linux-kernel - [PATCH v2 7/8] crypto: ccp: Use the stack and common buffer for INIT command

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Message-Id: <20210406224952.4177376-8-seanjc@google.com>
Date:   Tue,  6 Apr 2021 15:49:51 -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 7/8] crypto: ccp: Use the stack and common buffer for INIT command

Drop the dedicated init_cmd_buf and instead use a local variable.  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 | 10 ++++++----
 drivers/crypto/ccp/sev-dev.h |  1 -
 2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index e54774b0d637..9ff28df03030 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -233,6 +233,7 @@ static int sev_do_cmd(int cmd, void *data, int *psp_ret)
 static int __sev_platform_init_locked(int *error)
 {
 	struct psp_device *psp = psp_master;
+	struct sev_data_init data;
 	struct sev_device *sev;
 	int rc = 0;
 
@@ -244,6 +245,7 @@ static int __sev_platform_init_locked(int *error)
 	if (sev->state == SEV_STATE_INIT)
 		return 0;
 
+	memset(&data, 0, sizeof(data));
 	if (sev_es_tmr) {
 		u64 tmr_pa;
 
@@ -253,12 +255,12 @@ static int __sev_platform_init_locked(int *error)
 		 */
 		tmr_pa = __pa(sev_es_tmr);
 
-		sev->init_cmd_buf.flags |= SEV_INIT_FLAGS_SEV_ES;
-		sev->init_cmd_buf.tmr_address = tmr_pa;
-		sev->init_cmd_buf.tmr_len = SEV_ES_TMR_SIZE;
+		data.flags |= SEV_INIT_FLAGS_SEV_ES;
+		data.tmr_address = tmr_pa;
+		data.tmr_len = SEV_ES_TMR_SIZE;
 	}
 
-	rc = __sev_do_cmd_locked(SEV_CMD_INIT, &sev->init_cmd_buf, error);
+	rc = __sev_do_cmd_locked(SEV_CMD_INIT, &data, error);
 	if (rc)
 		return rc;
 
diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index 0fd21433f627..666c21eb81ab 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_data_init init_cmd_buf;
 
 	u8 api_major;
 	u8 api_minor;
-- 
2.31.0.208.g409f899ff0-goog