Currently, SEV guest driver retrieves the pointers to VMPCK and
os_area_msg_seqno from the secrets page. In order to get rid of this
dependency, use vmpck_id to index the appropriate key and the corresponding
message sequence number.
Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
---
drivers/virt/coco/sev-guest/sev-guest.c | 74 ++++++++++++-------------
1 file changed, 37 insertions(+), 37 deletions(-)
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index a5602c84769f..fcd61df08702 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -58,8 +58,7 @@ struct snp_guest_dev {
struct snp_derived_key_req derived_key;
struct snp_ext_report_req ext_report;
} req;
- u32 *os_area_msg_seqno;
- u8 *vmpck;
+ unsigned int vmpck_id;
};
/*
@@ -69,21 +68,24 @@ struct snp_guest_dev {
* Should the default key be wiped (see snp_disable_vmpck()), this parameter
* allows for using one of the remaining VMPCKs.
*/
-static int vmpck_id = -1;
-module_param(vmpck_id, int, 0444);
+static u32 vmpck_id = VMPCK_MAX_NUM;
+module_param(vmpck_id, uint, 0444);
MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP.");
/* Mutex to serialize the shared buffer access and command handling. */
static DEFINE_MUTEX(snp_cmd_mutex);
+static inline u8 *get_vmpck(struct snp_guest_dev *snp_dev)
+{
+ return snp_dev->secrets->vmpck[snp_dev->vmpck_id];
+}
+
static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
{
char zero_key[VMPCK_KEY_LEN] = {0};
+ u8 *key = get_vmpck(snp_dev);
- if (snp_dev->vmpck)
- return !memcmp(snp_dev->vmpck, zero_key, VMPCK_KEY_LEN);
-
- return true;
+ return !memcmp(key, zero_key, VMPCK_KEY_LEN);
}
/*
@@ -105,28 +107,24 @@ static bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
*/
static void snp_disable_vmpck(struct snp_guest_dev *snp_dev)
{
- dev_alert(snp_dev->dev, "Disabling VMPCK%d communication key to prevent IV reuse.\n",
- vmpck_id);
- memzero_explicit(snp_dev->vmpck, VMPCK_KEY_LEN);
- snp_dev->vmpck = NULL;
-}
-
-static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev)
-{
- u64 count;
-
- lockdep_assert_held(&snp_cmd_mutex);
+ u8 *key = get_vmpck(snp_dev);
- /* Read the current message sequence counter from secrets pages */
- count = *snp_dev->os_area_msg_seqno;
+ if (is_vmpck_empty(snp_dev))
+ return;
- return count + 1;
+ dev_alert(snp_dev->dev, "Disabling VMPCK%u communication key to prevent IV reuse.\n",
+ snp_dev->vmpck_id);
+ memzero_explicit(key, VMPCK_KEY_LEN);
}
/* Return a non-zero on success */
static u64 snp_get_msg_seqno(struct snp_guest_dev *snp_dev)
{
- u64 count = __snp_get_msg_seqno(snp_dev);
+ u64 count;
+
+ lockdep_assert_held(&snp_cmd_mutex);
+
+ count = snp_dev->secrets->os_area.msg_seqno[snp_dev->vmpck_id] + 1;
/*
* The message sequence counter for the SNP guest request is a 64-bit
@@ -150,7 +148,7 @@ static void snp_inc_msg_seqno(struct snp_guest_dev *snp_dev)
* The counter is also incremented by the PSP, so increment it by 2
* and save in secrets page.
*/
- *snp_dev->os_area_msg_seqno += 2;
+ snp_dev->secrets->os_area.msg_seqno[snp_dev->vmpck_id] += 2;
}
static inline struct snp_guest_dev *to_snp_dev(struct file *file)
@@ -160,15 +158,17 @@ static inline struct snp_guest_dev *to_snp_dev(struct file *file)
return container_of(dev, struct snp_guest_dev, misc);
}
-static struct aesgcm_ctx *snp_init_crypto(u8 *key, size_t keylen)
+static struct aesgcm_ctx *snp_init_crypto(struct snp_guest_dev *snp_dev)
{
struct aesgcm_ctx *ctx;
+ u8 *key;
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
if (!ctx)
return NULL;
- if (aesgcm_expandkey(ctx, key, keylen, AUTHTAG_LEN)) {
+ key = get_vmpck(snp_dev);
+ if (aesgcm_expandkey(ctx, key, VMPCK_KEY_LEN, AUTHTAG_LEN)) {
pr_err("Crypto context initialization failed\n");
kfree(ctx);
return NULL;
@@ -676,13 +676,14 @@ static const struct file_operations snp_guest_fops = {
.unlocked_ioctl = snp_guest_ioctl,
};
-static u8 *get_vmpck(int id, struct snp_secrets_page *secrets, u32 **seqno)
+static bool assign_vmpck(struct snp_guest_dev *dev, unsigned int vmpck_id)
{
- if (!(id < VMPCK_MAX_NUM))
- return NULL;
+ if (!(vmpck_id < VMPCK_MAX_NUM))
+ return false;
+
+ dev->vmpck_id = vmpck_id;
- *seqno = &secrets->os_area.msg_seqno[id];
- return secrets->vmpck[id];
+ return true;
}
struct snp_msg_report_resp_hdr {
@@ -1015,25 +1016,24 @@ static int __init sev_guest_probe(struct platform_device *pdev)
goto e_unmap;
/* Adjust the default VMPCK key based on the executing VMPL level */
- if (vmpck_id == -1)
+ if (vmpck_id == VMPCK_MAX_NUM)
vmpck_id = snp_vmpl;
ret = -EINVAL;
- snp_dev->vmpck = get_vmpck(vmpck_id, secrets, &snp_dev->os_area_msg_seqno);
- if (!snp_dev->vmpck) {
+ snp_dev->secrets = secrets;
+ if (!assign_vmpck(snp_dev, vmpck_id)) {
dev_err(dev, "Invalid VMPCK%d communication key\n", vmpck_id);
goto e_unmap;
}
/* Verify that VMPCK is not zero. */
if (is_vmpck_empty(snp_dev)) {
- dev_err(dev, "Empty VMPCK%d communication key\n", vmpck_id);
+ dev_err(dev, "Empty VMPCK%d communication key\n", snp_dev->vmpck_id);
goto e_unmap;
}
platform_set_drvdata(pdev, snp_dev);
snp_dev->dev = dev;
- snp_dev->secrets = secrets;
/* Allocate secret request and response message for double buffering */
snp_dev->secret_request = kzalloc(SNP_GUEST_MSG_SIZE, GFP_KERNEL);
@@ -1058,7 +1058,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
goto e_free_response;
ret = -EIO;
- snp_dev->ctx = snp_init_crypto(snp_dev->vmpck, VMPCK_KEY_LEN);
+ snp_dev->ctx = snp_init_crypto(snp_dev);
if (!snp_dev->ctx)
goto e_free_cert_data;
--
2.34.1
