diff mbox series

[RFC,v7,40/64] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command

Message ID 20221214194056.161492-41-michael.roth@amd.com
State New
Headers
Series Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support |

Commit Message

Michael Roth Dec. 14, 2022, 7:40 p.m. UTC 
  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(+)

Comments

Tom Lendacky Dec. 19, 2022, 6:04 p.m. UTC | #1 
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)
Kalra, Ashish Dec. 19, 2022, 11:24 p.m. UTC | #2 
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)
Tom Lendacky Dec. 20, 2022, 2:25 p.m. UTC | #3 
On 12/19/22 17:24, Kalra, Ashish wrote:
> 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 ?
> 

I'm assuming it was added so that any new elements added would be aligned 
on an 8 byte boundary (should the next element added be a __u64). I don't 
think that it is truly needed right now, though.

Thanks,
Tom
Sabin Rapan Jan. 11, 2023, 1:27 p.m. UTC | #4 
On 14.12.2022 21:40, Michael Roth wrote:
> +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++) {

Should be replaced with kvm_for_each_vcpu() as it was done for
sev_launch_update_vmsa() in c36b16d29f3a ("KVM: SVM: Use online_vcpus,
not created_vcpus, to iterate over vCPUs").
Prevents accessing uninitialized data in struct vcpu_svm.

--
Sabin.



Amazon Development Center (Romania) S.R.L. registered office: 27A Sf. Lazar Street, UBC5, floor 2, Iasi, Iasi County, 700045, Romania. Registered in Romania. Registration number J22/2621/2005.
Kalra, Ashish Jan. 11, 2023, 11:18 p.m. UTC | #5 
On 1/11/2023 7:27 AM, Sabin Rapan wrote:
> 
> 
> On 14.12.2022 21:40, Michael Roth wrote:
>> +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++) {
> 
> Should be replaced with kvm_for_each_vcpu() as it was done for
> sev_launch_update_vmsa() in c36b16d29f3a ("KVM: SVM: Use online_vcpus,
> not created_vcpus, to iterate over vCPUs").
> Prevents accessing uninitialized data in struct vcpu_svm.

Yes, fixed this one.

Thanks,
Ashish
diff mbox series

Patch

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];
+        };
+
+
+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);
+	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)