[PATCH v1 24/26] crypto: ccp: Add the SNP_PLATFORM_STATUS command

Michael Roth
2023-12-30T16:27:23Z

From: Brijesh Singh <brijesh.singh@amd.com>

This command is used to query the SNP platform status. See the SEV-SNP
spec for more details.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
Documentation/virt/coco/sev-guest.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/sev-guest.rst b/Documentation/virt/coco/sev-guest.rst
index 68b0d2363af8..6d3d5d336e5f 100644
--- a/Documentation/virt/coco/sev-guest.rst
+++ b/Documentation/virt/coco/sev-guest.rst
@@ -67,6 +67,22 @@ counter (e.g. counter overflow), then -EIO will be returned.
};
};

+The host ioctls are issued to a file descriptor of the /dev/sev device.
+The ioctl accepts the command ID/input structure documented below.
+
+::
+ 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
------------------

@@ -124,6 +140,17 @@ be updated with the expected value.

See GHCB specification for further detail on how to parse the certificate blob.

+2.4 SNP_PLATFORM_STATUS
+-----------------------
+:Technology: sev-snp
+:Type: hypervisor ioctl cmd
+:Parameters (out): struct sev_user_data_snp_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.
+
3. SEV-SNP CPUID Enforcement
============================

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 598878e760bc..e663175cfa44 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1962,6 +1962,48 @@ static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp, bool writable)
return ret;
}

+static int sev_ioctl_do_snp_platform_status(struct sev_issue_cmd *argp)
+{
+ struct sev_device *sev = psp_master->sev_data;
+ struct sev_data_snp_addr buf;
+ struct page *status_page;
+ void *data;
+ int ret;
+
+ if (!sev->snp_initialized || !argp->data)
+ return -EINVAL;
+
+ status_page = alloc_page(GFP_KERNEL_ACCOUNT);
+ if (!status_page)
+ return -ENOMEM;
+
+ data = page_address(status_page);
+ if (rmp_mark_pages_firmware(__pa(data), 1, true)) {
+ ret = -EFAULT;
+ goto cleanup;
+ }
+
+ buf.gctx_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_reclaim_pages(__pa(data), 1, true)) {
+ snp_leak_pages(__pa(data) >> PAGE_SHIFT, 1);
+ 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;
@@ -2013,6 +2055,9 @@ 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_do_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 71ba5f9f90a8..1feba7d08099 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,
};
--
2.25.1