[PATCH v6 02/16] virt: sev-guest: Move mutex to SNP guest device structure

Nikunj A Dadhania
2023-11-28T13:00:37Z

In preparation for providing a new API to the sev-guest driver for sending
an SNP guest message, move the SNP command mutex to the snp_guest_dev
structure. Drop the snp_cmd_mutex.

Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
---
drivers/virt/coco/sev-guest/sev-guest.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index aedc842781b6..8382fd657e67 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -39,6 +39,9 @@ struct snp_guest_dev {
struct device *dev;
struct miscdevice misc;

+ /* Mutex to serialize the shared buffer access and command handling. */
+ struct mutex cmd_mutex;
+
void *certs_data;
struct aesgcm_ctx *ctx;
/* request and response are in unencrypted memory */
@@ -65,9 +68,6 @@ static u32 vmpck_id;
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 bool is_vmpck_empty(struct snp_guest_dev *snp_dev)
{
char zero_key[VMPCK_KEY_LEN] = {0};
@@ -107,7 +107,7 @@ static inline u64 __snp_get_msg_seqno(struct snp_guest_dev *snp_dev)
{
u64 count;

- lockdep_assert_held(&snp_cmd_mutex);
+ lockdep_assert_held(&snp_dev->cmd_mutex);

/* Read the current message sequence counter from secrets pages */
count = *snp_dev->os_area_msg_seqno;
@@ -394,7 +394,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
struct snp_report_resp *resp;
int rc, resp_len;

- lockdep_assert_held(&snp_cmd_mutex);
+ lockdep_assert_held(&snp_dev->cmd_mutex);

if (!arg->req_data || !arg->resp_data)
return -EINVAL;
@@ -434,7 +434,7 @@ static int get_derived_key(struct snp_guest_dev *snp_dev, struct snp_guest_reque
/* Response data is 64 bytes and max authsize for GCM is 16 bytes. */
u8 buf[64 + 16];

- lockdep_assert_held(&snp_cmd_mutex);
+ lockdep_assert_held(&snp_dev->cmd_mutex);

if (!arg->req_data || !arg->resp_data)
return -EINVAL;
@@ -475,7 +475,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
int ret, npages = 0, resp_len;
sockptr_t certs_address;

- lockdep_assert_held(&snp_cmd_mutex);
+ lockdep_assert_held(&snp_dev->cmd_mutex);

if (sockptr_is_null(io->req_data) || sockptr_is_null(io->resp_data))
return -EINVAL;
@@ -564,12 +564,12 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
if (!input.msg_version)
return -EINVAL;

- mutex_lock(&snp_cmd_mutex);
+ mutex_lock(&snp_dev->cmd_mutex);

/* Check if the VMPCK is not empty */
if (is_vmpck_empty(snp_dev)) {
dev_err_ratelimited(snp_dev->dev, "VMPCK is disabled\n");
- mutex_unlock(&snp_cmd_mutex);
+ mutex_unlock(&snp_dev->cmd_mutex);
return -ENOTTY;
}

@@ -594,7 +594,7 @@ static long snp_guest_ioctl(struct file *file, unsigned int ioctl, unsigned long
break;
}

- mutex_unlock(&snp_cmd_mutex);
+ mutex_unlock(&snp_dev->cmd_mutex);

if (input.exitinfo2 && copy_to_user(argp, &input, sizeof(input)))
return -EFAULT;
@@ -702,7 +702,7 @@ static int sev_report_new(struct tsm_report *report, void *data)
if (!buf)
return -ENOMEM;

- guard(mutex)(&snp_cmd_mutex);
+ guard(mutex)(&snp_dev->cmd_mutex);

/* Check if the VMPCK is not empty */
if (is_vmpck_empty(snp_dev)) {
@@ -837,6 +837,7 @@ static int __init sev_guest_probe(struct platform_device *pdev)
goto e_unmap;
}

+ mutex_init(&snp_dev->cmd_mutex);
platform_set_drvdata(pdev, snp_dev);
snp_dev->dev = dev;
snp_dev->layout = layout;
--
2.34.1