Messages in this thread | | | Date | Mon, 9 Jan 2023 17:41:07 -0600 | Subject | Re: [PATCH RFC v7 52/64] KVM: SVM: Provide support for SNP_GUEST_REQUEST NAE event | From | "Kalra, Ashish" <> |
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On 1/8/2023 9:33 PM, Alexey Kardashevskiy wrote: > On 15/12/22 06:40, Michael Roth wrote: >> From: Brijesh Singh <brijesh.singh@amd.com> >> >> Version 2 of GHCB specification added the support for two SNP Guest >> Request Message NAE events. The events allows for an SEV-SNP guest to >> make request to the SEV-SNP firmware through hypervisor using the >> SNP_GUEST_REQUEST API define in the SEV-SNP firmware specification. >> >> The SNP_EXT_GUEST_REQUEST is similar to SNP_GUEST_REQUEST with the >> difference of an additional certificate blob that can be passed through >> the SNP_SET_CONFIG ioctl defined in the CCP driver. The CCP driver >> provides snp_guest_ext_guest_request() that is used by the KVM to get >> both the report and certificate data at once. >> >> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> >> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> >> Signed-off-by: Michael Roth <michael.roth@amd.com> >> --- >> arch/x86/kvm/svm/sev.c | 185 +++++++++++++++++++++++++++++++++++++++-- >> arch/x86/kvm/svm/svm.h | 2 + >> 2 files changed, 181 insertions(+), 6 deletions(-) >> >> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c >> index 5f2b2092cdae..18efa70553c2 100644 >> --- a/arch/x86/kvm/svm/sev.c >> +++ b/arch/x86/kvm/svm/sev.c >> @@ -331,6 +331,7 @@ static int sev_guest_init(struct kvm *kvm, struct >> kvm_sev_cmd *argp) >> if (ret) >> goto e_free; >> + mutex_init(&sev->guest_req_lock); >> ret = sev_snp_init(&argp->error, false); >> } else { >> ret = sev_platform_init(&argp->error); >> @@ -2051,23 +2052,34 @@ int sev_vm_move_enc_context_from(struct kvm >> *kvm, unsigned int source_fd) >> */ >> static void *snp_context_create(struct kvm *kvm, struct kvm_sev_cmd >> *argp) >> { >> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info; >> struct sev_data_snp_addr data = {}; >> - void *context; >> + void *context, *certs_data; >> int rc; >> + /* Allocate memory used for the certs data in SNP guest request */ >> + certs_data = kzalloc(SEV_FW_BLOB_MAX_SIZE, GFP_KERNEL_ACCOUNT); >> + if (!certs_data) >> + return NULL; >> + >> /* Allocate memory for context page */ >> context = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT); >> if (!context) >> - return NULL; >> + goto e_free; >> data.gctx_paddr = __psp_pa(context); >> rc = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_GCTX_CREATE, >> &data, &argp->error); >> - if (rc) { >> - snp_free_firmware_page(context); >> - return NULL; >> - } >> + if (rc) >> + goto e_free; >> + >> + sev->snp_certs_data = certs_data; >> return context; >> + >> +e_free: >> + snp_free_firmware_page(context); >> + kfree(certs_data); >> + return NULL; >> } >> static int snp_bind_asid(struct kvm *kvm, int *error) >> @@ -2653,6 +2665,8 @@ static int snp_decommission_context(struct kvm >> *kvm) >> snp_free_firmware_page(sev->snp_context); >> sev->snp_context = NULL; >> + kfree(sev->snp_certs_data); >> + >> return 0; >> } >> @@ -3174,6 +3188,8 @@ static int sev_es_validate_vmgexit(struct >> vcpu_svm *svm, u64 *exit_code) >> case SVM_VMGEXIT_UNSUPPORTED_EVENT: >> case SVM_VMGEXIT_HV_FEATURES: >> case SVM_VMGEXIT_PSC: >> + case SVM_VMGEXIT_GUEST_REQUEST: >> + case SVM_VMGEXIT_EXT_GUEST_REQUEST: >> break; >> default: >> reason = GHCB_ERR_INVALID_EVENT; >> @@ -3396,6 +3412,149 @@ static int snp_complete_psc(struct kvm_vcpu >> *vcpu) >> return 1; >> } >> +static unsigned long snp_setup_guest_buf(struct vcpu_svm *svm, >> + struct sev_data_snp_guest_request *data, >> + gpa_t req_gpa, gpa_t resp_gpa) >> +{ >> + struct kvm_vcpu *vcpu = &svm->vcpu; >> + struct kvm *kvm = vcpu->kvm; >> + kvm_pfn_t req_pfn, resp_pfn; >> + struct kvm_sev_info *sev; >> + >> + sev = &to_kvm_svm(kvm)->sev_info; >> + >> + if (!IS_ALIGNED(req_gpa, PAGE_SIZE) || !IS_ALIGNED(resp_gpa, >> PAGE_SIZE)) >> + return SEV_RET_INVALID_PARAM; >> + >> + req_pfn = gfn_to_pfn(kvm, gpa_to_gfn(req_gpa)); >> + if (is_error_noslot_pfn(req_pfn)) >> + return SEV_RET_INVALID_ADDRESS; >> + >> + resp_pfn = gfn_to_pfn(kvm, gpa_to_gfn(resp_gpa)); >> + if (is_error_noslot_pfn(resp_pfn)) >> + return SEV_RET_INVALID_ADDRESS; >> + >> + if (rmp_make_private(resp_pfn, 0, PG_LEVEL_4K, 0, true)) >> + return SEV_RET_INVALID_ADDRESS; >> + >> + data->gctx_paddr = __psp_pa(sev->snp_context); >> + data->req_paddr = __sme_set(req_pfn << PAGE_SHIFT); >> + data->res_paddr = __sme_set(resp_pfn << PAGE_SHIFT); >> + >> + return 0; >> +} >> + >> +static void snp_cleanup_guest_buf(struct sev_data_snp_guest_request >> *data, unsigned long *rc) >> +{ >> + u64 pfn = __sme_clr(data->res_paddr) >> PAGE_SHIFT; >> + int ret; >> + >> + ret = snp_page_reclaim(pfn); >> + if (ret) >> + *rc = SEV_RET_INVALID_ADDRESS; >> + >> + ret = rmp_make_shared(pfn, PG_LEVEL_4K); >> + if (ret) >> + *rc = SEV_RET_INVALID_ADDRESS; >> +} >> + >> +static void snp_handle_guest_request(struct vcpu_svm *svm, gpa_t >> req_gpa, gpa_t resp_gpa) >> +{ >> + struct sev_data_snp_guest_request data = {0}; >> + struct kvm_vcpu *vcpu = &svm->vcpu; >> + struct kvm *kvm = vcpu->kvm; >> + struct kvm_sev_info *sev; >> + unsigned long rc; >> + int err; >> + >> + if (!sev_snp_guest(vcpu->kvm)) { >> + rc = SEV_RET_INVALID_GUEST; >> + goto e_fail; >> + } >> + >> + sev = &to_kvm_svm(kvm)->sev_info; >> + >> + mutex_lock(&sev->guest_req_lock); >> + >> + rc = snp_setup_guest_buf(svm, &data, req_gpa, resp_gpa); >> + if (rc) >> + goto unlock; >> + >> + rc = sev_issue_cmd(kvm, SEV_CMD_SNP_GUEST_REQUEST, &data, &err); > > > This one goes via sev_issue_cmd_external_user() and uses sev-fd... > >> + if (rc) >> + /* use the firmware error code */ >> + rc = err; >> + >> + snp_cleanup_guest_buf(&data, &rc); >> + >> +unlock: >> + mutex_unlock(&sev->guest_req_lock); >> + >> +e_fail: >> + svm_set_ghcb_sw_exit_info_2(vcpu, rc); >> +} >> + >> +static void snp_handle_ext_guest_request(struct vcpu_svm *svm, gpa_t >> req_gpa, gpa_t resp_gpa) >> +{ >> + struct sev_data_snp_guest_request req = {0}; >> + struct kvm_vcpu *vcpu = &svm->vcpu; >> + struct kvm *kvm = vcpu->kvm; >> + unsigned long data_npages; >> + struct kvm_sev_info *sev; >> + unsigned long rc, err; >> + u64 data_gpa; >> + >> + if (!sev_snp_guest(vcpu->kvm)) { >> + rc = SEV_RET_INVALID_GUEST; >> + goto e_fail; >> + } >> + >> + sev = &to_kvm_svm(kvm)->sev_info; >> + >> + data_gpa = vcpu->arch.regs[VCPU_REGS_RAX]; >> + data_npages = vcpu->arch.regs[VCPU_REGS_RBX]; >> + >> + if (!IS_ALIGNED(data_gpa, PAGE_SIZE)) { >> + rc = SEV_RET_INVALID_ADDRESS; >> + goto e_fail; >> + } >> + >> + mutex_lock(&sev->guest_req_lock); >> + >> + rc = snp_setup_guest_buf(svm, &req, req_gpa, resp_gpa); >> + if (rc) >> + goto unlock; >> + >> + rc = snp_guest_ext_guest_request(&req, (unsigned >> long)sev->snp_certs_data, >> + &data_npages, &err); > > but this one does not and jump straight to drivers/crypto/ccp/sev-dev.c > ignoring sev->fd. Why different? Can these two be unified? > sev_issue_cmd_external_user() only checks if fd is /dev/sev which is > hardly useful. > > "[PATCH RFC v7 32/64] crypto: ccp: Provide APIs to query extended > attestation report" added this one.
SNP_EXT_GUEST_REQUEST additionally returns a certificate blob and that's why it goes through the CCP driver interface snp_guest_ext_guest_request() that is used to get both the report and certificate data/blob at the same time.
All the FW API calls on the KVM side go through sev_issue_cmd() and sev_issue_cmd_external_user() interfaces and that i believe uses sev->fd more of as a sanity check.
Thanks, Ashish
> > Besides, is sev->fd really needed in the sev struct at all? Thanks, > > >> + if (rc) { >> + /* >> + * If buffer length is small then return the expected >> + * length in rbx. >> + */ >> + if (err == SNP_GUEST_REQ_INVALID_LEN) >> + vcpu->arch.regs[VCPU_REGS_RBX] = data_npages; >> + >> + /* pass the firmware error code */ >> + rc = err; >> + goto cleanup; >> + } >> + >> + /* Copy the certificate blob in the guest memory */ >> + if (data_npages && >> + kvm_write_guest(kvm, data_gpa, sev->snp_certs_data, >> data_npages << PAGE_SHIFT)) >> + rc = SEV_RET_INVALID_ADDRESS; >> + >> +cleanup: >> + snp_cleanup_guest_buf(&req, &rc); >> + >> +unlock: >> + mutex_unlock(&sev->guest_req_lock); >> + >> +e_fail: >> + svm_set_ghcb_sw_exit_info_2(vcpu, rc); >> +} >> + >> static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) >> { >> struct vmcb_control_area *control = &svm->vmcb->control; >> @@ -3629,6 +3788,20 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) >> vcpu->run->vmgexit.ghcb_msr = ghcb_gpa; >> vcpu->arch.complete_userspace_io = snp_complete_psc; >> break; >> + case SVM_VMGEXIT_GUEST_REQUEST: { >> + snp_handle_guest_request(svm, control->exit_info_1, >> control->exit_info_2); >> + >> + ret = 1; >> + break; >> + } >> + case SVM_VMGEXIT_EXT_GUEST_REQUEST: { >> + snp_handle_ext_guest_request(svm, >> + control->exit_info_1, >> + control->exit_info_2); >> + >> + ret = 1; >> + break; >> + } >> case SVM_VMGEXIT_UNSUPPORTED_EVENT: >> vcpu_unimpl(vcpu, >> "vmgexit: unsupported event - exit_info_1=%#llx, >> exit_info_2=%#llx\n", >> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h >> index 12b9f4d539fb..7c0f9d00950f 100644 >> --- a/arch/x86/kvm/svm/svm.h >> +++ b/arch/x86/kvm/svm/svm.h >> @@ -101,6 +101,8 @@ struct kvm_sev_info { >> u64 snp_init_flags; >> void *snp_context; /* SNP guest context page */ >> spinlock_t psc_lock; >> + void *snp_certs_data; >> + struct mutex guest_req_lock; >> }; >> struct kvm_svm { >
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