[PATCH Part2 v6 46/49] ccp: add support to decrypt the page

Ashish Kalra
2022-06-20T23:19:41Z

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

Add support to decrypt guest encrypted memory, these API interfaces can be
used for example to dump VMCBs on SNP guest exit.

Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
drivers/crypto/ccp/sev-dev.c | 33 ++++++++++++++++++++++++++++++---
include/linux/psp-sev.h | 6 +++---
2 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f6306b820b86..9896350e7f56 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1852,11 +1852,38 @@ int snp_guest_page_reclaim(struct sev_data_snp_page_reclaim *data, int *error)
}
EXPORT_SYMBOL_GPL(snp_guest_page_reclaim);

-int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error)
+int snp_guest_dbg_decrypt_page(u64 gctx_pfn, u64 src_pfn, u64 dst_pfn, int *error)
{
- return sev_do_cmd(SEV_CMD_SNP_DBG_DECRYPT, data, error);
+ struct sev_data_snp_dbg data = {0};
+ struct sev_device *sev;
+ int ret;
+
+ if (!psp_master || !psp_master->sev_data)
+ return -ENODEV;
+
+ sev = psp_master->sev_data;
+
+ if (!sev->snp_inited)
+ return -EINVAL;
+
+ data.gctx_paddr = sme_me_mask | (gctx_pfn << PAGE_SHIFT);
+ data.src_addr = sme_me_mask | (src_pfn << PAGE_SHIFT);
+ data.dst_addr = sme_me_mask | (dst_pfn << PAGE_SHIFT);
+ data.len = PAGE_SIZE;
+
+ /* The destination page must be in the firmware state. */
+ if (snp_set_rmp_state(data.dst_addr, 1, true, false, false))
+ return -EIO;
+
+ ret = sev_do_cmd(SEV_CMD_SNP_DBG_DECRYPT, &data, error);
+
+ /* Restore the page state */
+ if (snp_set_rmp_state(data.dst_addr, 1, false, false, true))
+ ret = -EIO;
+
+ return ret;
}
-EXPORT_SYMBOL_GPL(snp_guest_dbg_decrypt);
+EXPORT_SYMBOL_GPL(snp_guest_dbg_decrypt_page);

int snp_guest_ext_guest_request(struct sev_data_snp_guest_request *data,
unsigned long vaddr, unsigned long *npages, unsigned long *fw_err)
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index cd37ccd1fa1f..8d2565c70c39 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -928,7 +928,7 @@ int snp_guest_decommission(struct sev_data_snp_decommission *data, int *error);
int snp_guest_page_reclaim(struct sev_data_snp_page_reclaim *data, int *error);

/**
- * snp_guest_dbg_decrypt - perform SEV SNP_DBG_DECRYPT command
+ * snp_guest_dbg_decrypt_page - perform SEV SNP_DBG_DECRYPT command
*
* @sev_ret: sev command return code
*
@@ -939,7 +939,7 @@ int snp_guest_page_reclaim(struct sev_data_snp_page_reclaim *data, int *error);
* -%ETIMEDOUT if the sev command timed out
* -%EIO if the sev returned a non-zero return code
*/
-int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error);
+int snp_guest_dbg_decrypt_page(u64 gctx_pfn, u64 src_pfn, u64 dst_pfn, int *error);

void *psp_copy_user_blob(u64 uaddr, u32 len);
void *snp_alloc_firmware_page(gfp_t mask);
@@ -997,7 +997,7 @@ static inline int snp_guest_page_reclaim(struct sev_data_snp_page_reclaim *data,
return -ENODEV;
}

-static inline int snp_guest_dbg_decrypt(struct sev_data_snp_dbg *data, int *error)
+static inline int snp_guest_dbg_decrypt_page(u64 gctx_pfn, u64 src_pfn, u64 dst_pfn, int *error)
{
return -ENODEV;
}
--
2.25.1