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Date:   Mon, 19 Dec 2022 12:04:26 -0600
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Subject: Re: [PATCH RFC v7 40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH
 command
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To:     Michael Roth <michael.roth@amd.com>, kvm@vger.kernel.org
Cc:     linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, x86@kernel.org,
        linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
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        pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com,
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        dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com,
        peterz@infradead.org, srinivas.pandruvada@linux.intel.com,
        rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com,
        bp@alien8.de, vbabka@suse.cz, kirill@shutemov.name,
        ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com,
        sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com,
        dgilbert@redhat.com, jarkko@kernel.org, ashish.kalra@amd.com,
        harald@profian.com, Brijesh Singh <brijesh.singh@amd.com>
References: <20221214194056.161492-1-michael.roth@amd.com>
 <20221214194056.161492-41-michael.roth@amd.com>
From:   Tom Lendacky <thomas.lendacky@amd.com>
In-Reply-To: <20221214194056.161492-41-michael.roth@amd.com>
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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.

> +        };
> +
> +
> +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.

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)