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Subject: Re: [PATCH Part2 v5 16/45] crypto: ccp: Add the SNP_PLATFORM_STATUS
 command
To:     Marc Orr <marcorr@google.com>
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References: <20210820155918.7518-1-brijesh.singh@amd.com>
 <20210820155918.7518-17-brijesh.singh@amd.com>
 <CAA03e5EGXiw2dZ-c1-Vugor1d=vZPwrP81K0LmpUxTrLCbc+Xg@mail.gmail.com>
From:   Brijesh Singh <brijesh.singh@amd.com>
Message-ID: <642ea2a3-1a4b-ae59-5ece-37b06b0b2090@amd.com>
Date:   Mon, 13 Sep 2021 06:17:33 -0500
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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
>>
>>