[PATCH Part2 v6 18/49] crypto: ccp: Provide APIs to query extended attestation report

Ashish Kalra
2022-06-20T23:07:47Z

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

Version 2 of the GHCB specification defines VMGEXIT that is used to get
the extended attestation report. The extended attestation report includes
the certificate blobs provided through the SNP_SET_EXT_CONFIG.

The snp_guest_ext_guest_request() will be used by the hypervisor to get
the extended attestation report. See the GHCB specification for more
details.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
drivers/crypto/ccp/sev-dev.c | 43 ++++++++++++++++++++++++++++++++++++
include/linux/psp-sev.h | 24 ++++++++++++++++++++
2 files changed, 67 insertions(+)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 97b479d5aa86..f6306b820b86 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -25,6 +25,7 @@
#include <linux/fs.h>

#include <asm/smp.h>
+#include <asm/sev.h>

#include "psp-dev.h"
#include "sev-dev.h"
@@ -1857,6 +1858,48 @@ int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error)
}
EXPORT_SYMBOL_GPL(snp_guest_dbg_decrypt);

+int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
+ unsigned long vaddr, unsigned long *npages, unsigned long *fw_err)
+{
+ unsigned long expected_npages;
+ struct sev_device *sev;
+ int rc;
+
+ if (!psp_master || !psp_master->sev_data)
+ return -ENODEV;
+
+ sev = psp_master->sev_data;
+
+ if (!sev->snp_inited)
+ return -EINVAL;
+
+ /*
+ * Check if there is enough space to copy the certificate chain. Otherwise
+ * return ERROR code defined in the GHCB specification.
+ */
+ expected_npages = sev->snp_certs_len >> PAGE_SHIFT;
+ if (*npages < expected_npages) {
+ *npages = expected_npages;
+ *fw_err = SNP_GUEST_REQ_INVALID_LEN;
+ return -EINVAL;
+ }
+
+ rc = sev_do_cmd(SEV_CMD_SNP_GUEST_REQUEST, data, (int *)&fw_err);
+ if (rc)
+ return rc;
+
+ /* Copy the certificate blob */
+ if (sev->snp_certs_data) {
+ *npages = expected_npages;
+ memcpy((void *)vaddr, sev->snp_certs_data, *npages << PAGE_SHIFT);
+ } else {
+ *npages = 0;
+ }
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(snp_guest_ext_guest_request);
+
static void sev_exit(struct kref *ref)
{
misc_deregister(&misc_dev->misc);
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index a3bb792bb842..cd37ccd1fa1f 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -945,6 +945,23 @@ void *psp_copy_user_blob(u64 uaddr, u32 len);
void *snp_alloc_firmware_page(gfp_t mask);
void snp_free_firmware_page(void *addr);

+/**
+ * snp_guest_ext_guest_request - perform the SNP extended guest request command
+ * defined in the GHCB specification.
+ *
+ * @data: the input guest request structure
+ * @vaddr: address where the certificate blob need to be copied.
+ * @npages: number of pages for the certificate blob.
+ * If the specified page count is less than the certificate blob size, then the
+ * required page count is returned with error code defined in the GHCB spec.
+ * If the specified page count is more than the certificate blob size, then
+ * page count is updated to reflect the amount of valid data copied in the
+ * vaddr.
+ */
+int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
+ unsigned long vaddr, unsigned long *npages,
+ unsigned long *error);
+
#else /* !CONFIG_CRYPTO_DEV_SP_PSP */

static inline int
@@ -992,6 +1009,13 @@ static inline void *snp_alloc_firmware_page(gfp_t mask)

static inline void snp_free_firmware_page(void *addr) { }

+static inline int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
+ unsigned long vaddr, unsigned long *n,
+ unsigned long *error)
+{
+ return -ENODEV;
+}
+
#endif /* CONFIG_CRYPTO_DEV_SP_PSP */

#endif /* __PSP_SEV_H__ */
--
2.25.1