Re: [PATCH Part2 v5 16/45] crypto: ccp: Add the SNP_PLATFORM_STATUS command

Dr. David Alan Gilbert
2021-09-22T17:35:34Z

* 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