From 4013364679757161d6b9754bfc33ae38be0a1b7f Mon Sep 17 00:00:00 2001 From: Michael Roth Date: Thu, 30 May 2024 06:16:32 -0500 Subject: [PATCH 072/100] i386/sev: Add support for SNP CPUID validation RH-Author: Paolo Bonzini RH-MergeRequest: 245: SEV-SNP support RH-Jira: RHEL-39544 RH-Acked-by: Thomas Huth RH-Acked-by: Bandan Das RH-Acked-by: Vitaly Kuznetsov RH-Commit: [72/91] 080e2942552dc7de8966e69d0d0d3b8951392030 (bonzini/rhel-qemu-kvm) SEV-SNP firmware allows a special guest page to be populated with a table of guest CPUID values so that they can be validated through firmware before being loaded into encrypted guest memory where they can be used in place of hypervisor-provided values[1]. As part of SEV-SNP guest initialization, use this interface to validate the CPUID entries reported by KVM_GET_CPUID2 prior to initial guest start and populate the CPUID page reserved by OVMF with the resulting encrypted data. [1] SEV SNP Firmware ABI Specification, Rev. 0.8, 8.13.2.6 Signed-off-by: Michael Roth Signed-off-by: Pankaj Gupta Message-ID: <20240530111643.1091816-21-pankaj.gupta@amd.com> Signed-off-by: Paolo Bonzini (cherry picked from commit 70943ad8e4dfbe5f77006b880290219be9d03553) Signed-off-by: Paolo Bonzini --- target/i386/sev.c | 164 +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 162 insertions(+), 2 deletions(-) diff --git a/target/i386/sev.c b/target/i386/sev.c index c57534fca2..06401f0526 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -200,6 +200,36 @@ static const char *const sev_fw_errlist[] = { #define SEV_FW_MAX_ERROR ARRAY_SIZE(sev_fw_errlist) +/* doesn't expose this, so re-use the max from kvm.c */ +#define KVM_MAX_CPUID_ENTRIES 100 + +typedef struct KvmCpuidInfo { + struct kvm_cpuid2 cpuid; + struct kvm_cpuid_entry2 entries[KVM_MAX_CPUID_ENTRIES]; +} KvmCpuidInfo; + +#define SNP_CPUID_FUNCTION_MAXCOUNT 64 +#define SNP_CPUID_FUNCTION_UNKNOWN 0xFFFFFFFF + +typedef struct { + uint32_t eax_in; + uint32_t ecx_in; + uint64_t xcr0_in; + uint64_t xss_in; + uint32_t eax; + uint32_t ebx; + uint32_t ecx; + uint32_t edx; + uint64_t reserved; +} __attribute__((packed)) SnpCpuidFunc; + +typedef struct { + uint32_t count; + uint32_t reserved1; + uint64_t reserved2; + SnpCpuidFunc entries[SNP_CPUID_FUNCTION_MAXCOUNT]; +} __attribute__((packed)) SnpCpuidInfo; + static int sev_ioctl(int fd, int cmd, void *data, int *error) { @@ -788,6 +818,35 @@ out: return ret; } +static void +sev_snp_cpuid_report_mismatches(SnpCpuidInfo *old, + SnpCpuidInfo *new) +{ + size_t i; + + if (old->count != new->count) { + error_report("SEV-SNP: CPUID validation failed due to count mismatch," + "provided: %d, expected: %d", old->count, new->count); + return; + } + + for (i = 0; i < old->count; i++) { + SnpCpuidFunc *old_func, *new_func; + + old_func = &old->entries[i]; + new_func = &new->entries[i]; + + if (memcmp(old_func, new_func, sizeof(SnpCpuidFunc))) { + error_report("SEV-SNP: CPUID validation failed for function 0x%x, index: 0x%x" + "provided: eax:0x%08x, ebx: 0x%08x, ecx: 0x%08x, edx: 0x%08x" + "expected: eax:0x%08x, ebx: 0x%08x, ecx: 0x%08x, edx: 0x%08x", + old_func->eax_in, old_func->ecx_in, + old_func->eax, old_func->ebx, old_func->ecx, old_func->edx, + new_func->eax, new_func->ebx, new_func->ecx, new_func->edx); + } + } +} + static const char * snp_page_type_to_str(int type) { @@ -806,6 +865,7 @@ sev_snp_launch_update(SevSnpGuestState *sev_snp_guest, SevLaunchUpdateData *data) { int ret, fw_error; + SnpCpuidInfo snp_cpuid_info; struct kvm_sev_snp_launch_update update = {0}; if (!data->hva || !data->len) { @@ -815,6 +875,11 @@ sev_snp_launch_update(SevSnpGuestState *sev_snp_guest, return 1; } + if (data->type == KVM_SEV_SNP_PAGE_TYPE_CPUID) { + /* Save a copy for comparison in case the LAUNCH_UPDATE fails */ + memcpy(&snp_cpuid_info, data->hva, sizeof(snp_cpuid_info)); + } + update.uaddr = (__u64)(unsigned long)data->hva; update.gfn_start = data->gpa >> TARGET_PAGE_BITS; update.len = data->len; @@ -842,6 +907,11 @@ sev_snp_launch_update(SevSnpGuestState *sev_snp_guest, if (ret && ret != -EAGAIN) { error_report("SNP_LAUNCH_UPDATE ret=%d fw_error=%d '%s'", ret, fw_error, fw_error_to_str(fw_error)); + + if (data->type == KVM_SEV_SNP_PAGE_TYPE_CPUID) { + sev_snp_cpuid_report_mismatches(&snp_cpuid_info, data->hva); + error_report("SEV-SNP: failed update CPUID page"); + } break; } } @@ -1004,7 +1074,8 @@ sev_launch_finish(SevCommonState *sev_common) } static int -snp_launch_update_data(uint64_t gpa, void *hva, uint32_t len, int type) +snp_launch_update_data(uint64_t gpa, void *hva, + uint32_t len, int type) { SevLaunchUpdateData *data; @@ -1019,6 +1090,90 @@ snp_launch_update_data(uint64_t gpa, void *hva, uint32_t len, int type) return 0; } +static int +sev_snp_cpuid_info_fill(SnpCpuidInfo *snp_cpuid_info, + const KvmCpuidInfo *kvm_cpuid_info) +{ + size_t i; + + if (kvm_cpuid_info->cpuid.nent > SNP_CPUID_FUNCTION_MAXCOUNT) { + error_report("SEV-SNP: CPUID entry count (%d) exceeds max (%d)", + kvm_cpuid_info->cpuid.nent, SNP_CPUID_FUNCTION_MAXCOUNT); + return -1; + } + + memset(snp_cpuid_info, 0, sizeof(*snp_cpuid_info)); + + for (i = 0; i < kvm_cpuid_info->cpuid.nent; i++) { + const struct kvm_cpuid_entry2 *kvm_cpuid_entry; + SnpCpuidFunc *snp_cpuid_entry; + + kvm_cpuid_entry = &kvm_cpuid_info->entries[i]; + snp_cpuid_entry = &snp_cpuid_info->entries[i]; + + snp_cpuid_entry->eax_in = kvm_cpuid_entry->function; + if (kvm_cpuid_entry->flags == KVM_CPUID_FLAG_SIGNIFCANT_INDEX) { + snp_cpuid_entry->ecx_in = kvm_cpuid_entry->index; + } + snp_cpuid_entry->eax = kvm_cpuid_entry->eax; + snp_cpuid_entry->ebx = kvm_cpuid_entry->ebx; + snp_cpuid_entry->ecx = kvm_cpuid_entry->ecx; + snp_cpuid_entry->edx = kvm_cpuid_entry->edx; + + /* + * Guest kernels will calculate EBX themselves using the 0xD + * subfunctions corresponding to the individual XSAVE areas, so only + * encode the base XSAVE size in the initial leaves, corresponding + * to the initial XCR0=1 state. + */ + if (snp_cpuid_entry->eax_in == 0xD && + (snp_cpuid_entry->ecx_in == 0x0 || snp_cpuid_entry->ecx_in == 0x1)) { + snp_cpuid_entry->ebx = 0x240; + snp_cpuid_entry->xcr0_in = 1; + snp_cpuid_entry->xss_in = 0; + } + } + + snp_cpuid_info->count = i; + + return 0; +} + +static int +snp_launch_update_cpuid(uint32_t cpuid_addr, void *hva, uint32_t cpuid_len) +{ + KvmCpuidInfo kvm_cpuid_info = {0}; + SnpCpuidInfo snp_cpuid_info; + CPUState *cs = first_cpu; + int ret; + uint32_t i = 0; + + assert(sizeof(snp_cpuid_info) <= cpuid_len); + + /* get the cpuid list from KVM */ + do { + kvm_cpuid_info.cpuid.nent = ++i; + ret = kvm_vcpu_ioctl(cs, KVM_GET_CPUID2, &kvm_cpuid_info); + } while (ret == -E2BIG); + + if (ret) { + error_report("SEV-SNP: unable to query CPUID values for CPU: '%s'", + strerror(-ret)); + return 1; + } + + ret = sev_snp_cpuid_info_fill(&snp_cpuid_info, &kvm_cpuid_info); + if (ret) { + error_report("SEV-SNP: failed to generate CPUID table information"); + return 1; + } + + memcpy(hva, &snp_cpuid_info, sizeof(snp_cpuid_info)); + + return snp_launch_update_data(cpuid_addr, hva, cpuid_len, + KVM_SEV_SNP_PAGE_TYPE_CPUID); +} + static int snp_metadata_desc_to_page_type(int desc_type) { @@ -1053,7 +1208,12 @@ snp_populate_metadata_pages(SevSnpGuestState *sev_snp, exit(1); } - ret = snp_launch_update_data(desc->base, hva, desc->len, type); + if (type == KVM_SEV_SNP_PAGE_TYPE_CPUID) { + ret = snp_launch_update_cpuid(desc->base, hva, desc->len); + } else { + ret = snp_launch_update_data(desc->base, hva, desc->len, type); + } + if (ret) { error_report("%s: Failed to add metadata page gpa 0x%x+%x type %d", __func__, desc->base, desc->len, desc->type); -- 2.39.3