features supported by the hypervisor */ u64 sev_hv_features __section(".data..ro_after_init") = 0; +/* + * These are also stored in .data section to avoid the need to re-parse + * boot_params and re-determine CPUID memory range when .bss is cleared. + */ +static int sev_snp_cpuid_enabled __section(".data"); +static unsigned long sev_snp_cpuid_pa __section(".data"); +static unsigned long sev_snp_cpuid_sz __section(".data"); +static const struct sev_snp_cpuid_info *cpuid_info __section(".data"); + static bool __init sev_es_check_cpu_features(void) { if (!has_cpuflag(X86_FEATURE_RDRAND)) { @@ -236,6 +264,171 @@ static int sev_es_cpuid_msr_proto(u32 func, u32 subfunc, u32 *eax, u32 *ebx, return 0; } +static bool sev_snp_cpuid_active(void) +{ + return sev_snp_cpuid_enabled; +} + +static int sev_snp_cpuid_xsave_size(u64 xfeatures_en, u32 base_size, + u32 *xsave_size, bool compacted) +{ + u64 xfeatures_found = 0; + int i; + + *xsave_size = base_size; + + for (i = 0; i < cpuid_info->count; i++) { + const struct sev_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 & (1UL << fn->ecx_in))) + continue; + if (xfeatures_found & (1UL << fn->ecx_in)) + continue; + + xfeatures_found |= (1UL << fn->ecx_in); + if (compacted) + *xsave_size += fn->eax; + else + *xsave_size = max(*xsave_size, 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 & ~3ULL)) + return -EINVAL; + + return 0; +} + +static void sev_snp_cpuid_hyp(u32 func, u32 subfunc, u32 *eax, u32 *ebx, + u32 *ecx, u32 *edx) +{ + /* + * Currently MSR protocol is sufficient to handle fallback cases, but + * should that change make sure we terminate rather than grabbing random + * values. Handling can be added in future 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 != 0) + sev_es_terminate(1, GHCB_TERM_CPUID_HYP); + + if (sev_es_cpuid_msr_proto(func, 0, eax, ebx, ecx, edx)) + sev_es_terminate(1, GHCB_TERM_CPUID_HYP); +} + +/* + * Returns -EOPNOTSUPP if feature not enabled. Any other return value should be + * treated as fatal by caller since we cannot fall back to hypervisor to fetch + * the values for security reasons (outside of the specific cases handled here) + */ +static int sev_snp_cpuid(u32 func, u32 subfunc, u32 *eax, u32 *ebx, u32 *ecx, + u32 *edx) +{ + bool found = false; + int i; + + if (!sev_snp_cpuid_active()) + return -EOPNOTSUPP; + + if (!cpuid_info) + return -EIO; + + for (i = 0; i < cpuid_info->count; i++) { + const struct sev_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; + found = true; + + break; + } + + if (!found) { + *eax = *ebx = *ecx = *edx = 0; + goto out; + } + + if (func == 0x1) { + u32 ebx2, edx2; + + sev_snp_cpuid_hyp(func, subfunc, NULL, &ebx2, NULL, &edx2); + /* initial APIC ID */ + *ebx = (*ebx & 0x00FFFFFF) | (ebx2 & 0xFF000000); + /* APIC enabled bit */ + *edx = (*edx & ~BIT_ULL(9)) | (edx2 & BIT_ULL(9)); + + /* OSXSAVE enabled bit */ + if (native_read_cr4() & X86_CR4_OSXSAVE) + *ecx |= BIT_ULL(27); + } else if (func == 0x7) { + /* OSPKE enabled bit */ + *ecx &= ~BIT_ULL(4); + if (native_read_cr4() & X86_CR4_PKE) + *ecx |= BIT_ULL(4); + } else if (func == 0xB) { + /* extended APIC ID */ + sev_snp_cpuid_hyp(func, 0, NULL, NULL, NULL, edx); + } else if (func == 0xd && (subfunc == 0x0 || subfunc == 0x1)) { + bool compacted = false; + u64 xcr0 = 1, xss = 0; + u32 xsave_size; + + if (native_read_cr4() & X86_CR4_OSXSAVE) + xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK); + if (subfunc == 1) { + /* boot/compressed doesn't set XSS so 0 is fine there */ +#ifndef __BOOT_COMPRESSED + if (*eax & 0x8) /* XSAVES */ + if (boot_cpu_has(X86_FEATURE_XSAVES)) + rdmsrl(MSR_IA32_XSS, xss); +#endif + /* + * 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 or XSAVES since SNP-capable hardware + * has the entries 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 or SNP guests. + */ + if (!(*eax & 0xA)) /* (XSAVEC|XSAVES) */ + return -EINVAL; + + compacted = true; + } + + if (sev_snp_cpuid_xsave_size(xcr0 | xss, *ebx, &xsave_size, + compacted)) + return -EINVAL; + + *ebx = xsave_size; + } else if (func == 0x8000001E) { + u32 ebx2, ecx2; + + /* extended APIC ID */ + sev_snp_cpuid_hyp(func, subfunc, eax, &ebx2, &ecx2, NULL); + /* compute ID */ + *ebx = (*ebx & 0xFFFFFFF00) | (ebx2 & 0x000000FF); + /* node ID */ + *ecx = (*ecx & 0xFFFFFFF00) | (ecx2 & 0x000000FF); + } + +out: + return 0; +} + /* * 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 @@ -244,15 +437,25 @@ static int sev_es_cpuid_msr_proto(u32 func, u32 subfunc, u32 *eax, u32 *ebx, void __init do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) { unsigned int fn = lower_bits(regs->ax, 32); + unsigned int subfn = lower_bits(regs->cx, 32); u32 eax, ebx, ecx, edx; + int ret; /* Only CPUID is supported via MSR protocol */ if (exit_code != SVM_EXIT_CPUID) goto fail; + ret = sev_snp_cpuid(fn, subfn, &eax, &ebx, &ecx, &edx); + if (ret == 0) + goto out; + + if (ret != -EOPNOTSUPP) + goto fail; + if (sev_es_cpuid_msr_proto(fn, 0, &eax, &ebx, &ecx, &edx)) goto fail; +out: regs->ax = eax; regs->bx = ebx; regs->cx = ecx; @@ -552,6 +755,19 @@ static enum es_result vc_handle_cpuid(struct ghcb *ghcb, struct pt_regs *regs = ctxt->regs; u32 cr4 = native_read_cr4(); enum es_result ret; + u32 eax, ebx, ecx, edx; + int cpuid_ret; + + cpuid_ret = sev_snp_cpuid(regs->ax, regs->cx, &eax, &ebx, &ecx, &edx); + if (cpuid_ret == 0) { + regs->ax = eax; + regs->bx = ebx; + regs->cx = ecx; + regs->dx = edx; + return ES_OK; + } + if (cpuid_ret != -EOPNOTSUPP) + return ES_VMM_ERROR; ghcb_set_rax(ghcb, regs->ax); ghcb_set_rcx(ghcb, regs->cx); @@ -603,3 +819,109 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, return ES_OK; } + +#ifdef BOOT_COMPRESSED +static struct setup_data *get_cc_setup_data(struct boot_params *bp) +{ + struct setup_data *hdr = (struct setup_data *)bp->hdr.setup_data; + + while (hdr) { + if (hdr->type == SETUP_CC_BLOB) + return hdr; + hdr = (struct setup_data *)hdr->next; + } + + return NULL; +} + +/* + * For boot/compressed kernel: + * + * 1) Search for CC blob in the following order/precedence: + * - via linux boot protocol / setup_data entry + * - via EFI configuration table + * 2) Return a pointer to the CC blob, NULL otherwise. + */ +static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp) +{ + struct cc_blob_sev_info *cc_info = NULL; + struct setup_data_cc { + struct setup_data header; + u32 cc_blob_address; + } *sd; + + /* Try to get CC blob via setup_data */ + sd = (struct setup_data_cc *)get_cc_setup_data(bp); + if (sd) { + cc_info = (struct cc_blob_sev_info *)(unsigned long)sd->cc_blob_address; + goto out_verify; + } + + /* CC blob isn't in setup_data, see if it's in the EFI config table */ + (void)efi_bp_find_vendor_table(bp, EFI_CC_BLOB_GUID, + (unsigned long *)&cc_info); + +out_verify: + /* CC blob should be either valid or not present. Fail otherwise. */ + if (cc_info && cc_info->magic != CC_BLOB_SEV_HDR_MAGIC) + sev_es_terminate(1, GHCB_SNP_UNSUPPORTED); + + return cc_info; +} +#else +/* + * Probing for CC blob for run-time kernel will be enabled in a subsequent + * patch. For now we need to stub this out. + */ +static struct cc_blob_sev_info *sev_snp_probe_cc_blob(struct boot_params *bp) +{ + return NULL; +} +#endif + +/* + * Initial set up of CPUID table when running identity-mapped. + * + * NOTE: Since SEV_SNP feature partly relies on CPUID checks that can't + * happen until we access CPUID page, we skip the check and hope the + * bootloader is providing sane values. Current code relies on all CPUID + * page lookups originating from #VC handler, which at least provides + * indication that SEV-ES is enabled. Subsequent init levels will check for + * SEV_SNP feature once available to also take SEV MSR value into account. + */ +void sev_snp_cpuid_init(struct boot_params *bp) +{ + struct cc_blob_sev_info *cc_info; + + if (!bp) + sev_es_terminate(1, GHCB_TERM_CPUID); + + cc_info = sev_snp_probe_cc_blob(bp); + + if (!cc_info) + return; + + sev_snp_cpuid_pa = cc_info->cpuid_phys; + sev_snp_cpuid_sz = cc_info->cpuid_len; + + /* + * These should always be valid values for SNP, even if guest isn't + * actually configured to use the CPUID table. + */ + if (!sev_snp_cpuid_pa || sev_snp_cpuid_sz < PAGE_SIZE) + sev_es_terminate(1, GHCB_TERM_CPUID); + + cpuid_info = (const struct sev_snp_cpuid_info *)sev_snp_cpuid_pa; + + /* + * We should be able to trust the 'count' value in the CPUID table + * area, but ensure it agrees with CC blob value to be safe. + */ + if (sev_snp_cpuid_sz < (sizeof(struct sev_snp_cpuid_info) + + sizeof(struct sev_snp_cpuid_fn) * + cpuid_info->count)) + sev_es_terminate(1, GHCB_TERM_CPUID); + + if (cpuid_info->count > 0) + sev_snp_cpuid_enabled = 1; +} diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 59e0dd04cb02..04ef5e79fa12 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -19,6 +19,8 @@ #include #include #include +#include +#include #include #include @@ -32,6 +34,8 @@ #include #include #include +#include +#include #include "sev-internal.h"