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    SubjectRe: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command
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    Hello Tom,

    On 12/19/2022 12:04 PM, Tom Lendacky wrote:
    > On 12/14/22 13:40, Michael Roth wrote:
    >> From: Brijesh Singh <brijesh.singh@amd.com>
    >>
    >> The KVM_SEV_SNP_LAUNCH_FINISH finalize the cryptographic digest and
    >> stores
    >> it as the measurement of the guest at launch.
    >>
    >> While finalizing the launch flow, it also issues the LAUNCH_UPDATE
    >> command
    >> to encrypt the VMSA pages.
    >>
    >> If its an SNP guest, then VMSA was added in the RMP entry as
    >> a guest owned page and also removed from the kernel direct map
    >> so flush it later after it is transitioned back to hypervisor
    >> state and restored in the direct map.
    >>
    >> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
    >> Signed-off-by: Harald Hoyer <harald@profian.com>
    >> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
    >> Signed-off-by: Michael Roth <michael.roth@amd.com>
    >> ---
    >>   .../virt/kvm/x86/amd-memory-encryption.rst    |  22 ++++
    >>   arch/x86/kvm/svm/sev.c                        | 119 ++++++++++++++++++
    >>   include/uapi/linux/kvm.h                      |  14 +++
    >>   3 files changed, 155 insertions(+)
    >>
    >> diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    >> b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    >> index c94be8e6d657..e4b42aaab1de 100644
    >> --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    >> +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
    >> @@ -513,6 +513,28 @@ Returns: 0 on success, -negative on error
    >>   See the SEV-SNP spec for further details on how to build the VMPL
    >> permission
    >>   mask and page type.
    >> +21. KVM_SNP_LAUNCH_FINISH
    >> +-------------------------
    >> +
    >> +After completion of the SNP guest launch flow, the
    >> KVM_SNP_LAUNCH_FINISH command can be
    >> +issued to make the guest ready for the execution.
    >> +
    >> +Parameters (in): struct kvm_sev_snp_launch_finish
    >> +
    >> +Returns: 0 on success, -negative on error
    >> +
    >> +::
    >> +
    >> +        struct kvm_sev_snp_launch_finish {
    >> +                __u64 id_block_uaddr;
    >> +                __u64 id_auth_uaddr;
    >> +                __u8 id_block_en;
    >> +                __u8 auth_key_en;
    >> +                __u8 host_data[32];
    >
    > This is missing the 6 bytes of padding at the end of the struct.
    >

    Yes will fix this, the documentation is missing that, the structure
    defination in include/uapi/linux/kvm.h includes it.

    But why do we need this padding ?

    >> +        };
    >> +
    >> +
    >> +See SEV-SNP specification for further details on launch finish input
    >> parameters.
    >>   References
    >>   ==========
    >> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
    >> index 379e61a9226a..6f901545bed9 100644
    >> --- a/arch/x86/kvm/svm/sev.c
    >> +++ b/arch/x86/kvm/svm/sev.c
    >> @@ -2243,6 +2243,106 @@ static int snp_launch_update(struct kvm *kvm,
    >> struct kvm_sev_cmd *argp)
    >>                         snp_launch_update_gfn_handler, argp);
    >>   }
    >> +static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd
    >> *argp)
    >> +{
    >> +    struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    >> +    struct sev_data_snp_launch_update data = {};
    >> +    int i, ret;
    >> +
    >> +    data.gctx_paddr = __psp_pa(sev->snp_context);
    >> +    data.page_type = SNP_PAGE_TYPE_VMSA;
    >> +
    >> +    for (i = 0; i < kvm->created_vcpus; i++) {
    >> +        struct vcpu_svm *svm = to_svm(xa_load(&kvm->vcpu_array, i));
    >> +        u64 pfn = __pa(svm->sev_es.vmsa) >> PAGE_SHIFT;
    >> +
    >> +        /* Perform some pre-encryption checks against the VMSA */
    >> +        ret = sev_es_sync_vmsa(svm);
    >> +        if (ret)
    >> +            return ret;
    >> +
    >> +        /* Transition the VMSA page to a firmware state. */
    >> +        ret = rmp_make_private(pfn, -1, PG_LEVEL_4K, sev->asid, true);
    >> +        if (ret)
    >> +            return ret;
    >> +
    >> +        /* Issue the SNP command to encrypt the VMSA */
    >> +        data.address = __sme_pa(svm->sev_es.vmsa);
    >> +        ret = __sev_issue_cmd(argp->sev_fd, SEV_CMD_SNP_LAUNCH_UPDATE,
    >> +                      &data, &argp->error);
    >> +        if (ret) {
    >> +            snp_page_reclaim(pfn);
    >> +            return ret;
    >> +        }
    >> +
    >> +        svm->vcpu.arch.guest_state_protected = true;
    >> +    }
    >> +
    >> +    return 0;
    >> +}
    >> +
    >> +static int snp_launch_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
    >> +{
    >> +    struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
    >> +    struct kvm_sev_snp_launch_finish params;
    >> +    struct sev_data_snp_launch_finish *data;
    >> +    void *id_block = NULL, *id_auth = NULL;
    >> +    int ret;
    >> +
    >> +    if (!sev_snp_guest(kvm))
    >> +        return -ENOTTY;
    >> +
    >> +    if (!sev->snp_context)
    >> +        return -EINVAL;
    >> +
    >> +    if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
    >> sizeof(params)))
    >> +        return -EFAULT;
    >> +
    >> +    /* Measure all vCPUs using LAUNCH_UPDATE before finalizing the
    >> launch flow. */
    >> +    ret = snp_launch_update_vmsa(kvm, argp);
    >> +    if (ret)
    >> +        return ret;
    >> +
    >> +    data = kzalloc(sizeof(*data), GFP_KERNEL_ACCOUNT);
    >> +    if (!data)
    >> +        return -ENOMEM;
    >> +
    >> +    if (params.id_block_en) {
    >> +        id_block = psp_copy_user_blob(params.id_block_uaddr,
    >> KVM_SEV_SNP_ID_BLOCK_SIZE);
    >> +        if (IS_ERR(id_block)) {
    >> +            ret = PTR_ERR(id_block);
    >> +            goto e_free;
    >> +        }
    >> +
    >> +        data->id_block_en = 1;
    >> +        data->id_block_paddr = __sme_pa(id_block);
    >> +
    >> +        id_auth = psp_copy_user_blob(params.id_auth_uaddr,
    >> KVM_SEV_SNP_ID_AUTH_SIZE);
    >> +        if (IS_ERR(id_auth)) {
    >> +            ret = PTR_ERR(id_auth);
    >> +            goto e_free_id_block;
    >> +        }
    >> +
    >> +        data->id_auth_paddr = __sme_pa(id_auth);
    >> +
    >> +        if (params.auth_key_en)
    >> +            data->auth_key_en = 1;
    >> +    }
    >> +
    >> +    data->gctx_paddr = __psp_pa(sev->snp_context);
    >
    > This is missing the copying of the params.host_data field into the
    > data->host_data field. This is needed so that the host_data shows up in
    > the attestation report.
    >

    Yes will fix this.

    Thanks,
    Ashish

    > Thanks,
    > Tom
    >
    >> +    ret = sev_issue_cmd(kvm, SEV_CMD_SNP_LAUNCH_FINISH, data,
    >> &argp->error);
    >> +
    >> +    kfree(id_auth);
    >> +
    >> +e_free_id_block:
    >> +    kfree(id_block);
    >> +
    >> +e_free:
    >> +    kfree(data);
    >> +
    >> +    return ret;
    >> +}
    >> +
    >>   int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
    >>   {
    >>       struct kvm_sev_cmd sev_cmd;
    >> @@ -2339,6 +2439,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void
    >> __user *argp)
    >>       case KVM_SEV_SNP_LAUNCH_UPDATE:
    >>           r = snp_launch_update(kvm, &sev_cmd);
    >>           break;
    >> +    case KVM_SEV_SNP_LAUNCH_FINISH:
    >> +        r = snp_launch_finish(kvm, &sev_cmd);
    >> +        break;
    >>       default:
    >>           r = -EINVAL;
    >>           goto out;
    >> @@ -2794,11 +2897,27 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu)
    >>       svm = to_svm(vcpu);
    >> +    /*
    >> +     * If its an SNP guest, then VMSA was added in the RMP entry as
    >> +     * a guest owned page. Transition the page to hypervisor state
    >> +     * before releasing it back to the system.
    >> +     * Also the page is removed from the kernel direct map, so flush it
    >> +     * later after it is transitioned back to hypervisor state and
    >> +     * restored in the direct map.
    >> +     */
    >> +    if (sev_snp_guest(vcpu->kvm)) {
    >> +        u64 pfn = __pa(svm->sev_es.vmsa) >> PAGE_SHIFT;
    >> +
    >> +        if (host_rmp_make_shared(pfn, PG_LEVEL_4K, true))
    >> +            goto skip_vmsa_free;
    >> +    }
    >> +
    >>       if (vcpu->arch.guest_state_protected)
    >>           sev_flush_encrypted_page(vcpu, svm->sev_es.vmsa);
    >>       __free_page(virt_to_page(svm->sev_es.vmsa));
    >> +skip_vmsa_free:
    >>       if (svm->sev_es.ghcb_sa_free)
    >>           kvfree(svm->sev_es.ghcb_sa);
    >>   }
    >> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
    >> index 9b6c95cc62a8..c468adc1f147 100644
    >> --- a/include/uapi/linux/kvm.h
    >> +++ b/include/uapi/linux/kvm.h
    >> @@ -1942,6 +1942,7 @@ enum sev_cmd_id {
    >>       KVM_SEV_SNP_INIT,
    >>       KVM_SEV_SNP_LAUNCH_START,
    >>       KVM_SEV_SNP_LAUNCH_UPDATE,
    >> +    KVM_SEV_SNP_LAUNCH_FINISH,
    >>       KVM_SEV_NR_MAX,
    >>   };
    >> @@ -2076,6 +2077,19 @@ struct kvm_sev_snp_launch_update {
    >>       __u8 vmpl1_perms;
    >>   };
    >> +#define KVM_SEV_SNP_ID_BLOCK_SIZE    96
    >> +#define KVM_SEV_SNP_ID_AUTH_SIZE    4096
    >> +#define KVM_SEV_SNP_FINISH_DATA_SIZE    32
    >> +
    >> +struct kvm_sev_snp_launch_finish {
    >> +    __u64 id_block_uaddr;
    >> +    __u64 id_auth_uaddr;
    >> +    __u8 id_block_en;
    >> +    __u8 auth_key_en;
    >> +    __u8 host_data[KVM_SEV_SNP_FINISH_DATA_SIZE];
    >> +    __u8 pad[6];
    >> +};
    >> +
    >>   #define KVM_DEV_ASSIGN_ENABLE_IOMMU    (1 << 0)
    >>   #define KVM_DEV_ASSIGN_PCI_2_3        (1 << 1)
    >>   #define KVM_DEV_ASSIGN_MASK_INTX    (1 << 2)

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