linux-kernel - [PATCH v2 4/4] crypto: ccp: When TSME and SME both detected notify user

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Date:   Tue, 29 Mar 2022 11:41:17 -0500
From:   Mario Limonciello <mario.limonciello@....com>
To:     Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S . Miller" <davem@...emloft.net>
CC:     open list <linux-kernel@...r.kernel.org>,
        "open list:AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER" 
        <linux-crypto@...r.kernel.org>,
        Kerneis Gabriel <Gabriel.Kerneis@....gouv.fr>,
        Richard Hughes <hughsient@...il.com>,
        "Mario Limonciello" <mario.limonciello@....com>
Subject: [PATCH v2 4/4] crypto: ccp: When TSME and SME both detected notify user

CC_ATTR_HOST_MEM_ENCRYPT is used to relay that memory encryption has been
activated by the kernel.

As it's technically possible to enable both SME and TSME at the same time,
detect this scenario and notify the user that enabling TSME and SME at the
same time is unnecessary.

Signed-off-by: Mario Limonciello <mario.limonciello@....com>
---
v1->v2:
 * Reword notice about TSME/SME
 * Use cc_platform_has instead
---
 drivers/crypto/ccp/psp-dev.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
index 3f47b2d81e3c..38cffc1de4ab 100644
--- a/drivers/crypto/ccp/psp-dev.c
+++ b/drivers/crypto/ccp/psp-dev.c
@@ -74,6 +74,13 @@ static unsigned int psp_get_capability(struct psp_device *psp)
 	}
 	psp->capability = val;
 
+
+	/* Detect TSME / SME both enabled */
+	if (psp->capability & PSP_CAPABILITY_PSP_SECURITY_REPORTING &&
+	    psp->capability & (PSP_SECURITY_TSME_STATUS << PSP_CAPABILITY_PSP_SECURITY_OFFSET) &&
+	    cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT))
+		dev_notice(psp->dev, "psp: Both TSME and SME are active, SME is unnecessary when TSME is active.\n");
+
 	return 0;
 }
 
-- 
2.34.1