linux-kernel - [RFC PATCH 02/11] virt: sev-guest: Move mutex to SNP guest device structure

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Date:   Mon, 30 Jan 2023 17:33:18 +0530
From:   Nikunj A Dadhania <nikunj@....com>
To:     <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC:     <bp@...en8.de>, <thomas.lendacky@....com>,
        <dionnaglaze@...gle.com>, <pgonda@...gle.com>, <jroedel@...e.de>,
        <mingo@...hat.com>, <tglx@...utronix.de>,
        <dave.hansen@...ux.intel.com>, <seanjc@...gle.com>,
        <pbonzini@...hat.com>, <nikunj@....com>, <michael.roth@....com>,
        <ketanch@...k.ac.in>
Subject: [RFC PATCH 02/11] virt: sev-guest: Move mutex to SNP guest device structure

In preparation to provide new API for sending SNP guest message to the
sev-guest driver, move the SNP command mutex to the snp_guest_dev
structure.

Signed-off-by: Nikunj A Dadhania <nikunj@....com>
---
 drivers/virt/coco/sev-guest/sev-guest.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 20bb38242018..106cabce1ccd 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -32,6 +32,9 @@ 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;
 	struct snp_guest_msg *request, *response;
@@ -45,9 +48,6 @@ 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 inline unsigned int get_ctx_authsize(struct snp_guest_dev *snp_dev)
 {
 	if (snp_dev && snp_dev->ctx)
@@ -96,7 +96,7 @@ 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;
@@ -338,7 +338,7 @@ static int get_report(struct snp_guest_dev *snp_dev, struct snp_guest_request_io
 	struct snp_report_req req;
 	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;
@@ -378,7 +378,7 @@ 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;
@@ -417,7 +417,7 @@ static int get_ext_report(struct snp_guest_dev *snp_dev, struct snp_guest_reques
 	struct snp_report_resp *resp;
 	int ret, npages = 0, resp_len;
 
-	lockdep_assert_held(&snp_cmd_mutex);
+	lockdep_assert_held(&snp_dev->cmd_mutex);
 
 	if (!arg->req_data || !arg->resp_data)
 		return -EINVAL;
@@ -502,12 +502,12 @@ 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;
 	}
 
@@ -525,7 +525,7 @@ 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.fw_err && copy_to_user(argp, &input, sizeof(input)))
 		return -EFAULT;
@@ -641,6 +641,7 @@ 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;
-- 
2.32.0