Re: [PATCH v7 1/1] KVM: SEV: Add KVM_SEV_SNP_HV_REPORT_REQ command

[Tom Lendacky <thomas.lendacky@amd.com>]

On 3/2/26 08:36, Thomas Courrege wrote:
> Add support for retrieving the SEV-SNP attestation report via the
> SNP_HV_REPORT_REQ firmware command and expose it through a new KVM
> ioctl for SNP guests.
> 
> Signed-off-by: Thomas Courrege <thomas.courrege@thorondor.fr>

You're missing my Reviewed-by: from the v6 series. Unless there were
some changes that need re-reviewing?

Thanks,
Tom

> ---
>  .../virt/kvm/x86/amd-memory-encryption.rst    | 27 ++++++++
>  arch/x86/include/uapi/asm/kvm.h               |  9 +++
>  arch/x86/kvm/svm/sev.c                        | 63 +++++++++++++++++++
>  drivers/crypto/ccp/sev-dev.c                  |  1 +
>  include/linux/psp-sev.h                       | 31 +++++++++
>  5 files changed, 131 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
> index b2395dd4769d..38522b174a7b 100644
> --- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
> @@ -618,6 +618,33 @@ approach to synchronizing firmware/certificate updates via file-locking,
>  which should make it easier to maintain interoperability across
>  tools/VMMs/vendors.
>  
> +22. KVM_SEV_SNP_HV_REPORT_REQ
> +-----------------------------
> +
> +The KVM_SEV_SNP_HV_REPORT_REQ command requests a hypervisor-generated
> +SNP guest attestation report. This report is produced by the SEV firmware
> +using the key selected by the caller.
> +
> +The ``key_sel`` field indicates which key the platform will use to sign the
> +report:
> +  * ``0``: If VLEK is installed, sign with VLEK. Otherwise, sign with VCEK.
> +  * ``1``: Sign with VCEK.
> +  * ``2``: Sign with VLEK.
> +  * Other values are reserved.
> +
> +Parameters (in): struct kvm_sev_snp_hv_report_req
> +
> +Returns:  0 on success, -negative on error
> +
> +::
> +        struct kvm_sev_snp_hv_report_req {
> +                __u64 report_uaddr;
> +                __u64 report_len;
> +                __u8 key_sel;
> +                __u8 pad0[7];
> +                __u64 pad1[4];
> +        };
> +
>  Device attribute API
>  ====================
>  
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 846a63215ce1..d86cb352ea89 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -745,6 +745,7 @@ enum sev_cmd_id {
>  	KVM_SEV_SNP_LAUNCH_UPDATE,
>  	KVM_SEV_SNP_LAUNCH_FINISH,
>  	KVM_SEV_SNP_ENABLE_REQ_CERTS,
> +	KVM_SEV_SNP_HV_REPORT_REQ,
>  
>  	KVM_SEV_NR_MAX,
>  };
> @@ -873,6 +874,14 @@ struct kvm_sev_receive_update_data {
>  	__u32 pad2;
>  };
>  
> +struct kvm_sev_snp_hv_report_req {
> +	__u64 report_uaddr;
> +	__u64 report_len;
> +	__u8 key_sel;
> +	__u8 pad0[7];
> +	__u64 pad1[4];
> +};
> +
>  struct kvm_sev_snp_launch_start {
>  	__u64 policy;
>  	__u8 gosvw[16];
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 3f9c1aa39a0a..62daa23ccd1b 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2271,6 +2271,66 @@ static int snp_launch_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return rc;
>  }
>  
> +static int sev_snp_hv_report_request(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct kvm_sev_info *sev = to_kvm_sev_info(kvm);
> +	struct sev_data_snp_msg_report_rsp *report_rsp;
> +	struct kvm_sev_snp_hv_report_req params;
> +	struct sev_data_snp_hv_report_req data;
> +	size_t rsp_size = sizeof(*report_rsp);
> +	void __user *u_report;
> +	void __user *u_params;
> +	int ret;
> +
> +	if (!sev_snp_guest(kvm))
> +		return -ENOTTY;
> +
> +	u_params = u64_to_user_ptr(argp->data);
> +	if (copy_from_user(&params, u_params, sizeof(params)))
> +		return -EFAULT;
> +
> +	if (params.report_len < rsp_size)
> +		return -ENOSPC;
> +
> +	u_report = u64_to_user_ptr(params.report_uaddr);
> +	if (!u_report)
> +		return -EINVAL;
> +
> +	report_rsp = snp_alloc_firmware_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
> +	if (!report_rsp)
> +		return -ENOMEM;
> +
> +	data.len = sizeof(data);
> +	data.key_sel = params.key_sel;
> +	data.gctx_addr = __psp_pa(sev->snp_context);
> +	data.hv_report_paddr = __psp_pa(report_rsp);
> +	data.rsvd = 0;
> +
> +	ret = sev_issue_cmd(kvm, SEV_CMD_SNP_HV_REPORT_REQ, &data,
> +			    &argp->error);
> +	if (ret)
> +		goto e_free_rsp;
> +
> +	if (!report_rsp->status) {
> +		if (params.report_len < (rsp_size + report_rsp->report_size))
> +			ret = -ENOSPC;
> +		else
> +			rsp_size += report_rsp->report_size;
> +
> +		params.report_len = sizeof(*report_rsp) + report_rsp->report_size;
> +	}
> +
> +	if (copy_to_user(u_report, report_rsp, rsp_size))
> +		ret = -EFAULT;
> +
> +	if (copy_to_user(u_params, &params, sizeof(params)))
> +		ret = -EFAULT;
> +
> +e_free_rsp:
> +	snp_free_firmware_page(report_rsp);
> +	return ret;
> +}
> +
>  struct sev_gmem_populate_args {
>  	__u8 type;
>  	int sev_fd;
> @@ -2678,6 +2738,9 @@ int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
>  	case KVM_SEV_SNP_LAUNCH_FINISH:
>  		r = snp_launch_finish(kvm, &sev_cmd);
>  		break;
> +	case KVM_SEV_SNP_HV_REPORT_REQ:
> +		r = sev_snp_hv_report_request(kvm, &sev_cmd);
> +		break;
>  	case KVM_SEV_SNP_ENABLE_REQ_CERTS:
>  		r = snp_enable_certs(kvm);
>  		break;
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 096f993974d1..30d715f19a25 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -252,6 +252,7 @@ static int sev_cmd_buffer_len(int cmd)
>  	case SEV_CMD_SNP_COMMIT:		return sizeof(struct sev_data_snp_commit);
>  	case SEV_CMD_SNP_FEATURE_INFO:		return sizeof(struct sev_data_snp_feature_info);
>  	case SEV_CMD_SNP_VLEK_LOAD:		return sizeof(struct sev_user_data_snp_vlek_load);
> +	case SEV_CMD_SNP_HV_REPORT_REQ:		return sizeof(struct sev_data_snp_hv_report_req);
>  	default:				return sev_tio_cmd_buffer_len(cmd);
>  	}
>  
> diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
> index 69ffa4b4d1fa..c651a400d124 100644
> --- a/include/linux/psp-sev.h
> +++ b/include/linux/psp-sev.h
> @@ -124,6 +124,7 @@ enum sev_cmd {
>  	SEV_CMD_SNP_GCTX_CREATE		= 0x093,
>  	SEV_CMD_SNP_GUEST_REQUEST	= 0x094,
>  	SEV_CMD_SNP_ACTIVATE_EX		= 0x095,
> +	SEV_CMD_SNP_HV_REPORT_REQ	= 0x096,
>  	SEV_CMD_SNP_LAUNCH_START	= 0x0A0,
>  	SEV_CMD_SNP_LAUNCH_UPDATE	= 0x0A1,
>  	SEV_CMD_SNP_LAUNCH_FINISH	= 0x0A2,
> @@ -594,6 +595,36 @@ struct sev_data_attestation_report {
>  	u32 len;				/* In/Out */
>  } __packed;
>  
> +/**
> + * struct sev_data_snp_hv_report_req - SNP_HV_REPORT_REQ command params
> + *
> + * @len: length of the command buffer in bytes
> + * @key_sel: Selects which key to use for generating the signature.
> + * @gctx_addr: System physical address of guest context page
> + * @hv_report_paddr: System physical address where MSG_EXPORT_RSP will be written
> + */
> +struct sev_data_snp_hv_report_req {
> +	u32 len;		/* In */
> +	u32 key_sel	:2,	/* In */
> +	    rsvd	:30;
> +	u64 gctx_addr;		/* In */
> +	u64 hv_report_paddr;	/* In */
> +} __packed;
> +
> +/**
> + * struct sev_data_snp_msg_export_rsp
> + *
> + * @status: Status : 0h: Success. 16h: Invalid parameters.
> + * @report_size: Size in bytes of the attestation report
> + * @report: attestation report
> + */
> +struct sev_data_snp_msg_report_rsp {
> +	u32 status;			/* Out */
> +	u32 report_size;		/* Out */
> +	u8 rsvd[24];
> +	u8 report[];
> +} __packed;
> +
>  /**
>   * struct sev_data_snp_download_firmware - SNP_DOWNLOAD_FIRMWARE command params
>   *