linux-kernel - [PATCH] crypto: ccp: Load the firmware twice when SEV API version

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Date:   Thu,  4 Aug 2022 04:02:23 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Jarkko Sakkinen <jarkko@...fian.com>,
        Harald Hoyer <harald@...fian.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        linux-crypto@...r.kernel.org (open list:AMD CRYPTOGRAPHIC COPROCESSOR
        (CCP) DRIVER - SE...), linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] crypto: ccp: Load the firmware twice when SEV API version < 1.43

From: Jarkko Sakkinen <jarkko@...fian.com>

SEV-SNP does not initialize to a legit state, unless the firmware is
loaded twice, when SEP API version < 1.43, and the firmware is updated
to a later version. Because of this user space needs to work around
this with "rmmod && modprobe" combo. Fix this by implementing the
workaround to the driver.

Reported-by: Harald Hoyer <harald@...fian.com>
Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
---
 drivers/crypto/ccp/sev-dev.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 799b476fc3e8..f2abb7439dde 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -76,6 +76,9 @@ static void *sev_es_tmr;
 #define NV_LENGTH (32 * 1024)
 static void *sev_init_ex_buffer;
 
+/*
+ * SEV API version >= maj.min?
+ */
 static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
 {
 	struct sev_device *sev = psp_master->sev_data;
@@ -89,6 +92,14 @@ static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
 	return false;
 }
 
+/*
+ * SEV API version < maj.min?
+ */
+static inline bool sev_version_less(u8 maj, u8 min)
+{
+	return !sev_version_greater_or_equal(maj, min);
+}
+
 static void sev_irq_handler(int irq, void *data, unsigned int status)
 {
 	struct sev_device *sev = data;
@@ -1274,6 +1285,7 @@ void sev_pci_init(void)
 {
 	struct sev_device *sev = psp_master->sev_data;
 	int error, rc;
+	int i;
 
 	if (!sev)
 		return;
@@ -1283,9 +1295,13 @@ void sev_pci_init(void)
 	if (sev_get_api_version())
 		goto err;
 
-	if (sev_version_greater_or_equal(0, 15) &&
-	    sev_update_firmware(sev->dev) == 0)
-		sev_get_api_version();
+	/*
+	 * SEV-SNP does not work properly before loading the FW twice in the API
+	 * versions older than SEV 1.43.
+	 */
+	for (i = 0; i < sev_version_greater_or_equal(0, 15) + sev_version_less(1, 43); i++)
+		if (sev_update_firmware(sev->dev) == 0)
+			sev_get_api_version();
 
 	/* If an init_ex_path is provided rely on INIT_EX for PSP initialization
 	 * instead of INIT.
-- 
2.37.1