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

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Date:   Tue, 28 Nov 2023 18:29:45 +0530
From:   Nikunj A Dadhania <nikunj@....com>
To:     <linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>,
        <x86@...nel.org>, <kvm@...r.kernel.org>
CC:     <bp@...en8.de>, <mingo@...hat.com>, <tglx@...utronix.de>,
        <dave.hansen@...ux.intel.com>, <dionnaglaze@...gle.com>,
        <pgonda@...gle.com>, <seanjc@...gle.com>, <pbonzini@...hat.com>,
        <nikunj@....com>
Subject: [PATCH v6 02/16] virt: sev-guest: Move mutex to SNP guest device structure

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@....com>
Reviewed-by: Tom Lendacky <thomas.lendacky@....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