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

Brijesh Singh
2021-09-13T11:17:41Z

On 9/9/21 10:18 PM, Marc Orr wrote:
> On Fri, Aug 20, 2021 at 9:00 AM 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);
> Calling `snp_leak_pages()` here seems wrong, because
> `snp_set_rmp_state()` calls `snp_leak_pages()` when it returns an
> error.

Agreed, i will fix in next rev.

>
>> + return -EFAULT;
>> + }
>> +
>> + 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
>>
>>