linux-kernel - [PATCH v2 6/8] crypto: ccp: Use the stack and common buffer for status commands

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Date:   Tue,  6 Apr 2021 15:49:50 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...e.de>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Subject: [PATCH v2 6/8] crypto: ccp: Use the stack and common buffer for
 status commands

Drop the dedicated status_cmd_buf and instead use a local variable for
PLATFORM_STATUS.  Now that the low level helper uses an internal buffer
for all commands, using the stack for the upper layers is safe even when
running with CONFIG_VMAP_STACK=y.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 drivers/crypto/ccp/sev-dev.c | 27 ++++++++++++---------------
 drivers/crypto/ccp/sev-dev.h |  1 -
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index bb0d6de071e6..e54774b0d637 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -315,15 +315,14 @@ static int sev_platform_shutdown(int *error)
 
 static int sev_get_platform_state(int *state, int *error)
 {
-	struct sev_device *sev = psp_master->sev_data;
+	struct sev_user_data_status data;
 	int rc;
 
-	rc = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS,
-				 &sev->status_cmd_buf, error);
+	rc = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, &data, error);
 	if (rc)
 		return rc;
 
-	*state = sev->status_cmd_buf.state;
+	*state = data.state;
 	return rc;
 }
 
@@ -361,15 +360,14 @@ static int sev_ioctl_do_reset(struct sev_issue_cmd *argp, bool writable)
 
 static int sev_ioctl_do_platform_status(struct sev_issue_cmd *argp)
 {
-	struct sev_device *sev = psp_master->sev_data;
-	struct sev_user_data_status *data = &sev->status_cmd_buf;
+	struct sev_user_data_status data;
 	int ret;
 
-	ret = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, data, &argp->error);
+	ret = __sev_do_cmd_locked(SEV_CMD_PLATFORM_STATUS, &data, &argp->error);
 	if (ret)
 		return ret;
 
-	if (copy_to_user((void __user *)argp->data, data, sizeof(*data)))
+	if (copy_to_user((void __user *)argp->data, &data, sizeof(data)))
 		ret = -EFAULT;
 
 	return ret;
@@ -469,21 +467,20 @@ EXPORT_SYMBOL_GPL(psp_copy_user_blob);
 static int sev_get_api_version(void)
 {
 	struct sev_device *sev = psp_master->sev_data;
-	struct sev_user_data_status *status;
+	struct sev_user_data_status status;
 	int error = 0, ret;
 
-	status = &sev->status_cmd_buf;
-	ret = sev_platform_status(status, &error);
+	ret = sev_platform_status(&status, &error);
 	if (ret) {
 		dev_err(sev->dev,
 			"SEV: failed to get status. Error: %#x\n", error);
 		return 1;
 	}
 
-	sev->api_major = status->api_major;
-	sev->api_minor = status->api_minor;
-	sev->build = status->build;
-	sev->state = status->state;
+	sev->api_major = status.api_major;
+	sev->api_minor = status.api_minor;
+	sev->build = status.build;
+	sev->state = status.state;
 
 	return 0;
 }
diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index e1572f408577..0fd21433f627 100644
--- a/drivers/crypto/ccp/sev-dev.h
+++ b/drivers/crypto/ccp/sev-dev.h
@@ -46,7 +46,6 @@ struct sev_device {
 	unsigned int int_rcvd;
 	wait_queue_head_t int_queue;
 	struct sev_misc_dev *misc;
-	struct sev_user_data_status status_cmd_buf;
 	struct sev_data_init init_cmd_buf;
 
 	u8 api_major;
-- 
2.31.0.208.g409f899ff0-goog