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Date:   Wed, 22 Sep 2021 18:35:27 +0100
From:   "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To:     Brijesh Singh <brijesh.singh@amd.com>
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
        linux-coco@lists.linux.dev, linux-mm@kvack.org,
        linux-crypto@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Joerg Roedel <jroedel@suse.de>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Ard Biesheuvel <ardb@kernel.org>,
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        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
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        Peter Zijlstra <peterz@infradead.org>,
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        Borislav Petkov <bp@alien8.de>,
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        Andi Kleen <ak@linux.intel.com>, tony.luck@intel.com,
        marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com
Subject: Re: [PATCH Part2 v5 16/45] crypto: ccp: Add the SNP_PLATFORM_STATUS
 command
Message-ID: <YUtpX5q7WQ9RJISf@work-vm>
References: <20210820155918.7518-1-brijesh.singh@amd.com>
 <20210820155918.7518-17-brijesh.singh@amd.com>
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* Brijesh Singh (brijesh.singh@amd.com) wrote:
> The command can be used by the userspace to query the SNP platform status
> report. See the SEV-SNP spec for more details.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  Documentation/virt/coco/sevguest.rst | 27 +++++++++++++++++
>  drivers/crypto/ccp/sev-dev.c         | 45 ++++++++++++++++++++++++++++
>  include/uapi/linux/psp-sev.h         |  1 +
>  3 files changed, 73 insertions(+)
> 
> diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst
> index 7acb8696fca4..7c51da010039 100644
> --- a/Documentation/virt/coco/sevguest.rst
> +++ b/Documentation/virt/coco/sevguest.rst
> @@ -52,6 +52,22 @@ to execute due to the firmware error, then fw_err code will be set.
>                  __u64 fw_err;
>          };
>  
> +The host ioctl should be called to /dev/sev device. The ioctl accepts command
> +id and command input structure.
> +
> +::
> +        struct sev_issue_cmd {
> +                /* Command ID */
> +                __u32 cmd;
> +
> +                /* Command request structure */
> +                __u64 data;
> +
> +                /* firmware error code on failure (see psp-sev.h) */
> +                __u32 error;
> +        };
> +
> +
>  2.1 SNP_GET_REPORT
>  ------------------
>  
> @@ -107,3 +123,14 @@ length of the blob is lesser than expected then snp_ext_report_req.certs_len wil
>  be updated with the expected value.
>  
>  See GHCB specification for further detail on how to parse the certificate blob.
> +
> +2.3 SNP_PLATFORM_STATUS
> +-----------------------
> +:Technology: sev-snp
> +:Type: hypervisor ioctl cmd
> +:Parameters (in): struct sev_data_snp_platform_status
> +:Returns (out): 0 on success, -negative on error
> +
> +The SNP_PLATFORM_STATUS command is used to query the SNP platform status. The
> +status includes API major, minor version and more. See the SEV-SNP
> +specification for further details.
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 4cd7d803a624..16c6df5d412c 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1394,6 +1394,48 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
>  	return ret;
>  }
>  
> +static int sev_ioctl_snp_platform_status(struct sev_issue_cmd *argp)
> +{
> +	struct sev_device *sev = psp_master->sev_data;
> +	struct sev_data_snp_platform_status_buf buf;
> +	struct page *status_page;
> +	void *data;
> +	int ret;
> +
> +	if (!sev->snp_inited || !argp->data)
> +		return -EINVAL;
> +
> +	status_page = alloc_page(GFP_KERNEL_ACCOUNT);
> +	if (!status_page)
> +		return -ENOMEM;
> +
> +	data = page_address(status_page);
> +	if (snp_set_rmp_state(__pa(data), 1, true, true, false)) {
> +		__free_pages(status_page, 0);
> +		return -EFAULT;
> +	}
> +
> +	buf.status_paddr = __psp_pa(data);
> +	ret = __sev_do_cmd_locked(SEV_CMD_SNP_PLATFORM_STATUS, &buf, &argp->error);
> +
> +	/* Change the page state before accessing it */
> +	if (snp_set_rmp_state(__pa(data), 1, false, true, true)) {
> +		snp_leak_pages(__pa(data) >> PAGE_SHIFT, 1);
> +		return -EFAULT;
> +	}

Could we find a way of returning some of these errors into the output,
rather than interepreting them from errno values?

Dave

> +	if (ret)
> +		goto cleanup;
> +
> +	if (copy_to_user((void __user *)argp->data, data,
> +			 sizeof(struct sev_user_data_snp_status)))
> +		ret = -EFAULT;
> +
> +cleanup:
> +	__free_pages(status_page, 0);
> +	return ret;
> +}
> +
>  static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
>  {
>  	void __user *argp = (void __user *)arg;
> @@ -1445,6 +1487,9 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)
>  	case SEV_GET_ID2:
>  		ret = sev_ioctl_do_get_id2(&input);
>  		break;
> +	case SNP_PLATFORM_STATUS:
> +		ret = sev_ioctl_snp_platform_status(&input);
> +		break;
>  	default:
>  		ret = -EINVAL;
>  		goto out;
> diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
> index bed65a891223..ffd60e8b0a31 100644
> --- a/include/uapi/linux/psp-sev.h
> +++ b/include/uapi/linux/psp-sev.h
> @@ -28,6 +28,7 @@ enum {
>  	SEV_PEK_CERT_IMPORT,
>  	SEV_GET_ID,	/* This command is deprecated, use SEV_GET_ID2 */
>  	SEV_GET_ID2,
> +	SNP_PLATFORM_STATUS,
>  
>  	SEV_MAX,
>  };
> -- 
> 2.17.1
> 
> 
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK